WO2007039538A1

WO2007039538A1 - A process for preparing homoblock co-polysulfones and polysulfones prepared therefrom

Info

Publication number: WO2007039538A1
Application number: PCT/EP2006/066824
Authority: WO
Inventors: Prakash Druman Trivedi; Atul Ramaniklai Raja; Mukesh Shambhubhai Jesani; Modi Haresh Sevantilal
Original assignee: Solvay Specialities India Private Limited
Priority date: 2005-09-30
Filing date: 2006-09-28
Publication date: 2007-04-12
Also published as: TW200724571A; IN2005MU01231A

Abstract

The present invention relates to a process of preparing block copolymers comprising of at least two types of homoblocks, selected from either PSSD, PSSB, TPES, PSS, TMPSS or PESK or selected from at least one of PSSD, PSSB, TPES, PSS, TMPSS or PESK and at least one of PPSU, PES or PSU, wherein each of the said homoblock has an identical or different molecular weight of at least 1000 and has at least 5 % of the overall weight and wherein the block copolymer has a molecular weight of at least 2000, the process steps comprising of preparing each of the aforesaid homoblocks by heating at least one aromatic diol/dihydroxy compound with at least one aromatic dihalo compound, one of which contains at least one sulfone group, in the presence of at least one alkali optionally in at least one solvent and further optionally in the presence of an azeotropic agent, reacting the aforesaid homoblocks together at a temperature between 1300C to 2500C optionally in at least a solvent, and further optionally followed by end-capping said block copolymer recovering the block copolymer and to the block copolymer prepared therefrom.

Description

A PROCESS FOR PREPARING HOMOBLOCK CO- POLYSULFONES AND POLYSULFONES PREPARED THEREFROM

FIELD OF THE INVENTION

The present invention relates to a process of preparing block copolymers and the block copolymers prepared therefrom.

Particularly, the present invention relates to a process of preparing block 5 copolymers comprising of at least two types of homoblocks belonging to the family of polysulfones, more particularly selected from PSSD, PSU, PSS, PPSU, PSSB, PES, TPES, PESK and TMPSS, and to the block copolymer prepared therefrom.

Furthermore, the present invention relates to di- and tri-blocks as well as

10 random multi-block copolymers and the process of their preparation. These homoblocks may have varying molecular weights or may have similar molecular weights as compared to their molecular weights present in block copolymers. These block copolymers show a single glass transition temperature (Tg), good transparency and can be readily processed using traditional plastics processing

15 techniques. They can be used directly for molding, extrusion and also used as a compatibilizer for their high molecular weight homologues. BACKGROUND OF THE INVENTION

The family of polysulfone polymers is well known in the art and three types of polysulfone have been available commercially viz. Polysulfone (PSU),

20 Polyether Sulfone (PES) and Polyphenylene Sulfone (PPSU).

The commercially available Polysulfones (PSU, PPSU, PES) have good high temperature resistance and generally do not degrade or discolor at their processing temperatures of 350⁰C to 400⁰C. Additionally, they are transparent, light amber colored amorphous plastics with excellent mechanical and electrical

25 properties, and good chemical and flame resistance. These Polysulfones are readily processible using common plastics processing techniques such as injection molding, compression molding, blow molding and extrusion. This makes them very versatile and useful plastics, having a myriad of applications in electronics, the electrical industry, medicine, general engineering, food

30 processing and other industries. The Polysulfone PSU was discovered in early 1960 at Union Carbide (U.S. Patent No. 4,108,837, 1978). Since then, activity in improving the quality of PSU has remained strong and improvements are sought continuously over the years in color, thermal stability, molecular weights and reduction in residual monomer and solvent.

While, there are many similarities among PSU, PES, and PPSU as regards color, electrical properties, chemical resistance, flame resistance etc., there are also important differences. The foremost difference among these is the Glass Transition Temperature (Tg). PSU has a Tg of 189°C, PES has a Tg of 225°C, while PPSU has a Tg of 222°C. Thus, PSU has an overall lower thermal resistance in terms of its dimensional stability compared to PPSU and especially PES, which has the highest thermal resistance. Besides this, PES also has a higher tensile strength (> 90 MPa) compared to PSU and PPSU (both 70-75 MPa). On the other hand, PPSU has an outstanding impact resistance, like Polycarbonate (PC) and its Izod notched impact strength is 670-700 J/m. Both PES and PSU have lower Izod notched impact strengths of only 50-55 J/m. Similarly, it is known in the art that articles made from PPSU can withstand > 1000 sterilization cycles without crazing, while PSU based articles withstand about 80 cycles and PES based articles withstand only about 100 cycles. PSU, on the other hand, has the lightest color and can be more readily processed, while PPSU is darker and more difficult to process than either PSU or PES.

Thus, a combination of PSU properties such as easy processibility and light color properties with PPSU properties such as high temperature and impact resistance would be desirable. Incorporating a proportion of PSU into PPSU may also bring down the overall cost. Although the physical blending of PPSU and PSU is one way of accomplishing this, it destroys one of the most important properties of the two homopolymers, namely their transparency. Similarly, physical blend of PES and PSU is not only opaque but also not processible to give blends of desirable properties, as they are very incompatible polymers. In any case, these combinations only show Tg < 225C.

The higher Tg Polyaryl ether sulfone (TMPES) is prepared by using 3,3',5,5'-tertamethyl-4'4'-dihydroxydiphenyl sulfone and 4,4'dichlorodiphenyl sulfone as monomers, Other Polyaryl sulfones having biphenyl units like 4,4'- di-(4-chlorophenyl-sulfonyl)-biphenyl and 4,4'-di-(4-hydroxyphenyl-sulfonyl)-biphenyl are mentioned in

U.S. Patent No. 5,008,364, which are stable at high temperatures. Other combinations as given below are also desirable for their having higher Tg than 220C (Tg of PES) to further boost the high temperature resistance by incorporating these and to make the high temperature resistant polymers more readily processible by incorporating PES, PSU or PPSU in their chain structures. The unit chain structures of some of the family of polysulfones are given below :

PPSU : -C₆H₄-SO₂-C₆H₄-O-C₆H₄-C₆H₄-O- PSU : -C₆H₄- SO₂- C₆H₄- O— C₆H₄- C(CH₃)₂— O- PES : -C₆H₄-SO₂-C₆H₄-O-C₆H₄-SO₂-C₆H₄-O- PSSD : -C₆H₄-SO₂-C₆H₄-C₆H₄-SO₂-C₆H₄-O-C₆H₄-SO₂-

C₆H₄-O-

PSSB : -C₆H₄-SO₂-C₆H₄-C₆H₄-SO₂-C₆H₄-O-C₆H₄-C₆H₄-O- TPES : -C₆H₄-SO₂-C₆H₄-O-C₈H₈-SO₂- C₈H₈-O- PSS : -C₆H₄-SO₂-C₆H₄-C₆H₄-SO₂-C₆H₄-O- PESK : -C₆H₄-CO₂-C₆H₄=O=C₆H₄-SO₂-C₆H₄-O-

TMPSS : -C₆H₄-SO₂-C₆H₄-C₆H₄-SO₂-C₆H₄-O-C₈H₈-SO₂-C₈H₈-

O-

The polysulfones are prepared using one or more aromatic Dihalo compounds like Dichlorodiphenyl sulfone (DCDPS), Dichloro benzophenone (DCB) or Dichlorodiphenyl disulfonylbiphenyl (CSB) and their respective mono, di tri or tetra methyl or alkyl derivatives and one or more of aromatic di-hydroxy monomer like Bisphenol A, Dihydroxy diphenylsulfone (DHDPS), Biphenol, Dihydroxydiphenyl disulfonylbiphenyl (HSB), Dihydroxy diphenyl ether, Dihydroxy diphenyl methane, {Bis-(3,5-dimethyl-4-hydroxyphenyl)sulfone } their respective mono, di, tri or tetra substituted Methyl derivatives, etc.

