DD296497A5 - METHOD FOR THE PRODUCTION OF STAR COPOLYMERS - Google Patents

Abstract

The copolymers described are represented by general formula (I), in which either PA = a vinylaromatic or methacrylic polymer sequence; PB = an acrylic polymer sequence; and PC, possibly present, a methacrylic polymer sequence; or PA and PC = a polymer sequence stemming from the same acrylic monomer; and PB = a methacrylic polymer sequence; PD = a vinylaromatic or methacrylic polymer sequence, and simultaneously PE = an acrylic polymer sequence; or PD = an acrylic polymer sequence, and simultaneously PE = a methacrylic polymer sequence; n = number of branches of (PA-PB-PC), between 2 and 20 inclusive and m = number of branches of (PD-PE) between 0 and 18 inclusive, with n+m </= 20, each branch (PA-PB-PC) and (PD-PE) comprising only one polymer sequence, the two sequences then being different; and N = cross-linked nodule of at least one multifunctional reticulation monomer presenting at least two double polymerisable bonds per molecule. Application: either thermoplastic elastomers, shock type rigid thermoplastic polymers or shock type reinforcement polymers.

Description

Field of application of the invention

The invention relates to a process for the preparation of star copolymers, in particular based on vinyl aromatic blocks and / or methacryl blocks and acrylic blocks.

Characteristic of the known state of the art

Heterophasic material currently represents a focus of interest within the polymer sciences and the copolymer blocks of a linking family thereof are of particular interest. The microphase separation, which is caused by copolymers containing immiscible blocks, is the cause of novel, interesting and sometimes surprising properties, and is also dependent on the particular morphology of the phases. Their possibilities have been impressively illustrated by the discovery and industrial development of thermoplastic elastomers.

For several years, interest has been focused, inter alia, on macromolecules which have a particular topochemistry, such as those of star polymers. The methods for anionic homogeneous-phase polymerization leading to polymer chains end-capped with organometallic ends (living polymers) have been used in particular for the synthesis of star macromolecules. Here, "living" monocarbanionic polystyrenes are reacted with electrophilic polyfunctional compounds, examples being SiCl ₄ , trichloromethylbenzene compounds or phosphonitrile chloride, with which Morton et al., J. Polymer., 57, 471 (1962) and other authors describe the preparation of star Later, J.-G. Zilliox et al., J. Polymer Sei.: Part C, No. 22, pp. 145-156 (1986), carried out an anionic block copolymerization using as its second monomer a The resulting macromolecules consist of a crosslinked core surrounded and protected by a variety of solvated linear chains, European Patent Application No. 0274318 describes a system with which the anionic "living" polymerization of acrylic or methacrylic monomers, optionally with vinyl monomers and ins special with bulky acrylates, such as tert-butyl acrylate, can control. This system is based on the complex formation between the ion pairs of a classical initiator such as sec-butyllithium and a ligand or complexing agent with adapted steric and electronic characteristics. Cyclic polyethers (or crown ethers) and cyclic polythioethers belong to these ligands and enable a fast and quantitative, perfect "living" polymerization, inter alia, with tert-butyl acrylate In the US Patent 4767824 a further ligand is a salt of an alkali or alkaline earth metal a mineral acid such as lithium chloride.

The Applicant has been able to show that these systems of starters and ligands are applicable to a synthesis of star copolymers. These star copolymers, the composition of which is selected from blocks having soft, semi-solid or solid properties depending on the particular function of the resulting copolymer, exhibit more favorable theological behavior than the corresponding linear block copolymers in that they are less viscous. International Patent Application WO 86/00626 describes the preparation of star polymers comprising acrylic blocks by means of polymerization techniques for group transfer according to the "arm-first", "core-first" or "poor-core-arm" method (in US Pat corresponding example 8, the international patent application describes the preparation of a star copolymer of the general formula (PBu-PMMA4h-N by means of the "core-firsf" technique):

The synthesis of copolymers with acrylic and methacrylic blocks wherein the other monomer has no conjugated carbonyl group (styrene, substituted styrene, etc.) can not be accomplished by this technique. However, this is possible according to the invention.

The synthesis of star copolymers whose arms comprise two or three blocks, and wherein an acrylate-type monomer is polymerized in the first pass, followed by polymerization with a methacrylate monomer, in other words, the methacrylate polymerization initiated by polyacrylate anions is known Help of this technique also not feasible. According to the invention, a tert-butyl polyacrylate anion can act as an initiator for the methacrylate monomer and vice versa.

Object of the invention

The aim of the invention is the provision of novel star copolymers.

Explanation of the essence of the invention

The invention is based on the object, a process for the preparation of star copolymers of the general formula I.

(PA-PB-PC) _n

(PD-PE)

-N (I)

to provide in which

PA represents a polymer block of at least one monomer A selected from aromatic vinyl monomers and methacrylic monomers;

PB represents a polymer block of at least one acrylic monomer B; and

PC, if present, represents a polymer block of at least one monomer C selected from methacrylic monomers;

PA and PC each represent a polymer block of the same acrylic monomer; and

PB represents a polymer block of at least one monomer B selected from methacrylic monomers;

- PD represents a polymer block of at least one monomer D selected from aromatic vinyl monomers and methacrylic monomers and at the same time PE represents a polymer block of at least one acrylic monomer E; or PD represents a polymer block of at least one acrylic monomer D and at the same time PE represents a polymer block of at least one methacrylic monomer E;

- η denotes the number of branches (PA-PB-PC) and has a value of 2 to 20 inclusive, andm designates the number of branches (PD-PE) and takes a value of 0 to 18, with the proviso that the sum η + m does not exceed 20;

each of the branches (PA-PB-PC) and (PD-PE) may further comprise only a single polymer block, the two blocks being different and containing one acrylic monomer and the other monomer selected from vinyl aromatic monomers and methacrylic monomers; and

- N represents a crosslinked core of at least one polymerized monomer Mr, wherein the monomer Mr consists of a multifunctional crosslinking agent which contains at least two polymerizable double bonds per molecule.

