CA1316280C - Block polymers containing methacrylic acid and derivatives thereof - Google Patents

Abstract

ABSTRACT

Novel diene/methacrylate ester block polymers, especially tertiary butyl methacrylate ester block polymers are uniquely prepared at near ambient temperatures and capable of being hydrolyzed and neutralized to yield the corresponding methacrylic acid and methacrylic acid salt (ionomer) derivatives. The compositions are usefully employed in the preparation of thermoplastic elastomers, adhesives and laminating films.

35,858-F

Description

1316~sn BLOCK POLYME~S CONTAINING METHACRYLIC ACID AND
DERIVATIVES THEREOF

The present invention relates to block polymers comprising methacrylic acid and derivatives of methacrylic acid a~ well as method for the preparation of ~uch block polymers. In the past, carboxylic acid containing polymers have been typically ~ynthe~ized by the direct free radical polymerization of various carboxylic acids, as well as ester, or anhydride derivatives thereof with various vinyl comonomer~. The corre~ponding carboxylic qalt derivatives or ionomers are typically prepared by partial or complete neutralization of carboxylic acid group~ with variou~
basic compoundq. Previou~ly known synthetic routes have re~ulted in the random placement of such acid or ionic groups along polymer backbones. It would be desirable to provide similar polymeric structures having controlled composition and architecture, predictable molecular weights and narrow molecular weight di~tributionq.
It is previously known to use anionic polymeri~ation technique~ for the preparation of block polymers having controlled morphology and compo~ition 35,858-F -1--2- 131~28~

as well as architecture and predictable molecular weights, as well as narrow molecular weight di~tributions. However, previous attempts to prepare diene-containing block copolymers additionally comprising carboxylic acid or ester moieties have not been succeqsful due to competing reactions involving the carbonyl functionality of such monomers. The incidents of ~uch unde~ired competing reactions can be severely reduced or even eliminated by the use of protecting groups in the block copolymer chain. For example, 1,1-diphenylethylene polymerized between blockq of ethylenically unsaturated carboxylic acids or esters and diene blocks may be employed to prepare block copolymers in relatively high purity.
Regardless of the method of preparation, such techniques have required the use of reduced tempera-tures as low as -50C or -80C due to the instability of the intermediate anionic species. Moreover, 1,1--diphenylethylene iq both expensive and of a limited availability, and accordingly, processes involving its use have proven exces-qively costly.

Group Transfer Polymerization techniques have recently been employed in order to prepare block polymerq of polar monomers such as the alkyl methacrylates. Disadvantageously such techniques are not applicable to the preparation of diene containing block polymers.
It would be desirable i f there were provided a process for preparing block polymers of diene and carboxylic acids as well as esters or neutral salts thereof which do not require the use of commercially impractical reaction conditions such as reduced 35,858-F -2-_3 131 ~28a ternperatures les~ than 0C. In addition, it would be desirable to provide a process for the preparation of block polymers comprising dienes and carboxylic acids, as well a~ esters or neutral salts thereof that doe3 not require the use o~ expensive reagent~ such as 1,1-diphenylethylene.
According to the present invention, there are now provided novel block polymers compriqing in polymerized form one or more conjugated diene or hydrogenated diene moieties and one or more moieties selected from the group consisting of hydrolyzable esters of methacrylic acid having from 2 to 20 carbons in the ester group, methacrylic acid and salts of methacrylic acid. In a preferred embodiment these block polymers correspond to the Formula:
A-DtD-A)x (I), ,. ~
wherein A is a polymer comprising one or more moieties selected from the group consisting of hydrolyzable esters of methacrylic acid having from 2 to 20 carbons in the eqter group, methacrylic acid and salts of methacrylic acid, D is a diene polymer or a hydrogenated diene polymer, and x is a number from 0 to 3 equal to the average number of branches in the block polymer. The block polymers of the invention may be in the form of diblock-, triblock-, or star block polymers-In addition, the present invention encompasses a method for the preparation of such block polymers comprising contacting a living diene polymer anion with one or more hydrolyzable methacrylate ester monomers having from 2 to 20 carbons in the ester group under 35,8~8-F _3_ ~4~ ~3~6~0 anionic polymerization conditions. By later applied conventional techniques, the ester functionality of the block polymer may be altered to yield acid or neutral salt derivatives having an ordered placement of functional groups. In addition, residual ethylenic functionality may be hydrogenated. According to the present method, it has been found expeditious to prepare the block polymers of the invention in high yields utilizing commercially acceptable reaction conditions, especially temperatures for the initial methacrylate ester addition on the order of 0C to a~out 35C, preferably from 10C to 35C . Moreover, by use of the present process, the need to use 1,1-diphenylethylene to obtain addition of the methacrylate ester to the block polymer is avoided.

