SE544611C2 - Polymer particles - Google Patents

Abstract

A polymer particle prepared from a nucleated composition, formed spontaneously and instantaneously in absence of surfactant, stabilizer, or dispersant and without extended agitation, and comprising a monomer of formula (I), and a process for preparation of said polymer particle are provided:(I)wherein;(a) X is -CH2-, -O-CH2-CH2-, -O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Y is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CH2, -NH-C(O)-C(CH3)=CH2,-O-CH=CH2, -O-CH2-CH=CH2, -CH=CH2,-CH2-CH=CH2, -O-C(O)-CH2-CH2-SH, -NH-C(O)-CH2-CH2-SH, or SH;(c) Z is -CH2-XP-Y, a hydrogen, a functional group, an alkyl group, or a functionalized alkyl group; and(d) each of 1, m, n, and p is independently a number in the range 0-25.

Description

A polymer is a macromolecule built up of many small building blocks, also referred toas monomers. The polymers are often divided into synthetic ones and natural ones. Thesynthetic polymers are manmade. The natural polymers are the polymers found in nature butcan also be synthesized and/or modified in laboratories and industries. The composition of apolymer is deterrnined by the monomers used for its preparation. The monomers will bringcertain Characteristics to the polymer. For example, a functional monomer will provide thepolymer with functional groups and a cross-linking monomer will provide a cross-linkedpolymer network. After polymerization, the polymer may be processed further by a range ofpost-polymerization procedures in order to prepare it for its final application. For example,functionalization will provide new functional groups, coupling with molecules of various sizesand types will provide new characteristics and properties, further cross-linking or attachmentto surfaces will increase the stability, and derivatization with biocompatible compounds willincrease the biocompatibility of the polymer.

Polymers can be prepared in different size and shape. Polymer particles are particularlyinteresting since they are used in a wide range of applications in many sectors in the society[Gokmen and Prez, Progress in Polymer Science 37 (2012) 365-405]. In laboratory andchemical industry settings, polymer particles are used as stationary phases in various small andlarge-scale separations and purif1cations (e.g., in liquid chromatography and solid-phaseextraction), as supports (solid phases) in solid-phase synthesis, as supports for immobilizationof macromolecules and cells, as catalysts, etc. Emerging applications in medicine include theiruse as carriers in drug delivery and tissue engineering, as immunologic adjuvants in vaccines,and as recognition elements in assay and sensor applications. In the environmental and energyf1elds, polymer particles are useful as sorption media for purif1cation of water, for hydrogenstorage, and for carbon capture/sequestration. Another application area is in printing andadditive manufacturing for the production of 2D- and 3D-structures and objects. Polymer particles are also used in a wide range of consumer products such as cosmetics, detergents, and toothpaste. Hence, there is a large need of polymer particles as Well as efficient and sustainablemethods for their preparation.

Polymer particles of various sizes and shapes can be prepared by a range of methods,for example, by mechanical disintegration of monolithic polymers, by dispersionpolymerization, by precipitation polymerization, by suspension polymerization, or by emulsionpolymerization. Mechanical disintegration of monolithic polymers into particles is a tediousprocedure and typically provides irregularly shaped particles; fractionation is required toprovide the desired size range, often resulting in low yields. While both dispersionpolymerization and precipitation polymerization involve precipitation of the polymer duringthe polymerization, the former method typically provides micro-sized particles Whileprecipitation polymerization provides particles in the sub-micron size range. In both methods,the particles precipitate as they polymerize from a homogenous highly diluted solution ofmonomers dissolved in an organic solvent. In dispersion polymerization, a colloidal stabilizeris present in the solution. Key to both dispersion polymerization and precipitationpolymerization is that the solvent should be a good solvent for the monomers but a poor solventfor the polymer particles to promote precipitation during the polymerization. In suspensionpolymerization, Water-insoluble monomers are suspended in a continuous Water phase byvigorous mixing. Stabilizers, for example, polymers or detergents, are used to stabilize andprevent coalescence of the droplets formed during the agitation. Addition of a Water-immiscibleporogenic solvent to the suspended phase influences on the size and porosity of the particles.Polymerization is typically carried out by free-radical polymerization using an initiatordissolved in the suspended phase. Mixing is continued throughout the full polymerization timeperiod. A Wide range of particle sizes, from sub-micrometer to several millimeters in diameter,can be produced by suspension polymerization. In emulsion polymerization, Water-insolublemonomers and surfactants are dispersed in a continuous Water phase by vigorous stirring,resulting in the formation of monomer-containing small micelles and larger droplets ofmonomers. Polymerization of the monomers in the micelles, using a Water-soluble initiator,provides polymer particles, Which continuously grow by diffusion of monomers from the largermonomer droplets to the micelles until the monomers are depleted in the droplets. Typical sizesof the resulting particles are around 100 nm. In mini-emulsion polymerization, a co-stabilizeris used in addition to the surfactant and high-sheer mixing by, for example, ultrasound isapplied. Polymerization using a Water-soluble initiator provides polymer particles in the sizerange 50-500 nm. In micro-emulsion polymerization, a high concentration of surfactant is used to produce a therrnodynamically stable micro-emulsion of monomer-filled micelles, Which are polymerized after addition of a Water-soluble initiator. The typical particles size of the resultingparticles is in the range 10-50 nm.

Overall, current methods for producing polymer particles are rather complex, labor-intensive, and non-sustainable; improved methods are clearly needed. The present inventionaddresses these needs by providing environmentally friendly, low energy-consuming, and sustainable methods for the production of polymer particles.

SUMMARY OF THE INVENTION The invention provides synthetic polymer particles suitable for a range of applications.In one embodiment, a polymer particle prepared from a nucleated composition, formedspontaneously and instantaneously in absence of surfactant, stabilizer, or dispersant and Without extended agitation, and comprising a monomer of the following forrnula: (1).i eeeeee eeeeeeeee eeeeeeee frå, eeeeeeeeeeee “fl X» MW*Wherein; (a) X is -CH2-, -O-CHz-CHr, -O-CH2~CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Y is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CHz, -O-CH=CH2, -O-CHz-CH=CHz, -CH=CHz,-CHz-CH=CH2, -O-C(O)-CHz-CHz-SH, -NH-C(O)-CHz-CH2~SH, or SH; (c) Z is -CHg-Xp-Y, a hydrogen, a functional group, an alkyl group, or a functionalizedalkyl group; and (d) each of l, m, n, and p is independently a number in the range 0-In another embodiment the polymer particle is further comprised of additional co-polymerized monomer(s).

In another embodiment the invention provides a process for preparing said polymerparticle comprising the steps: (a) dissolving the monomer(s) in a Water-miscible solvent, forrning a solution comprising said monomer(s); (b) interfacing said solution and a Water phase, in absence of surfactant, stabilizer, ordispersant and Without extended agitation, to form a mixture in Which spontaneousand instantaneous formation of nucleated droplets comprising said monomer takesplace; and (c) polymerizing said monomer(s) by a polymerization reaction.

The novel process of the invention is based on a concept that is different thanconventional and prior-art methods for the production of polymer particles. The inventionprovides, spontaneously and instantaneously, droplets of monomers through a simple,environmentally friendly, and energy-efficient procedure. The droplets nucleate When apreferred proportion of a solution, comprising monomers dissolved in a Water-miscible solvent,is interfaced With a Water phase. Only a brief initial mixing is required to interface the tWoliquids for the formation of the droplets; no extended mechanical agitation is required and nosurfactants, stabilizers, or dispersants are needed. A non-toxic harrnless solvent such as ethanolcan be used as the Water-miscible solvent, making the procedure environmentally friendly byobviating the use of harrnful solvents. The droplets are easily transforrned into solid particlesby polymerization. The polymer particles of the invention may be used directly for the intendedapplication or may be further processed before their final use. The particles are useful in allapplications Where polymer particles are needed. The particles of the invention are particularlysuitable for use as supports in solid-phase synthesis, as drug carriers in targeted drug deliveryand sustained drug release, as contrast agents or markers in medical imaging, and as sorbents in separations and purifications.

BRIEF DESCRIPTION OF THE DRAWINGS Figure l. (a) Right triangle phase diagram of the ternary system PETRA-ethanol-Waterbefore polymerization. The region providing nucleated droplets, appropriate for polymerizationto particles, is located below the dotted line. (b) Right triangle phase diagram afterpolymerization.