Examples of the vinyl aromatic monomers used in the star copolymers according to the invention are: styrene, substituted styrenes, such as e.g. A-methylstyrene, 4-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3 methylstyrene, 3-tert-butylstyrene, 2,4-dichlorostyrene and 2,6-dichlorostyrene; 1-vinylnaphthalene and mixtures of these monomers. Particularly noteworthy are styrene and α-methylstyrene.

Examples of the methacrylic monomers used in the star copolymers according to the invention are: alkyl methacrylates whose alkyl radical is optionally substituted, for example by at least one halogen atom such as fluorine or chlorine, and / or at least one hydroxyl group, and having 1 to 18 carbon atoms, e.g. the preferred methyl methacrylate, and 2,2,2-trifluoroethyl, n-propyl, isopropyl, η-butyl, sec-butyl, tert-butyl, n-amyl, i-amyl, hexyl -, ethyl, ethyl-2-hexyl, cyclohexyl, octyl, i-octyl, decyl, .beta.-hydroxyethyl, hydroxypropyl and hydroxybutyl methacrylates; glycidyl methacrylate; norbornyl; isobornyl; methacrylonitrile; Dialkylmethacrylamide and mixtures of these monomers. Examples of the acrylic monomers used in the star copolymers according to the invention are: primary, secondary or tertiary alkyl acrylates whose alkyl group is optionally substituted, e.g. by at least one halogen atom, such as chlorine or fluorine, and / or at least one hydroxyl group and after protection of this hydroxyl group contains 1-18 carbon atoms. Particular mention may be made here of ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, tert-butyl acrylate, ethyl 2-hexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate and isodecyl acrylate. Also applicable are phenyl acrylate, norbornyl acrylate, isobornyl acrylate and alkylthioalkyl or alkoxyalkyl acrylates, especially methoxy and ethoxyethyl acrylates, and also acrylonitrile and dialkylacrylamides.

In particular, the crosslinking monomer Mr may be selected from the polymethyl acrylates and polyacrylates of polyols such as the alkylene glycol dimethacrylates, e.g. Ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate and propylene glycol dimethacrylate; the alkylene glycol diacrylates, such as. Ethylene glycol diacrylate, 1,3- or 1,4-butylene glycol diacrylate, trimethylolpropane trimethacrylate; and vinyl methacrylate and vinyl acrylate.

The branches (PA-PB-PC) and optionally the branches (PD-PE) of the star copolymer according to the invention, based on 100 parts by weight of the copolymer, about 80-98Gew.-parts and the core N is about 20-2Gew . parts. The star block copolymers of the present invention may have an average molecular weight of about 1,000-500,000 per block. Their polydispersity index is also about 1.1 to 2.

According to one embodiment of the present invention, the blocks formed from a sequence of acrylic and / or methacrylic monomers, as defined above, may be hydrolyzed to a corresponding acrylic acid and / or methacrylic acid block, which block may then optionally be added to the corresponding alkali acrylate and / or methacrylate acid block. or methacrylate sequence is saponified. According to another embodiment of the present invention, the blocks formed by a sequence of acrylic and / or methacrylic monomers as defined above may have been transesterified to another block of acrylic and / or methacrylic monomers, for example by passing a tertiary or secondary acrylate through replaced primary acrylate

 The present invention also provides a process for the preparation of a star copolymer of the general formula:

(PA-PB-PC)

-iN (PD-PE) _m

PA, if present, is a polymer block of at least one monomer A selected from vinyl aromatic monomers and methacrylic monomers;

PB represents a polymer block of at least one acrylic monomer B; and PC, if present, represents a polymer block of at least one monomer C selected from methacrylic monomers;

PA and PC each represent a polymer block of the same acrylic monomer; and PB represents a polymer block of at least one monomer B selected from methacrylic monomers; PD represents a polymer block of at least one monomer D selected from aromatic vinyl monomers and methacrylic monomers and at the same time PE represents a polymer block of at least one acrylic monomer E; or PD represents a polymer block of at least one acrylic monomer D and at the same time PE represents a polymer block of at least one methacrylic monomer E;

η denotes the number of branches (PA-PB-PC) and has a value of 2 to 20 inclusive, and m designates the number of branches (PD-PE) and assumes a value of 0 to 18 inclusive, provided that the sum η + m does not exceed 20;

each of the branches (PA-PB-PC) and (PD-PE) may further comprise only a single polymer block, the two blocks being different and containing one acrylic monomer and the other monomer selected from vinyl aromatic monomers and methacrylic monomers; and

N represents a crosslinked core of at least one polymerized monomer Mr, the monomer Mr consisting of a multifunctional crosslinking agent containing at least two polymerizable double bonds per molecule, characterized in that

1. an anionic polymerization of at least one monomer A by means of an initiator system, consisting of at least one monofunctional starter of the general formula:

(R) _p -M (II)

wherein

My alkali or alkaline earth metal, with a valence ρ of 1 or 2; and R represents a straight-chain or branched alkyl radical having 2 to 6 carbon atoms or an optionally substituted aryl radical, or an alkyl radical having 1 to 6 carbon atoms which is substituted by at least one phenyl group;

and optionally at least one ligand selected from alkali or alkaline earth metals, organic alkali metal salts and macrocyclic nitrogen-free chelating agents to obtain a living (living type) chain portion of the block polymer PA ";