Anionic polymerization techniques are well known and previously disclosed in the art. See, for example, M. Morton, "Anionic Polymerization Principles and Practice", Academic Press ( 1983). Briefly, a living anion is prepared by use of a reactive anionic polymerization initiator. Suitable initiators include the well known metals such as sodium and lithium as well as the more preferred metal alkyl compounds 15 particularly lithium alkyls. A particularly preferred monofunctional anionic initiator is sec-butyl lithium.
Di- and other multifunctional initiators are also previously known in the art. Preferred difunctional anionic initiators include those compositions disclosed 20 in U.SO Patents 4,172,190; 4,196,154; 4,172,100;

4,182,818; 4,196,153; 4,200,718; 4,205,016; and 4,201,729. Block polymers having up to four reactive living ends may be prepared by the use ~A 35 ' 858-F -4-: ., .

` -5~ 131~

of suitable multifunctional anionic initiator technology.
Aliphatic dienes, particularly conjugated aliphatic dienes, such a~ butadiene or isoprene are particularly well suited for the preparation of block polymers having a desirable low glass tran~ition temperature (Tg). Such block polymers possessing elastomeric properties preferably have glass transition temperatures less than about 0C, most preferably less than about -25C. By the use of conventional hydrogenation techniques, residual unsaturation in such block polymers may be substantially reduced thereby imparting improved ultraviolet light stability to the polymers. The re~ulting elastomers are particularly well suited for use in impact modification of thermoplastic polymers for use in preparing ~tructures requiring improved environmental weathering resistance.

The block polymers of the present invention may be prepared utilizing conventional anionic polymerization conditions and initiators. In the first step, a living diene polymer anion is prepared by anionic polymerization techniques and retained in solution for use in the next step. The initial polymerization is preferably conducted in a solvent, particularly an inert, aprotic, organic liquid such as toluene, hexane, cyclohexane, etc. A preferred solvent is cyclohexane.
Suitable diene polymers include homopolymers of the above mentioned dienes and polymers thereof with polymerizable ethylenically unsaturated comonomers.
Preferred diene polymers are block polymers containing 35,858-F -5--6- l 3~ ~ j?~

one or more diene homopolymer block~ and one or more monovinylidene aromatic monomer homopolymer block~.
In one preferred embodiment, it has been ~ound de3irable to employ a living diene polymer anion a~
further defined by the formula:

M~D"-M)y~,(D"-M)y~ (M-D~)y~~ or -(M-D''~tD''-M)y~]X (II) wherein D" i~ a diene homopolymer block, M i~ a monovinyliden-e aromatic monomer homopolymer block, y i~
a number greater than 0 that i~ equal to the average number of repeating diene and monovinylidene aromatic monomer homopolymer blockq, and x i~ a~ previou~ly defined. The re~ulting block polymer~ of the invention therefore corre~pond to the formula:

MtD~-M~yA~ (Dl-M~yA, (M-DI~yA~ or AtM-D~y~tDJ~M~yA]X, (III) wherein D' i~ a diene homopolymer block or a hydrogenated derivative thereof, and M, A, x, and y are a~ previou~ly defined. In the above equation~, the first, ~econd and third appearing compound~ are prepared by the use of a monofunctional initiator and the initial polymerization of either the monovinylidene aromatic monomer or the diene monomer re~pectively.
The composition~ corre~ponding to the fourth formula are prepared by the use of multifunctional initiators.
In the re~ulting block polymer~, it iY
desirable that the diene polymer block (D of formula I) comprise homopolymer blocks of a monovinylidene aromatic monomer and diene homopolymer block~ ~uch that 35,858-F -6-131~