For PPSU, the di-hydroxy compound used is Biphenol (HO-C₆H_4-C₆H_4-OH), for PES, it is DHDPS, for PSU, it is Bisphenol A (HO-C₆H₄-C(CH₃)₂-C6H4-OH), and for TPES, it is TMDHDPS (HO-C₆H₂(CH₃)₂-SO₂-C₆H₂(CH₃)₂-OH), while DCDPS is used as a second monomer for all these Polysulfones.

For PSSD, the di-hydroxy compound used is DHDPS

(HO-C₆H_4-SO_2-C₆H₄-OH), and for PSSB, it is Biphenol (HO-C₆H₄-C₆H₄-OH), for TMPSS, it is TMDHDPS (HO-C₆H₂(CH₃)₂-SO₂-C₆H₂(CH₃)₂-OH), for PSS, it is HSB (OH- C₆H₄-SO₂-C₆H₄-C₆H₄-SO₂-C₆H₄-OH); while CSB (Cl- C₆H_4-SO_2-C₆H₄-C₆H₄-SO₂-C₆H₄-Cl) is used as a second monomer. PESK can be made by using DCB (Dichlorobenzophenone) and DHDPS. Similarity other homopolymers can be made by reacting DCB with other Dihydroxy compound like DHDPS, Biphenol, TMDHDPS and HSB.

The homoblocks prepared above can be reacted with other homoblock like PSS, PSSD, PPSU, PES, PSU, TPES, PSSB and TMPSS, etc.

The use of more than one dihydroxy monomers is also known. For example, the polymer known as "PAS" manufactured by Amoco includes a small quantity of hydroquinone in addition to DCDPS and DHDPS. The third monomer is added at the start of the manufacturing process and so gets polymerized in a random sequence in the polymer chain.

Other random copolymers in the prior art have shown that a third monomer may also be added in much larger quantities. Thus, GB Patent 4, 331, 798 (1982) and US patent 5, 326, 834 (1994) teach the preparation of terpolymers using 80-40 mole % of DHDPS and correspondingly 20-60 mole % of Biphenol with near equivalent mole % of DCDPS. Since both patents teach that polymerization is to be started with the monomers themselves, it can be seen that the distribution of DHDPS and Biphenol in the final copolymer will be at random. Thus, one gets a random sequence such as : — ABAABBBAABAAABBABABBAAABB--, where A and B are present in a random sequence and in variable amounts depending upon the initial concentrations of A and B or DHDPS and Biphenol (DCDPS moiety will be present in between A-A, A-B & B-B groups, although not shown here). Similarly, European Patent No. 0,331,492 teaches the synthesis of random terpolymers of DCDPS and DHDPS/Biphenol or Bisphenol A/Biphenol. Again, starting from three monomers to give random terpolymers (and not block copolymers) by building up molecular weights, in which the sequence of A & B in the chains, being random, cannot be predicted.

The prior art shows that block copolymers have been prepared where only one of the blocks is polysulfone. Hedtmann-Rein and Heinz (US Patent 5,036,146 - 1991) teach the preparation of a block copolymer of PSU with a polyimide (PI). In this case, a homoblock of an amine terminated polysulfone was prepared first. This was prepared using DCDPS, Bisphenol A and p-aminophenol to give a homoblock having a molecular weight in the range of 1500 to 20000. The homoblock produced was subsequently reacted with a tetracarboxylic acid, such as benzophenonetetracarboxylic dianhydride, and another diamine, such as 4,4'- diaminodiphenylmethane, to make a block copolymer of PSU-PI. The copolymers were prepared in the melt phase at 350⁰C.

McGrath and coworkers (Polymer preprints, 25, 14, 1984) have prepared PSU-Polyterphthalate copolymers. This was done using DCDPS (0.141 mole) and a mixture of hydroquinone and biphenol (0.075 mole each) to give a homoblock in solution, and then reacting the homoblock with a terephthaloyl chloride and biphenol, using solution or interfacial techniques, to give a block copolymer.

McGrath et al (Polymer Preprints, 26, 275, 1985) have further described preparations using acetyl end capped PSU with p- acetoxy benzoic acid or biphenol diacetate/terephthalic acid to obtain block copolymers of PSU/Polyethers, the latter part being highly crystalline or even liquid crystalline polymers. The synthesis of the block copolymer was carried out as a melt or in the presence of diphenyl sulfone at 200 - 300⁰C. Block copolymer preparation was indicated by the fact that the product was not soluble in common organic solvents.

Maresca et al have prepared Polyaryl ethers contains at least 20 %by weight of bis-(3,5-dimethyl-4-hydroxyphenyl)sulfone with improved glass transition temperatures. Wang and coworkers (Polymer International, 50(2), 249 2001 have synthesised novel random and block copolymers composed of Phthalimidine and Perflouroisopropylidene-Polyaryl ether sulfones.

Gerhard and coworkers(US Patent 3,647,751) have prepared Polyarylether sulfones using dihalo-diphenyl-disulphonearyls and of alkali metal bis- phenolates.

McGrath and coworkers (Polymer Preprints, 26, 277, 1985) have also developed block copolymers of PSU and PEEK using a hydroxy terminated oligomeric PSU homoblock and difluoro benzophenone alone or optionally adding hydroquinone and/or biphenol. The first method, rather than giving a block copolymer, gives PSU blocks joined by difluorobenzophenone. However, the second method has the possibility of producing both random and block structures in the copolymers of PSU and PEEK.

While the above investigations have prepared PSU block copolymers, it can be seen that most have opted for the combination of hydroxy terminated PSU with other monomers, which on polymerization give block copolymers. In this process, it is quite likely that the polymerizing monomers would give block sizes so varied that some of the PSU blocks may be joined by nothing more than a single monomer unit having a molecular weight of only 300 or less, and certainly < 1000. Thus, the molecular weight of the second block will not be that of a PSU oligomer, which should ideally be >1000 to be called a block. Thus, depending on the concentration, it is likely that the second homoblock will be no more than a single or double monomer unit. Such a situation can be averted by preparing the two homoblocks separately and reacting them to give a block copolymer.

Noshay and coworkers (J. Polymer Sci. A-I, 3147, 1971) have prepared block copolymers of amine terminated dimethyl Siloxanes and hydroxy terminated PSU. The hydroxy terminated PSU was prepared using a slight excess of Bisphenol A (0.495 mole) over DCDPS (0.450 mole). The -ONa groups were then converted to -OH groups using oxalic acid and the product was precipitated. The dried PSU powder was reacted with a separately prepared amine terminated polysiloxane in ether at 60⁰C. It may be noted that while PSU is plastic, Polysiloxane is elastomeric and hence the combination gives a block copolymer with thermoplastic elastomer like properties.

Surprisingly however, there has been no described method, nor synthesis carried out, whereby two Sulfone homoblocks have been used to form a block copolymer with thermoplastic properties.

