HK1077311B - Halogenated optical polymer composition - Google Patents

Description

Halogenated optical polymer compositions

Cross Reference to Related Applications

This application is a continuation-in-part U.S. patent application serial No. 10/067,669 entitled "halogenated optical polymer composition" filed on 4.2.2002, which is incorporated herein by reference, and the priority is claimed herein in accordance with 35u.s.c. § 120.

Background

Technical Field

The present invention relates generally to polymeric materials, and more particularly to halogenated polymeric materials useful in the manufacture of telecommunications devices.

Background

In optical communication systems, information is transmitted over an electromagnetic carrier wave at the optical frequency generated by sources such as lasers and light emitting diodes.

One preferred device for transferring or directing optical frequency waves from one point to another is an optical waveguide. The operation of optical waveguides is based on the fact that: when the light-transmitting medium is surrounded or otherwise confined by an outer medium having a lower refractive index, light introduced along the axis of the inner medium substantially parallel to the boundary with the outer medium is highly reflected at the boundary, trapping the light in the light-transmitting medium, thereby creating a guiding effect along the longitudinal axis of the inner medium. Many optical devices are manufactured by incorporating such an optical waveguide structure as a light transmission element. Examples of such devices are planar optical slab waveguides, channel optical waveguides, ridge waveguides, optical couplers, optical splitters, optical switches, optical filters, arrayed waveguide gratings, waveguide bragg gratings, and variable attenuators. For light of a particular frequency, the optical waveguide may support a single optical mode or multiple modes, depending on the size of the inner light guiding region and the magnitude of the difference in refractive index of the inner medium and the surrounding outer medium.

Optical waveguide devices and other optical interconnect devices can be fabricated from organic polymer materials. Optical devices fabricated from planar waveguides fabricated from glass are relatively less affected by temperature, while devices fabricated from organic polymers exhibit significant changes in properties with temperature. This is due to the fact that organic polymer materials have a relatively high thermo-optic coefficient (dn/dT). Therefore, when the organic polymer changes with temperature, the refractive index of the organic polymer also changes considerably. This property can be exploited to fabricate activated, thermally tunable or controllable devices incorporating light transmitting elements made of organic polymers. An example of a thermally tunable device is a 1 x 2 switching element activated by the thermo-optic effect. Thus, by applying a thermal gradient induced by the resistive heater, light from the input waveguide can be converted between the two output waveguides. Typically, the heating/cooling process is performed in a time interval of one to several milliseconds.

However, most polymeric materials contain carbon-hydrogen bonds with strong absorption in the 1550nm wavelength range, which is commonly used in telecommunications applications, resulting in unacceptably high insertion loss for devices made from such materials. By reducing the concentration of C-H in the material by replacing the C-H bond with a C-D or C-halogen bond, it is possible to reduce the absorption loss at infrared wavelengths. While planar waveguides made from fluorinated polyimides and deuterated or fluorinated polymethacrylates achieve single mode losses as small as 0.10dB/cm at 1300nm, it is difficult to fabricate optical devices from these materials. For example, conventional methods for fabricating these waveguides include the use of reactive ion etching methods, which are cumbersome and can result in high waveguide loss due to scattering. Moreover, deuteration is not an effective way to reduce losses in the 1550nm wavelength range. Fluorinated polyimides and deuterated or fluorinated polymethacrylates have higher losses, typically on the order of 0.6dB/cm, near 1550nm in the telecommunications window. O-H and N-H bonds also cause strong losses at wavelengths near 1310nm and 1550 nm. Thus, there is a need for compositions with very low concentrations of O-H and N-H bonds.

Photopolymers have attracted particular interest in optical interconnect applications because they can be patterned using standard photolithographic techniques. Photolithography involves selectively polymerizing a layer of photopolymer by exposing the material to a pattern of actinic radiation. The material exposed to actinic radiation is polymerized while the material not exposed remains unpolymerized. The patterned layer may be developed by removing the unexposed, unpolymerized material, for example, using an appropriate solvent.

Summary of The Invention

One aspect of the present invention relates to an energy curable composition comprising a compound having: an aromatic or heteroaromatic moiety; at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an-O-or-S-linkage; and at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties.

Another aspect of the invention relates to an energy curable composition comprising a compound having: an isocyanurate moiety; three fluoroalkylene, arylene, or polyether moieties attached to the isocyanurate moiety at the nitrogen atom of the isocyanurate; and at least one ethylenically unsaturated moiety attached to one of the fluoroalkylene, arylene, or polyether moieties.

Another aspect of the invention relates to a polymeric material comprising a polymer or copolymer of an energy curable compound having: an aromatic or heteroaromatic moiety; at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an-O-or-S-linkage; and at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties.

Another aspect of the invention relates to a polymeric material comprising a polymer or copolymer of an energy curable compound having: an isocyanurate moiety; three fluoroalkylene, arylene, or polyether moieties attached to the isocyanurate moiety at the nitrogen atom of the isocyanurate; and at least one ethylenically unsaturated moiety attached to one of the fluoroalkylene, arylene, or polyether moieties.

Another aspect of the invention relates to an optical element comprising a polymeric core comprising a polymer or copolymer of an energy curable compound having: an aromatic or heteroaromatic moiety; at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an-O-or-S-linkage; and at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties.

Another aspect of the invention relates to an optical element comprising a polymeric core comprising a polymer or copolymer of an energy curable compound having: an isocyanurate moiety; three fluoroalkylene, arylene, or polyether moieties attached to the isocyanurate moiety at the nitrogen atom of the isocyanurate; and at least one ethylenically unsaturated moiety attached to one of the fluoroalkylene, arylene, or polyether moieties.

The compositions and devices of the present invention have a number of advantages over prior art compositions and devices. For example, the compositions of the present invention have extremely low optical loss at telecommunications wavelengths, making them suitable for use in the manufacture of planar waveguides or other optical devices. The compositions of the present invention have a higher refractive index than similar compositions that do not include aromatic or heteroaromatic moieties, making them useful for tuning the refractive index of different layers of an optical device. The compositions of the invention also have a higher hydrolytic stability than similar compositions based on carboxylic acid esters.

Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the written description and claims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed.

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more aspects of the present invention and, together with the description, serve to explain the principles and operations of the invention.

Brief description of the drawings

FIG. 1 is a schematic view of a planar waveguide optical element of the present invention.

Detailed description of the preferred embodiments

The present invention provides energy curable compositions that can be cured to produce polymeric materials with low optical loss at communications wavelengths. As used herein, an energy curable composition is a composition that can be cured by at least one of heat and actinic radiation. In one embodiment of the present invention, an energy curable composition includes a compound having: an aromatic or heteroaromatic moiety; two fluoroalkylene, arylene, or polyether moieties each linked to an aromatic or heteroaromatic moiety through an-O-or-S-linkage; and at least one ethylenically unsaturated moiety attached to one of the fluoroalkylene, arylene, or polyether moieties. In compounds particularly suitable for use in the compositions of the present invention, the-O-or-S-bond is directly attached to an aromatic atom of an aromatic or heteroaromatic moiety. Suitable compounds for use in the compositions of the present invention have an ethylenically unsaturated moiety attached to each fluoroalkylene, arylene, or polyether moiety. Direct attachment to the aromatic atom is preferred over attachment through an intervening methylene group because it allows the compound to have lower losses at telecommunications wavelengths. Preferably, the-O-or-S-bond is not part of a carboxylic ester. For example, the energy curable composition of the present invention may include a compound having formula (I):

R-(Y-CH₂-Rf-CH₂-O-E)_n(I)

wherein R is an aromatic or heteroaromatic moiety; y is O or S; rf comprises a fluoroalkylene moiety, or a fluoropolyether moiety; e is an ethylenically unsaturated moiety; and n is an integer between about 2 and about 10.