the monovinylidene aromatic monomer homopolymer blocks are interposed between the A block~ and the diene homopolymer blocks or hydrogenated derivatives thereof.
Suitably, the weight ratio of monovinylidene aromatic monomer homopolymer block to diene homopolymer block may be from 1/100 to 10/1. Preferably, in order to preserve the ela~tomeric properties of the block polymer, the weight ratio of monovinylidene aromatic tO monomer homopolymer block to diene homopolymer block is from 1/100 to 1/1. A preferred monovinylidene aromatic monomer is ~tyrene.
Next, the living diene polymer anion is contacted with a hydrolyzable methacrylate ester monomer having from 2 to 20 carbon~ in the ester group under anionic polymerization condition~ so as to prepare a diene/methacrylate e~ter block polymer. The living polymer i~ then terminated by any ~uitable technique. At this point, re~idual unsaturation of the diene polymer may be hydrogenated if desired. The re~ulting block polymer may be represented by the formula: A'-DtD-A'~X, wherein A' is a polymer compri~ing one or more hydrolyzable methacrylate eqter moieties having from 2 to 20 carbons in the e~ter group, D i3 a diene polymer or a hydrogenated diene polymer, and x~1 corre3ponds to the functionality of the initiator used.
The addition of the hydrolyzable ester functionality to the living diene anion has been found to be beneficially advanced by the addition to the reaction mixture of a polar, aprotic organic compound in a quantity sufficient to modify the polymerization rate of the reaction. Suitable polar organic compounds 35,858-F -7--8- ~ 3 ~

include polar aprotic organic compounds exempliPied by the cyclic ethers, particularly tetrahydrofuran.
Preferably, the polar organic compound i5 employed in an amount from 0.5 to 90 weight percent, most preferably from 25 to 75 weight percent based on total ~olvent weight. Preferably, the polar organic compound is added to the reaction mixture after formation of the living diene polymer anion.
To produce the highly desired methacrylic acid containing block polymer~ of the invention, the ester functionality of the above block polymers may be hydrolyzed. AQ an aid in such hydrolysis, it i~
de~irable that the hydrolyzable methacrylate ester be ~elected to provide ea~e of operating conditionq and good ~electivity to the methacrylic acid derivative upon hydrolysi~. Suitable hydrolyzable methylacrylate e~ter~ are tho~e capable of addition under anionic polymerization condition~ to a living diene anion preferably at a temperature from 0C to 35C. In a highly preferred embodiment, the hydrolyzable ester group of the methacrylate e~ter iq easily removable under nonaqueou~ hydrolysis reaction conditions.
Suitably, the hydrolysis i~ conducted by heating the resulting polymer containing hydrolyzable methacrylate e~ter group~, optionally in the presence of a catalytic amount of an acid.
Preferred hydrolyzable methacrylate e~ters for use in the pre~ent invention are the tertiary alkyl methacrylateq. Utilizing tertiary alkyl methacrylates, it has been discovered that polymerization temperatures on the order of 0C to 35C may be suitably employed in the polymerization. Thiq beneficial effect iq believed to be due to the stability of the t-alkyl 35,858-F -8-9 ~ 3 ~ ~ ~ 8 ~

methacrylate enolate anion at such temperatures.
Advantageously, heating of the resulting methacrylate est;er containing block polymer, optionally in the presence oP at leaqt a catalytic amount of an acid re~ultq in alkyl-oxygen cleavage and the release of relatively volatile aliphatic reaction products and the formation of the de-~ired methacrylic acid functionalized block polymers. ~uitable acids for the above hydrolysis include the aromatic sulfonic acids, e-qpecially toluene ~ulfonic acid. It is understood that hydrolysis of only a portion of the ester functionality may be obtained according to the present method if deqired.
Because 4-7 carbon membered alkanes which are the alkanes resulting from hydrolysis of tertiary butyl-, or ~-methyl-2-butyl-, and other 4-7 carbon tertiary alkyl methacrylate esters are easily volatilized, they are the preferred tertiary alkyl methacrylate e~ter~ for use in the present invention.
A highly preferred hydrolyzable, tertiary alkyl methacrylate is t-butyl methacrylate.