The usual method of preparation of these polysulfones consists of the following process :

An aprotic organic solvent selected from Sulfolane, N-methyl pyrrolidone (NMP), or Dimethyl sulfoxide (DMSO), usually distilled over an alkali, is placed in the reactor. DCDPS or any one of similar dihalo monomer like

Dichlorodiphenyl disulfonylbiphenyl (CSB), Dichloro benzophenone, etc. and one of the second dihydroxy monomer (Biphenol, DHDPS, TMDHDS or HSB etc.), generally in the near mole proportion 1.00:1.00, are added to this reactor along with sodium or potassium carbonate. Toluene or monochlorobenzene (MCB) is added to facilitate dehydration. The temperature of the mixture is then slowly increased to from 140⁰C to 230⁰C depending on the solvent utilized, whereupon the alkaline carbonate reacts with the phenol to give a salt and liberate water. The water gets distilled off, which is facilitated by toluene or MCB, if present. The reaction mixture after water removal is then heated to a temperature in the range of 170⁰C to 250⁰C, depending on the solvent, alkali and the dihydroxy monomer used, until the desired viscosity or molecular weight is attained. Thereafter, the growing chains are optionally end-capped with MeCl and the reaction mass is filtered to remove salt and then polymer chains are precipitated in water or MeOH, further treated to remove the residual solvent, and dried. Alternately, solvent may be flashed off and reaction mass may be passed through a devolatizing extruder directly to remove residual solvent and for polymer granulation.

Adding more than one hydroxy monomer to the above leads to ter-copolymers with three, instead of two, monomer units incorporated randomly in the chains.

It is desirable that a method of block copolymer formation is evolved whereby two plastics, both of which are sulfone-based homoblocks, are connected to form a single chain as a block copolymer. As noted earlier, block copolymers of different polysulfones are not known in the art. In general, as known in art, three requirements need to be met for the successful formation of block copolymers from homoblocks : i) The two homoblocks should have end groups that react with each other, i.e.

- OH & -CNO. ii) Each homoblock should have two identical end groups i.e. -OH or -CNO. iii) The two homoblocks should be mixed in exact stoichiometric proportions to give high molecular weights block copolymers.

The present invention discloses a process of preparing block copolymers using two or more different polysulfones homoblocks while the strict requirement of each homoblock having exactly similar end groups is avoided. Similarly, the exact stoichiometry for two or more homoblocks can be avoided for high molecular weight block polymer formation. SUMMARY OF THE INVENTION

The present invention relates to a process of preparing block copolymers, comprising of at least two types of homoblocks, selected from either PSSD, PSSB, TPES, PSS, TMPSS or PESK or selected from at least one of PSSD, PSSB, TPES, PSS, TMPSS or PESK and at least one of PPSU, PES or PSU, wherein each of the said homoblock has an identical or different molecular weight of at least 1000 and has at least 5 % of the overall weight and wherein the block copolymer has a molecular weight of at least 2000, the process steps comprising of : (a) preparing each of the aforesaid homoblocks by heating at least one aromatic diol/dihydroxy compound with at least one aromatic dihalo compound, one of which contains at least one sulfone group, in the presence of at least one alkali optionally in at least one solvent and further optionally in the presence of an azeotropic agent,

(b) reacting the aforesaid homoblocks together at a temperature between 130⁰C to 250⁰C optionally in at least a solvent, and further optionally followed by end-capping said block copolymer,

(c) recovering the block copolymer. The present invention also relates to the block copolymers prepared using the aforesaid process and block copolymers comprising of at least two types of homoblocks, selected from either PSSD, PSSB, TPES, PSS, TMPSS or PESK or selected from at least one of PSSD, PSSB, TPES, PSS, TMPSS or PESK and at least one of PPSU, PES or PSU, that are linked together either directly or by a linking group to form block copolymer chains, wherein each of the homoblock has an identical or different molecular weight of at least 1000 and has at least 5 % of overall weight and wherein the block copolymer has a molecular weight of at least 2000.

These novel block copolymers are prepared using a technique whereby lower molecular weight homoblocks are first separately prepared and then mixed in different proportions and reacted further to give high molecular weight block copolymers. It becomes possible, using this technique, to ensure the formation of the block structures, as well as their sequences and the block molecular weights. Besides segmented multi-blocks copolymers, even high molecular weight di-blocks or tri- blocks as well as multi-blocks with known block molecular weights are feasible using this method. Block copolymers thus prepared find usage as novel polysulfone plastics, and also as compatibilizers. DESCRIPTION OF THE INVENTION

In general, two possible chain end structures exist on a polymeric chain of a homoblock of a polysulfone. These end groups are -Cl, emanating from a dihalo (DCDPS, CSB, DCB, etc) moiety and -OH emanating from the Phenolic monomer. A mixture of the both end groups is also possible for a given homoblock polymeric chain.

For block copolymers, one expects, based on prior art, that the one homoblock should have only two -Cl end groups per chain and the second homoblock should have only two -OH end groups per chain. Mixing and reacting them in right stoichiometric proportion would then yield a high molecular weight block copolymer. However, since it is possible to have -Cl or -OH mixed end groups on both the homoblocks, the present invention shows that it is possible to do away with this stringent requirement stated earlier that each homoblock should have the same two identical end groups and the two homoblocks must be mixed in right stoichiometric proportion.

Polysulfones usually have some -Cl and some -OH end groups. The concentration of each is decided by two important factors : firstly the initial molar ratio of dihalo compound like DCDPS, DCB or CSB etc to dihydroxy Phenolic monomer used and secondly the molecular weight of the polymer that is allowed to build up, if the mole ratio is not strictly 1:1. The ratio of the two monomers is a very important factor because, in order to build a very high molecular weight, the ratio must be kept closer to 1:1 on a molar basis. Usually, no monomer should be present in a concentration of more than approximately 1-2 mole % higher than the other monomer. Thus, the mole ratio generally remains within the range 1.02: 1.00 to 1.00: 1.02 to get high molecular weights. An increase in the concentration of any one monomer to a value outside of this range generally results in a disturbance in stoichiometry to such a substantial extent that the molecular weight of the copolymer does not get built up enough and most polymeric properties suffer, as they do not reach optimum values. However, for the preparation for oligomeric homoblocks, such a stringent stoichiometry is surprisingly not necessary since high molecular weight build up is not required. Thus, for homoblock preparation, a monomer ratio as high as 1.15:1.00 has been employed successfully in the present invention. The monomer ratio range, in homoblock, has thus been increased from 1.02:1.00 to 1.15:1.00, without sacrificing the ultimate molecular weights of the block copolymer.

The present invention relates to novel polysulfone block copolymer structures and the novel process by which their preparation takes place. In particular, this invention relates to the preparation of new types of block copolymers made using PES, PPSU, PSSD, PSSB, PSS, TPES, PSU, TMPSS and PESK, or similar polysulfone homoblocks and the methods of their preparation. The block copolymers may be made using at least two types of different polysulfones and may be made using more than two types of polysulfones. The process of the present invention involves the preparation of novel block copolymers of the polysulfone family using solution polymerization techniques. These block copolymers are prepared using lower molecular weight, oligomeric homoblocks of, for example, Polyphenylene Sulfone (PPSU), PES, PSSB, PSSD, TPES, PSS, TMPSS, PSU and PESK.

An important aspect of the present invention is that the present invention relates to a block copolymer having a high deflection temperature and high glass transition temperature. The block copolymer retains useful mechanical and physical properties at elevated temperatures (> 220 C) and in harsh chemical environments. The block copolymer disclosed in the prior art had lower heat deflection temperatures and therefore could be used only for applications requiring continuous use temperatures below 180 C and could not be used in high temperature application such as lamp housings, aerospace composites and other articles that exposed to thermal and mechanical stress. A major novel and unexpected aspect of the process of the present invention is that it can do away with the stringent requirements that the given homoblock should have only one type of two end groups as well as the stoichiometry between homoblocks used must be 1:1. Thus, the process of the present invention makes it possible to prepare high molecular weight block copolymers without having identical end groups on each homoblock as well as without the stoichiometry being closely controlled. The present invention therefore greatly simplifies the formation of block copolymers. Also, greater combinations of composition range of block copolymers can be readily made using same homoblocks by this invention as compare to the earlier methods of segmented block copolymer preparations. Of course, using homoblocks with identical end groups and having them in exact stoichiometric proportions does not harm the process in any way, but these are no longer preconditions for the build up of high molecular weight block copolymers.