As described in more detail in connection with the examples below, the-O-linked acrylates of the present invention (e.g., in the above formula Y ═ O and E ═ CO-CH ═ CH)₂) Can be synthesized in two steps from the corresponding aromatic or heteroaromatic halide and a fluoroalkylene or polyether diol according to the following reaction scheme:

R(Cl)_n+HO-CH₂-Rf-CH₂base-OH + n → R (O-CH)₂-Rf-CH₂-OH)_n+ n bases H⁺Cl^-

R(O-CH₂-Rf-CH₂-OH)_n+nCH₂CHCOCl + n base → R (O-CH)₂-Rf-CH₂-OCOCH＝CH₂)_n+ n bases H⁺Cl^-

Reaction of an aromatic or heteroaromatic halide with a fluoroalkylene or polyether diol and n equivalents of a base produces an-O-linked alcohol. the-O-linked alcohol is then capped with an acrylate to provide the-O-linked acrylate of the present invention. Alternatively, the-O-linked alcohol may be capped with other ethylenically unsaturated moieties by methods familiar to those skilled in the art.

In the above formula, Y ═ S and E ═ CO-CH ═ CH₂The compounds of (a) can be synthesized from the alkali metal salts of the corresponding aromatic or heteroaromatic polythiols and fluoroalkylene, arylene or polyether diols according to the following reaction scheme:

HO-CH₂-Rf-CH₂-OH+2C₄F₉SO₂cl +2 base → C₄F₉SO₂-O-CH₂-Rf-CH₂-OSO₂C₄H₉+2 bases H⁺Cl^-

R(S^-M⁺)_n+n C₄F₉SO₃-CH₂-Rf-CH₂-OSO₂C₄H₉→R-(S-CH₂-Rf-CH₂-OSO₂C₄H₉)_n+nC₄H₉SO₃ ^-M⁺

R-(S-CH₂-Rf-CH₂-OSO₂C₄H₉)_n+n NaOH→R-(S-CH₂-Rf-CH₂-OH)_n+n C₄H₉SO₃ ^-Na⁺

R-(S-CH₂-Rf-CH₂-OH)_n+n CH₂CHCOCl + n base → R- (S-CH)₂-Rf-CH₂-OCOCH+CH₂)_n+ n bases H⁺Cl^-

The fluoroalkylene, arylene or polyether diol is converted to bis (tetrafluorobutanesulfonate) which is then reacted with an alkali metal salt of a polyfunctional aromatic or heteroaromatic polythiol. The resulting-S-linked tetrafluorobutanesulfonate ester is saponified to give-S-linked alcohol, which is capped with an acrylate to give the-S-linked acrylate of the present invention. Alternatively, the-S-linked alcohol may be capped with other ethylenic unsaturation by methods familiar to those skilled in the art.

In the above compounds, the aromatic or heteroaromatic moiety (R) may be any desired aromatic or heteroaromatic moiety. Suitable aromatic or heteroaromatic moieties for use in the present invention have as few hydrogen atoms as possible. Particularly suitable aromatic or heteroaromatic moieties have no hydrogen atoms at all. Examples of suitable aromatic moieties for use in the present invention include

Wherein each X is independently selected from H, D, F, Cl, Br, alkyl, aryl, heteroaryl, alkoxy, and aryloxy, and wherein Y ═ O or S. Those skilled in the art will recognize that other aromatic moieties may be used in the present invention.

Examples of suitable heteroaromatic moieties include:

wherein each X is independently selected from the group consisting of H, D, F, Cl, Br, alkyl, aryl, heteroaryl, alkoxy, and aryloxy. Those skilled in the art will recognize that other heteroaromatic moieties may also be used in the present invention.

Another suitable heteroaromatic moiety is a cyclotriphosphazene moiety. the-O-linked cyclotriphosphazene compound can be prepared, for example, by reacting hexachlorocyclotriphosphazene with a suitable diol and sodium hydride, as shown in the reaction scheme below. the-S-linked cyclotriphosphazene compound can be obtained, for example, by reacting hexachlorocyclotriphosphazene with a suitable dithiol and sodium metal, as shown in the following reaction scheme. the-O-linked and-S-linked alcohols can be capped with ethylenic unsaturation by methods familiar to those skilled in the art.

As mentioned above, the aromatic or heteroaromatic moieties R are incorporated into the compounds of the present invention by their corresponding halide or sulfide salts. For example, the aromatic moiety octafluorobiphenylene may be introduced using decafluorobiphenyl. The heteroaromatic 1, 3, 5-triazine moiety may be introduced using cyanuric chloride. The 1, 5-thiadiazole moiety may be introduced using 1, 5-dimercaptothiadiazole dipotassium salt.

In another embodiment of the present invention, an energy curable composition includes a compound having: an isocyanurate moiety; three fluoroalkylene, arylene, or polyether moieties attached to the isocyanurate moiety at the nitrogen atom of the isocyanurate; and at least one ethylenically unsaturated moiety attached to one of the fluoroalkylene, arylene, or polyether moieties. Particularly suitable compounds for use in the compositions of the present invention have an ethylenically unsaturated moiety attached to each fluoroalkylene, arylene, or polyether moiety. For example, the energy curable composition of the present invention may include a compound having formula (II):

wherein Rf comprises a fluoroalkylene, arylene, or polyether moiety, and E is an ethylenically unsaturated moiety.

As more fully described in U.S. patent 6,191,233, incorporated herein by reference, isocyanurate alcohols can be synthesized from cyanuric acid and a fluoroalkylene or polyether diol by the following reaction:

triphenylphosphine/diethyl azodicarboxylate is used to activate alkylene or polyether diol and react with cyanuric acid, resulting in nucleophilic substitution on the nitrogen of cyanuric acid to obtain isocyanurate alcohol. The isocyanurate alcohol is capped with an ethylenically unsaturated moiety by techniques familiar to those skilled in the art to provide an isocyanurate of formula (II).

In the compositions of the present invention, the fluoro moiety (Rf) may be any desired fluoroalkylene or arylene moiety. In one embodiment of the present invention, Rf has the formula- (CF)₂) -, where x is an integer from 1 to about 10. As mentioned above, the fluoroalkylene moiety is incorporated into the compounds of formula (I) and (II) via the corresponding diol. Thus, 2, 2, 3, 3, 4, 4, 5, 5-octafluorohexane-1, 6-diol can be used to introduce the fluoroalkylene moiety- (CF)₂)₄-. Likewise, 2, 2, 3, 3, 4, 4, 5, 5, 6,6, 7, 7-dodecafluorooctan-1, 8-diol can be used to introduce the fluoroalkylene moiety- (CF. sub.₂)₆-. In another embodiment of the present invention, Rf has the formula- (C)₆F₄)_x-, where x is an integer from 1 to about 10. Similarly, 2, 3, 5, 6-tetrafluoroxylene- α, α' -diols can be used to convert the fluorinated arylene moiety- (C)₆F₄) -incorporation into the compounds of formulae (I) and (II). One skilled in the art will recognize that other fluoro diols may be used to provide different fluoro alkylene or arylene moieties Rf.

Suitable fluoropolyether Rf moieties for use in the present invention include:

-CF₂O-[(CF₂CF₂O)_m(CF₂O_n]-CF₂-，

-CF(CF₃)O(CF₂)₄O[CF(CF₃)CF₂O]_pCF(CF₃)-，

-CF₂O-(CF₂CF₂O)_m-CF₂-，

-CF₂CF₂O-(CF₂CF₂CF₂O)_j-CF₂CF₂-，

-CF₂CF₂CF₂O-(CF₂CF₂CF₂CF₂O)_h-CF₂CF₂CF₂-，

-CF₂O-(CF₂CF₂O)_m-(CF₂CF₂CF₂CF₂O)_h-(CF₂CF₂O)_k-CF₂-, and

-CF₂O-(CF₂CF₂O)_m-CF₂CF₂CF₂O)₁-CF₂CF₂O-(CF₂CF₂CF₂O)_j-(CF₂CF₂O)_kCF₂-，

wherein k and m refer to the number of randomly distributed repeating substituent groups of the perfluoroethylene oxide skeleton, and can be an integer or 0; i and j refer to the number of randomly distributed perfluoropropyleneoxy backbone repeating substituent groups, and may be an integer or 0; h is the number of randomly distributed repeated replacement groups of the perfluorotetramethylene oxide skeleton, and can be an integer or 0; n is the number of randomly distributed perfluoroethylene oxide and perfluoromethylene oxide skeleton repeating subunits, and can be an integer or 0; and p means-CF (CF)₃)CF₂The number of the repeating subunit of the O-skeleton may be an integer or 0.