2. reacting this chain portion with at least one monomer B in the presence of at least one of the above-defined ligands to obtain a living Biblock copolymer of the formula (PA-PB) ";

3. reacting this living Biblock copolymer with at least one monomer C in the presence of at least one of the above-defined ligands to obtain a living triblock copolymer of the formula (PA-PB-PC), wherein step (3) is omitted and the process can be started by carrying out the step (1) with the monomer B, or by forming only one of the living blocks PA "or PB" or PC ;

4. if appropriate, forms a living Biblock copolymer of the general formula (PD-PE) "by carrying out steps (1) and (2) using at least one monomer D and at least one monomer E, or a living block PD" or PE "forming step (1) with the monomers D or E;

5. the living copolymer (PA-PB-PC) ", (PA-PB)" or (PB-PC) "or the living block PA", PB "or PC", optionally mixed with the living Biblock copolymer ( PD-PE) "or the living block PD" or PE "prepared according to step (4) in an environment which promotes the performance of their anionic polymerization with at least one

Reacting monomer Mr in a 4- to 26-fold molar excess per reactive center and deactivating the double bonds by reaction with a proton source, in particular consisting of an alcohol, water or a protonic acid; and

6. optionally carries out a transesterification of the resulting star copolymer in an acidic medium. The monofunctional initiators of the general formula (II) used in Example (1) are, for example, sec-butyl lithium, n-butyl lithium and α-methylstyryllithium, 1,1-diphenylhexyllithium, diphenylmethyllithium or sodium or potassium and S-methylphenyllithium. If the block PA consists of a vinylaromatic monomer, the starter selected is sec-butyllithium, n-butyllithium and α-methylstyryllithium.

The ligand is on the one hand selected from mineral salts of alkali or alkaline earth metals, such as. Chlorides, fluorides, bromides, iodides, borides, sulfates, nitrates and borates, and on the other hand, organic alkali metal salts, e.g. the alcoholates, the carboxylic acid esters substituted in the α-position by the metal and the compounds in which the alkali metal is associated with one of the following groups:

(A) the groups of the general formula:

0-CR ₁ (III)

wherein R _{1 represents} a straight-chain or branched alkyl radical having 1-20 carbon atoms or a cycloalkyl radical having 3-20 carbon atoms or an aryl radical having 6-14 carbon atoms;

(B) the groups of the general formula:

OC - (- CYZ -) - СН _д Х ₃ -я (IV)

wherein

Y and Z are the same or different and are selected from a hydrogen atom and halogen atoms; ρ is an integer value of 0-4;

X represents a halogen atom; and

q means an integer value of 0-2;

(C) the groups of the general formula:

0-SO ₂ -CT ₃ (V)

wherein T is selected from a hydrogen atom and halogen atoms; and

(D) the groups of the general formula:

B (R ₂ ) ₄ (VI)

wherein R _{2 is} selected from a hydrogen atom and alkyl and aryl radicals.

Examples of groups of the general formula (III) are acetate, propionate and benzoate groups. Examples of groups of the general formula (IV) are α-bromoacetate and trifluoroacetate groups. Examples of groups of the general formula (V) are trifluoromethanesulfone and methanesulfone groups. Examples of groups of the general formula (VI) are borohydride and tetraphenylboride groups.

The ligand may also consist of a macrocyclic, nitrogen-free complexing agent selected from cyclic polyethers (also known as "crown ethers") and cyclic polythioethers, especially macrocyclic polyethers whose macrocyclic ring contains at least 14 carbon and oxygen atoms, each Oxygen atom is separated from the other oxygen atoms of the ring by 2 or 3 carbon atoms. Such macrocyclic polyethers have already been described in US Pat. Nos. 3,687,778 and 4,826,941, the contents of which are hereby incorporated by reference.

In the method according to the invention, the proportion of the ligand used with respect to the initiator in step (1) can vary widely. This amount may for example be present in large excess with respect to the molar amount of the initiator. This amount can also be equal to or less than the molar amount of the initiator. Preferably, the ligand, based on the initiator, is used in a molar amount of at least 1 to about 50.

In the process according to the invention, the polymerization steps (1) to (5) are carried out with the exclusion of moisture and oxygen and in the presence of at least one solvent, which is preferably selected from aromatic solvents, such as. As benzene and toluene or tetrahydrofuran, diglyme, tetraglyme or o-terphenyl, biphenyl, decalin, tetralin or dimethylformamide.

The polymerization or copolymerization temperature ranges from about -78 ⁰ C to 0 ⁰ C, preferably in the range of about -78 ° C.bis-20 ° C.

The copolymers of the invention can at a temperature in the range of 7O ⁰ C to about 170 ⁰ C, under a pressure of 1-15 bar and in the presence of 0.5 to about 10 wt .-%, based on the copolymer, of an acid catalyst such as Paratoluene sulfonic acid, methantoluenesulfonic acid or hydrochloric acid, in a polar solvent, such as. As dioxane, be hydrolyzed. After hydrolysis, the copolymers have acrylic acid and / or methacrylic acid sequences and can be precipitated in heptane, then filtered, washed to remove traces of catalyst and finally dried. Finally, the compounds can also be neutralized with potassium methoxide or with tetramethylammonium hydroxide in solution in a mixture of toluene and methanol to obtain the corresponding ionomeric triad blocks. If the copolymers according to the invention comprise a block derived from a tertiary or secondary alkyl acrylate, this block can also be transesterified in a known manner to give a block of primary alkyl acrylate.