In the hydrolysis, a ~mall or catalytic amount of the acid and mild temperatures on the order of 50 to 100C are employed. A ~uitable ~olvent selected to maintain solubility may be employed to lead to higher degrees of hydroly~is. An example of such a suitable solvent include~ toluene, particularly where the amount of an incorporated hydrolyzable methacrylate ester ~unctionality is less than about 10 percent by weight.
Block polymers containing additional amounts of hydrolyzable methacrylate ester functionality may more beneficially be maintained in solution by the u~e of more polar solvents such as, for example, alcohols.

35,858-F -9-- 1 0- ~ Q

In a desirable embodiment, the hydrolysis reaction is conducted quantitatively in order to be able to more accurately control the final acid or ion content of the block polymer.

In addition to the catalytic acid hydrolysis, the methacrylate e~ter functionality may also be hydrolyzed by the uqe of an alkali metal superperoxide quch a~ potas~ium superperoxide in a quitable ~olvent ~uch as a mixture of dimethyl ~ulfoxide and tetrahydrofuran. The re~ulting hydrolyzed product may be acidified with ~mall amount~ of an acid ~uch as hydrogen chloride to improve qolubility. Due to the difficulty in handling such reagent~, the latter method i~ not preferred for commercial u3e.
Where de~ired, the acid functionality of the methacrylic acid containing block polymer3 may be neutralized by contacting with a quitable baqic reagent. Exampleq include ammonium and metal hydroxide~ particularly the alkali metal hydroxides.
Particularly deqirable metal ~altq of methacrylic acid include 30dium, potaqsium, aluminum, tin, zinc~ or nickel ~alt~. By quch techniques, ionomeric block copolymer~ containing methacrylic acid salt moietie~
are prepared.
Although any de~ired amount of neutralization oP the acid functionality may be employed, in a preferred embodiment from 5 to 75 percent by weight of the functional moietie~ of the block polymer are the neutral salt~ thereof. In other re~pects, the neutralization procesq to produce ionomeric functionality in the resulting 35,858-F -10-diene/methacrylic acid block polymers is as previously known in the art.
In a de~ired embodiment of the present invention, the ethylenic unsaturation of the polydiene block polymer3 of the invention is hydrogenated to provide modified polymeric properties. Such hydrogenation i~ accomplished by the use of conventional processing conditions such as contacting with hydrogen in the presence of a noble metal catalyst. The above described hydrogenation process may be accomplished at any point during the synthesis.
That is, the hydrogenation may be performed after addition of the hydrolyzable methacrylate e~ter functionality but before hydrolysi~, after hydrolysi~
but before neutralization, or after neutralization.
The modified block polymer~ of the pre~ent invention may suitably be employed aq surfactants, elastomers, and as adhesives. In addition, by the selective addition of methacrylate ester functionality to diene block polymerq according to the present invention, properties such as refractive index may be modified in order to provide ela~tomers for particularly utilization in the preparation of transparent impact modified thermoplastic polymers.
Having described the invention, the following examples are provided as further illustrative and are not to be construed as limiting.

35,858-F -11--l2- 1~628Q

_ample 1 Block copolymers are prepared by reaction of suitable monomers with a difunctional initiator.
Isoprene, 40 g, i~ added to a stirred, heated, glass bowl polymerization reactor that ha~ been previou~ly purged with nitrogen and charged with cyclohexane (500 ml). The initiator, 1,3-phenylene-bis(3-methyl-1-phenylpentylidene)bis(lithium), prepared according to the teachings of USP 4,196,154, (0.5mmole) as a 1.35 Molar solution in cyclohexane is added and the reactor i~ heated to 60C and maintained at thi~ temperature for 2 hour~. Following complete isoprene polymerization, an aliquot of the living polymer solution (containing approximately 10 g of polymer) i~ removed for further modification.
In the next step, tertiary-butyl methacrylate (4.0 g) is added to the living polymer qolution in a reactor at about 25C. The reaction i~ continued one additional hour. The polymerization is terminated by adding methanol to the reactor and the product i~
recovered by precipitation from a methanol/water 301ution (90/10 by volume). Analysi~ by nuclear magnetic re-~onance spectroscopy indicate~ a final polymerized tertiary-butyl methacrylate content of 29 mole percent. The tacticity a~ measured by C~3 NMR i~
greater than 99 percent. A clear film suitable for use as a coating or packaging sheet may be cast from cyclohexane ~olution.
Example 2 The reaction conditions of Example 1 are substantially repeated excepting that the solvent 35,858-F -12-employed during tertiary-butyl methacrylate addition is a mixture of cyclohexane and tetrahydrofuran (50/50 by volume). The resulting polymer ha~ a polymerized tertiary-butyl methacrylate content of 30 weight percent. The polymer has a 1,4-diene polymer content o~ 92 mole percent, and 52 percent syndiotacticity about the methacrylate quaternary carbon.
Exam~le 3 The reaction conditions of Example 1 are sub~tantially repeated excepting that a minor amount of ~tyrene monomer (5 weight percent) is added to the iqoprene aliquot in a reactor and polymerized to form a terminal block prior to addition of the tertiary-butyl methacrylate. The re~ulting triblock polymer has the formula: A-M-D-M-A, wherein A, M, and D represent the polymerized monomers tertiary-butyl methacrylate, ~tyrene and i~oprene, respectively. Analysis by nuclear magnetic resonance spectroscopy indicates the final polymerized monomer content i~ approximately 62 percent isoprene, 5 percent qtyrene, and 33 percent tertiary-butyl methacrylate.