This process also makes it possible by proper control of end groups to prepare block copolymers in which the two homoblocks have a variety of molecular weights and the block copolymer can also have a large range of composition, which was not easy or even not possible in other type of block copolymers discussed earlier.

The novel block copolymers are made by first using initially separately prepared lower molecular weight homoblocks with reactive chain end groups. By the term "homoblock", it is meant that each block has either a PES or PSSB or TPES or PSSD or PPSU or TMPSS or PSS, PSU or PESK or some such polysulfone structure and different homoblocks have structures differing from each other. The two homoblocks are separately prepared and are arranged to have two end groups which in turn are either the same or different. It is important to realize as taught by this invention that there should be, nevertheless, a near stoichiometric balance of the two differing end groups, in this case say -Cl and -OH. What is important is that both end groups are allowed to be present on both the homoblocks.

The different ways of preparing homoblocks are as follows : The first set of homoblocks is prepared with predominantly halogen end groups, such as -F, -Cl, -Br and -I. The second set of homoblocks is prepared with predominantly the second type of end group, which is capable of reacting with a halogen end group, such as -OH (which may be present as the salts -OK, -ONa, or -OLi). This is done by taking large mole access of dihalo monomer as compared to dihydroxy monomer in the first case and reversing the ratio in the second. In general, when the lower molecular weight homoblock having predominantly one type of end group is reacted with another homoblock having predominantly the second type of end group, block copolymers having high molecular weights are obtained. Thus, for example, reacting low molecular weight PSSB homoblock having predominantly -OH end groups with low molecular weight PSSD homoblock having predominantly -Cl end groups gives novel block copolymers with [PSSD - PSSB]z or { [PSSB - PSSD]z }in the block copolymer sequence. When one homoblock has predominantly all the same end groups (-Cl for example) and is reacted with a second homoblock having predominantly all of a second type of end groups (-OH for example), the block copolymer obtained has blocks of PSSD & PSSB having similar molecular weights as that of the starting homoblocks. The present invention thus makes it possible for the molecular weights of homoblocks to be nearly same as their molecular weights as block in part of the chains. It is also possible to prepare, according to this invention, block copolymers where the homoblock of PSSD has halogen end groups and the PSSB homoblock has phenolic -OH end groups, as well as the reverse where PSSD has the hydroxy end groups and PSSB has halogen end groups. As shown by this invention, the end groups may be interchangeable for a given homoblock. Where each homoblocks has non-identical end groups (-Cl and -OH for example), it is important to have them in relatively same stoichiometry counting both the homoblocks. In case of making one or both high molecular weight homoblocks, it is important to keep end groups of both different to the extent possible, as in the case of di-blocks and tri-blocks preparations.

It is, however, possible according to this invention to have both homoblocks to have both end groups and still being used for making high molecular weight block copolymers. This can be done by taking both monomers in near equal mole ratio. In such cases, the end groups will be halogen and hydroxy, irrespective of molecular weights of homoblocks. Thus, using the above example, it is possible to make PSSD and PSSB homoblocks both having -Cl and -OH end groups and reacting together to form block copolymers of desired molecular weight. In such cases, the block copolymers formed may have blocks having in-chain molecular weights, which are similar or higher than the homoblocks' molecular weights.

The aforesaid method of preparation of homoblocks is true and same for all the homoblocks, viz. PSSD, PSU, PPSU, PSSB, PES, TPES, PSS, PESK or TMPSS, etc.

This invention also teaches that besides random homoblock sequence in the block copolymer thus prepared, one can also make di- and tri-block copolymers by adjusting the molecular weights of the homoblocks and the stoichiometry of the two homoblocks reacted to form the block copolymers.

The invention therefore teaches preparation of di-block, tri-block as well as segmented block copolymers where the homoblocks may alternate or be present in random sequence.

If the molecular weights of the homoblocks are kept low enough and end groups are carefully controlled, this invention makes it possible to build high molecular weight copolymers having essentially alternate homoblock structures in the chains. In such block copolymers all the blocks will have similar molecular weights to those of the two initial homoblocks. If the molecular weights of the homoblocks are kept high, then one can build di- and tri-block copolymers of relatively high molecular weights.

It is also another important part of this invention as given above that z, degree of block copolymerization, can be varied from as low as 1 (for a di- block) to as high as 100 or higher for an alternate or random multi block copolymer. It is also another important part of this invention that special tri-block copolymers can also be prepared by using judicious control of the molecular weight, stoichiometry and end groups of the homoblocks.

The novel aspect of this invention is the recognition that by varying the stoichiometry of the basic monomers that are used for the preparation of homoblocks, particularly when they are of lower molecular weights, one can make these homoblocks with predominantly known end groups. Thus using one monomer, say, CSB in an excess of, say, 3 mole % over DHDPS i.e. a molar stoichiometry of >1.03: 1.00, one obtains PSSD with essentially only -Cl as end groups. This is due to the fact that higher concentrations of CSB lead to essentially complete reaction of all of the -OH groups present on DHDPS, thereby limiting the molecular weight build up but providing essentially only -Cl end groups for the homoblock PSSD. Similarly, when Biphenol is used at higher concentration in a homoblock preparation with CSB, one gets essentially all end groups as -OH, as its Na or K salt. PSSB, having essentially these phenolic groups, will not react with itself to give higher molecular weights PSSB. Similarly, PSSD with -Cl end groups also cannot react with itself to give higher molecular weight PSSD. Under such conditions, molecular weight does not further increase, giving indication that the chains with other end groups are used up.

However, when a homoblock of PSSD with essentially all -Cl end groups is mixed with a homoblock of PSSB with essentially all -OK end groups, further polymerization occurs and a PSSB-PSSD block is generated. Allowing this reaction to proceed further results in random block copolymer formation with a structure of the type [PSSB-PSSD}z where z is greater than or equal to 1, and is dependant on the molecular weights of homoblocks, and the stoichiometry and the molecular weight that is allowed to be built up.

The aforesaid method of preparation of homoblocks is true and same for all the homoblocks, viz. PSSD, PSU, PPSU, PSSB, PES, TPES, PSS, PESK or TMPSS.

One important aspect of this invention is deliberate use of higher ratios of the two monomers for the preparation of homoblocks to give essentially one type of end groups. The ratio may be 1.03 - 1.15:1.00, that is having 3 to 15 mole % higher quantity of one monomer over the second monomer. Another important aspect of this invention is that the homoblocks can also be conveniently prepared using near equal stoichiometry of the two base monomers, keeping the molecular weights of the homob locks as desired and, by mixing, preparing high molecular weight block copolymers of the desired composition.

The important aspect of this invention is therefore the preparation of lower molecular weight homoblocks with known end groups and their mixing in the right proportions to yield random block copolymers of higher molecular weights.

A further novel and important aspect of this invention is the preparation of di- and tri-block copolymers. These di- and tri-block copolymers are also materials of a novel composition. For this preparation, it is again recognized that homoblocks can be prepared with different molecular weights with essentially known end groups. In general, recognizing that controlling molecular weights of homoblocks and block copolymers give good control on number of homoblocks present in a block copolymer, one can stop the reaction at di or tri block stage. Polysulfones of sufficiently high molecular weight or inherent viscosity, (Inhv.) are required to give optimum mechanical and other polymer properties, one can build that range of molecular weight homoblocks. Thus, PSSD of a number average molecular weight (Mn) say of 50000 with -Cl end groups and PSSB of say similar molecular weight with -OK end groups, when mixed and reacted in a proportion of 1 : 1 on a molar basis will give almost double the molecular weight, giving a di-block. The molecular weight can be controlled on-line using gel permeation chromatography (GPC).