Block polymers of vinyl aromatic monomers and polymethyl methacrylate star copolymers of the present invention are hard-material blocks. Blocks of polyalkyl methacrylate wherein alkyl is not methyl may be referred to as semi-rigid or semi-soft blocks; Blocks of polyalkyl acrylate form soft blocks, with aging stability. Depending on the content of rigid, soft and semi-rigid blocks are obtained as star polymers according to the invention thermoplastic elastomers (with a content of 60-90Gew .-% of soft acrylic blocks), which are particularly suitable for the production of injection molded parts; thermoplastic hard polymers (containing about 10-50% by weight of soft sequences) and reinforcing polymers for different thermoplastic matrices (containing 40-80% by weight of soft blocks

 The following examples serve to illustrate the present invention without limiting it.

In the examples:

St = styrene

Ci-MeSt = a-methylstyrene

tBA = tert-butyl acrylate

nBA = n-butyl acrylate

MMA = methyl methacrylate

BMAE = ethylene glycol bismethacrylate (H ₂ C = C (CH ₃ ) COOCH ₂ ) 2

APTS = p-toluenesulfonic acid monohydrate

THF = tetrahydrofuran.

In all examples, the exclusion chromatography is performed using a WATERS GPC 501 apparatus equipped with two linear columns, operating with tetrahydrofuran as eluent at a flow rate of 1 ml / min. The mean molecular weights were determined using a membrane osmometer HP 502.

embodiments

Examples 1 to 7 General Procedure

The synthetic route can be schematized as follows:

sec.-BuL i CX ₄ -MeSt tBA

_St __PSt * Li ⁺ (LiCl)> (PSt-PtBA) 4i ⁺ (LiCl)

LiCl

BMAE H ⁺

(PSt-PtBA) -PBMAE

The solvents and styrene monomer are purified by conventional anionic polymerization techniques.

The acrylic monomers are treated sequentially with calcium hydride and triethylaluminum.

The styrene polymerization is started in THF at -78 ° C. with the aid of an organolithium compound which is obtained by reacting sec-butyllithium with a-MeStin in a slight molar excess (10X) in the presence of 5 mol of LiCl per mole of organolithium compound.

After 15 minutes at -78 ° ^C. , tert-butyl acrylate is added to the reaction medium via metal lines under an inert gas atmosphere. The anionic block copolymerization with tert-butyl acrylate is carried out within 2 h in THF at -78 ⁰ C.

The living BIBLOCK copolymer thus obtained (PSt-PtBA) ^- Li ⁺ is then coupled at -78 ⁰ C, by adding to BM AE in 4- to 26fachem molar excess, based on the active Organolithiumzentren, added there and at least 2 h to react leaves. The copolymer solution is then stirred in a large excess of methanol, the precipitate is washed, filtered and dried at 100 ⁰ C. This gives a star block copolymer with a variable number of side chains (n equal to 2 to 6).

In order to give the material the properties of a thermoplastic elastomer, the block PtBA is transesterified to PnBA.

The transesterification reaction takes place under acid catalysis with the aid of APTS.

In a coolable flask and under an inert gas atmosphere, a precisely weighed amount of the star copolymer is dissolved in a mixture of toluene / n-butanol. The amount of n-butanol corresponds to at least a three-fold molar excess, based on dietBA units.

After dissolution, the amount of APTS required for quantitative transesterification of the acrylic block is added (corresponding to 3-5 mol%, based on PtBA). The solution is then heated for 5 hours at reflux temperature (~ 100Ό.

After the reaction, stir the solution of the star block polymer (PSt-PnBA4n-PBMAE in large excess of methanol / H ₂ O (50/50).) The precipitate is washed and filtered The precipitation step is repeated twice to completely eliminate catalyst traces ,

The final product is then dried at 100 ° C under reduced pressure. The yield of the transesterification reaction is determined by proton NMR and by differential thermal analysis.

- There is a disappearance of the peak for the tert-butyl group at 1.39 ppm and the appearance of a peak for CH _{2 of} the ester group n-BA at 4 ppm.

- At -45 ° C is a glass point, observed due to the block PnBA, while at about + 45 ° C, the glass point, due to the block PtBA disappears.

Under the conditions given above, the yield of the esterification reaction is about 95%. The remaining 5%

consist of acrylic acid units, which can then be neutralized.

Table I below shows the characteristic properties of the various products.

Table I

Ex. Mn 90000 Mn t BA Mw / M η Mole BMAE η % PSt PTBA 70000 PtBA Wt .-% PSt RBA Mol sek. BuLi coupling * 66000 * # * * 1 65000 63000 70.5 1.05 9.0 4.5 86 2 49000 57000 76.0 1.10 9.6 5.5 87 3 120000 47000 67.0 1.10 4.0 4.5 76 4 64000 40000 68.5 1.20 26.0 6.0 80 5 39500 76 1.08 8.7 4.2 82 6 90000 80 1.06 9.0 3.7 80 7 51000 82 1.05 7.2 3.7 92

* These values were determined by gel exclusion chromatography

* * These values were determined by ¹ H-NMR.

Table II shows the mechanical properties of the copolymers according to Examples 1, 2, 3 and 5 after transesterification

Table M

Ex. polymer breakdown voltage elongation (PSt-PnBA) _n PBMAE * # ** ST "N / mm ² (kg / mm ² ) εΤ (%) 1 27-63 10.8 (1.1) 416 2 13-57 10.8 (1.1) 373 3 19- ^ 17 9.8 (1.0) 417 5 9.5 to 39.5 12.7 (1.3) 530

* These values were determined by stress-strain curves at a pulling speed of 2 cm / min

* · M η χ 1СГ ³ .