These fluoropolyethers are incorporated into the formula (I) via the corresponding diolsA compound (I) is provided. HOCH of the formula fluorolin is available, for example, from auremont u.s.a. of Thorofare, NJ₂CF₂O-[(CF₂CF₂O)_m(CF₂O)_n]-CF₂CH₂OH, fluoropolyether diol. FLUOROLINK D has a molecular weight of about 2000g/mol, FLUOROLINK D10 has a molecular weight of about 1000 g/mol. Formula HOCH₂CF₂O-(CF₂CF₂O)_m-CF₂CH₂OH fluoropolyether diols may also be used to provide the fluoropolyether moiety of the compound of formula (I). Fluorotriethylene glycol (m ═ 1) and fluorotetraethylene glycol (m ═ 2) are commercially available from the exfluoro research corp. Having the formula HOCH₂CF₂CF₂CF₂O-(CF₂CF₂CF₂CF₂O)_h-CF₂CF₂CF₂CH₂Fluorinated poly (tetramethylene glycol) of OH is commercially available from Exfluor research corp. wherein the average value of h is about 1.2. Those skilled in the art will recognize that other fluoropolyether moieties, such as perfluoropoly (propylene glycol), may be incorporated into the compounds of the present invention through their corresponding polyether diols. Those skilled in the art will also appreciate that the polyether examples used in the present invention may have a molecular weight distribution such that the h, i, j, k, m, n, and p subscripts described above have non-integer averages.

Those skilled in the art will appreciate that the ethylenic unsaturation of the present invention is not limited to the acrylates described in the examples below. Alternative ethylenically unsaturated moieties such as methacrylates, haloacrylates, halomethacrylates, vinyl, allyl, and maleimide are also contemplated for use in the present invention such compounds can be prepared by methods of capping alcohols as would be understood in the art using alternative ethylenically unsaturated moieties.

In other embodiments of the present invention, the energy curable composition may include a compound that is an oligomeric homolog of formula (I). The oligomeric compounds of the invention comprise an aromatic or heteroaromatic core, and a fluoroalkylene, arylene or poly-alkylene linkage connected to the core via an-O-or-S-bondOne or more additional-R-Y-CH₂-Rf-CH₂the-Y-moiety being linked to the fluoroalkylene, arylene or polyether moiety via an-O-or-S-linkage, the-CH terminal₂-Rf-CH₂The O-moiety is end-capped with an ethylenically unsaturated moiety. For example, the oligomeric compounds of the invention may have the following structural formula:

R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-O-E)_m)_n；

R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-O-E)_l)_m)_n；

or

Wherein each R is an aromatic or heteroaromatic moiety; each Y is O or S; each Rf includes a fluoroalkylene moiety, or a fluoropolyether moiety; each E is an ethylenically unsaturated moiety; each j and m is 2, 3, or 4, and the sum of subscripts n in each formula is 2, 3, or 4. Those skilled in the art will appreciate that the above formulas are intended only as exemplary oligomer structures. The oligomers of the present invention can have various other structures.

Similarly, the energy curable composition may include a compound that is an oligomeric homolog of formula (II). The oligomeric compounds of the invention include an isocyanurate core, and a fluoroalkylene, arylene, or polyether moiety attached to the isocyanurate through the nitrogen on the isocyanurate. One or more additional-isocyanurates- (CH)₂-Rf-CH₂) The moiety is attached to the fluoroalkylene, arylene, or polyether moiety through the nitrogen of the isocyanurate. terminal-CH₂-Rf-CH₂The O-moiety is end-capped with an ethylenically unsaturated moiety. For example, the oligomeric compounds of the invention may have the following structural formula:

C₃N₃O₃-(CH₂-Rf-CH₂-C₃N₃O₃-(CH₂-Rf-CH₂-O-E)₂)₃；

C₃N₃O₃(CH₂-Rf-CH₂-C₃N₃O₃-(CH₂-Rf-CH₂-C₃N₃O₃-(CH₂-Rf-CH₂-O-E)₂)₂)₃；

or

Wherein C is₃N₃O₃Is an isocyanurate core; each Rf includes a fluoroalkylene moiety, or a fluoropolyether moiety; each E is an ethylenically unsaturated moiety; each of n, n1, and n2 is 0, 1,2, or 3; and the sum of subscripts n in each formula is 3. Those skilled in the art will appreciate that the above formulas are intended only as exemplary oligomer structures. The oligomers of the present invention can have various other structures.

The structure of the compounds of the present invention is determined primarily by the molar ratios of the reactants used to prepare the compounds. For example, reacting one mole of cyanuric chloride with three moles of a fluoro-diol gives a simple cyanuric ester alcohol:

increasing the relative amount of aromatic or heteroaromatic compounds will extend the chain. For example, 2 moles of 1, 4-dichlorobenzene is reacted with 3 moles of fluoro-diol to produce an-O-linked oligoalcohol:

mixed monomers and oligomers can be prepared using mixtures of fluoro-diols or (hetero) aromatics.

The ethylenically unsaturated-O-linked, -S-linked, and isocyanurate compounds of the present invention typically have a molecular weight of from about 1,000g/mol to about 10,000 g/mol. Suitable compounds have a molecular weight of about 2,000g/mol to about 6,000 g/mol. Such compounds may be considered oligomers, macromers or macromers. The compound having a molecular weight of 1,000g/mol or more is nonvolatile and is therefore suitable in a method of manufacturing an optical element such as a planar waveguide device.

The macromers of the present invention have much higher viscosities than the monomers used in conventional compositions for making polymeric optical elements. Typically, the compositions of the present invention have a viscosity of at least 100 centipoise, and can be as high as several thousand centipoise (e.g., 5000 centipoise), as measured by ASTM1343-93 using a Gilmont falling ball viscometer at 25 ℃. A viscosity of at least 100 centipoise is particularly desirable in the manufacture of planar waveguide devices using the compositions of the present invention.

The energy curable compositions of the present invention may include a selected amount of a free radical initiator. The free radical initiator may be a photoinitiator that generates free radical species upon exposure to actinic radiation. Any photoinitiator known to initiate acrylate polymerization may be used. The photoinitiator is desirably thermally inactive at typical ambient temperatures, preferably below about 60 ℃. Suitable free radical type photoinitiators include, without limitation, quinoxaline compounds; o-polyketaldehyde based compounds; an alpha-carbonyl compound; an acyloin ether; a triarylimidazolyl dimer; an alpha-hydrocarbon substituted aromatic acyloin; polynuclear quinones and s-triazines.

Suitable photoinitiators include aromatic ketones such as benzophenone, acrylated benzophenone, 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, 1, 2-benzoanthraquinone, 2, 3-dichloronaphthoquinone, benzyldimethylaldehyde acetophenone and other aromatic ketones such as benzoin, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether and benzoin phenyl ether, methyl benzoin, ethyl benzoin and other benzoins. Conventional photoinitiators are 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), benzoin ethyl ether, benzoin isopropyl ether, benzophenone, benzodimethylketal (IRGACURE 651), 2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1173), 1- [4- (2-hydroxyethoxy) phenyl ] -2-hydroxy-2-methyl-propan-1-one (DAROCUR 2959), 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one (IRGACURE 907), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one (IRGACURE), Poly {1- [4- (1-methylvinyl) phenyl ] -2-hydroxy-2-methylpropan-1-one } (ESACURE KIP) and [4- (4-methylphenylsulfanyl) -phenyl ] phenyl methanone (QUANTACURE BMS from Great lakes fine Chemicals Limited, london, england). The most suitable photoinitiators are those which do not readily yellow upon irradiation. Such photoinitiators include, for example, the benzodimethylketal (IRGACURE 651), ethyl 2, 4, 6-trimethylbenzoylphenylphosphinate (LUCERIN TPO-L, available from BASF), 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1173, available from Ciba Specialty Chemicals of Tarrytown, NY), 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), and 1- [4- (2-hydroxyethoxy) phenyl ] -2-hydroxy-2-methylpropan-1-one (DAROCUR 2959). For more highly fluorinated energy curable compositions, such as those comprising L-12043 and L-9367 from 3M, there is a need for a fluorinated photoinitiator, 2- (1H, 1H, 2H, 2H-heptadecafluoro-1-decyloxy) -2-methyl-1-phenylpropan-1-one, such as described in U.S. Pat. No. 5,391,587, which is incorporated herein by reference.