If di-blocks are allowed to react further to give still higher molecular weight, we get a tri- and tetra-block and so on. Thus, di-blocks of the structure — [PSSB-PSSD} will further react to give tri-blocks of the structure -[--]- [-PSSB- PSSD-PSSB} and - [-PSSD-PSSB-PSSD} and which, on further reaction, will yield tetra-blocks and higher multi-blocks. Thus, by controlling molecular weight, stoichiometry and end groups, this invention makes it possible to prepare di-block and tri-block and multi-block copolymers of PSSB and PSSD.

This invention further makes it possible to prepare a tri block using three different types of homoblocks as follows. First a di block is prepared using two homoblocks, where two end groups present on one homoblock are same and similarly second homoblock has two similar end groups on its chains but different than the first one. This di-block is reacted with third homoblock with two end groups similar to either first or second homoblock to give tri-blocks.

The block polymers thus produced may be checked for GPC molecular weight, Inhv., DSC, Tg, MFI, etc. for quality control. The block copolymers may be used as powder for compounding and subsequently for granulation or may be added as a compatibilizer to the already separately manufactured high molecular weight homologue polysulfones.

The present invention seeks to achieve the following :

• to provide novel block copolymers of two or more different polyaryl sulfone homoblock contents, with controlled structures of di-blocks, tri-blocks and multi-blocks.

• to use these homoblocks of polyaryl sulfones having low molecular weight and controlled chain end groups to prepare high molecular weight block copolymers. • to prepare high molecular weight di-block and tri-block copolymers using the homoblocks of lower molecular weight and reactive chain ends.

• to prepare two types of homoblocks each essentially having either only halogen or hydroxy end groups and thus giving a multi-block copolymer on reaction between the two, the block molecular weight being similar to the initial homoblock molecular weight.

• to prepare block copolymers of two polyaryl sulfones, where the ratio of the two homoblocks is in the range 95:5 to 5:95.

• to prepare block copolymers of two or more homoblocks of polyaryl sulfones, which are transparent and which show a single intermediate Tg. • to prepare block copolymers that are thermally stable and processible in the temperature range of 350⁰C to 400⁰C, using traditional injection molding, extrusion or other acceptable plastics processing methods.

• to provide a process by which the homoblocks of polyaryl sulfones of known molecular weights and controlled end groups are prepared. • to provide a process for the preparation of low molecular weight controlled chain end homoblocks and another process for the preparation of high molecular weight block copolymers having di /tri/multi-block in-chain structures.

According to this invention there is provided a process that allows one to prepare low molecular weight, controlled chain-end homoblocks and utilize these homoblocks to prepare di-, tri-, and multi-block copolymers of high molecular weight.

The invention preferably uses Sulfolane, NMP, DMAc, DMSO, DMSO2, Diphenyl sulfone or any other aprotic organic solvent for the preparation of low molecular weight homoblocks and the high molecular weight block copolymers thereof. Preferably MCB or Toluene or any other non-reacting solvent is used as a diluent and dehydrating agent for the salt formation, dehydration and polymerization steps.

Preferably the process uses the above mentioned solvent in the temperature range of 120⁰C to 250⁰C and with alkali such as NaOH, KOH, NaHCO₃,

KHCO₃, Na₂CO₃ or K₂CO₃ either by themselves or in a combination of these or any other such suitable alkaline substances.

According to this invention there is provided a process of producing novel homoblocks and multi-block copolymers, using an aprotic organic solvent or solvents in the temperature range of 120°C-250°C and then end capping with MeCl or any suitable end capping agent. The process includes the preferred steps of filtration of the salt and precipitation of the block copolymer from the reaction mixture in a non-solvent like H₂O or MeOH or a mixture of the two, and then giving further water/or MeOH treatments to reduce the residual solvent content of the powder and subsequently drying the polymeric powder.

The present invention will now be described with reference to the following examples. The specific examples illustrating the invention should not be construed to limit the scope thereof. EXAMPLES : EXAMPLE 1 : TPSS : A block-copolymer of 50:50 PSSD:PSSB

The following three part procedure was used to prepare this TPSS (PSSD - PSSB) block copolymer.

Part 1 : The preparation of the PSSD homoblock.

PSSD is made by using DHDPS and CSB as monomers. A 4 -necked, 3 -litre glass flask was equipped with an overhead stirrer attached to a stainless steel paddle through its center neck. Through one of its side necks, a Cloisonne adapter was attached. The other neck of the Cloisonne adapter was attached to a Dean-Stark trap and a water-cooled condenser. A thermocouple thermometer was inserted through another of the side necks. A nitrogen gas inlet was inserted through the other side neck. The flask was placed in an oil bath, which was connected to a temperature controller. Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (523 gms) and 4,4' Dihydroxy diphenyl sulfone (DHDPS) (250 gms) were added to the flask with CSB : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent. The temperature of the reactants was slowly increased to 220⁰C over 5 hours and the stirring speed was set to 400 rpm. The water formed due to the reaction of Na2CO3 with DHDPS was distilled over as an azeotrope with toluene and collected in the Dean-Stark trap. The toluene was then returned to the reaction mixture once it had been separated from the water. Once the water had been completely removed, toluene addition back to the reaction vessel was stopped. The toluene was then removed completely from the reaction mixture as the temperature of the reactants increased. The desired temperature was reached after 5 hours. The reaction temperature was then maintained at 220⁰C and when the viscosity started to increase the stirring speed was raised to 500 rpm. At the required Mn of 17,000, MW of about 20,000 and MWD 1.19, the reaction was stopped by reducing temperature to < 130C. The relatively high molar ratio of CSB to DHDPS gave PSSD of a relatively low molecular weight and with predominantly end groups of -Ph-Cl Part 2 : The preparation of the PSSB homoblock. PSSB is made by using Biphenol and CSB as monomer Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and Biphenol (188 gms) were added to the flask and Biphenol : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent. The temperature of the reactants was slowly increased to 220⁰C over 5 hours and the stirring speed was set to 400 rpm. The water formed due to the reaction was distilled over as an azeotrope with toluene and collected in the Dean-Stark trap. The toluene was then returned to the reaction mixture once it had been separated from the water. Once the water had been completely removed, toluene addition back to the reaction vessel was stopped. The toluene was then removed completely from the reaction mixture as the temperature of the reactants increased. The desired temperature was reached after 4 hours. The reaction temperature was then maintained at 220⁰C and when the viscosity started to increase the stirring speed was raised to 500 rpm. At the required Mn of 29,000, MW of about 38,000 and MWD 1.31, reaction mass was quickly cooled to stop further polymerization. The relatively high molar ratio of Biphenol to CSB gave PSSB of a relatively low molecular weight and with predominantly end groups of -Ph-OH.

Part 3 : The preparation of the block copolymer. The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 220⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² pressure of nitrogen to remove salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 88,000, an Mw of 121,000 and an MWD of 1.37 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSD are 259°C and 1.29 respectively, while those of high molecular weight PSSB itself are 270⁰C and 1.320. The transparent granules of block copolymer (TPSS) showed a DSC Tg of 266°C and a specific gravity of 1.31. The transparency of the granules, the single GPC peak, the intermediate

Tg and the specific gravity of the product clearly indicate that a block-copolymer of PSSD and PSSB had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSD and PPSB. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure I) EXAMPLE 2 : TPSS : A block-copolymer of 90:10 PSSD:PSSB The following three part procedure was used to prepare TPSS

(PSSD:PSSB) block copolymer.

Part 1 : The preparation of the PSSD homoblock : PSSD is made by using DHDPS and CSB as monomer An experimental set up similar to that described in Example 1 was used. Sulfolane (1687 gms, 1500 ml/mole) and toluene (700 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (461 gms) and 4,4' Dihydroxy diphenyl sulfone (DHDPS) (225 gms) were added to the flask and CSB : DHDPS being in a molar ratio of 1.02: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (112.5 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 17,000, an Mw of23,000 and an MWD of 1.36.