Example 8 General implementation

sec-BuLi

t BA

MMA

- »PMMA Li (LiCl)

(PMMA-PtBA) 'Li (LiCl)

BMAE H

LiCl

(PMMA PtOA) ^ - PBMAE

The solvents are purified by conventional anionic polymerization techniques. The acrylic monomers are treated sequentially with calcium hydrate and triethylaluminum. The first block PMMA is started in THF at -78 ° C. by an organolithium compound which is obtained by allowing sec-butyllithium to react with Me-MeSt in a slight molar excess in the presence of 5 mol of LiCl per mole of organolithium compound. After a polymerization time of 1 hour at - 78 ° C., tBA using metal lines added under inert atmosphere to the reaction medium and executes the anionic block copolymerization with the second monomer within 1 h in THF at -78 ^0C.

The coupling of the living bi-block copolymer (PMMA-PtBA) ~Lr obtained with BMAE and its recovery takes place under the conditions described for Examples 1 to 7. The PtBA block is then transesterified to PnBA. The transesterification reaction is carried out by acid catalysis with the aid of APTS as described for Examples 1 to 7

 Under these conditions, the PMMA block remains intact and the yield of the transesterification reaction, as in the previous examples, is about 95%.

 Table III below shows the characteristics of a product prepared under these conditions.

Table III

Ex. Mn Mn t BA M w / M η MoIBMAE η % PMMA PTBA PtBA * Wt .-% PMMA PtBA Molsek.-BuLi * coupling 8th 56000 41000 65 1.08 5.6 4.1 67

* These values were determined by gel exclusion chromatography

** These values were determined by ¹ H-NMR.

Table IV shows the mechanical properties of the product according to Example 8 after transesterification. Table IV

Ex. Polymer Breaking stress Elongation at break

(PMMA-PnBA) _n PBMAE · *

c77 N / mm ² (kg / mm ² ) ε ~ Γ (%)

8 15-41 12.7 (1.3) 460

* These values were determined by stress-strain curves at a pulling speed of 2cm / min. "Μ7Γ χ кг ³ .

Examples 9 and 10 General implementation

sec. -BuLi

S t> PS t * L i ⁺ > (PSt-PtBA) * Li ⁺ (LiCl)

t BA

> PS t * L i ⁺ LiCl

MMA

(PSt-PtBA-PMMA) 4i ⁺ (LiCl)

BMAE H ⁺

3 »i> (PSt-PtBA-PMMA) PBMAE

The three monomers St, tBA and MMA are polymerized sequentially using the experimental conditions described for Examples 1-8.

The resulting living triplet block copolymer (PSt-PtBA-PMMA) ^- Li ⁺ is then coupled to BMAE using the techniques described for the previous examples.

To impart the properties of a thermoplastic elastomer to the material, the PtBA block is then transesterified to PnBA using the conditions described in Examples 1-8.

Table V below shows the characteristics of the products produced in this way.

Table V

Ex. Mn Mn Mn t BA Mw / M η Mole BMAE η % PSt PtBA PMMA PSt PTBA PtBA * Wt .-% PSt PtBA PMMA Molsek.-BuLi coupling 9 10 160000 101000 145000 86000 120000 63500 72 60 1.1 1.07 6.0 5.6 5.0 4.4 60 77

* These values were determined by gel exclusion chromatography

* * These values were determined by ¹ H-NMR.

Table VI below shows the mechanical properties of the product obtained according to Example 10 after transesterification.

Table VI Polymer (PSt-PtBA-PMMA) _n PBMAE * # Elasticity limit σ ~ 7 N / mm ² (kg / mm ² ) * Breaking stress σ ~ 7 N / mm ² (kg / mm ² ) » Breaking strain εΤ (%) * Ex. 22,5-63,5-15 8.83 (0.90) 12.36 (1.26) 235 10

* These values were determined by stress-strain curves at a pulling speed of 2 cm / min. ·· Wn χ 10 " ³ .

Examples and 12 General implementation

sec.-BuIi t β Α

- M e S t -> P <4 HeSt'Li * (LiCl)

LiCl

(Poi-MeS t -P tBA) Li (LiCl)

( -Mest-PtBA

P В И A E

The copolymerization is carried out under the conditions described for Examples 1 and 7, using a-MeSt instead of styrene.

The coupling of the living bis-block copolymer (Pa-MeSt-PtBArLr with BMAE and the transesterification of PtBA to PnBA are carried out under the conditions given above.

Table VII below summarizes the characteristics of the products obtained.

Table VII

Ex. Pa-MeSt-RBa * Mn " t BA Mw / M η Mole BMAE η % 140000 102000 RBA * Weight% ** Pa-MeSt-RBA Molsek.-BuLi # coupling 11 12 109000 75000 70 70 1,12 1,2 6.0 5.2 3.8 3.5 78 87

* These values were determined by gel exclusion chromatography

* These values were determined by ¹ H NMR.

Example 13

sec.-BuLi al -HeSt

LiCl

tBA HMA PSt~Li * (LiCl) > (PSt-PtBA) ^- Li ⁺ (LiCl)? (PSt-PtBA-PHMA) ^- Li ⁺ (LiCl)

(A)

S ее. - B iL i © <, - HeSt

LiCl

MMA

(P t 9 A) Li (LiCl)

(PtSA-PMMA) Li (LiCl) (S)

BMAE

(A) ♦ (B)

(PSt-PtBA PMMA)

(PtBA PMMA)

PBMAE

The block copolymerization of the living polymer (A) is carried out under the conditions described for Examples 9 and 10. The first block RBA of the polymer (B) is started in THF at -78 ° C by an organolithium compound, which is obtained by reaction of sec-butyllithium with present in a slight molar excess of a-MeSt in the presence of 5 moles LiCI per mole of organolithium compound receives. After a polymerization time of 30 min at -78 ° C is added methyl methacrylate via a metal line and under an inert atmosphere to the reaction medium. The anionic block copolymerization takes place in THF at -78 ° C within 1 h.