Figure 2. Influence of interfacing method on the particle size distribution ofpoly(PETRA). Interfacing Was carried out by (a) manual shaking (20 inversions); (b) stirringusing an overhead stirrer equipped With a radial flow impeller (700 rpm, 3 min); (c) homogenization using a homogenizer equipped With a dispersing element (8 000 rpm, l min); and (d) homogenization using an ultrasonic homogenizer equipped With an ultrasonic probe(6 >< 10 s, 20 W). DLS analysis (intensity based, n=30) Was carried out on particles dissolvedin Water.

Figure 3. Influence of polymerization conditions on the particle size distribution ofpo1y(PETRA). Polymerization Was carried out by subjecting the samples to (a) heat (60 °C for6 h); or (b) UV light (350 nm for 2 h). DLS analysis (intensity based, n=l0) Was carried out onparticles dissolved in Water.

Figure 4. Derivatization of the polymer particle With (a) linkers to provide a solid-phasesynthesis support; (b) drugs to provide a drug-carrier suitable for sustained and/or controlleddrug release; (c) affmity ligands to provide a ligand-particle conjugate; (d) imaging probes toprovide a particle-based contrast agent; and (e) PEG chains to increase the biocompatibility ofthe polymer particle. The figure is schematic and although only one conjugated molecule isdraWn in each example, it should be understood that a multitude of molecules can be conjugatedto each particle.

Figure 5. Schematic draWing showing cross-sections of polymer particle-based drugcarriers prepared by (a) conjugating the drug to the particle; (b) adsorbing the drug to the surfaceof the particle; and (c) entrapping the drug in the polymer network.

DETAILED DESCRIPTION Several embodiments of the present invention are described in more detail below, Withreference to the accompanying draWings in order for those skilled in the art to be able to carryout the invention. The invention may, hoWever, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein. Furthermore, theterrninology used in the detailed description of the particular embodiments is not intended tobe limiting of the invention.

The invention provides in one embodiment polymer particles of Well-definedcompositions and size distributions. The size distribution is adjusted by adjusting theparameters of the preparation process. Typically, the polymer particles are in the size range 1-5000 nm. More typically, the polymer particles are in the size range 5-1500 nm. Most typically,the polymer particles are in the size range 10-1000 nm. The polymer particles are suitable fora range of applications, either applied directly as provided by the invention”s preparation process or after further post-polymerization processing.

The polynier particles of the invention are coniposed of polynier networks, formed bypolynierization of n1onon1ers, used as polynier building blocks. The group of n1onon1ers usedin the inVention can be divided into cross-linking n1onon1ers and non-cross-linking n1onon1ers.In one en1bodin1ent of the inVention, the polynier particles are con1prised of a polynierized cross-linking n1onon1er of the following forrnula (1): (1) ............... ..“...~....... är'z a: w: v Mwz-:n mms* Wherein; (a) X is -CH2-, -O-CHz-CHr, -O-CH2~CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Y is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CHz, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CHz, -O-CH=CH2, -O-CHz-CH=CH2, -CH=CHz,-CHz-CH=CH2, -O-C(O)-CHz-CHz-SH, -NH-C(O)-CH2-CH2~SH, or SH; (c) Z is -CHg-Xp-Y, a hydrogen, a functional group, an alkyl group, or a functionalizedalkyl group; and (d) each of l, ni, n, and p is independently a nun1ber in the range 0-Exaniples of other cross-linking n1onon1ers that can be applied as a polynier buildingblock in the inVention include, but are not lin1ited to, divinylbenzene [H2C=CH-C6H4-CH=CH2], ether [C9H16O5],[H2C=C(CH3)CO2CH2CH[OR(H)]CH2OH(R); R = H or COC(CH3)=CH2], diVinyl sulfone[(HzC=CH)2SO2], [HzC=CH-C(O)-O-CH=CHz],[H2C=C(CH3)-C(O)-O-CH=CH2], ethylene glycol diacrylate [H2C=CH-C(O)-O-CH2-CHz-O-C(O)-CH=CH2], ethylene glycol diniethacrylate [H2C=C(CH3)-C(O)-O-CH2-CH2-O-C(O)-C(CH3)=CH2], di(ethylene glycol) diniethacrylate [[H2C=C(CH3)-C(O)-O-CH2CH2]2O], di(ethylene glycol) diacrylate [[H2C=CH-C(O)-O-CH2-CH2]20], l,4-butanediol diacrylate [H2C=CH-C(O)-O-(CHz)4-O-C(O)-CH=CH2), l,4-butanedioldiniethacrylate [H2C=C(CH3)-C(O)-O-(CH2)4~O-C(O)-C(CH3)=CHz), glycerol propoxylatetriglycidyl ether, tri(propylene glycol)diacrylate [H2C=CH-C(O)-(O(CH2)3)3-O-C(O)-CH=CH2], tri(propylene glycol)din1ethacrylate [HgC=C(CHg)-C(O)-(O(CH2)3)3-O-C(O)-C(CH3)=CH2], poly(ethylene glycol-400)-diacrylate [H2C=CH-C(O)-(OCHzCHz)9~O-C(O)- glycerol diglycidyl glycerol diniethacrylate Vinyl acrylate Vinyl niethacrylate CH=CH2], poly(ethylene glyco1-400)-dirneth-acry1ate [H2C=C(CH3)-C(O)-(OCH2CH2)9-O-C(O)-C(CH3)=CH2], N,N”-methylenediacrylamide [H2C=CH-C(O)-NH-CH2-NH-C(O)-CH=CH2], N,N”-methylenedimethacrylarnide [H2C=C(CH3)-C(O)-NH-CH2-NH-C(O)-C(CH3)=CHz], [H2C=CH-C(O)-NH-C6H4-NH-C(O)-CH=CH2], N,N°-phenylenedimethacrylamide [HgC=C(CHg)-C(O)-NH-C6H4-NH-C(O)-C(CH3)=CH2], 3,5-bis(acryloylamido)benzoic acid [H2C=CH-C(O)-NH-C6H3(COzH)-NH-C(O)-CH=CH2], 3,5-bis(rnethacryloylamido)benzoic acid [H2C=C(CHs)~C(O)-NH-C6H3(CO2H)-NH-C(O)-C(CH3)=CH2], N,O-bisacryloyl-L-phenylalanino1 [H2C=CH-C(O)-NH-CH(CH2-C6Hs)~CH2-O-C(O)-CH=CH2], N,O-bismethacryloyl-L-phenylalaninol[H2C=C(CH3)-C(O)-NH-CH(CHz-C6Hs)~CHz-O-C(O)-C(CH3)=CHz],[H2C=CH-C(O)-O-CH=CH2], Vinyl rnethacrylate [H2C=C(CH3)-C(O)-O-CH=CH2], diallylsuccinate [(CH2CO2CH2CH=CH2)2], [(H2C=CH-O-CH2)3C(C2H5)], 2,4,6-tria11y10xy-1,3,5-triazine [C12H15N3O3], 1,3,5-tria11y1-1,3,5-triazine-2,4,6(1H,3H,5H)-tri0ne, tris[2-(acryloyloxy)ethyl]-isocyanuratq difirirnethylol-propane)[((H2C=CH-C(O)-O-CHz)zC(C2Hs)~CH2)2O], di(trirnethylolpropane)tetramethacrylate [((H2C=C(CH3)-C(O)-O-CH2)zC(C2Hs)~CH2)zO],tetraacrylate [C(CH2-O-C(O)-CH=CHz)4], pentaerythritol tetramethacrylate [C(CH2-O-C(O)-C(CH3)=CH2)4], pentaerythritol triacrylate (PETRA) [HO-CH2-C(CH2-O-C(O)-CH=CH2)3], pentaerythritol trimethacrylate [HO-CH2-C(CH2-O-C(O)-C(CH3)=CH2)3],trimethylolpropane triacrylate [CHg-CHg-C(CH2-O-C(O)-CH=CH2)3], trimethylolpropanetrimethacrylate (TRIM) [CH3-CH2-C(CH2-O-C(O)-C(CH3)=CH2)3], trimethylolpropanebenzoate [(H2C=CH-C(O)-O-CH2)2C(C2H5)-CH2-O-C(O)-C6H5],trimethylolpropane benzoate dirnethacrylate [(H2C=C(CH3)-C(O)-O-CH2)2C(C2H5)-CH2-O-C(O)-C6H5], trimethylolpropane allyl ether [H2C=CH-CH2-O-CH2-C(C2H5)(CH2OH)2,trimethylolpropane diallyl ether [C2H5C(CH2OCH2CH=CH2)2CH2OH], trimethylolpropaneethoxylate ( 1 EO/ OH) [H2C=CH-C (O)-O-CHz-CHz-O-CHz)zC(CzHs)~CHz-O-CHz-CHz-O-CH;], pentaerythritol ethoxylate (3/4 EO/OH)tetraacrylate [C[CH2(OCH2CHz)nO-C(O)-CH=CH2]4, pentaerythritol ethoxylate (3/4 EO/OH)tetramethacrylate [C[CH2(OCHzCHz)nO-C(O)-C(CH3)=CH2]4, pentaerythritol propoxylate(5/4 PO/OH)tetraacry1ate [C[CHg[OCH2CH(CH3)]11O-CH=CH2]4, pentaerythritol propoxylate(5/4 PO/OH) tetramethacrylate [C[CHg[OCHgCH(CHg)]nO-C(CH3)=CH2]4, pentaerythritolethoxylate (15/4 EO/OH) tetraacrylate [C[CH2(OCH2CHz)nO-C(O)-CH=CH2]4,pentaerythritol ethoxylate (15/4 EO/OH) tetramethacrylate [C[CH2(OCH2CH2)HO-C(O)-C(CH3)=CH2]4, trimethylolpropane ethoxylate (lEO/OH) rnethyl ether dirnethacrylate N,N°-phenylenediacrylamide Vinyl acrylate trimethylolpropane trivinyl ether tetraacrylatepentaerythritol diacrylate rnethyl ether diacrylate [H2C=C(CH3)-C(O)-O-CHz-CHz-O-CHz)zC(CzHs)~CHz-O-CHz-CHz-O-CHs],trimethylolpropane ethoxylate (1/3 EO/OH) triacrylate [(H2C=CH-C(O)-O-(CH2-CH2-O)nCH2)3C-C2Hs], ethoxylate (1/3 EO/OH)[(H2C=C(CH3)-C(O)-O-(CH2-CH2-O)11CH2)3C-C2H5], trimethylolpropane ethoxylate (7/3EO/OH) triacrylate [(H2C=CH-C(O)-O-(CH2-CH2-O)HCH2)3C-CzHs], trimethylolpropaneethoxylate (7/3 EO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(CHz-CHz-O)nCHz)sC-C2H5], trimethylolpropane ethoxylate (14/3 EO/OH) triacrylate [(H2C=CH-C(O)-O-(CH2-CH2-O)nCH2)3C-C2H5], trimethylolpropane ethoxylate (14/3 EO/OH) trimethacrylate[(H2C=C(CH3)-C(O)-O-(CH2-CHz-O)HCH2)3C-CzHs],(1/PO/OH) triacrylate [(H2C=CH-C(O)-O-(C3H6O)n-CHz)3C-CzHs], trimethylolpropanepropoxylate (1/PO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(C3H6O)n-CH2)3C-C2H5],trimethylolpropane propoxylate (2PO/OH) triacrylate [(H2C=CH-C(O)-O-(C3H6O)n-CH2)3C-C2H5], trimethylolpropane propoxylate (2PO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(C3H6O)n-CH2)3C-C2H5], glycerol propoxylate (lPO/OH) triacrylate [[H2C=CH-C(O)-O-[CH(CH3)~CH2-O]1CH2][H2C=CH-C(O)-O-[CH(CH3)~CHz-O]m][H2C=CH-C(O)-O-[CH(CHs)~CHz-O]nCHz][-CH],[CHFCH-C(O)-O-(C3H6O)X-(CH2CH2O)y-CH[CHz-(OCHzCH2)y-(OC3H6)X-O-C(O)-CH=CH2]2], triolein [CH3-(CH2)7-CH=CH-(CH2)7-C(O)-O-CH(CH2-O-C(O)-(CH2)7-CH=CH-(CH2)7-CH3)2], trimethylolpropane triglycidyl ether [C15H26O6], 2,2-bis[4-(2-hydroxy-S-methacryloyloxypropoxy)phenyl]-propane, bisphenol-Adirnethacrylate, pentaerythritol tetrakis(3-mercaptopropionate) [(HS-CH2-CH2-C(O)-O-CH2)4C], trimethylolpropane tris(3-mercaptopropionate) [(HS-CH2-CH2-C(O)-O-CH2)3C-C2H5], 2-hydroxyrnethyl-2-rnethyl-1ß-propanediol tris-(S-mercaptopropionate) [(HS-CH2-CH2-C(O)-O-CH2)3C-CH3], 2,2-bis(su1fany1rnethy1)-1ß-propanedithiol [(HS-CH2)4C],glycol di-S-mercaptopropionate, p01y(ethy1ene glycol) dithiol [HS-CHg-CHg-(O-CHQ-CH2)n-SH], 1,3,4-thiadiaz01e-2,5-dithioL [C2H2N2S3], toluene-ßA-dithiol [CH3C6H3(SH)2],benzene-lA-dithiol, benzene-IJ-dithiol, LS-benzenedithiol [C6H4(SH)2], bipheny1-4,4'-dithiol [HS-C6H4-C6H4-SH], p-terpheny1-4,4”-dithio1 [HS-C6H4-C6H4-C6H4-SHLhexa(ethylene glycol) dithiol [HS-(CHg-CHg-O)5-CH2-CH2-SH], tetra(ethy1ene glycol)dithiol [HS-(CHg-CHg-Oß-CHg-CHg-SH], 2,2'-(ethylenedioxy)diethanethiol [HS-CHg-CHg-O-CHz-CHæO-CHz-CHrSH], 1,4-benzenedimethane-thiol [C6H4(CH2SH)2], 1,16-hexadecanedithiol [HS-(CH2)16-SH], dithiothreitol [HS-CHg-CH(OH)-CH(OH)-CH2-SH],2-rnercaptoethyl ether [O(CH2CH2SH)2], LS-propanedithiol [HS-(CH2)3-SH], 1,4-butanedithiol [HS-(CH2)4-SH], LS-pentanedithiol [HS-(CH2)5-SH], Ló-hexane dithiol [HS- trimethylolpropane trimethacrylate trimethylolpropane propoxylate glycerol ethoxylate-co-propoxylate triacrylate ethoxylated (CH2)6-SH], 4arrn-PEG-SH [C(CH2-O-(CH2CH2O)11CH2CH2SH)4], Sarrn-PEG-SH, andanalogs and derivatives of these.