The initiator for use in the present invention may also include a selected amount of a thermal initiator that generates free radical species when heated. Suitable known thermal initiators include, but are not limited to, substituted or unsubstituted organic peroxides, azo compounds, pinacols, thiurams, and mixtures thereof. Examples of suitable organic peroxides include, but are not limited to, benzoyl peroxide, p-chlorobenzoyl peroxide, methyl ethyl ketone peroxide, t-butyl perbenzoate, cumene hydroperoxide, di-sec-butyl peroxide, and 1, 1-di (t-butylperoxy) -3, 3, 5-trimethylcyclohexane. Suitable azo compound initiators include, but are not limited to, 2 ' -azobisisobutyronitrile, (1-phenylethyl) azodiphenylmethane, dimethyl-2, 2 ' -azobis (1-cyclohexanecarbonitrile), and 2, 2 ' -azobis (2-methylpropane). Other examples of photo-and thermal initiators can be found in publications known to the person skilled in the art.

The free radical generating photo or thermal initiator may be present in the energy curable composition in an amount selected to polymerize the composition upon exposure to a suitable type of sufficient energy. For example, the photoinitiator is present in an amount sufficient to effect polymerization upon exposure to sufficient actinic radiation. The initiator is generally present in an amount of about 0.01% to about 10% by weight of the total composition, or more typically about 0.1% to about 6%, and suitably about 0.5% to about 4%, based on the total weight of the composition. Mixtures of initiators may also be used. In certain specific cases, such as when curing by exposure to electron beam radiation, energy curable compositions may not require free radical initiators because the free radicals may be generated in situ by the action of electron beam radiation.

Other additives may also be incorporated into the energy curable composition depending on the purpose and end use of the composition. Examples of these include solvents, antioxidants, light stabilizers, volume expanders, fillers such as silica, titanium dioxide, glass spheres, etc. (especially in the nanoscale state, particle size less than about 100nm), dyes, radical scavengers, contrast enhancers, nitrones and UV absorbers. Antioxidants include such compounds as phenols, and particularly hindered phenols include IRGANOX 1010 from Ciba Specialty Chemicals of Tarrytown, New York; a sulfide; an organoboron compound; an organic phosphorus compound; n, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxyhydrocinnamamide) available from Ciba Specialty Chemicals under the trade name IRGANOX 1098. Light stabilizers and more particularly hindered amine light stabilizers include, but are not limited to, the poly [ (6-morpholino-s-triazine-2, 4-diyl) [ (2, 2, 6, 6-tetramethyl-4-piperidinyl) imino ] -hexamethylene [ (2, 2, 6, 6-tetramethyl-4-piperidinyl) imino ] ] available under the trade name CYASORB UV-3346 from cytec industries of Wilmington, Delaware. The volume expansion compound includes such materials as the spiro monomer known as Bailey monomer. Examples of dyes include methylene green, methylene blue, and the like. Suitable free radical scavengers include oxygen, hindered amine light stabilizers, hindered phenols, 2, 6, 6-tetramethyl-1-piperidinyloxy free radical (TEMPO), and the like. Suitable contrast enhancing agents include other radical scavengers such as nitrones. UV absorbers include benzotriazoles, hydroxybenzophenones, and the like. Each of these additives may be present in an amount of up to about 6%, typically from about 0.1% to about 1%, based on the total weight of the composition.

The energy curable compositions of the present invention may include monomers other than the-O-linkages, -S-linkages, and isocyanurate compounds described herein. For example, the composition may include other low loss halogenated monomers, such as fluoroacrylates described in U.S. patent No. 6,306,563. The composition may also include non-halogenated monomers, such as ethoxylated bisphenol a diacrylate. Those skilled in the art will appreciate that the types and amounts of monomers and oligomers and other monomers described herein can be adjusted to provide the desired properties to the energy curable composition and polymeric materials made therefrom. The use of alternative monomers is strictly limited by their compatibility with the cured polymeric material of the present invention. Generally, all of the components of the energy curable composition are mixed with each other, most desirably a substantially homogeneous mixture. The energy curable compositions of the present invention preferably comprise at least about 10 weight percent of the (hetero) aromatic-O-linked, (hetero) aromatic-S-linked, or isocyanurate compounds described herein. The energy curable compositions of the present invention may include substantially greater than 10% by weight of these compounds (e.g., 25%, 50%, 75%, 99.5%).

The invention also includes polymeric materials that are polymers or copolymers of the compounds described herein as-O-linked, -S-linked, and isocyanurate compounds. The energy curable compositions of the present invention can be polymerized by exposure to an appropriate type and amount of energy. For example, a composition formulated with a thermal initiator may be polymerized by the application of heat. The initiation temperature depends on the thermal initiator and is generally a temperature of from about 60 ℃ to about 200 ℃, preferably from 70 ℃ to 100 ℃. The thermal polymerization time can vary from a few seconds to a few hours, depending on the temperature and the initiator used.

Compositions formulated with photoinitiators can be polymerized by exposure to actinic radiation, which is defined as light in the visible, ultraviolet, or infrared regions of the electromagnetic spectrum, as well as electron, ion, or ion beams, or X-ray radiation. The actinic radiation may be in the form of incoherent or coherent light, for example, from a laser. The source of actinic radiation and the exposure process, time, wavelength and intensity can vary widely depending on the desired degree of polymerization, the refractive index of the material, and other factors known to those of ordinary skill in the art. Such conventional photopolymerization methods and their operating parameters are well known in the art. The source of actinic radiation and the wavelength of the radiation can vary widely and any conventional wavelength and source of radiation can be used. Preferably, the photoinitiator requires photochemical excitation to be carried out with relatively short wavelength (high energy) radiation so that exposure to radiation typically encountered prior to treatment (e.g., room light) does not result in premature polymerization of the energy curable composition. Thus, exposure to ultraviolet or deep ultraviolet light is useful.

Suitable light sources include high pressure xenon or mercury-xenon arc lamps equipped with appropriate filters to select the desired wavelength for treatment. Likewise, short wavelength coherent radiation is also useful for the practice of the present invention. Argon ion lasers operating in the UV mode at several wavelengths near 350nm are suitable. Also, frequency-doubled argon ion lasers with a wavelength output of approximately 257nm are very suitable. Electron beam or ion beam excitation may also be used. Alternatively, the treatment may employ a high intensity source of actinic radiation such as a laser induced multiphoton process. Typical exposure times vary from a few tenths of a second to about a few minutes, depending on the actinic source. When partial cure is desired, it is generally preferred that the degree of cure be from about 50% to 90%. The photopolymerization temperature is generally from about 10 ℃ to about 60 ℃; however, room temperature is preferred.