Subsequently, the two living polymers are mixed by means of a suitable apparatus at -78 ° C under inert atmosphere. After homogenization of the solution, the mixture of living double and triple block copolymers is coupled at -78 ° C by adding BMAE in a 4- to 26-fold molar excess relative to the active organolithium centers and allowed to react within 2 hours.

The recovery of the polymer after the coupling step is carried out under the conditions described for the previous examples.

The PtBA blocks are then transesterified to PnBA. The transesterification reaction is carried out by acid catalysis with the aid of APTS under the conditions described for the previous examples.

Under these conditions, the PMMA blocks are retained and the yield of the transesterification is about 95%. Table VIII below shows the characteristic features of a product obtained in this case.

Table VIII

Ex. side branch Mn PST-PtBA-PMMA * Mn PSt-PtBA ♦ Mn PtBA * tBA% by weight ** Mw / Mη PSt-PtBA-PMMA # 13 A 113000 98000 72000 60 1.15 Ex. side branch Mn PtBA-PMMA * Mw / M η PtBA-PMMA * MTT PtBA Mw / M η PtBA # tBA% by weight ** 13 B 157000 1.15 97000 1.1 71

Table VIII (continued)

Mol DMAE M η to % Molsek.-BuLi coupling coupling 8.0 760000 79

* These values were determined by gel exclusion chromatography

* These values were determined by ¹ H NMR.

Examples

MHA

sec.-BuLi Ci-HeSt

LiCl

tBA MMA

-Ϊ РММаЧі * (LiCl) -> (PMHA-PtBA) * Li * (LiCl) -> (PMMA-PtBA-PMHA) * Li * (LiCl)

sec. - BuL i

(Х-HeSt ммА

·> TBA tr PtSA Li * (LiCl)> (PtBA-PMMA) Li * (LiCl)

LiCl

(B)

BMAE

(PHHA-PtBA PMMA)

(PtBA PMMA)

PBMAE

The anionic block copolymerization of the living polymers (A) and (B) is carried out under the conditions described for Examples 8 and 13 respectively.

Coupling of the mixture of living copolymers (PMMA-RBA-PMMA) ^- Li ⁺ and (PtBA-PMMA) ^- Lr to BMAE and the transesterification of the blocks PtBA to PnBA are carried out under the conditions given for Example 13.

Table IX below summarizes the characteristic properties of a product obtained in this way.

Table IX

Ex. Side branch Mn PMMA-PtBA-PMMA Mn PMMA-PtBA * / Mn PtBA -N- tBA% by weight Mw / Mη PMMA-PtBA-PMMA * 14 A 62000 52000 41200 61 1.15 Ex. side branch Mn PtBA-PMMA ♦ Mw / M η PtBA-PMMA * PtBA # Mw / M η PtBA tBA% by weight 14 B 42000 1.12 32000 1.1 75

Table IX (continued)

Mol DMAE M η to % Molsek.-BuLi Coupling * coupling 9.0 344000 81

* These values were determined by gel exclusion chromatography. ** These values were determined by ¹ H-NMR.

Example 15

tBA MMA

MMA>PMMa'k * (LiCt)> (PMMA-PtBA) 'K ⁺ (LiCl)> (PMMA-P tBA-PHMA ) ~ K * (LiCl)

(Ph) -chic

LiCl

(A)

t8a

LiCl

MMA - ♦ PtBA ^- K ⁺ (LiCl)> (PtBA - PMM A) 'K * (LiCt)

(В)

BMAE

(PMMA -PtBA-PMMA)

(PtBA PMHA)

PBMAE

The anionic block copolymerization of the living polymers (A) and (B) takes place under the respective test conditions given for Examples 8 and 10, except that diphenylmethylpotassium is used here as starter.

The coupling of the mixture of the living copolymers (PMMA-PtBA PMMA) ^- K ⁺ (LiCl) and (PtBA PMMA) ^- K ⁺ (LiCl) to BMAE and transesterification of the blocks PtBA to PnBA carried out under the for Example 13 specified conditions.

Table X below shows the characteristic features of a product obtained in this case.

Table X

side branch Mn PMMA-PtBA-PMMA Mn PMMA-PtBA Mn PtBA tBA% by weight Mw / Mη PMMA-PtBA-PMMA A 62000 52000 41200 61 1.15 side branch "Mn" PtBA-PMMA Mw / Mη PtBA-PMMA Wn PtBA Mw / M η PtBA tBA% by weight B 42000 1.12 32000 1.1 75

Table X (continued)

Mol DMAE M η to % Molsek.-BuLi Coupling * Coupling • 9.0 344000 81

♦ These values were determined by gel exclusion chromatography.

Example 16

sec-BuLi

St

LiCl

Pst Li ⁺

t BA

(LiCl)

(PSt-PtBA) Li ⁺ (LiCl) (A)

TBA

sec.BuLi 0I ₄ -MeSt

LiCl

(PtBA) Li ⁺ (LiCl) (B)

BMAE

Η ^Ί

(PSt-PtBA) _n (PtBA) _m

-PBMAE

The block copolymerization of the living polymer (A) is carried out under the conditions given for Examples 9 and 10.

The PtBA block of polymer (B) is started in THF at -78 ° C by an organolithium compound obtained by reacting sec-butyllithium with a-MeSt present in a slight molar excess in the presence of 5 moles of LiCl per mole of Organolithium compound reacts.

Subsequently, the two living polymers are mixed by means of a suitable experimental apparatus at -78 ° C under an inert atmosphere. After homogenization of the solution, the mixture of mono- and biblock-living copolymers is coupled at -78 ° C by adding BMAE in an A to 26-fold molar excess based on the active organolithium centers and allowing them to react for at least 2 hours.

The recovery of the polymer after coupling is carried out under the conditions described for the previous examples.