Exaniples of non-crosslinking n1onon1ers that can be used in the invention include, butare not lin1ited to, acid-containing n1onon1ers such as acrylic acid, niethacrylic acid (MAA),trifluoroniethacrylic acid, itaconic acid, Vinylacetic acid, 4-Vinylbenzoic acid (4-VBA), 4-Vinylphenylboronic acid, Vinylsulfonic acid, and Vinylphosphonic acid; ester-containingn1onon1ers such as Vinyl acetate, Vinyl propionate, Vinyl pivalate, allyl acetate, niethyl acrylate,n1ethyl niethacrylate, ethyl acrylate, ethyl niethacrylate, propyl acrylate, propyl niethacrylate,butyl acrylate, butyl niethacrylate, pentyl acrylate, pentyl niethacrylate, cyclohexyl acrylate,cyclohexyl niethacrylate, benzyl acrylate, benzyl niethacrylate, isobornyl acrylate, isobornylniethacrylate, hydroxybutyl acrylate, hydroxybutyl niethacrylate, Vinyl decanoate, Vinyl 4-tert-butylbenzoate, glycidyl acrylate, and glycidyl niethacrylate; aniide-containing n1onon1ers suchas acrylaniide, niethacrylaniide, and N-Vinylacetaniide; aniino-containing n1onon1ers such asallyl an1ine, 2-an1inoethyl niethacrylate, 2-(diethylan1ino)ethyl niethacrylate,(Vinylbenzyl)trin1ethylan1n1oniun1 chloride, and 4-an1inostyrene; heteroaron1atic n1onon1erssuch as l-Vinyliniidazole, 4-Vinylpyridine, 2-Vinylpyridine, l-Vinyl-2-pyrrolidinone, N-Vinylcaprolactani, and N-Vinylphtaliniide; hydroxyl-containing n1onon1ers such as 4-alpha-Vinylbenzyl alcohol, 2-hydroxyethyl acrylate, hydroxystyrene, 2-hydroxyethyl niethacrylate (HEMA), S-hydroxypropyl acrylate, S-hydroxypropyl niethacrylate, 4- hydroxypropyl acrylate, 4-hydroxypropyl niethacrylate, S-hydroxypentyl acrylate, 5-hydroxypentyl niethacrylate, 2,3-dihydroxypropyl acrylate, 2,3-dihydroxypropyl niethacrylate,N-hydroxyniethylacrylaniide, N-hydroxyniethylniethacrylaniide, allyl alcohol, hydroxyethylVinyl ether, and allyl-2-hydroxy-2-phenyl ether; Vinyl acid halides such as acryloyl chloride,niethacryloyl chloride; halide-containing n1onon1ers such as Vinyl broniide and Vinyl chloride;thiol-containing n1onon1ers such as 2-propene-l-thiol; silane-containing n1onon1ers such asVinyltriniethylsilane, Vinyltriniethoxysilane, and 3-glycidoxypropyl-triniethoxysilane;aron1atic n1onon1ers such as styrene, 2-Vinyl anthracene, 9-Vinyl anthracene, l-Vinylnaphtalene,2-Vinylnaphtalene, l-Vinylphenanthrene, 9-Vinylphenanthrene, 4-Vinylbiphenyl, 4-Vinyl-o-terphenyl, 4-Vinylpyrene, 5-Vinylpyrene, 2-Vinyltetracene; and analogs and deriVatiVes of these.