In assessing the relative advantages of a particular energy curable composition or polymeric material based on structure, it is useful to determine the molar concentration of light absorbing bonds with hydrogen for a particular candidate material. Since C-H, N-H, and the harmonic of O-H bond stretching vibration are the main sources of the absorption loss of the communication wavelength, reducing the concentration of these bonds will reduce the absorption loss of the material. Similar harmonics of sulfur-hydrogen bonds are very weak and occur above 1900nm and are therefore not a significant source of absorption loss. Specific compoundsHydrogen (C) of_H) The molar concentration of (A) may be determined from the number of C-H, N-H, and O-H bonds (H) per molecule; molecular weight (Mw) of the compound; and the density (p) of the material, as shown in the following equation:

one skilled in the art will appreciate that C of the formulated energy curable composition_HC through each individual component_HThe weighted average of the values is obtained. Although C is unlikely to be obtained_HThe exact relationship with the specific material or absorption loss of the device being fabricated, but this relationship gives a preliminary indication of which material can be used to reduce the value of optical loss. When such calculations are made for polymeric materials, the density of cured films using compounds is most appropriate, as loss of cured film is of most interest. However, since measuring the density of such a film is difficult, the density of the liquid can be used, while knowing that this approximation does introduce a small amount of error. Suitable energy curable compositions and polymeric materials of the present invention have a C of less than about 55M_H. Suitable energy curable compositions and polymeric materials have a C of less than about 30M_H. Particularly suitable energy curable compositions and polymeric materials have a C of less than about 20M_H. For waveguide applications, most suitable compositions and polymeric materials have a C of less than about 20M_H. Or even less than about 10M. The skilled person is aware of C_HControl can be exercised by judicious selection of the Rf and R moieties of the-O-linked, -S-linked, and isocyanurate compounds described herein, as well as judicious selection of other monomers or oligomers in the energy curable composition. Compounds containing Rf and R moieties having large molecular weights and few hydrogen atoms tend to impart energy curable compositions and thus poly(s) formed therefromThe compound has low C_HThe value is obtained. Some exemplary materials C are given in the examples below_HThe value is obtained.

The energy curable compositions and polymeric materials of the present invention suitable for optical applications have an absorption loss of less than about 0.5dB/cm at a wavelength of 1550 nm. Suitable energy curable compositions and polymeric materials have an absorption loss of less than about 0.3dB/cm at a wavelength of 1550 nm. Particularly suitable energy curable compositions and polymeric materials have absorption losses of less than about 0.2 dB/cm. Energy curable compositions and polymeric materials having absorption losses of less than about 0.15dB/cm, or even less than 0.1dB/cm, are highly desirable. The absorption losses of representative energy curable compositions and polymeric materials of the present invention are given in the examples below.

The compounds, energy curable compositions and polymeric materials of the present invention have many advantages over conventional compounds, compositions and polymeric materials. For example, the compositions of the present invention have a very low C_HAnd therefore have extremely low optical losses at communications wavelengths, making them suitable for use in the manufacture of planar waveguides and other optical devices. The compositions of the present invention have a higher refractive index than similar compositions that do not include aromatic or heteroaromatic moieties, making them useful for tuning the refractive index of different layers of an optical device. The compositions of the present invention also provide macromers having more than two ethylenically unsaturated moieties, providing cured polymeric materials having a high degree of crosslinking. The compositions of the invention also have a higher hydrolytic stability than similar compositions based on carboxylic acid esters.

The compositions and polymers of the present invention are particularly useful in the manufacture of optical components such as planar optical waveguides. A method of making a polymer waveguide is disclosed in commonly-owned and pending U.S. patent application serial No. 09/846,697. An example of a waveguide structure is shown in fig. 1. In one embodiment of the invention, a suitable substrate 2 is strictly chemically cleaned, for example, with concentrated aqueous sodium hydroxide. The substrate 2 is then primed with an acrylate, thiol, amino or isocyanato-functionalized chloro or alkoxy silane compound. For example, it may be treated with (3-acryloxypropyl) trichlorosilane. Optionally followed by applying a photosensitive adhesion promoting tie layer composition by a spin-on coating process. In this and subsequent spin-coating steps, the edge beads formed during spinning can be removed by methods well known to the skilled person (e.g. washing the periphery of the sheet with a suitable solvent during the last few seconds of spinning). The bonding layer is preferably highly crosslinkable and contains ethylenic unsaturation, thiol moieties, or both. If employed, the tie layer composition is exposed to sufficient actinic radiation to cure the tie layer to at least the extent that it is above its gel point. Additionally, suitable tie layers may include other polymers such as epoxies, polyacrylates, or poly (vinyl ethers). Thereafter, the photosensitive buffer composition layer 4 was coated by spin coating. The buffer composition is formulated in accordance with the present invention and, as described above, is formulated to have a refractive index that is about 1% to about 3% lower than the core material when cured. The buffer composition is exposed to sufficient actinic radiation to partially cure it to a level below full cure and above its gel point. Photosensitive cladding composition 6 is then applied to polymer buffer surface 5 by spin coating. The cladding composition is formulated in accordance with the present invention and, as described above, is formulated to have a refractive index, when cured, of about 0.3% to about 1.5% lower than the core material. The laminate so constructed is exposed to sufficient actinic radiation to partially cure the cladding composition to a level below full cure and above its gel point. A layer of a photosensitive, polymerizable core composition formulated in accordance with the present invention is then applied to the polymer cladding surface 7 by spin coating. The core composition is then imagewise exposed to sufficient actinic radiation to effect at least partial polymerization of the image-forming moieties and to form at least one non-image-forming moiety of the core composition. For example, a photomask may be used. In this method, the photomask is lowered to a predetermined level above the core composition layer, typically less than about 20 μm above the core composition layer, more typically from about 5 μm to about 20 μm above the core composition layer. The distance from the mask to the surface of the core composition layer may be controlled by, for example, using a spacer such as a thin wire having a desired thickness. Exposure is performed through a photomask with sufficient actinic radiation to partially cure the core composition to a level below full cure but above its gel point, resulting in exposed areas of partially polymerized core and unexposed areas of liquid core composition.

Alternatively, the core composition may be imaged by writing with a high resolution beam of actinic radiation, such as a beam produced by a laser. Regardless of the exposure method used, the unexposed core composition may be developed by rinsing with a suitable solvent, leaving exposed partially polymerized patterned core 8. The patterned core may define a waveguide structure, for example, having a rectangular or square cross-section. Subsequently, a photosensitive upper cladding composition 10 is applied to the core surface 9 by spin coating. The upper cladding composition covers the top and side surfaces of the patterned core features. The upper cladding composition is formulated in accordance with the present invention and, as described above, is formulated to have a refractive index, when cured, of about 0.3% to about 1.5% lower than the core material. The structure is exposed to sufficient actinic radiation to fully cure the film. Finally, the structure may be heat treated to ensure complete polymerization of all layers and to remove any residual volatile species.

In fig. 3 a cross-sectional view of an example of a waveguide structure according to the invention is shown. The structure comprises a polymer patterned core 8 comprising a polymeric material which is a polymer or copolymer of a compound of formula (I). The polymer patterned core is adjacent to the polymer cladding 6 on at least one side and adjacent to the polymer upper cladding 10 on at least one side. The cladding is disposed on the substrate 2. The cladding layer is either placed directly on the substrate or on the buffer layer 4 located on the substrate. The skilled artisan will appreciate that many alternative waveguide structures that are conceivable in the art that can be fabricated using the compositions and polymers disclosed herein are considered to fall within the scope of the present invention. The waveguide structures of the present invention have propagation losses of less than 0.5dB/cm, 0.3dB/cm, 0.2dB/cm, 0.15dB/cm, and even 0.1 dB/cm.

Those skilled in the art will appreciate that the thickness and refractive index of the various layers are critical to the performance of the waveguide device. The refractive index of each layer can be defined by judicious formulation of the energy curable compositions of the invention. the-O-linked, -S-linked and isocyanurate compounds of the present invention tend to have higher refractive indices than similar diol acrylates. As will be fully described in the examples below, the skilled person is able to formulate energy curable compositions having selected refractive indices by using different relative amounts of compounds of formula (I) and formula (II) and other energy curable monomers. Typically, the core has a refractive index of about 1.30 to about 1.7. As mentioned above, the buffer layer, cladding and upper cladding should have a lower refractive index than the core. The thickness of each layer is determined in the spin-coating step by the spin rate and duration and by the viscosity of the energy curable composition. The height of the core waveguide is defined by the spin-coating step, while the width of the waveguide is determined by the dimensions of the photomask structure features. The dimensions and refractive indices of the layers are selected according to known methodologies to provide the desired waveguide properties for the final device. In one aspect of the invention, the single-mode waveguide core has cross-sectional dimensions of about 7 μm, the core has a refractive index of about 1.323 at 1550nm, the lower cladding has a thickness of about 2 μm, the lower cladding has a refractive index of about 1.316 at 1550nm, the buffer layer has a thickness of about 10 μm, the buffer layer has a refractive index of about 1.308 at 1550nm, the upper cladding has a thickness of about 15 μm, and the upper cladding has a refractive index of about 1.316 at 1550 nm.