Example 4 The reaction conditions of Example 3 are ~ubstantially repeated excepting that the solvent employed during the polymerization of tertiary butyl 3 methacrylate i~ a mixture of cyclohexane and tetrahydrofuran (S0/50 by volume). The re~ulting polymer ha3 a polymerized tertiary-butyl methacrylate content of 30 mole percent. The polymer ha~ 92 mole percent, 1,4-diene polymer content and 52 percent 35,858-F -13--14- 13~2~

syndiotacticity about the diene double bond. The molecular weight distribution is 1.25.
_amPle 5 The reaction conditions of Example 1 are substantially repeated excepting that a monofunctional initiator, sec-butyl lithium, 0.5 mmoles, i~ employed to prepare diblock polymers of the formula: A-~, wherein A and D repre~ent the polymerized form of tertiary-butyl methacrylate and isoprene respectively.
The resulting polymer has a tertiary-butyl methacrylate content of about 33 weight percent. The number average molecular weight aY determined by gel permeation chromatography i~ 126,000 g/mole. The molecular weight distribution is 1.09.

The block copolymer of Example 1 (2.0 g.) in toluene solution iq heated to 80C in the presence of para-toluene sulfonic acid (5 mole percent) to evolve isobutylene and a triblock copolymer of the formula A-D-A, having polymerized i30prene center block and 2~ methacrylic acid terminal blocks. Sub~tantially complete conversion of tertiary-butyl groups is obtained in about 90 minutes. The product iq cast from toluene solution to result in a clear film suitable for u~e as a coating or an adhe-~ive film.
3o ExamDle 7 The methacrylic acid functionalized triblock polymer of Example 6 is converted to an ionomer functionalized poiymer by titrating the ~ame in tetrahydrofuran solution utilizing potassium hydroxide 35,858-F _14-:1 3 1 ~

(0.1 Molar in methanol) and phenolphthalein as an indicator. Greater than 95 percent conversion of acid functionality is obtained. The resulting polymer is compression molded to prepare a thin disk ~or further property testing. The disk i~ elastic and insoluble in hydrocarbon solvents.

35,858-F -15-

Claims (74)

1. A thermoplastic block copolymer comprising in polymerized form one or more diene or hydrogenated diene moieties and one or more blocks of a monomer selected from the group consisting of hydrolyzable tertiary alkyl esters of methacrylic acid, having from 4 to 7 carbons in the tertiary alkyl group, methacrylic acid and salts of methacrylic acid, said polymer not containing protecting groups interposed between the diene blocks and the ester, acid or salt blocks.

2. A thermoplastic block copolymer according to Claim 1, wherein the diene is butadiene or isoprene.

3. A thermoplastic block copolymer according to Claim 1 additionally comprising in polymerized form a block of a monovinylidene aromatic monomer.

4. A thermoplastic block copolymer according to Claim 3, wherein the monovinylidene aromatic monomer is styrene.

35,858-F -16-

5. A thermoplastic block copolymer according to Claim 1, wherein the tertiary alkyl methacrylate is tertiary butyl methacrylate.

6. A thermoplastic block copolymer according to Claim 1, wherein the salt is a sodium, potassium, aluminum, tin, zinc, or nickel salt.