In another enibodinient, the invention provides a process for preparing said polynierparticles coniprising the steps: (a) dissolving the n1onon1er(s) in a Water-niiscible solVent, forrning a solution coniprising said n1onon1er(s); (b) interfacing said solution and a Water phase to form a mixture in Which spontaneousand instantaneous formation of nucleated droplets comprising said monomer(s)takes place; and (c) polymerizing said monomer(s).

The process of the invention is particularly adVantageous since it is energy-efficient andenvironmentally friendly. The first step of the process is the preparation of a solutioncomprising the monomer(s) dissolved in a Water-miscible solvent. The resulting solution ishereafter referred to as the solution. Examples of suitable solVents for the preparation of thesolution include, but are not limited to, Water-miscible alcohols, acetonitrile, N,N-dimethylforrnamide (also named DMF), dimethyl sulfoxide (also named DMSO), acetone,acetic acid, acetaldehyde, hexamethylphosphoric triamide (also named HMPT),dimethoxyethane (also named glyme, monoglyme, dimethyl glycol, ethylene glycol dimethylether, dimethyl cellosolve, and DME), l,4-dioxane, N-methyl-2-pyrrolidone (also namedNMP), pyridine, tetrahydrofuran (also named THF), or combinations thereof. Examples ofalcohols include, but are not limited to, methanol, ethanol, l,2-ethanediol (also named ethyleneglycol), l-propanol, 2-propanol, 1,2-propanediol (also named propylene glycol), 1,3-propanediol, l-butanol, 2-butanol, l,2-butanediol, l,3-butanediol, l,4-butanediol, l-pentanol,2-pentanol, 3-pentanol, 1,2-pentanediol, l,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, l,4-pentanediol, l,5-pentanediol, glycerol (also named glycerine), erythritol (also named butane-l,2,3,4-tetrol), pentaerythritol (also named 2,2-bis(hydroxymethyl)propane-l,3-diol), furfurylalcohol, diethylene glycol (also named DEG), triethylene glycol (also named triglycol, TEG,and TREG), tetraethylene glycol, and pentaethylene glycol.

The next step of the process comprises interfacing the solution With Water by simplyadding the solution to Water or by, in addition, including a brief mixing/blending procedure,thereby forrning a mixture of monomer(s), Water-miscible solvent, and Water. In some cases,the momentum of the solution being added to the Water phase is enough to cause sufficientturbulence to mix/blend the tWo liquids. Upon mixing/blending, the Water-miscible solVentpartitions into the Water phase and nucleation (droplet forrnation) of the monomer(s) occurs.Key to successful nucleation is to provide preferred fractions of the three (or more) componentsin the mixture. The preferred fractions are estimated from an experimentally deterrnined phasediagram. As an example, a temary phase diagram of pentaerythritol triacrylate (PETRA), ethanol, and Water has been acquired and is provided in the format of a right triangle phase diagram in Figure la. Within the nucleation region, located below the dotted line in Figure la, nucleation occurs spontaneously and instantaneously when the components areinterfaced/mixed. In the most preferred embodiments, the composition is comprised of at themost about 20 mass percent (i.e., at the most about 0.2 mass fractions) of a water misciblesolvent and at the most about l mass percent (i.e., at the most about 0.01 mass fractions) ofmonomer(s). Only an interfacing or initial brief mixing/blending is required; no continuedmixing or agitation is required. The droplets remain stable in the mixture during time periodsthat are sufficiently long to allow for a polymerization of the monomer(s) to form solid polymerparticles. The size of the droplets is indicated in Figure la. Mixtures of compositions locatedoutside of the nucleation region form either (i) a single phase or (ii) unstable, aggregateddroplets. Upon polymerization, mixtures from the single-phase region may undergoprecipitation polymerization and mixtures from the unstable region may form aggregatedpolymer particles of large size distributions and/or monolithic gels. Hence, polymer particlesof narrow size distribution are formed only from mixtures located in the nucleation region.Figure lb shows the resulting particle sizes of the polymer particles formed after subjecting thetemary mixtures of PETRA, ethanol, and water in Figure la to polymerization conditions.

As mentioned above, no extensive mixing or agitation is needed for nucleation to takeplace when the composition of the components is located within the nucleation region of thephase diagram. The methods for interfacing the solution and the water phase include, but arenot limited to, batch-wise methods and flow system methods. The batch-wise methods include,but are not limited to, mixing by turbulent addition, mixing by manual inversion, mixing byautomated inversion, mixing by manual shaking, mixing by automated shaking, mixing usinga vortexer, mixing by ultrasonic treatment, mixing using a magnetic stirrer, mixing using anoverhead stirrer, mixing using a blender, mixing using a disperser device, and mixing using ahomogenizer. The flow system methods include, but are not limited to, mixing using a staticmixer, mixing using a microfluidic mixer, mixing using a micromixer, continuous-flowcapillary mixing, microfluidic mixing using Y junctions, microfluidic mixing using T junctions,and mixing using various three- or four-way intersections or connectors. Mixing devicesproduced by microfabrication or 3D-printing are useful. Industrial scale mixing devicesinclude, but are not limited to, impellers, turbines, anchors, helical ribbons, high-sheardispersers, ribbon blenders, paddle mixers, double cone blenders, static mixers, liquid whistles,dispersion mixers, mixing paddles, and continuous-flow mixers.

Figure 2 shows that there is no significant influence of the interfacing method on the resulting particle size distribution of poly(PETRA) particles.

No extended mixing/agitation is needed for the formation of the droplets When thecomposition is located in the nucleation region of the phase diagram. No stabilizer is neededfor the forrnation of droplets When the composition is located in the nucleation region of thephase diagram. The term stabilizers are here used to denote suspension stabilizers, suspendingagents, suspension agents, emulsifiers, emulsion agents, emulsifying agents, dispersants,dispersing agents, surfactants, and other agents used for similar purpose as the ones listed. Theterms are used interchangeably herein.

In the third step of the process, the polymers are formed by assembling the monomersthrough a polymerization reaction, including, but not limited to, a free-radical polymerization,a thiol-ene polymerization, an anionic polymerization, a cationic polymerization, a redox-initiated polymerization, a chain-growth polymerization, a step-growth polymerization, acondensation polymerization, a living polymerization, a reVersible-deactivation radicalpolymerization, and a reVersible addition-fragmentation chain transfer (RAFT) polymerization.Free-radical initiators useful in the present inVention include those norrnally suitable for free-radical initiation. These species include, but are not limited to, azo compounds, organicperoxides, benzoine ethers, benzyl ketals, alpha-dialkoxy acetophenones, alpha-hydroxyalkylphenones, alpha-amino alkylphenones, acyl phosphine oxides, benzophenones, and thio-xanthones. Examples of azo compounds include low molecular Weight azo initiators and macroazo initiators. Low molecular Weight azo initiators include, but are not limited to, 2,2°-azobis(2-methylbutyronitrile), 2,2 ° -azobis(2-methylpropionitrile), l , l ° -azobis(cyclohexanecarbo-nitrile), phenyl-azo-triphenylmethane, and 4,4”-azobis(4-cyanovaleric acid). Commercialproducts of this type include, but are not limited to, VAZO 52, VAZO 64, VAZO 67, andVAZO 88 initiators from DuPont. Macro azo initiators include, but are not limited to,compounds comprising polydimethylsiloxane units, such as the VPS series from Wako, andcompounds comprising polyethyleneglycol units, such as the VPE series from Wako. Examplesof peroxides include, but are not limited to, tert-butyl peroxide, cumyl peroxide, acetylperoxide, benzoyl peroxide, lauroyl peroxide, tert-butyl hydroxyperoxide, and tert-butylperbenzoate. The rate of the decomposition of peroxides may be increased by the addition oftertiary amines, such as, but not limited to, N,N-dimethylaniline. Anionic initiators useful inthe present inVention include those norrnally suitable for anionic initiation. Examples of anionicinitiators include, but are not limited to, metal alkyls such as n-butyllithium. Cationic initiatorsuseful in the present inVention include those norrnally suitable for cationic initiation. Examplesof cationic initiators include, but are not limited to, sulfuric acid, tin(IV)chloride, boron trifluoride, and iodine. Redox-initiated polymerizations use a redox pair for initiation, exemplified by, but not limited to, organic peroxides and tertiary amines, such as the benzoylperoxide and N,N-dimethyl-p-toluidine redox pair. The polymerization may be manipulated bythe addition of quenchers or inhibitors. In the case of thiol-ene polymerizations, examples ofquenchers include, but are not limited to, 3-mercaptopropionic acid and other thiols. Initiators,quenchers, and/or inhibitors are added either to the solution or to the Water phase.