Examples

Example 1

In a three-necked flask equipped with a mechanical stirrer, dropping funnel and thermocouple, 250g (0.25mol) FLUOROLINK D10, 15g (0.082mol) cyanuric chloride, 0.25g Butylated Hydroxytoluene (BHT), 300ml toluene and 300ml nonafluorobutylethyl ether (obtained from 3M under the trade name HFE-7200) were mixed. The reaction mixture was ice-cooled, and 40mL of triethylamine (0.28mol) was added dropwise with stirring. The temperature of the reaction mixture was maintained below 30 ℃ during the introduction the reaction mixture was stirred at room temperature overnight.

The reaction mixture was again cooled with ice, and 25mL of acryloyl chloride (0.31mol) was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the dropwise addition. The reaction mixture was stirred at room temperature for 3 hours.

The reaction mixture was again cooled with ice and 35mL of triethylamine were introduced. The reaction mixture was stirred at room temperature overnight, then washed 3 times with methanol, concentrated by rotary evaporation, and passed through a 0.2 μm filter. The molecular structure of the resulting colorless liquid was determined by NMR to be:

Rf＝-CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂-

the liquid loss of the compound at a wavelength of 1550nm was 0.10 dB/cm. The compound has a C of about 11M_H. To a small sample of this compound was introduced α, α -diethoxyacetophenone (1% by weight). The resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.323 at a wavelength of 1550 nm.

Example 2

In a 3-neck flask equipped with a mechanical stirrer, dropping funnel and thermocouple, 51.3g perfluorotetraethylene glycol (0.125mol), 7.42g cyanuric chloride (0.04mol) and 100mL acetonitrile were mixed. The reaction mixture was ice-cooled, and 40mL of triethylamine (0.28mol) was added dropwise with stirring. The temperature of the reaction mixture was maintained below 30 ℃ during the introduction. The reaction mixture was stirred at room temperature for 1 hour.

BHT (0.1g) was introduced into the reaction mixture. The reaction mixture was again cooled with ice, and 11.5mL of acryloyl chloride (0.141mol) was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the introduction. The reaction mixture was stirred at room temperature overnight.

The reaction mixture was washed 3 times with methanol, concentrated by rotary evaporation and passed through a 0.2 μm filter. The molecular structure of the resulting colorless liquid was determined by NMR to be:

Rf＝-CF₂O(CF₂CF₂O)₂CF₂-

the liquid loss of this compound at a wavelength of 1550nm was 0.27 dB/cm. The compound has a C of about 24M_H. To a small sample of this compound was introduced α, α -diethoxyacetophenone (1% by weight). The resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.368 at a wavelength of 1550 nm.

Example 3

In a 3-neck flask equipped with a dropping funnel, a magnetic stir bar and a thermocouple, 10.84g of hexachlorobenzene (0.038mol) and 100ml of dimethylacetamide were mixed. The mixture was heated at 110 ℃ with magnetic stirring. After the hexachlorobenzene was completely dissolved, 13.2g of potassium carbonate (0.096mol) was introduced. The mixture was stirred at 110 ℃ for 4 hours, then 76.05g of FLUOROLINK D10(0.076mol) were introduced. The reaction mixture was stirred at 110 ℃ overnight, then cooled and washed with an equal volume of water. Rotary evaporation was performed to concentration and remove any remaining water to give a liquid with a refractive index of 1.338 at the sodium D line. The infrared spectrum of the liquid is 1636cm^-1Showing a strong aromatic ether peak. The liquid is considered to be an-O-linked alcohol having the structure:

Rf＝-CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂-

in a three-necked flask equipped with a mechanical stirrer, a dropping tube and a thermocouple, 53.1g of the above diol (0.024mol), 0.1g of BHT, 11.6mL of triethylamine (0.083mol) and 100mL of ethylnonafluorobutyl ether were mixed. The reaction mixture was cooled with ice, and 5.6mL of acryloyl chloride (0.069mol) was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the introduction. The reaction mixture was stirred at room temperature for 1 hour.

The reaction mixture was washed 3 times with an equal volume of methanol, concentrated by rotary evaporation and passed through a 0.2 μm filter. The molecular structure of the resulting colorless liquid was confirmed by NMR to be two

Rf＝-CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂-

The liquid loss of this compound at 1550nm wavelength was 0.15 dB/cm. The compound has a C of about 10M_H. To a small sample of this compound was introduced α, α -diethoxyacetophenone (1% by weight). The resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.344 at a wavelength of 1550 nm.

Example 4

In a three-necked flask equipped with a mechanical stirrer, condenser and thermocouple, 100g (0.1mol) FLUOROLINK D10, 17g decafluorobiphenyl (0.05mol), 18g potassium carbonate (0.13mol) and 500mL LN, N-dimethylacetamide were mixed. The reaction mixture was stirred under nitrogen at 110 ℃ overnight. The reaction mixture was cooled, washed with water, and concentrated by rotary evaporation to give the-O-linked alcohol intermediate.

In a three-necked flask equipped with a mechanical stirrer, dropping funnel and thermocouple, the-O-linked alcohol intermediate, 9mL of acryloyl chloride (0.11mol), 0.1g of BHT were mixed. The reaction mixture was stirred at 70 ℃ for 3 hours. The reaction mixture was cooled with ice, and 15mL of triethylamine was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the dropwise addition. The reaction mixture was stirred at room temperature overnight, then washed 3 times with methanol, concentrated by rotary evaporation, and passed through a 0.2 μm filter. The molecular structure of the resulting colorless liquid was determined by NMR to be:

Rf＝-CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂-

the compound has a liquid loss of 0.10dB/cm at a wavelength of 1550 nm. The compound has a C of about 10M_H. To a small sample of this compound was introduced α, α -diethoxyacetophenone (1% by weight). The resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.340 at a wavelength of 1550 nm.

Example 5

In a three-necked flask equipped with a dropping funnel, mechanical stirrer and thermocouple, 93.9g of FLUOROLINK D10(0.094mol) and 37ml of nonafluorobutanesulfonyl fluoride (0.21mol) were mixed. The reaction mixture was cooled with ice, and 32mL of triethylamine was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the dropwise addition. The reaction mixture was stirred at room temperature for 1 hour, after which time the infrared spectrum indicated complete reaction of the hydroxyl groups of FLUOROLINK. The sample was washed once with methanol and concentrated by rotary evaporation to give FLUOROLINKD10 bis (nonafluorosulfonate).

In a three-necked flask equipped with a condenser, thermocouple, and magnetic stir bar, 72.7g FLUOROLINK D10 bis (nonafluorosulfonate), 5.25g dipotassium 1, 5-dimercaptothiadiazole, and 100mL dimethyl sulfoxide were mixed. The reaction mixture was magnetically stirred at 100 ℃ overnight, then 13mL of 4M NaOH was introduced and the reaction mixture was magnetically stirred at 100 ℃ for 6 hours. The reaction mixture was cooled and its pH adjusted to below 3.5 by introducing a 10% aqueous solution of sulfuric acid. The reaction mixture was washed twice with water and concentrated by rotary evaporation to give the-S-linked alcohol.

In a three-necked flask equipped with a dropping funnel, mechanical stirrer and thermocouple, 33g of an S-linked alcohol (0.015mol), 100mL of ethyl nonafluorobutyl ether, 0.05g of BHT and 3.9mL of acryloyl chloride (0.048mol) were mixed.