The PtBA blocks are then transesterified to PnBA. The transesterification reaction occurs in acid catalysis with the aid of APTS under the conditions given above.

Table XI below summarizes the characteristics of a product obtained in this way.

Table Xl Mn PSt-PtBA Mn PSt Mn PtBA tBA% by weight Mw / Mη PSt-PtBA side branch 50000 15000 35000 68 1.15 A Mn "PtBA Mw / M η PtBA side branch 60000 1.10 B

The mechanical properties of this product after transesterification are given in the following Table XII. Table XII

MoIDMAE % σ, N / mm ² (kg / mm ² ) ε,% Molsek.-BuLi coupling 6.86 (0.70) 707 17 88

Example 17

• MMA

sec-BuLi

oL-MeSt

LiCl

PMMA Li ⁺ (LiCl) [A]

t BA

sec.BuLi Ы-MeSt

LiCl

PtBA Li ⁺ (LiCl) [B]

BMAE

(PMMA) _n I

(PtBA)

PBMAE

The copolymerization of the living polymers (A) and (B) is carried out under the conditions given for Examples 8 and 10.

The blocks PtBA and PMMA are started in THF at -78 ° C. by an organolithium compound which is obtained by reacting sec-butyllithium with a-MeSt present in a slight molar excess in the presence of 5 mol of LiCl per mol

Organolithium compound reacts.

After a polymerization time of 15 min at -78 ⁰ C or MMA tBA are added via a metal line under an inert atmosphere to the reaction mixture. The anionic copolymerization takes place within 1 h in THF at -78 ° C.

Subsequently, the two living polymers are mixed under an inert atmosphere at -78 ° C in a suitable experimental apparatus. After homogenization of the solution, the mixture of living homopolymers is coupled at -78 ° C by adding BMAE in a 4- to 26-fold molar excess based on the active organolithium centers

Add and react for at least 2 hours.

Recovery of the polymer occurs after coupling under the conditions given above.

The PtBA blocks are then transesterified to PnBA. The transesterification reaction takes place in acid catalysis with the aid of

APTS under the conditions given above.

Under these conditions intact PMMA blocks are obtained and the transesterification yield is about 95%.

Table XIII below summarizes the characteristic properties of a product obtained in this way.

Table XIII

Side branch Mn PtBA Mw / M η PtBA A 100000 1.15 side branch Wn PMMA Mw / M η PMMA B 15000 1.15

The mechanical properties of this product after transesterification are summarized in the following Table XIV. Table XIV

BMAEMn x10 ³

M η after coupling

coupling

Breaking tension o _r N / mm ² (kg / mm ² )

elongation

5.0

887000

0.69 (0.07)

65

This value was determined by gel exclusion chromatography.

Example 18 St Sec.-BuLi оч-MeSt Pst Li ⁺ (LiCl) St LiCl PSt ^- Li " ¹ (LiCl) Sec.-BuLi •

t BA

(PSt-PtBA) Li ⁺ (LiCl)

[A]

LiCl

[B]

BMAE H

 +

(PSt-PtBA) _n

(PSt)

-PBMAE

The block copolymerization of the living polymer (A) is carried out under the conditions given for Examples 9 and 10.

The first block (PSt-PtBA) is started in THF at -78 ° C. by an organolithium compound which is obtained by reacting sec-butyllithium with a-MeSt in a slight molar excess and in the presence of 5 mol of LiCl per mole of organolithium compound implements. After 15 minutes of polymerization of styrene at -78 ° C., tBA is added to the reaction mixture via a metal line under an inert atmosphere. The anionic block copolymerization takes place within 15 min

at -78 ° C in THF.

Subsequently, the two living polymers are mixed at -78 ° C under inert atmosphere in a suitable experimental apparatus. After homogenization of the solution, the mixture of mono- and BIBLOCK-live copolymers at -78 ⁰ C is coupled by BMAE in a 4 to 26 times molar excess, based on the reactive Organolithiumzentren,

Add and let react for at least 2h.

The recovery of the polymer after coupling is carried out under the conditions given above.

The PtBA block is then transesterified to PnBA. The transesterification reaction takes place under acid catalysis with the aid of

APTS under the conditions given above.

Table XV below shows the characteristic features of a product obtained in this way.

Table XV Mn PStPtBA Mn PSt Mn PtBA tBA% by weight Mw / Mη PSt-PtBA side branch 92000 15000 77000 80 1.15 A Table XV (continued) side branch Mw / M η PSt B 1.05

The mechanical properties of this product after transesterification are summarized in the following Table XVI. Table XVI

MoIDMAE % breakdown voltage elongation Molsek.-BuLi coupling a, N / mm ² (kg / mm ² ) 26 70 7.55 (0.70) 707

Claims (12)