Part 2 : The preparation of the PSSB homoblock. PSSB is made by using Biphenol and CSB as monomer. Sulfolane (437 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB)

(50.8 gms) and Biphenol (18.6 gms) were added to the flask and Biphenol : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (12.5 gms) was added.

The rest of the procedure is the same as that described in Part 2 of Example 1. The homoblock obtained had GPC molecular weights of Mn 10,000, an Mw of 12,000 and an MWD of 1.20.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1(9 parts) and Part 2 (1 parts) were mixed together and the block polymerization was conducted at 220⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 90,000, an Mw of 131,000 and an MWD of 1.37 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSD are 260⁰C and 1.29 respectively, while those of PSSB are 270⁰C and 1.330. The transparent granules of block copolymer showed a DSC Tg of 266°C and a specific gravity of 1.34. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer (TPSS) of PSSD and PSSB had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSD and PPSB. The detailed properties are summarized in Table 1. EXAMPLE 3 : DPSS : A block-copolymer of 50:50 PSSD:PSS

The following three part procedure was used to prepare this DPSS (PSSD - PSS) block copolymer.

Part 1 : The preparation of the PSSD homoblock PSSD is made by using DHDPS and CSB as monomer

An experimental set up similar to that described in Example 1 was used.

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (523 gms) and 4,4' Dihydroxy diphenyl sulfone (DHDPS) (250 gms) were added to the flask and CSB : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 20,000, an Mw of 22,000 and an MWD of 1.10.

Part 2 : The preparation of the PSS homoblock.

PSS is made by using HSB and CSB as monomer

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and 4,4 'Bis [(4-hydroxyphenyl) sulfonyl] Biphenyl(HSB) (471 gms) were added to the flask and HSB : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 2 of Example 1. The homoblock obtained had GPC molecular weights of Mn 29,000, an Mw of 38,000 and an MWD of 1.31.

Part 3 : The preparation of the block copolymer. The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refluxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %. GPC analysis of the block copolymer showed an Mn of 89,000, an Mw of 122,000 and an MWD of 1.37 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSD are 259°C and 1.29 respectively, while those of PSS are 270⁰C and 1.32. The transparent granules of block copolymer (DPSS) showed a DSC Tg of 267°C and a specific gravity of 1.31. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PSSD and PSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSD and PPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure II). EXAMPLE 4 :TMPES : A block -copolymer of 25:75 PES:TPES

The following three step procedure was used to prepare this TMPES (PES- TPES) block copolymer.

Part - 1 : The preparation of the PES homoblock

An experimental set up similar to that described in Example 1 was used. Sulfolane (300 gms, 1000 ml/mole), and toluene (1000 ml/mole) were placed in the flask , through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Dihydroxy diphenylsulfone (DHDPS) (62.8 gms), 4,4' Dichlorodiphenyl sulfolane (DCDPS) (71.75 gms) were added to the flask. The DCDPS and DHDPS being in a molar ratio of 1.00:1.005 and the reactants were stirred for 30 minutes. Anhydrous sodium carbonate (32.2 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent. The temperature of the reactants was slowly increased to 236°C over 6 hrs and the stirring speed was set to 400 rpm. The water formed due to the reaction OfNa₂CO₃ with DHDPS was distilled over as an azeotrope with toluene and collected in the Dean-stark trap. The toluene was then returned to the reaction mixture once it had been separated from the water. Once the water had been completely removed, toluene addition back to the reaction vessel was stopped. The toluene was then removed completely from the reaction mixture as the temperature of the reactants increased. The desired temperature was reached after 6 hours. The reaction temperature was then maintained at

236°C and when the viscosity started to increase the stirring speed was raised to 500 rpm. At the required Mn of 19,300, MW of about 22,000 and MWD 1.14. The reaction mixture was allowed to cool near 200⁰C. The relatively equal molar ratio of DHDPS to DCDPS gave PES of a relatively low molecular weight and with predominantly end groups of -Ph-OH. Part -2 : The preparation of the TPES homoblock

Sulfolane (900 gms, 1000 ml/m), and toluene (645 gms, 1000 ml/mole) were placed in the flask , through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Tetramethyl Biphenolsulfone ( TMDHDPS ) (229.5 gms) and 4,4 ' Dichlorodiphenylsulfone (DCDPS) (221.7 gms) were added to the flask. The DCDPS and TMDHDPS were taken in a molar ratio of 1.03 : 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate Na2CO3 (96.7 gms) was added. The temperature of the reactants was slowly increased to 236°C over 6 hrs and the stirring speed was set to 400 rpm. The water formed due to the reaction of N_a2CC>3 with TMDHDPS was distilled over as an azeotrope with toluene and collected in the Dean-stark trap. The toluene was then returned to the reaction mixture once the water had been completely removed, toluene addition back to the reaction vessel was stopped. The toluene was then removed completely from the reaction mixture as the temperature of the reactants increased. The desired temperature was reached after 6 hrs. Once the water had been completely removed the reaction temperature was then maintained at 236°C and when the viscosity started to increase the stirring speed was raised to 500 rpm. At the required Mn of 18,200, Mw of 20,000 and MwD 1.10. The relatively high molar ratio of DCDPS to TMDHDPS gave TMPES of a relatively low molecular weight and with predominantly end groups of -Ph-Cl. Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 236°C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (250 gms, 200 ml/mole) and its temperature reduced to 220⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (200 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refluxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 79,800, an Mw of 115,000 and an MWD of 1.44 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PES are 225°C and 1.37 respectively, whilst those of TPES are 271⁰C and 1.33. The transparent granules of block copolymer showed a DSC Tg of 267°C and a specific gravity of 132. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer(TMPES) of PES and TPES had indeed been formed and that the product was not simply a blend of the two homopolymers, PES and TPES. Table 3. The detailed chemical reaction is given in (Figure III). EXAMPLE 5 : TMPES : A block -copolymer of 40:60 PES:TPES

The following three step procedure was used to prepare TMPES (PES:TPES) block copolymer.

Part - 1 : The preparation of the PES homoblock

An experimental set up similar to that described in Example 1 was used. Sulfolane (480 gms, 1000 ml/m), and toluene ( 344 gms, 1000 ml/mole) were placed in the flask , through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Dihydroxy diphenylsulfone (DHDPS) (100.5 gms) ,4,4 ' Dichlorodiphenyl sulfone (DCDPS) (114.8 gms) were added to the flask. The DCDPS and DHDPS being in a molar ratio of 1.00:1.005 and the reactants were stirred for 30 minutes. Anhydrous sodium carbonate (50 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 4. The homoblock obtained had GPC molecular weights of Mn 23,000, an Mw of26,000 and an MWD of 1.11. Part -2 : The preparation of the TPES homoblock

Sulfolane ( 720 gms, 1000 ml/m), and toluene (516 gms, 1000 ml/mole) were placed in the flask , through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Tetramethyl Biphenolsulfone ( TMDHDPS ) (183.6 gms) and 4,4 ' Dichlorodiphenylsulfone (DCDPS) (177.4 gms) were added to the flask . The DCDPS and TMDHDPS were taken in a molar ratio of 1.03: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate Na2CO3 (75 gms) was added.