The reaction mixture was cooled with ice, and 7.3mL of triethylamine (0.052mol) was added dropwise. The temperature of the reaction mixture was maintained below 30 ℃ during the dropwise addition. The reaction mixture was stirred at room temperature for 1 hour, washed 3 times with methanol, concentrated by rotary evaporation and passed through a 0.2 μm filter. NMR confirmed that the resulting colorless liquid was approximately 40% FLUOROLINK D10 diacrylate and approximately 60% was:

Rf＝-CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂-

the liquid loss of the composition at a wavelength of 1550nm was 0.25 dB/cm. the-S-linked compound has a C of about 11M_H. FLUOROLINK D10 diacrylate has a C of about 14M_H. The entire composition had a C of about 12.3M_H. To a small sample of the compound, α -diethoxyacetophenone (1% by weight) was introduced and the resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.336 at a wavelength of 1550 nm.

Example 6

In a three-necked flask equipped with a mechanical stirrer and a condenser, 100g of fluorotetraethylene glycol (HOCH) was mixed₂CF₂O(CF₂CF₂O)₂CF₂CH₂OH，0.24mol) (ii) a 40g of hexachlorobenzene; 5.6g sodium sulfite (0.068 mol); 80g of potassium carbonate (0.55 mol); 0.10g of butylated hydroxytoluene; and 300mL of dimethyl sulfoxide. The mixture was heated to 100 ℃ and mechanically stirred overnight. The mixture was cooled to room temperature, washed three times with deionized water, and concentrated in vacuo at 70 ℃ for 1 hour with rotary evaporation to remove the solvent. The resulting liquid is considered to be an-O-linked alcohol having the structure:

Rf＝-CF₂O(CF₂CF₂O)₂CF₂-

this substantially solvent-free mixture was dissolved in 200mL of fluorinated solvent HFE7200 obtained from 3M and filtered with a 0.2 micron filter. To the filtered mixture was introduced 40mL of acryloyl chloride (0.47 mol). Triethylamine (64mL, 0.46mol) was added dropwise with mechanical stirring while maintaining the temperature between 40 ℃ and 50 ℃ with an ice bath. A white precipitate formed during the introduction of triethylamine. The mixture was mechanically stirred for 4 hours, filtered through a 0.2 micron filter, and then washed three times with equal volumes of water. The mixture was concentrated in vacuo at 70 ℃ for 1 hour using rotary evaporation to give the diacrylate corresponding to the above-mentioned-O-linked alcohol.

The compound had a liquid loss of 0.21dB/cm at a wavelength of 1550nm and had a viscosity of about 55 cP. To a small sample of this compound was introduced α, α -diethoxyacetophenone (1% by weight). The resulting energy curable composition was cured under UV light for 300 seconds while purging with nitrogen. The refractive index of the cured sample was 1.440 at a wavelength of 1550 nm.

Example 7

The core, cladding and buffer compositions were formulated as follows:

composition of	Material of example 1	Perfluoropolyether diacrylates	2, 2-diethoxyacetophenone
				Core	100 parts by weight		1 part by weight
Cladding layer	55 parts by weight	45 parts by weight	1 part by weight
				Buffer layer		100 parts by weight	1 part by weight

The perfluorinated ether diacrylate has

CH₂＝CHCO₂CH₂CF₂(CF₂CF₂O)_n(CF₂O)_nCF₂CH₂O₂CCH＝CH₂And has a molecular weight of about 2100.This material can be prepared by acrylating FLUOROLINK D, available from Ausimont USA, Red Bank, NJ.

The unoxidized four inch silicon wafer was cleaned by soaking in 4M aqueous sodium hydroxide for 1 hour and then rinsed with deionized water for 12 minutes. The silicon wafer was blown dry with nitrogen and further dried on a hot plate at 120 ℃ for 10 minutes. The wafer was cooled and then treated with pure (3-acryloxypropyl) trichlorosilane by means of a clean room swab. Excess silane was removed from the wafer surface by washing with ethanol and then gently wiped with a clean room cloth to remove particulate matter. While spinning on a spin coater, the silicon wafer was rinsed with ethanol and then dried on a hot plate at 120 ℃ for 2 minutes.

The core, cladding and buffer compositions were filtered through a 0.1 μm TEFLON filter and loaded into a 10ml pipette. The wafer was placed in the center of a chuck of a stainless steel spin coater (available from the cost Effective Equipment division of Brewer Science, inc., rola, MO). About 7mL of the buffer composition was dispensed in the center of the wafer and the wafer was rotated to provide a 10 μm thick layer of the buffer composition. The spin program was spinning at 150rpm for 30 seconds; linearly increased to 700rpm at 100rpm/sec and rotated for 20 seconds. During the 700rpm portion of the program, acetone was dispensed with a small nozzle along the top and bottom edges of the wafer to remove edge beads.

The wafer was transferred to a sealed vacuum-cleaning chamber with an internal volume of 3 liters. The chamber consists of aluminum walls, VITON o-rings, and quartz windows, and can be evacuated of air or purged with nitrogen. A clamp and check valve on the cassette lid were used to ensure that a positive pressure of nitrogen was established during purging. This also ensures that no air leaks in during the purge cycle. Also, by ensuring that the chamber is sealed, air can be easily evacuated during the vacuum cycle. Typically, the chamber can be evacuated to 0.2 torr or less using a standard rotary vein mechanical pump. For process consistency, a standard purge cycle is established. Vacuum was applied for 30 seconds until a level of 6 torr was reached. Followed by nitrogen purge at 9.9L/minAnd washing for 2 minutes. The wafer was then passed through a 3 ° diffuser using a TamarackUV light source at about 10.9W/cm²Irradiated for 37 seconds to partially polymerize the buffer layer.

The wafer was re-centered in the spin coater fixture, about 7mL of the cladding composition was applied, and the wafer was spun to obtain a 2 μm thick cladding composition. The spin program was spun at 150rpm for 30 seconds, ramped up to 6000rpm at 100rpm/sec, and spun for 50 seconds, ramped from 100rpm/sec to 700rpm, and spun for 20 seconds. During the 700rpm portion of the program, acetone was dispensed with a small nozzle along the top and bottom edges of the wafer to remove edge beads. The wafer was then transferred to a vacuum-cleaning chamber. Vacuum was applied for 30 seconds until a level of 6 torr was reached. Followed by a nitrogen purge at 9.9L/min for 2 minutes. The wafer was then passed through a 3 ° diffuser using a Tamarack UV light source at about 10.9W/cm²The cladding was partially polymerized by irradiation for 40 seconds.

The wafer was re-centered in the spin coater fixture, about 7mL of core composition was applied, and the wafer was spun to obtain a 6 μm thick layer of core composition. The spin program was spun at 150rpm for 30 seconds, ramped up to 4000rpm at 100 rpm/second, and spun for 50 seconds, ramped to 700rpm at 100 rpm/second, and spun for 20 seconds. During the 700rpm portion of the program, acetone was dispensed with a small nozzle along the top and bottom edges of the wafer to remove edge beads. The core composition was cleaned from the outside of the silicon wafer by 1cm using GALDEN HT110 perfluorinated ether solvent (Ausimont USA) through a 5mL syringe.

The wafer was then placed on a vacuum chuck in a vacuum blow box. A bundle of 25mm thick plastic sheets with a 5 inch diameter hole in the center of the bundle, incorporating five small loops of 35mm thick wire, was lowered onto the silicon wafer with the wire loops placed at the 1cm edge of the silicon wafer free of core composition. The photomask is lowered to above the silicon wafer and rests on the extractable plastic wedge at an elevation angle relative to the silicon wafer. The photomask has transparent regions that define the core of the waveguide. The chamber was closed and the chamber was evacuated for 30 seconds or until the pressure dropped to about 6 torr. Followed by 9.9L/minNitrogen purge was performed for 2 minutes. The wedge was withdrawn and the photomask was placed on a 35mm thick loop of the cable bundle. The wafers were then processed using a Tamarack UV light source without a diffuser at 10.9W/cm²The exposure was carried out for 100 seconds. The photomask allows the exposed core region to be partially polymerized, while not allowing the exposed core region to remain substantially free of polymerization. The wedge is replaced, the photomask is raised, and the wafer is removed from the cassette.