To promote the polymerization, the building blocks can be exposed to a source ofenergy, such as, but not limited to, ultraviolet (UV) radiation, gamma radiation, and/or a heatsource providing an elevated temperature for a time period sufficiently long to promote thepolymerization. Preferably, the reaction is carried out at a temperature of about -30-100 °C,more preferably at a temperature of 10-90 °C, and most preferably at a temperature of 30-70°C. For polymerizations promoted by UV light, radiation in a Wavelength of about 200-400 nmis preferred. Combinations of elevated temperatures and UV light can also be applied. Figure 3shoWs the resulting particle size distributions When the polymerizations Were carried out at anelevated temperature and under the influence of UV light, respectively.

In one embodiment, the invention provides directly (i.e., after the polymerization step)a polymer particle suitable for the final application. In another embodiment the polymer particleobtained after the polymerization step is subjected to post-polymerization processing,including, but not limited to, derivatization, conjugation, decoration, modif1cation, orfunctionalization to fumish it for the final application. A range of different final applicationsexists, some of Which are shown in FigureThe invention provides in one embodiment a polymer particle suitable to be applied asa support (solid phase) in solid-phase synthesis of molecules (Figure 4a). Examples ofmolecules to be synthesized by solid-phase synthesis using the polymer particle of the inventionas a solid phase include, but are not limited to, peptides, proteins, oligonucleotides, peptidenucleic acids, carbohydrates, small organic molecules, and molecule libraries. For applicationsas a solid phase support, the polymer particle should preferentially be provided With a functionalgroup that can serve as a starting point for the solid-phase synthesis couplings. In oneembodiment, one of the monomers used as a polymer building block provides such a functionalgroup. This functional group may be used directly as the starting point for the solid-phasesynthesis. In another embodiment, the polymer particle is derivatized to provide a differentfunctional group. Examples of functional groups suitable to be used as the starting point for thesynthesis include, but are not limited to, amino groups, hydroxyl groups, and carboxyl groups.In another embodiment, a linker, a handle, or an intemal reference molecule, such as an intemal reference amino acid, is coupled to the functional group to provide a starting point for the solid- phase Synthesis. A linker or handle facilitates subsequent cleavage of the synthesized assemblyfrom the polymer particle by providing a bond that is easy to chemically cleave. Examples oflinkers and handles include, but are not limited to, the PAL linker, the HMPA linker, the HMFAlinker, the PAM linker, the XAL linker, and the BAL linker. An internal reference moleculefacilitates quantification of the cleavage yield.

In one embodiment, the invention provides a polymer particle for drug deliveryapplications by either covalently conjugating a drug to the particle, adsorbing non-covalently adrug to the particle surface, or entrapping a drug in the particle°s polymer network (Figure 4band Figure 5). The drug is either a biological drug or a conventional small molecule drug.

In one embodiment, the polymer particle is provided With a functional group suitablefor click chemistry, such as, but not limited to, the Huisgen l,3-dipolar cycloaddition, theStaudinger reaction, the thiol-ene reaction, and the Diels-Alder reaction. By a click reaction,the polymer particle is thereafter easily derivatized With a preferred molecule or used for in-situ labeling of cells and tissue.

In one embodiment of the invention, the polymer particle is derivatized With a ligand.The ligand is selected from a group of ligands including, but not limited to, nucleic acids,nucleotides, amino acids, peptides, peptide mimetics, proteins, antibodies, mini-bodies,enzymes, cell-penetrating ligands, carbohydrates, small organic molecules, boronic acids, dyes,cofactors, cell adhesion molecules, metal complexes, biotin, avidin, and streptavidin. Theligand-particle conjugate is useful for targeting to biomarkers, cells, tissue, and other biologicalmolecules and structures. The ligand-particle conjugate is useful also in biological screenings,molecular recognition studies, and tissue engineering applications. When the ligand is anaff1nity ligand, the conjugate is useful in aff1nity capture, separations, and purif1cations.

In one embodiment of the invention, the polymer particle is conjugated to, or derivatizedWith, a molecule that can be imaged by an imaging modality selected from the group of imagingmodalities including, but not limited to, fluorescent imaging, x-ray, computed tomography(CT), magnetic resonance imaging (MRI), positron emission tomography (PET), single-photonemission computed tomography (SPECT), electron microscopy, optoacoustic imaging, andmagnetic imaging. The polymer particle containing the conjugated imaging probe (can also becalled a reporter molecule), functions as a contrast agent or imaging agent during in vitro andin vivo imaging (Figure 4d).

In one embodiment, a biocompatible particle is provided through further polymerizationreactions to provide star, brush, or comb polymers on the surface of the particle. In one particular embodiment, PEG chains are conjugated to the particle to increase the biocompatibility of the particle (Figure 4e). In one embodiment, the polymer particle iscomprised of a PEG-containing monomer. In another embodiment, the polymer particle isderiVatized With a natural polymer including, but not limited to, chitosan, chitin, alginate,gelatin, starch, carrageenan, dextran, and cyclodextrins.

In one embodiment, the inVention provides a polymer particle suitable for 2D- and 3D-printing applications.

Combinations of any of the embodiments are possible. For example, in oneembodiment, a polymer particle is derivatized With a drug, an imaging probe, and an aff1nityligand to provide a particle capable of targeted theranostics (i.e., combined therapy anddiagnosis). The applications of the polymer particles of the inVention are not limited to the embodiments listed here.

EXAMPLES Example lIdentification of Composítíons Provídíng Nucleated Droplets and Polymerízed Partícles Firstly, a temary PETRA-ethanol-Water phase diagram Was constructed foridentification of the nucleation region. Water and ethanol Were purged With nitrogen gas priorto use. Temary mixtures (10 mL) of PETRA, ethanol, and Water Were prepared by interfacingVolumes (1-50 vol%) of a solution of PETRA (2.5 mM-150 mM) in ethanol With Volumes (50-99 vol%) of Water. The ethanolic solution Was added to the Water phase and the two liquidsWere manually interfaced by inVerting (shaking) the sample approximately 20 times. Theresulting mixtures Were inspected and subjected to dynamic light scattering (DLS) analysisusing a Nanotrac Ultra Particle Size Analyzer from Mictrotrac (Montgomeryyille, PA, USA)to determine the size distribution of the droplets. The mean droplet size Was calculated basedon intensity using the Rayleigh-Debye theory (n = 10). The mass fractions of ethanol andPETRA, respectively, in each of the temary mixtures Were calculated. The calculated data Werecombined With the DLS data and plotted in a phase diagram (Figure la). Secondly, mixturesfor polymerization testing in small scale Were prepared following the same procedure, exceptthat the Water phases Were preheated to 60 °C and the ethanolic solutions included AIBN (40mM) used as a free-radical initiator. Polymerizations Were carried out for 6 h in a Water bath set at 60 °C and the samples Were cooled to room temperature before characterization. The resulting mixtures Were inspected and analyzed by DLS. The data Were plotted in a phase diagram (Figure lb).