The rest of the procedure is the same as that described in Part 2 of Example 4. The homoblock obtained had GPC molecular weights of Mn 20,000, an Mw of 22,000 and an MWD of 1.10.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 236°C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (250 gms, 200 ml/mole) and its temperature reduced to 220⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (200 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and

Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 80,900, an Mw of 119,000 and an MWD of 1.47 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PES are 225°C and 1.37 respectively, whilst those of TPES are 271⁰C and 1.33. The transparent granules of block copolymer showed a DSC Tg of 258°C and a specific gravity of 132. The transparency of the granules (TMPES), the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PES and TPES had indeed been formed and that the product was not simply a blend of the two homopolymers, PES and TPES. The detailed properties are summarized in Table 3. The detailed chemical reaction is given in (Figure III). EXAMPLE 6 : TMPES : A block -copolymer of 60:40 PES:TPES

The following three step procedure was used to prepare this PES- TMPES block copolymer. Part - 1 : The preparation of the PES homoblock

An experimental set up similar to that described in Example 1 was used.

Sulfolane (720 gms, 1000 ml/m), and toluene (516 gms, 1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Dihydroxy diphenylsulfone (DHDPS) (150.7 gms), 4,4 ' Dichlorodiphenyl sulfone (DCDPS) (172.2 gms) were added to the flask. The DCDPS and DHDPS being in a molar ratio of 1.00:1.005 and the reactants were stirred for 30 minutes. Anhydrous sodium carbonate (75 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent. The rest of the procedure is the same as that described in Part 1 of

Example 4. The homoblock obtained had a GPC molecular weight of Mn 25,000, an Mw of 28,000 and an MWD of 1.12.

Part -2 : The preparation of the TPES homoblock

Sulfolane (480 gms, 1000 ml/m), and toluene (344 gms, 1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 40⁰C. Tetramethyl Biphenolsulfone (TMDHDPS) (122.4 gms) and 4,4 ' Dichlorodiphenylsulfone (DCDPS) (118.24 gms) were added to the flask. The DCDPS and TMDHPS were taken in a molar ratio of 1.03: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate Na2CO3 (50 gms) was added.

The rest of the procedure is the same as that described in Part 2 of Example 4. The homoblock obtained had a GPC molecular weight of Mn 18,000, an Mw of 20,000 and an MWD of 1.10.

Part 3 : The preparation of the block copolymer. The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 236°C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (250 gms, 200 ml/mole) and its temperature reduced to 220⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (200 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %. GPC analysis of the block copolymer showed an Mn of 85,700, an Mw of

1,26,000 and an MWD of 1.47 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PES are 225°C and 1.37 respectively, whilst those of TPES are 271°C and 1.33. The transparent granules of block copolymer showed a DSC Tg of 247°C and a specific gravity of 1.32. The transparency of the granules (TMPES), the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PES and TPES had indeed been formed and that the product was not simply a blend of the two homopolymers, PES and TPES. The detailed properties are summarized in Table 2. The detailed chemical reaction is given in (Figure III) EXAMPLE 7 : TMDPSS : A block -copolymer of 50:50 PSSD:TMPSS The following three part procedure was used to prepare this PSSD -

TMPSS block copolymer.

Part 1 : The preparation of the PSSD homoblock

PSSD is made by using DHDPS and CSB as monomers.

An experimental set up similar to that described in Example 1 was used. Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (523 gms) and 4,4' Dihydroxy diphenyl sulfone (DHDPS) (250 gms) were added to the flask and CSB : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 18,000, an Mw of 22,000 and an MWD of 1.22. Part 2 : The preparation of the TMPSS homoblock.

TMPSS is made by using TMDHDPS and CSB as monomer

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and Tetramehtyl dihydroxydiphenyl Sulfone (309 gms TMDHDPS) were added to the flask and TMDHDPS : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refluxed three times with de-ionized water at 90⁰C to completely remove all salts and

GPC analysis of the block copolymer showed an Mn of 85,000, an Mw of 120,000 and an MWD of 1.41 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSD are 259°C and 1.29 respectively, while those of TMPSS are 268°C and 1.31. The transparent granules of block copolymer (TMDPSS) showed a DSC Tg of 264°C and a specific gravity of 1.31. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PSSD and TMPSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSD and TMPPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure IV). EXAMPLE 8 : TMBPSS : A block -copolymer of 50:50 PSSB:TMPSS

The following three part procedure was used to prepare TMBPSS (PSSB: TMPSS) block copolymer. Part 1 : The preparation of the PSSB homoblock :

PSSB is made by using Biphenol and CSB as monomer

An experimental set up similar to that described in Example 1 was used.

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (523 gms) and Biphenol (186 gms) were added to the flask and CSB : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent. The rest of the procedure is the same as that described in Part 1 of

Example 1. The homoblock obtained had GPC molecular weights of Mn 19,000, an Mw of 23,000 and an MWD of 1.21.

Part 2 : The preparation of the TMPSS homoblock.

TMPSS is made by using TMDHDPS and CSB as monomer Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and Tetramehtyl dihydroxydiphenyl Sulfone (309 gms TMDHDPS) were added to the flask and TMDHDPS : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 2 of Example 1. The homoblock obtained had GPC molecular weights of Mn 23,000, an Mw of 26,000 and an MWD of 1.11.

Part 3 : The preparation of the block copolymer. The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane(504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refluxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 88,000, an Mw of 124,000 and an MWD of 1.40 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSB are 270⁰C and 1.33 respectively, while those of TMPSS are 268°C and 1.31. The transparent granules of block copolymer showed (TMBPSS) a DSC Tg of 268°C and a specific gravity of 1.32. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PSSB and TMPSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSB and TMPPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure V). EXAMPLE 9 : TMDPPSU :A block -copolymer of 50:50 PPSU:TMPSS The following three part procedure was used to prepare this

PPSU - TMPSS block copolymer.

Part 1 : The preparation of the PPSU homoblock : PPSU is made by using Biphenol and DCDPS as monomer An experimental set up similar to that described in Example 1 was used. Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Dichloro diphenylsulfone (DCDPS) (298 gms) and Biphenol (186 gms) were added to the flask and DCDPS : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 23,000, an Mw of 29,000 and an MWD of 1.26. Part 2 : The preparation of the TMPSS homoblock.

The rest of the procedure is the same as that described in Part 2 of Example 1. The homoblock obtained had GPC molecular weights of Mn 25,000, an Mw of 35,000 and an MWD of 1.40.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 82,000, an Mw of 115,000 and an MWD of 1.40 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PPSU are 220⁰C and 1.29 respectively, while those of TMPSS are 268°C and 1.31. The transparent granules of block copolymer showed (TMDPPSU) a DSC Tg of 240⁰C and a specific gravity of 1.30. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PPSU and TMPSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PPSU and TMPPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure VI). EXAMPLE 10 : TMDPES : A block -copolymer of 50:50 PES:TMPSS

The following three part procedure was used to prepare this PES - TMPSS block copolymer. Part 1 : The preparation of the PES homoblock

PES is made by using DHDPS and DCDPS as monomer

An experimental set up similar to that described in Example 1 was used.

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Dichloro diphenylsulfone (DCDPS) (298 gms) and 4,4' Dihydroxy diphenyl sulfone (DHDPS) (250 gms) were added to the flask and DCDPS : DHDPS being in a molar ratio of 1.04:1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent. The rest of the procedure is the same as that described in Part 1 of

Example 1. The homoblock obtained had GPC molecular weights of Mn 25,000, an Mw of 29,000 and an MWD of 1.16.

Part 2 : The preparation of the TMPSS homoblock. TMPSS is made by using TMDHDPS and CSB as monomer Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and Tetramehtyl dihydroxydiphenyl Sulfone (309 gms TMDHDPS) were added to the flask and TMDHDPS : CSB being in a molar ratio of 1.01 : 1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 2 of Example 1. The homoblock obtained had GPC molecular weights of Mn 25,000, an Mw of 35,000 and an MWD of 1.40. Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %. GPC analysis of the block copolymer showed an Mn of 85,000, an Mw of 115,000 and an MWD of 1.35 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PES are 225°C and 1.29 respectively, while those of TMPSS are 268°C and 1.31. The transparent granules of block copolymer showed (TMDPES) a DSC Tg of 255°C and a specific gravity of 1.30. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PES and TMPSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PES and TMPPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure VII). EXAMPLE 11 : BPSK : A block -copolymer of 50:50 PSSB:PESK

The following three part procedure was used to prepare this PSSB - PESK block copolymer.