The wafer was replaced in the center of the spin coater fixture and spun at 1300rpm for 60 seconds during the first 40 seconds of the spin cycle, the wafer was rinsed with GALDEN HT110 solvent through the squeeze bottle to remove any unpolymerized core composition. As a result of this development step, only partially polymerized core regions remain on the silicon wafer.

The wafer was repositioned in the center of the spin coater fixture. About 7mL of cladding was applied to the surface of the silicon wafer and the wafer was spun to give a 15 μm thick layer of cladding composition. The spin program was spun at 150rpm for 30 seconds and then ramped up to 700rpm at 100 rpm/second for 30 seconds. During the 700rpm portion of the program, acetone was dispensed only along the bottom edge of the wafer with a small nozzle to remove edge beads. The wafer was then transferred to a vacuum-cleaning chamber. Vacuum was applied for 30 seconds until a level of 6 torr was reached. Followed by a nitrogen purge at 9.9L/min for 2 minutes. The wafers were then passed through a 3 ° diffuser using a Tamarack UV light source at about 10.9W/cm²The cladding was partially polymerized by irradiating for 500 seconds.

The loss of the waveguide thus produced was measured on a Newport AUTOALIGN system using the cutback method. The waveguide having a length of up to 5.5cm, manufactured by the method of this example, has a propagation loss of about 0.08dB/cm at 1550 nm.

Those skilled in the art will appreciate that various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention. It is therefore intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (24)

1. A composition curable by at least one of heat and actinic radiation comprising:

a compound having the structure:

R-(Y-CH₂-Rf-CH₂-O-E)_n

wherein

R is an aromatic or heteroaromatic moiety;

y is O or S;

rf comprises a fluoroalkylene, arylene, or polyether moiety;

e is an ethylenically unsaturated moiety; and

n is 2, 3 or 4;

at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an ether or thioether;

at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties, and wherein the composition has an absorption loss of less than 0.5dB/cm at a wavelength of 1550 nm.

2. The composition of claim 1, wherein the compound has a structural formula selected from the group consisting of:

R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-O-E)_m)_n，

R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-Y-R-(Y-CH₂-Rf-CH₂-O-E)_j)_m)_n，

and

wherein

Each R is an aromatic or heteroaromatic moiety;

each Y is O or S; each Rf includes a fluoroalkylene moiety, or a fluoropolyether moiety;

each E is an ethylenically unsaturated moiety;

each j is 1,2 or 3;

each m is 1,2 or 3;

each n subscript is 0, 1,2, 3, or 4; and is

The sum of the subscripts of n in each formula is 2, 3 or 4.

3. A composition according to claim 1, wherein the aromatic or heteroaromatic moiety is selected from the group consisting of:

4. the composition of claim 1 wherein the fluoroalkylene, arylene, or polyether moiety is selected from the group consisting of:

-(CF₂)_x-，

-(C₆F₄)_x-

-CF₂O-[(CF₂CF₂O)_m(CF₂O)_n]-CF₂-，

-CF(CF₃)O(CF₂)₄O[CF(CF₃)CF₂O]_pCF(CF₃) -, and

-CF₂O-(CF₂CF₂O)_m-CF₂-，

wherein x is an integer between 1 and 10;

m and n are respectively a randomly distributed perfluoroethylene oxide and perfluoromethylene oxide skeletonThe number of repeating subunits, and p denotes-CF (CF)₃)CF₂The number of O-backbone repeat subunits.

5. The composition according to claim 1, wherein each ethylenically unsaturated moiety is selected from the group consisting of acrylates, methacrylates, halogenated acrylates, halogenated methacrylates, vinyl ethers, and allyl ethers.

6. The composition according to claim 1, having a C of less than 55M_H。

7. A composition according to claim 1 having a C of less than 20M_H。

8. A composition according to claim 1 having a C of less than 10M_H。

9. The composition according to claim 1, having an absorption loss at 1550nm of less than 0.5 dB/cm.

10. The composition according to claim 1, having an absorption loss at 1550nm of less than 0.2 dB/cm.

11. The composition according to claim 1, having an absorption loss at 1550nm of less than 0.1 dB/cm.

12. The composition of claim 1 further comprising an initiator.

13. The composition according to claim 1, wherein the compound is present in an amount of at least 10% by weight.

14. A polymeric material comprising a polymer or copolymer of a composition curable by at least one of heat and actinic radiation, the composition comprising a compound having:

an aromatic or heteroaromatic moiety;

at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an ether or thioether;

at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties,

wherein

The compound has the following structural formula:

R-(Y-CH₂-Rf-CH₂-O-E)_n

wherein

R is an aromatic or heteroaromatic moiety;

y is O or S;

rf comprises a fluoroalkylene, arylene, or polyether moiety;

e is an ethylenically unsaturated moiety; and

n is 2, 3 or 4.

15. A polymeric material according to claim 14, wherein the aromatic or heteroaromatic moiety is selected from the group consisting of:

16. the polymeric material of claim 14, wherein the fluoroalkylene, arylene, or polyether moiety is selected from the group consisting of:

-(CF₂)_x-，

-(C₆F₄)_x-

-CF₂O-[(CF₂CF₂O)_m(CF₂O)_n]-CF₂-，

-CF(CF₃)O(CF₂)₄O[CF(CF₃)CF₂O]_pCF(CF₃) -, and

-CF₂O-(CF₂CF₂O)_m-CF₂-，

wherein x is an integer between 1 and 10;

m and n respectively denote the number of randomly distributed repeating subunit of perfluoroethylene oxide and perfluoromethylene oxide skeleton, and p denotes-CF (CF)₃)CF₂The number of O-backbone repeat subunits.

17. The polymeric material of claim 14, having a C of less than 55M_H。

18. The polymeric material of claim 14, having a C of less than 20M_H。

19. The polymeric material of claim 14, having a C of less than 10M_H。

20. The polymeric material of claim 14, having an absorption loss at 1550nm of less than 0.5 dB/cm.

21. An optical element comprising a polymeric core comprising a polymer or copolymer of a compound curable by at least one of heat and actinic radiation, the compound having:

an aromatic or heteroaromatic moiety;

at least two fluoroalkylene, arylene, or polyether moieties, each fluoroalkylene, arylene, or polyether moiety being linked to an aromatic or heteroaromatic moiety through an ether or thioether;

at least one ethylenically unsaturated moiety, each ethylenically unsaturated moiety being attached to one of the fluoroalkylene, arylene, or polyether moieties,

wherein

The compound has the following structural formula:

R-(Y-CH₂-Rf-CH₂-O-E)_n

wherein

R is an aromatic or heteroaromatic moiety;

y is O or S;

rf comprises a fluoroalkylene, arylene, or polyether moiety;

e is an ethylenically unsaturated moiety; and

n is 2, 3 or 4.

22. The optical element of claim 21 wherein the fluoroalkylene, arylene, or polyether moiety is selected from the group consisting of:

-(CF₂)_x-，

-(C₆F₄)_x-

-CF₂O-[(CF₂CF₂O)_m(CF₂O)_n]-CF₂-，

-CF(CF₃)O(CF₂)₄O[CF(CF₃)CF₂O]_pCF(CF₃) -, and

-CF₂O-(CF₂CF₂O)_m-CF₂-，

wherein x is an integer between 1 and 10;

m and n respectively denote the number of randomly distributed repeating subunit of perfluoroethylene oxide and perfluoromethylene oxide skeleton, and p denotes-CF (CF)₃)CF₂The number of O-backbone repeat subunits.

23. The optical element of claim 21 wherein the polymeric core has a C of less than 55M_H。

24. The optical element of claim 21 wherein the polymer core has an absorption loss at 1550nm of less than 0.5 dB/cm.