Example 2Synthesis of Poly(PE T RA) Particles;Demonstration of the Applicabilitj/ of Different Interfacing Methods A solution containing PETRA (0.04 M) and AIBN (0.08 M) in ethanol Was prepared.The ethanol used had previously been purged With nitrogen gas for 10 min. The solution (lvolume part) Was then added to preheated (60 °C) Water that had previously been purged Withnitrogen gas for l h (39 volume parts). The solution and the Water phase Were interfaced byapplying either (i) manual shaking (20 inversions); (ii) an IKA Labortechnik Eurostar digitaloverhead stirrer (IKA-Werke Gmbh & Co., Staufen, Gerrnany) equipped With a Heidolph TR20 radial floW impeller operating at 700 rpm for 3 min; (iii) a model Dl25 basic dispersingdevice equipped With an S25N-25F dispersing element (IKA-Werke Gmbh & Co., Staufen,Germany) operating at 8000 rpm for l min; or (iv) a Bandelin Sonoplus ultrasonic homogenizerequipped With a VS70T titanium alloy probe (Bandelin Gmbh, Berlin, Germany) operating at20 W for 6 x 10 s. The total volume of each mixture Was 500 mL. Therrnolytically initiatedpolymerizations Were carried out in a 60 °C Water bath for 6 h. The polymerized mixtures Werecentrifuged (9 500 rpm, 2 h). The supematants Were discarded and the particles Were retained.The particles Were incubated repeatedly first With ethanol, then With Water, and finally againWith ethanol. After each incubation, the samples Were centrifuged (9 500 rpm, 2 h) anddecanted. The absorbance of the supematants Was measured at 210 nm. Extractions Wererepeated until the absorbance of the supematants Was < 0.05 absorbance units. Finally, theparticles Were dried in vacuo ovemight. The dried particles Were dissolved in Water for DLSanalysis (Table l, Figures 2a-d). The mean particle size Was calculated based on intensity usingthe Rayleigh-Debye theory. The polydispersity index Was calculated as dv/ dN, Where dv and dNare the mean particle sizes based on volume and numbers, respectively, calculated using the Lorenz-Mie theory.

Table 1. Influence of Interfacing Method on Size and Polydispersity of Poly(PETRA) Particles (DLS , n=30) Interfacing Method Mean Particle Size i SD (nm) Mean Polydispersity Index i SDManual shaking (20 inversions) 262 i 21 1.27 i 0.11Overhead stirrer (700 rpm, 3 min) 248 i 25 1.36 i 0.18Disperser/homogenizer (8 000 rpm, 1 min) 258 i 16 1.29 i 0.16Ultrasonic homogenizer (6 X 10 s, 20 W) 258 i 18 1.33 i 0.Example 3Synthesis of Poly(PE T RA ) Particles;Demonstration of the Applicabilitj/ of Dzflerent Free-Radical Generation Methods A solution Was prepared by dissolving PETRA (0.04 M) and AIBN (0.04 M) in ethanolthat had previously been purged With nitrogen gas for 10 min. The solution (l volume part) Wasthen added to Water that had previously been purged With nitrogen gas for l h (9 volume parts).Preheated (60 °C) Water Was used for therrnolytically initiated polymerizations and Water ofroom temperature Was used for photolytically initiated polymerizations. The solution and theWater phase Were interfaced by inverting the sample manually (shaking) approximately 20times. The total volume of the mixture Was 250 mL. Therrnolytically initiated polymerizationsWere carried out in a 60 °C Water bath for 6 h. Photolytically initiated polymerizations Werecarried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT)for 2 h. The polymerized mixtures Were centrifuged (9 500 rpm, 2 h) and the supematants Werediscarded. The particles Were incubated repeatedly first With ethanol, then With Water, andfinally again With ethanol. After each incubation, the samples Were centrifuged (9 500 rpm, 2h) and decanted. The absorbance of the supematants Was measured at 210 nm. Extractions Wererepeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, theparticles Were dried in vacuo ovemight. The dried particles Were dissolved in Water for DLS analysis (Table 2, Figures 3a,b).

Table 2. Influence of Polymerization Conditions on Size and Polydispersity of Particles (DLS, n=10) Polymerization Conditions Mean Particle Size i SD (nm) Mean Polydispersity Index i SD 60 °C (Water bath), 6 h 415 i 32 1.23 i 0.16350 nm (UV flood lamp), 2 h 427 i 40 1.23 i 0.18ExampleSynthesis of Polj/(PE TRA-co-Allylamine) Particles A solution Was prepared by dissolving PETRA (0.04 M), allylamine (0.l55 M) andAIBN (0.04 M) in ethanol that had previously been purged With nitrogen gas for 10 min. Thesolution (l volume part) Was added to Water that had previously been purged With nitrogen gasfor l h (9 volume parts). The solution and the Water phase Were interfaced by manual shaking(20 inversions). The total volume of the mixture Was 250 mL. A photolytically initiatedpolymerization Was carried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixture Was centrifuged (9 500 rpm, 2 h) and the supematant Was discarded. The particles Were incubated repeatedly first With ethanol, thenWith Water, and finally again With ethanol. After each incubation, the samples Were centrifuged(9 500 rpm, 2 h) and decanted. The absorbance of the supematant Was measured at 210 nm.Extractions Were repeated until the absorbance of the supematant Was < 0.05 absorbance units.Finally, the particles Were dried in vacuo ovemight. The particles tested positively in Kaiser°squalitative ninhydrin test, indicating the presence of free amino groups.

Example 4 demonstrates that the invention provides particles With free amino groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 5Synthesis of P0ly(PE T RA-co-MAA ) Particles A solution Was prepared by dissolving PETRA (0.04 M), methacrylic acid (MAA; 0.32M), and AIBN (0.04 M) in ethanol that had previously been purged With nitrogen gas for 10min. The solution Was then added to Water that had previously been purged With nitrogen gasfor l h. The solution and the Water phase Were interfaced by manual shaking (20 inversions).The total volume of the mixture Was 250 mL. A photolytically initiated polymerization Wascarried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT)for 2 h. The polymerized mixture Was centrifuged (9 500 rpm, 2 h) and the supematant Wasdiscarded. The particles Were incubated repeatedly first With ethanol, then With Water, andfinally again With ethanol. After each incubation, the samples Were centrifuged (9 500 rpm, 2h) and decanted. The absorbance of the supematant Was measured at 210 nm. Extractions Wererepeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, the particles Were dried in vacuo ovemight.

Example 6Synthesis of P0ly(PE T RA-c0-4- VBA) ParticlesA solution Was prepared by dissolving PETRA (0.04 M), 4-vinylbenzoic acid (4-VBA;0.04 M) and AIBN (0.04 M) in ethanol that had previously been purged With nitrogen gas for10 min. The solution Was then added to Water that had previously been purged With nitrogengas for l h. The solution and the Water phase Were interfaced by manual shaking (20 inversions).The total volume of the mixture Was 250 mL. A photolytically initiated polymerization Was carried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixture Was centrifuged (9 500 rpm, 2 h) and the supematant Wasdiscarded. The particles Were incubated repeatedly first With ethanol, then With Water, andfinally again With ethanol. After each incubation, the sample Was centrifuged (9 500 rpm, 2 h)and decanted. The absorbance of the supematant Was measured at 210 nm. Extractions Wererepeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, theparticles Were dried in vacuo ovemight.

Examples 5 and 6 demonstrate that the invention provides particles With free carboxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 7Synthesis of P0ly( T RIM-co-HEMA ) Particles A solution Was prepared by dissolving trimethylolpropane trimethacrylate (TRIM; 0.04M), 2-hydroxyethyl methacrylate (0.04 M), and AIBN (0.04 M) in ethanol that had previouslybeen purged With nitrogen gas for 10 min. The solution Was then added to Water that hadpreviously been purged With nitrogen gas for l h. The solution and the Water phase Wereinterfaced by manual shaking (20 inversions). The total volume of the mixture Was 100 mL. Aphotolytically initiated polymerization Was carried out under a DYMAX UV (350 nm) curingflood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixture Was centrifuged(9 500 rpm, 2 h) and the supematant Was discarded. The particles Were incubated repeatedlyfirst With ethanol, then With Water, and finally again With ethanol. After each incubation, thesample Was centrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematant Wasmeasured at 210 nm. Extractions Were repeated until the absorbance of the supematant Was< 0.05 absorbance units. Finally, the particles Were dried in vacuo ovemight.Example 7 demonstrates that the invention provides particles With free hydroxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 8Post-Polymerization Derivatization of P0ly(PE T RA) Particles with the PAL LinkerPoly(PETRA) particles Were prepared as described in Example 3. Fmoc-Gly-OH (0.595g, 2 mmol) Was dissolved in DMF (l mL) and added to the dried poly(PETRA) particles (200mg). N,N”-diisopropylcarbodiimide (DIPCDI; 0.252 g, 2 mmol) in DMF (l mL) and 4-dimethylaminopyridine (DMAP; 25 mg, 0.2 mmol) in DMF (l mL) Were added. The sample Was placed on a rotating shaker for 2 days. The particles Were centrifuged and repetitivelysuspended in DMF (5 times). Deprotection Was carried out by treatment With piperidine-DMF(2 x 10 min). The particles Were again Washed With DMF. Qualitative ninhydrin test (Kaisertest) Was positive. The PAL linker Was coupled by adding Fmoc-PAL-OH (0.99 g, 2 mmol) inDMF (3 mL), DIPCDI (0.252 g, 2 mmol) in DMF (1 mL) and l-hydroxybenzotriazole (HOBt;0.306 g, 2 mmol) in DMF (3 mL). The sample Was placed on a rotating shaker for 2 days. Theparticles Were centrifuged (9 500 rpm, 1 h) and Washed repeatedly With DMF and finally Withmethanol.