7. A method for preparing thermoplastic block copolymers comprising in polymerized form one or more diene moieties and one or more methacrylic acid moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable tertiary alkyl methacrylate ester monomers having from 4 to 7 carbons in the ester group under anionic polymerization conditions to thereby prepare a diene/methacrylate ester block polymer, and 2) hydrolyzing the ester functionality of the resulting diene/methacrylate ester block polymer.

8. A method according to Claim 7, wherein the ester group is tertiary butyl.

9. A method according to Claim 7, wherein the anion and one or more monomers are contacted in the presence of a solvent comprising a polar organic compound.

10. A method according to Claim 9, wherein the solvent comprises tetrahydrofuran.

35,858-F -17-

11. A method according to Claim 7, wherein the anion and one or more monomers are contacted at a temperature from about 0°C to about 35°C.

12. A method according to Claim 7, wherein the hydrolysis is conducted by contacting the diene/methacrylate ester block polymer with an acid.

13. A method according to Claim 12, wherein the hydrolysis is conducted under essentially anhydrous conditions.

14. A method according to Claim 12, wherein the acid is an aromatic sulfonic acid.

15. A method for preparing thermoplastic block copolymers comprising in polymerized form one or more diene moieties and one or more methacrylic acid salt moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable tertiary alkyl methacrylate ester monomers having from 4 to 7 carbons in the ester group under anionic polymerization conditions to form a diene/methacrylate ester block polymer;
2) hydrolyzing at least some of the ester functionality of the diene/methacrylate ester block polymer to form methacrylic acid functionality; and 3) neutralizing at least some of the methacrylic acid functionality of the resulting block polymer.

35,858-F -18-

16. A method according to Claim 15, wherein the methacrylic acid functionality is neutralized by contacting with a base.

17. A method according to Claim 16, wherein the base is a sodium, potassium, aluminum, tin, zinc or nickel hydroxide.

18. A method according to Claim 15, wherein the tertiary alkyl methacrylate is tertiary butyl methacrylate.

19. A method according to Claim 15, wherein the diene polymer anion and methacrylate ester monomer are contacted at a temperature from 0°C to 35°C.

20. A method according to Claim 15, wherein the diene/methacrylate ester block polymer is hydrolyzed by contacting with an acid.

21. A method according to Claim 15, wherein the hydrolysis is conducted under essentially anhydrous conditions.

22. A method according to Claim 20, wherein the acid is an aromatic sulfonic acid.

35,858-F -19-- 19a - 64693-4240

23. A method according to Claim 15, wherein the poly-erization is effected in contact with tetrahydrofuran.

24. A method according to Claim 15, wherein the poly-merization is effected in contact with from 90 to 99.5 weight percent cyclohexane, toluene, hexane, or a mixture thereof and from 10 to 0.5 weight percent polar organic compound.

25. A method according to Claim 19, wherein the diene polymer anion comprises an anion of a block polymer comprising one or more diene homopolymer blocks and one or more monovinylidene aromatic monomer homopolymer blocks.

26. A method according to Claim 25, wherein the monovinylidene aromatic monomer is styrene and the diene is butadiene or isoprene.

27. A method according to Claim 25, wherein the weight ratio of monovinylidene aromatic monomer homopolymer block to diene homopolymer block is 1/100 to 10/1.

28. A method according to Claim 25, wherein the block polymer anion is of the formula:
M?D"-M)y-, (D"-M)y-, (M-D")y-, or -(M-D"?[?D?-M)y-]x, wherein D" is a diene homopolymer block, M is a monovinylidene aromatic monomer homopolymer block, x is a number from 0 to 3 equal to the average number of branches in the block polymer anion, and y is a number greater than 0 equal to the average number of (D"-M) or (M-D") blocks.

29. A method according to Claim 19, wherein the diene polymer anion and tertiary alkyl methacrylate monomer(s) are contacted at a temperature from 0°C to 35°C.

30. A method according to Claim 29, wherein the temperature is from 10°C to 35°C.

31. A method for preparing block polymers comprising in polymerized form one or more hydrogenated diene moieties and one or more hydrolyzable methacrylate ester moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable methacrylate ester monomers having from 2 to 20 carbons in the ester group under anionic polymerization conditions to form a diene/methacrylate ester block polymer; and C-35,858 -20-2) hydrogenating at least some of the ethylenic unsaturation of the diene block in the diene/methacrylate ester block polymer.