1. Star block copolymers of the general formula (I): (PA-PB-PC) 4-N (I) (PD-PE) _m J wherein PA represents a polymer block of at least one monomer A selected from aromatic vinyl monomers and methacrylic monomers; PB represents a polymer block of at least one acrylic monomer B; and PC, if present, represents a polymer block of at least one monomer C selected from methacrylic monomers; or - PA and PC each represent a polymer block of the same acrylic monomer; and PB represents a polymer block of at least one monomer B selected from methacrylic monomers; - PD represents a polymer block of at least one monomer D selected from aromatic vinyl monomers and methacrylic monomers and at the same time PE represents a polymer block of at least one acrylic monomer E; or PD represents a polymer block of at least one acrylic monomer D and at the same time PE represents a polymer block of at least one methacrylic monomer E; - η denotes the number of branches (PA-PB-PC) and has a value of 2 to 20 inclusive, and m denotes the number of branches (PD-PE) and has a value of 0 to 18 inclusive, that the sum η + m does not exceed 20; each of the branches (PA-PB-PC) and (PD-PE) may further comprise only a single polymer block, the two blocks being different and containing one acrylic monomer and the other monomer selected from vinyl aromatic monomers and methacrylic monomers; and - N represents a crosslinked core of at least one polymerized monomer Mr, wherein the monomer Mr consists of a multifunctional crosslinking agent which contains at least two polymerizable double bonds per molecule. 2. Copolymers according to claim 1, characterized in that the vinyl aromatic monomer is selected from styrene, substituted styrenes and mixtures thereof. 3. Copolymers according to one of claims 1 or 2, characterized in that the methacrylic monomer is selected from C 1 -C ₁₈ -alkyl methacrylates, optionally substituted by halogen and / or hydroxyl; glycidyl methacrylate; norbornyl; isobornyl; methacrylonitrile; dialkyl; Methacrylic acid and mixtures thereof. 4. Block copolymer according to one of claims 1 to 3, characterized in that the acrylic monomer is selected from C ^ Cis-alkyl acrylates; phenyl; isobornyl; norbornyl; Alkylthioalkyl or alkoxyalkyl acrylates; acrylonitrile; dialkyl; Acrylic acid and mixtures thereof. Copolymer according to any one of Claims 1 to 4, characterized in that the crosslinking monomer Mr is chosen from polyolpolymethacrylates and polyacrylates, vinyl acrylate and vinyl methacrylate and mixtures thereof. 6. block copolymer according to one of claims 1 to 5, characterized in that its side branches (PA-PB-PC) and optionally (PD-PE) and its core N, based on 10OGew.-parts of the copolymer 80-98 wt Make out parts or 20-2g parts. 7. Block copolymer according to one of claims 1 to 6, characterized in that each of the blocks has an average molecular weight of 1000 to 500,000. 8. Block copolymer according to one of claims 1 to 7, characterized in that it has a polydispersity index of 1.1-2. 9. A process for preparing a star block copolymer of the general formula: (PA-PB-PC) 11 (I) (PD-PE) _m wherein PA, if present, represents a polymer block of at least one monomer A selected from aromatic vinyl monomers and methacrylic monomers; PB represents a polymer block of at least one acrylic monomer B; and PC, if present, represents a polymer block of at least one monomer C selected from methacrylic monomers; or PA and PC each represent a polymer block of the same acrylic monomer; and PB represents a polymer block of at least one monomer B selected from methacrylic monomers; - PD represents a polymer block of at least one monomer D selected from aromatic vinyl monomers and methacrylic monomers and at the same time PE represents a polymer block of at least one acrylic monomer E; or PD represents a polymer block of at least one acrylic monomer D and at the same time PE represents a polymer block of at least one methacrylic monomer E; - η denotes the number of branches (PA-PB-PC) and has a value of 2 to 20 inclusive, and m denotes the number of branches (PD-PE) and has a value of 0 to 18, with the proviso that that the sum η + m does not exceed 20; each of the branches (PA-PB-PC) and (PD-PE) may further comprise only a single polymer block, the two blocks being different and containing one acrylic monomer and the other monomer selected from vinyl aromatic monomers and methacrylic monomers; and - N represents a crosslinked core of at least one polymerized monomer Mr, wherein the monomer Mr consists of a multifunctional crosslinking agent containing at least two polymerizable double bonds per molecule, characterized in that (1) carrying out an anionic polymerization of at least one monomer A with the aid of an initiator system consisting of at least one monofunctional starter of the general formula: (R) p-M (II) wherein • M is an alkali or alkaline earth metal, with a valence ρ of 1 or 2; and R is a straight-chain or branched alkyl radical having 2 to 6 carbon atoms or an optionally substituted aryl radical, or an alkyl radical having 1 to 6 carbon atoms, which is substituted by at least one phenyl group and optionally at least one ligand selected from alkali metals or alkaline earth metals, organic Alkali metal salts and macrocyclic, nitrogen-free complexing agents to give a living chain portion of the block polymer PA "; (2) reacting this chain portion with at least one monomer B in the presence of at least one of the above-defined ligands to obtain a living copolymer of two blocks of the formula (PA-PB) "; (3) reacting this living copolymer of two blocks with at least one monomer C in the presence of at least one of the above-defined ligands to obtain a living copolymer of three blocks of the formula (PA-PB-PC), the step (3 ) and the process can be started by performing the step (1) with the monomer B, or by forming only one of the living blocks PA "or PB" or PC "; (4) optionally forming a living copolymer of two blocks of the general formula (PD-PE) ^- by carrying out steps (1) and (2) using at least one monomer D and at least one monomer E; or forming a living block PD "or PE ~ by performing step (1) with the monomers D or E; (5) the living copolymer (PA-PB-PC) ", (PA-PB)" or (PB-PC) "or a living block PA", PB "or PC" optionally mixed with the living copolymer of two Blocks (PD-ΡΕΓ or the living block PD "or PE" prepared according to step (4), in an environment permitting their anionic polymerization to be carried out with at least one monomer Mr in a 4- to 26-fold molar excess per reactive center and the double bonds deactivated by reaction with a proton source, in particular consisting of an alcohol, water or a proton acid; (6) optionally transesterification of the resulting Stem copolymer in an acidic environment. 10. The method according to claim 9, characterized in that in the polymerization steps, the molar ratio of ligand to initiator is at least equal to 1 and can take values up to 50. 11. The method according to any one of claims 9 and 10, characterized in that one carries out the polymerizations of stages 1) to 5) at a temperature in the range of - 78 ° C to 0 ° C. 12. The method according to any one of claims 7 to 9, characterized in that one carries out the polymerizations of stages 1) to 5) in at least one solvent.