Example 8 demonstrates that the carboxyl-containing poly(PETRA) particles can be derivatizedafter polymerization to provide amino groups suitable for further derivatizations/couplings. Theparticles of Example 8, functionalized With a cleavable linker, are suitable as a solid-phase synthesis support.

Example 9Post-Polymerízatíon Derívatízatíon of Polj/(PE T RA-co-Allylamíne) Partícles with FIT CPoly(PETRA-co-allylamine) particles Were prepared as described in Example 4. FITC(fluorescein isothiocyanate; 5 mg) Was dissolved in ethanol (5 mL) and added to driedpoly(PETRA-co-allylamine) particles (100 mg). The sample Was placed on a rotating shakerfor 2 days. The particles Were centrifuged (9 500 rpm, 1 h) and Washed repeatedly With ethanol until the supematant Was colorless.

Example 10Post-Polymerízatíon Derívatízatíon of P0ly(PE T RA-co-Allylamíne) Partícleswith a Radíopaque DerívatíveN-succinimidyl 2,3,5-triiodobenzoate Was synthesized in 85% yield by reacting N-hydroxysuccinimide (l.266 g, 11 mmol), 2,3,5-triiodobenzoic acid (1.998 g, 10 mmol), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (2,108 g, 11 mmol) in methylene chloride (200mL). After 100 h, the solution Was extracted With Water (3 times) and saturated aqueous NaCl(3 times). The organic phase Was dried over MgSO4, evaporated, and dried in vacuum.Poly(PETRA-co-allylamine) particles Were prepared as described in Example 4. The particlesWere mixed With N-succinimidyl 2,3,5-triiodobenzoate in DMF. The particles Were centrifuged (9 500 rpm, 1 h) and Washed repeatedly With DMF and finally methanol.

Examples 9 and 10 demonstrate that the particles of the invention can be derivatizedWith fluorescent and radiopaque derivatives, making the particles suitable as imaging probes and contrast agents.

Example llPost-Polymerízatíon Derívatízatíon of P0ly(PE T RA-co-Allylamíne) Partícles with PE G Poly(PETRA-co-allylamine) particles Were prepared as described in Example 4. Theparticles (10 mg) Were dissolved in Water (l mL). Polyethylene glycol N-succinimidylpropionate (10 mg) Were dissolved in Water (0.25 mL) and added to the particles. The sampleWas placed on a rotating shaker for l day. The particles Were centrifuged (9 500 rpm, l h) andWashed repeatedly With methanol.

Example ll demonstrates that the particles of the invention can be derivatized With PEG, providing particles suitable for biomedical and medical applications.

Example 12Synthesis of Po1y(Trimethy1o1propane E thoxylate T ríacrylate) PartíclesThree different solutions, each containing a branched PEG-containing cross-linker (0.02M; Table 3) and AIBN (0.04 M), Were prepared by dissolving the respective cross-linker inethanol. Each solution (l volume part) Was then added to Water (19 Volume parts; previouslypurged With nitrogen gas for l h) and interfacing Was carried out by inverting the samplesmanually (shaking) approximately 20 times. The total volume of each mixture Was 1000 mL.Therrnolytically initiated polymerizations Were carried out in a 60 °C Water bath for 6 h. Thepolymerized reaction mixtures Were analysed by DLS, showing mean particle size and polydispersity index as indicated in TableTable 3. Composition, Size, and Polydispersity of Po1y(Trimethy1o1propane Ethoxylate Triacrylate) Particles(DLS, n=20) CmSSLínker Mea: gårëcrlgelfize Mean Polyiissrlašrsity IndexTrimethylolpropane Ethoxylate (1 EO/OH) Triacrylate 274 i 17 1.35 i 0.14Trimethylolpropane Ethoxylate (7/3 EO/OH) Triacrylate 162 i 4 1.18 i 0.05Trimethylolpropane Ethoxylate (14/ 3 EO/OH) Triacrylate 165 i 3 1.17 i 0.Example 13Synthesis of Poly( T rimethylolløropane Ethoxylate T riacrylate) Particles;Demonstration of the Applicabilitj/ of Various Interfacing Methods Solutions Were prepared by dissolving trimethylolpropane ethoxylate (7/3 EO/OH)triacrylate (0.0l M) and AIBN (0.02 M) in ethanol. Each solution (l volume part) Was thenadded to Water (9 volume parts; previously purged With nitrogen gas for l h). The solutions andthe Water phases Were interfaced by applying either (i) manual shaking (20 inversions); (ii) anIKA Labortechnik Eurostar digital overhead stirrer (IKA-Werke Gmbh & Co., Staufen,Gerrnany) equipped With a Heidolph TR 20 radial floW impeller operating at 1000 rpm for 30s; (iii) a model Dl25 basic dispersing device equipped With an S25N-25F dispersing element(IKA-Werke Gmbh & Co., Staufen, Gerrnany) operating at 8000 rpm for 30 s. The total volumeof each mixture Was 100 mL. Photolytically initiated polymerizations Were carried out under aDYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT) for 2 h. Thepolymerized reaction mixtures Were analysed by DLS (n=20), shoWing mean particle size and polydispersity index as indicated in TableTable 4. Influence of Interfacing Method on Size and Polydispersity of Poly(Trimethylolpropane EthoxylateTriacrylate) Particles Interfacing Method Mean Particle Size i SD (nm) Mean Polydispersity Index i SDManual shaking (20 inversions) 170 i 4 1.22 i 0.11Overhead stirrer (1000 rpm, 30 s) 177 i 8 1.29 i 0.12Disperser/homogenizer (8 000 rpm, 30 s) 188 i 5 1.20 i 0.09ExampleSynthesis of Poly( T rimethylolløropane E thoxylate T riacrylate-co-HEMA ) Particles A solution Was prepared by dissolving trimethylolpropane ethoxylate (7/3 EO/OH)triacrylate (0.0l8 M), 2-hydroxyethyl methacrylate (0.0l8 M), and AIBN (0.0l8 M) in ethanol.The solution (l volume part) Was then added to Water (9 volume parts; previously preheated to60 °C and purged With nitrogen gas for l h). The solution and the Water phase Were interfacedby inverting the sample manually (shaking) approximately 20 times. The total volume of themixture Was 250 mL. A therrnolytically initiated polymerization Was carried out in a 60 °CWater bath for 6 h. The polymerized reaction mixture Was analysed by DLS (intensity mode;n=l0), shoWing a mean particle size of 366 i l7 nm.

Example 14 demonstrates that the invention provides particles With free hydroxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 15Synthesis of P0ly(PE T RA-co-PE GMAA ) A solution Was prepared by dissolving PETRA (0.04 M), poly(ethylene glycol)methacrylate (PEGMAA; 0.08 M), and AIBN (0.08 M) in ethanol that had previously beenpurged With nitrogen gas. The solution (1 Volume part) Was then added to Water (39 Volumeparts; previously preheated to 60 °C and purged With nitrogen gas for 1 h). The solution andthe Water phase Were interfaced by inverting the sample manually (shaking) approximately 20times. The total Volume of the mixture Was 500 mL. A therrnolytically initiated polymerizationWas carried out in a 60 °C Water bath for 6 h. The polymerized mixture Was centrifuged (9 500rpm, 2 h) and the supematant Was discarded. The particles Were incubated repeatedly first Withethanol, then With Water, and finally again With ethanol. After each incubation, the sample Wascentrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematant Was measured at210 nm. Extractions Were repeated until the absorbance of the supematant Was < 0.05absorbance units. Finally, the particles Were dried in vacuo ovemight. The dried particles Weredissolved in Water for DLS analysis (intensity mode; n=l0), shoWing a mean particle size of250 i 15 nm.

Examples 12-15 demonstrate that the method of the inVention can be applied to thepreparation of PEG-containing particles. These particles are biocompatibility and suitable for biomedical and medical applications.

Example 16Synthesis of Polymer Partícles by T híol-Ene Polymerízatíon of PE T MP and TA TA TOA solution Was prepared by dissolving pentaerythritol tetrakis(3-mercaptopropionate)(PETMP; 20 mM), 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATATO; 26 mM),and AIBN (8 mM) in ethanol. One Volume part of the solution Was added to 39 Volume partsof 60 °C pre-heated Water. The solution and the Water phase Were interfaced by manual shaking(20 inversions). Polymerization Was carried out at 60 °C for 2 h. The polymerized reaction mixture Was analyzed by DLS, showing a mean particle size of 490 i 35 nm.