32. A method according to Claim 31, wherein the anion and one or more hydrolyzable methacrylate ester monomers are contacted in the presence of a solvent comprising a polar organic compound.

33. A method according to Claim 31, wherein the anion and one or more methacrylate ester monomers are contacted at a temperature from 0°C to 35°C.

34. A method according to Claim 31, wherein the hydrogenation is conducted by contacting the diene/methacrylate ester block polymer with hydrogen in the presence of a noble metal catalyst.

35. A method for preparing block polymers comprising in polymerized form one or more diene moieties and one or more methacrylic acid moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable methacrylate ester monomers having from 2 to 20 carbons in the ester group under anionic polymerization conditions to thereby prepare a diene/methacrylate ester block polymer, and 2) hydrolyzing the ester functionality of the resulting diene/methacrylate ester block polymer.

36. A method according to Claim 35, wherein the ester group is a tertiary alkyl group.

C-35,858 -21-

37. A method according to Claim 35, wherein the ester group is tertiary butyl.

38. A method according to Claim 35, wherein the anion and one or more monomers are contacted in the presence of a solvent comprising a polar organic compound.

39. A method according to Claim 38, wherein the solvent comprises tetrahydrofuran.

40. A method according to Claim 35, wherein the anion and one or more monomers are contacted at a temperature from 0°C to 35°C.

41. A method according to Claim 35, wherein the hydrolysis is conducted by contacting the diene/methacrylate ester block polymer with an acid.

42. A method according to Claim 41, wherein the hydrolysis is conducted under essentially anhydrous conditions.

43. A method according to Claim 41, wherein the acid is an aromatic sulfonic acid.

44. A method according to Claim 41, wherein the diene/methacrylate ester block polymer is a diene/tertiary butyl methacrylate block polymer.

45. A method according to Claim 41, wherein the diene/methacrylate ester block polymer is of the formula: A'-D?D-A'?x, wherein A' is a polymer comprising one or more hydrolyzable methacrylate ester moieties having from 2 to 20 carbons in the ester group, D is a diene polymer or a hydrogenated diene polymer, and x is a number from zero to 3 equal to the C-35,858 -22-average number of repeating units of (D-A') in the block polymer.

46. A method according to Claim 45, wherein D
is a block polymer comprising one or more diene homopolymer blocks and one or more monovinylidene aromatic monomer homopolymer blocks.

47. A method according to Claim 46, wherein the monovinylidene aromatic monomer is styrene.

48. A method for preparing block polymers comprising in polymerized form one or more hydrogenated diene moieties and one or more methacrylic acid moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable methacrylate ester monomers having Prom 2 to 20 carbons in the ester group under anionic polymerization conditions to form a diene/methacrylate ester block polymer;
2) hydrogenating at least some of the ethylenic unsaturation of the diene block in the diene/methacrylate ester block polymer; and 3) hydrolyzing the ester functionality of the hydrogenated diene/methacrylate ester block polymer.

49. A method for preparing block polymers comprising in polymerized form one or more hydrogenated diene moieties and one or more methacrylic acid moieties comprising:
1) contacting a living diene polymer anion containing ethylenic unsaturation with one or more hydrolyzable methacrylate ester monomers having from 2 to 20 carbons in the ester group under anionic C-35,858 -23-polymerization conditions to form a diene/methacrylate ester block polymer;
2) hydrolyzing the ester functionality of the diene/methacrylate ester block polymer to form a diene/methacrylic acid block polymer; and 3) hydrogenating at least some of the ethylenic unsaturation of the diene block in the diene/methacrylic acid block polymer.

50. A method according to Claims 48 or 49, wherein the diene is butadiene or isoprene.

51. A method according to Claims 48 or 49, wherein the methacrylate ester monomer is tertiary butyl methacrylate.

52. A method according to Claim 48 or 49, wherein the hydrolysis is conducted by contacting the methacrylate ester block polymer with an acid.

53. A method according to Claim 52, wherein the hydrolysis is conducted under essentially anhydrous conditions.

54. A method according to Claim 48 or 49, wherein the hydrogenation is conducted by contacting the block polymer with hydrogen in the presence of a noble metal catalyst.

55. A method for preparing block polymers comprising in polymerized form one or more diene moieties and one or more methacrylic acid salt moieties comprising:
1) contacting a living diene polymer anion with one or more hydrolyzable methacrylate ester C-35,858 -24-monomers having from 2 to 20 carbons in the ester group under anionic polymerization conditions to form a diene/methacrylate ester block polymer;
2) hydrolyzing at least some of the ester functionality of the diene/methacrylate ester block polymer to form methacrylic acid functionality; and 3) neutralizing at least some of the methacrylic acid functionality of the resulting block polymer.

56. A method according to Claim 55, wherein the methacrylic acid functionality is neutralized by contacting with a base.

57. A method according to Claim 56, wherein the base is a metallic compound.

58. A method according to Claim 57, wherein the metallic compound is a sodium, potassium, aluminum, tin, zinc or nickel hydroxide.

59. A method according to Claim 55, wherein the methacrylate ester monomer is a tertiary alkyl methacrylate.

60. A method according to Claim 59, wherein the tertiary alkyl methacrylate is tertiary butyl methacrylate.

61. A method according to Claim 55, wherein the anion and hydrolyzable methacrylate ester are contacted in the presence of a solvent comprising a polymerization rate modifying amount of a polar organic compound.

C-35,858 -25-

62. A method according to Claim 61, wherein the polar organic compound is tetrahydrofuran.

63. A method according to Claim 55, wherein the diene polymer anion comprises an anion of a block polymer comprising one or more diene homopolymer blocks and one or more monovinylidene aromatic monomer homopolymer blocks.

64. A method according to Claim 63, wherein the block polymer anion is of the formula:
M?D"-M)y-, (D"-M)y-, (M-D")y-, or -(M-D"?[?D"-M)y-]x, wherein D" is a diene homopolymer block, M is a monovinylidene aromatic monomer homopolymer block, x is a number from 0 to 3 equal to the average number of branches in the block polymer anion, and y is a number greater than 0 equal to the average number of (D"-M) or (M-D") blocks.

65. A method according to Claim 55, wherein the diene polymer anion and methacrylate ester monomer are contacted at a temperature from 0°C to 35°C.

66. A method according to Claim 55, wherein the diene/methacrylate ester block polymer is hydrolyzed by contacting with an acid.

67. A method according to Claim 55, wherein the hydrolysis is conducted under essentially anhydrous conditions.

68. A method according to Claim 66, wherein the acid is an aromatic sulfonic acid.

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69. A method for preparing block polymers comprising in polymerized form one or more hydrogenated diene moieties and one or more methacrylic acid salt moieties comprising:
1) contacting a living diene polymer anion containing ethylenic unsaturation with one or more hydrolyzable methacrylate ester monomers having from 2 to 20 carbons in the ester group under anionic polymerization conditions to form a diene/methacrylate ester block polymer;
2) hydrogenating at least some of the ethylenic unsaturation of the diene block in the diene/methacrylate ester block polymer;
3) hydrolyzing at least some of the ester functionality of the hydrogenated diene/methacrylate ester block polymer to form methacrylic acid functionality; and 4) neutralizing at least some of the methacrylic acid functionality of the resulting block polymer.

70. A method according to Claim 69, wherein the diene polymer anion comprises an anion of a block polymer comprising one or more diene homopolymer blocks and one or more monovinylidene aromatic monomer homopolymer blocks.

71. A method according to Claim 70, wherein the block polymer anion is of the formula:
M?D"-M)y-, (D"-M)y-, (M-D")y-, or -(M-D"?[?D"-M)y-]x, C-35,858 -27-wherein D" is a diene homopolymer block, M is a monovinylidene aromatic monomer homopolymer block, x is a number from 0 to 3 equal to the average number of branches in the block polymer anion, and y is a number greater than 0 equal to the average number of (D"-M) or (M-D") blocks.

72. A method according to Claim 69, wherein the diene is butadiene or isoprene.

73. A method according to Claim 71, wherein the monovinylidene aromatic monomer is styrene.

74. A method according to Claim 69, the block polymer is hydrogenated by contacting with hydrogen in the presence of a noble metal catalyst.

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