Example 17Synthesis 0f Polymer Partícles by T híol-Ene Polymerízatíon 0f PE T MP and PETRAA solution Was prepared by dissolving pentaerythritol tetrakis(3-mercaptopropionate)(PETMP; 20 mM), PETRA (26 mM), and AIBN (8 mM) in ethanol. One Volume part of thesolution Was added to 39 volume parts of 60 °C pre-heated Water. The solution and the Waterphase Were interfaced by manual shaking (20 inversions). Polymerization Was carried out at 60°C for 2 h. The polymerized reaction mixture Was analyzed by DLS, showing a mean particle size of 348 i 48 nm.

Example 18Synthesis 0f Polymer Partícles by T híol-Ene Polymerízatíon 0fPE T MP and PETRA under the Influence 0f a QuencherA solution Was prepared by dissolving pentaerythritol tetrakis(3-mercaptopropionate)(PETMP; 20 mM), PETRA (26 mM), and AIBN (8 mM) in ethanol. One Volume part of thesolution Was added to 39 Volume parts of 60 °C pre-heated Water. The solution and the Waterphase Were interfaced by manual shaking (20 inversions). Polymerization Was carried out at 60°C during a total time of 2 h. After 50 min, 3-mercaptopropionic acid Was added to a finalconcentration of 2 mM in the mixture. The polymerized reaction mixture Was analyzed by DLS, showing a mean particle size of 280 i 17 nm.

Example 19Synthesis 0f Polymer Partícles by T híol-Ene Polymerízatíon 0fPETMP, PETRA, and benzyl methacrylate A solution Was prepared by dissolving pentaerythritol tetrakis(3-mercaptopropionate)(PETMP; 1.25 mM), PETRA (2.5 mM), benzyl methacrylate (5 mM), and AIBN (5 mM) inethanol. One volume part of the solution Was added to 1.5 Volume parts of Water of roomtemperature. The solution and the Water phase Were interfaced by manual shaking (20inversions). The total Volume Was 500 mL. Polymerization Was carried out at 60 °C for 2 h.The polymerized reaction mixture Was analyzed by DLS, shoWing a mean particle size of 430i 14 nm.

Examples 16-19 demonstrate the preparation of particles by thiol-ene polymerization.

Claims (12)

1. A polymer particle of a size of about 10 to 1000 nm prepared from a nucleated composition, formedspontaneously and instantaneously in absence of surfactant, stabilizer, or dispersant and Without extended agitation, and comprising a monomer of the following forrnula (1):

2. Wherein; (a) X is -CH2-, -O-CHz-CHr, -O-CH2~CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Y is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CHz, -O-CH=CHz, -O-CH2-CH=CH2, -CH=CHz,-CHz-CH=CHz, -O-C(O)-CHz-CHz-SH, -NH-C(O)-CHz-CHz-SH, or SH; (c) Z is -CHg-Xp-Y, a hydrogen, a functional group, an alkyl group, or a functionalized alkylgroup; and (d) each of l, m, n, and p is independently a number in the range 0-2. The polymer particle of claim 1 Wherein the nucleated composition further comprises a monomer.

3. The polymer particle of claim 2 Wherein said monomer contains a functional group selected fromthe group consisting of the amino group, the hydroxyl group, the carbonyl group, the aldehyde group,the haloforrnyl group, the carboxyl group, the carboxylate group, the ester group, the carbonate estergroup, the amide group, the imine group, the imide group, the azide group, the azo group, thehydrocarbyl group, the aromate group, the halo group, the cyanate group, the nitrate group, the nitrilegroup, the nitrite group, the nitro group, the nitroso group, the pyridyl group, the oxime group, thethiol group, the sulfide group, the disulf1de group, the sulfinyl group, the sulfonyl group, the sulfinogroup, the sulfo group, the thiocyanate group, the thioketone group, the thio ester group, thephosphino group, the phosphono group, the phosphate group, the borono group, the boronate group, the borino group, and the borinate group.

4. The polymer particle of any of the previous claims Wherein the nucleated composition is formed byinterfacing a Water phase and a solution comprising said monomer(s) dissolved in a Water-miscible solVent.

5. A process for preparing a polynier particle of about 10 to 1000 nn1, coniprising the steps: (a) providing a n1onon1er of the following forrnula (1): (1)Wherein; (i) X is -CH2-, -O-CHg-CHT, -O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-; (ii) Y is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CH2, -O-CH=CH2, -O-CH2-CH=CH2, -CH=CHz,-CHz-CH=CHz, -O-C(O)-CHz-CHz-SH, -NH-C(O)-CHz-CHz~SH, or SH; (iii) Z is -CHg-Xp-Y, a hydrogen, a functional group, an alkyl group, or afunctionalized alkyl group; and (iv) each of l, ni, n, and p is independently a number in the range 0-(b) dissolVing said n1onon1er in a Water-niiscible solVent, forrning a solution coniprising then1onon1er; (c) interfacing said solution and a Water phase, in absence of surfactant, stabilizer, or dispersantand Without extended agitation, to forrn a niixture in Which spontaneous and instantaneousforrnation of nucleated droplets con1prising said n1onon1er takes place; and (d) polynierizing said n1onon1er by a polynierization reaction.

6. The process of claini 5 Wherein said solution further coniprises a n1onon1er.

7. The process of claini 6 Wherein said n1onon1er contains a functional group selected from the groupconsisting of the an1ino group, the hydroxyl group, the carbonyl group, the aldehyde group, thehaloforrnyl group, the carboxyl group, the carboxylate group, the ester group, the carbonate ester group,the an1ide group, the in1ine group, the in1ide group, the azide group, the azo group, the hydrocarbylgroup, the aron1ate group, the halo group, the cyanate group, the nitrate group, the nitrile group, thenitrite group, the nitro group, the nitroso group, the pyridyl group, the oxinie group, the thiol group, thesulf1de group, the disulf1de group, the sulfinyl group, the sulfonyl group, the sulfino group, the sulfo group, the thiocyanate group, the thioketone group, the thio ester group, the phosphino group, thephosphono group, the phosphate group, the borono group, the boronate group, the borino group, andthe borinate group.

8. The process of claim 5 Wherein said Water-miscible solvent is selected from a group of solventsconsisting of methanol, ethanol, l,2-ethanediol, l-propanol, 2-propanol, l,2-propanediol, 1,3-propanediol, l-butanol, 2-butanol, l,2-butanediol, l,3-butanediol, l,4-butanediol, l-pentanol, 2-pentanol, 3-pentanol, l,2-pentanediol, l,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, l,4-pentanediol, l,5-pentanediol, glycerol, erythritol, pentaerythritol, furfuryl alcohol, diethylene glycol,triethylene glycol, tetraethylene glycol, pentaethylene glycol, acetonitrile, N,N-dimethylforrnamide,dimethyl sulfoxide, acetone, acetic acid, acetaldehyde, hexamethylphosphoric triamide,dimethoxyethane, l,4-dioxane, N-methyl-2-pyrrolidone, pyridine, tetrahydrofuran, or combinations thereof.

9. The process of claim 5 Wherein said interfacing step is augmented by a mixing procedure selectedfrom the group of mixing procedures comprising batch-Wise mixing methods including mixing byturbulent addition, mixing by manual inversion, mixing by automated inversion, mixing by manualshaking, mixing by automated shaking, mixing using a vortexer, mixing by ultrasonic treatment, mixingusing a magnetic stirrer, mixing using an overhead stirrer, mixing using a blender, mixing using adisperser device, and mixing using a homogenizer, flow system mixing methods including mixing usinga static mixer, mixing using a microfluidic mixer, mixing using a micromixer, continuous-flow capillarymixing, microfluidic mixing using Y junctions, microfluidic mixing using T junctions, and mixing usingvarious three- or four-Way intersections or connectors, mixing by devices produced by microfabricationor 3D-printing, and industrial scale mixing devices including impellers, turbines, anchors, helicalribbons, high-shear dispersers, ribbon blenders, paddle mixers, double cone blenders, static mixers, liquid Whistles, dispersion mixers, mixing paddles, and continuous-flow mixers.

10. l0. The process of claim 5 Wherein said polymerization reaction is a free-radical polymerization.

11. ll. The process of claim 5 Wherein said polymerization reaction is a thiol-ene polymerization.

12. The process of any of claims 5-ll Wherein said mixture is comprised of at the most about 20 mass percent of the Water miscible solvent and at the most about l mass percent of the monomer.