Part 1 : The preparation of the PSSB homoblock

PSSB is made by using Biphenol and CSB as monomer An experimental set up similar to that described in Example 1 was used.

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (523 gms) and Biphenol (186 gms) were added to the flask and CSB : DHDPS being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes.

Anhydrous sodium carbonate (123 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 19,000, an Mw of23,000 and an MWD of 1.21.

Part 2 : The preparation of the PESK homoblock.

PESK is made by using DCB and DHDPS as monomer

Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Dichloro Diphenyl benzophenone (DCB) (251 gms) and 4,4'Dihydroxy diphenylsulfone(DHDPS) (253 gms) were added to the flask and DHDPS : DCB being in a molar ratio of 1.01:1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 230⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 210⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and

GPC analysis of the block copolymer showed an Mn of 88,000, an Mw of 124,000 and an MWD of 1.40 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSSB are 270⁰C and 1.33 respectively, while those of PESK are

185°C and 1.28. The transparent granules of block copolymer showed (BPSK) a DSC Tg of 235°C and a specific gravity of 1.32. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PSSB and PESK had indeed been formed and that the product was not simply a blend of the two homo polymers, PSSB and PESK. The detailed properties are summarized in Table 1.

The detailed chemical reaction is given in (Figure VIII).

EXAMPLE 12 : TMDPSU : A block -copolymer of 50:50 PSU:TMPSS

The following three part procedure was used to prepare this PSU - TMPSS block copolymer.

Part 1 : The preparation of the PSU homoblock PSU is made by using Bisphenol A and DCDPS as monomer An experimental set up similar to that described in Example 1 was used. Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Dichloro diphenylsulfone (DCDPS) (298 gms) and Bisphenol A (250 gms) were added to the flask and DCDPS : Bisphenol A being in a molar ratio of 1.04: 1.00 and the reaction mixture was stirred for 30 minutes. Anhydrous Potassium Carbonate (154 gms) was added. A nitrogen atmosphere was maintained in the flask by purging. The toluene acts as an azeotropic solvent.

The rest of the procedure is the same as that described in Part 1 of Example 1. The homoblock obtained had GPC molecular weights of Mn 20,000, an Mw of 25,000 and an MWD of 1.25. Part 2 : The preparation of the TMPSS homoblock.

TMPSS is made by using TMDHDPS and CSB as monomer Sulfolane (4410 gms, 3500 ml/mole) and toluene (1000 ml/mole) were placed in the flask, through which nitrogen gas was bubbled continuously, and heated to 45°C. 4,4' Bis [(4-Chlorophenyl) Sulfonyl] Biphenyl (CSB) (503 gms) and Tetramehtyl dihydroxydiphenyl SuIf one (309 gms TMDHDPS) were added to the flask and TMDHDPS : CSB being in a molar ratio of 1.01:1.00, and the reaction mixture was stirred for 30 minutes. Anhydrous sodium carbonate (123 gms) was added. The toluene acts as an azeotropic solvent.

Part 3 : The preparation of the block copolymer.

The reaction mixtures of Part 1 and Part 2 were mixed in equal proportions by weight and the block polymerization was conducted at 220⁰C. After the required MW was achieved, as shown by GPC, the reaction mixture was quenched with Sulfolane (504 gms, 400 ml/mole) and its temperature reduced to 200⁰C. Methyl Chloride gas was then bubbled through the reaction mixture for 3 hrs to ensure complete end capping. The reaction mixture was then diluted with Sulfolane (400 ml/mole) for a second time. The polymer solution was filtered through a 15 micron filter in a pressure filter funnel using 2 kg/cm² of nitrogen to remove any salts. The block copolymer was finally recovered by slowly adding the salt-free polymer solution to de-ionized water (13 ml/gm of polymer) under high-speed agitation. The precipitated polymer was then recovered by filtration. The precipitated polymer was ground and refiuxed three times with de-ionized water at 90⁰C to completely remove all salts and Sulfolane. The precipitated polymer was then filtered and dried in an oven at 140⁰C until the moisture content as determined by Karl Fischer titration was < 0.5 %.

GPC analysis of the block copolymer showed an Mn of 80,000, an Mw of 115,000 and an MWD of 1.44 based on the polystyrene standards. Thus, the copolymer produced had a significantly higher molecular weight than the two homoblocks used as monomer units, indicating the preparation of a block copolymer. The block copolymer powder was then mixed with 0.25 % heat stabilizer and granulated using a twin screw extruder. The Tg and the specific gravity of PSU are 190⁰C and 1.29 respectively, while those of TMPSS are 268°C and 1.31. The transparent granules of block copolymer showed

(TMDPSU) a DSC Tg of 230⁰C and a specific gravity of 1.30. The transparency of the granules, the single GPC peak, the intermediate Tg and the specific gravity of the product clearly indicate that a block-copolymer of PES and TMPSS had indeed been formed and that the product was not simply a blend of the two homo polymers, PSU and TMPPS. The detailed properties are summarized in Table 1. The detailed chemical reaction is given in (Figure IX).

Various homoblocks can be prepared using one or more dichloro compounds and one or more dihydroxy compounds, some of which are listed below : AROMATIC DIHALO COMPOUNDS :

Dichloro diphenyl sulfone (DCDPS), 4,4' Bis (4 - chlorophenyl sulfonyl) biphenyl (CSB), Dichloro Benzophenone, Dichloro diphenyl ether, Dichloro biphenyl, Dichloro diphenyl methylene, Di Methyl dichloro diphenyl sulfone, tetra methyl dichloro diphenyl sulfone, dihalodiphenyl biphenyl, dihalo diphenoxy biphenyl, dihalo diphenyl biphenyl diether (disulfone or diketo) (C1-C6H4-C6H4-X-C6H4-C6H4-X-C6H4-C6H4-CL), C1-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-C1-,

C1-C6H4-X-C6H4-C6H4-Y-C6H4-C1-,

C1-C6H4-C6H4-X-C6H-Y-C6H4-C6H4-C1-,

C1-C6H4-C6H4-X-C6H4-Y-C6H4-C1, where X = -O-, -SO2-, -CO-, -CH2- or a combination of any two

C1-C6H4-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-CL where

X = -O-, -SO2-, -CO-, -CH2- and

Y= -O-, -SO2-, -CO-, -CH2-, and -Cl implies any halogen.

AROMATIC DIHYDROXY COMPOUNDS :

Dihydroxy diphenyl Sulfone (DHDPS), Bisphenol A, Biphenol,

Hydroquinone, Dimethyl Dihydroxy diphenyl sulfone, Tetramethyl dihydroxy diphenyl sulfone, Tetramethyl Bisphenol A, Tetramethyl Biphenol, Dihydroxy Diphenyl Ketone, Bis (hydroxy phenyl sulfonyl) Biphenyl, Bis (hydroxy phenyl keto) Biphenyl, Bis (hydroxy phenoxy) Biphenyl,

HO-C6H4X-C6H4-C6H4-Y-C6H4-OH where X & Y = -0-,-S02-,-C0-, -CH2- and phenyl or biphenyl rings may be having one or two methyl substitution,

HO-C6H4-X-C6H4-Y-C6H4-OH, with or without methyl substitutions.

Claims

C L A I M S

1. A process of preparing block copolymers comprising of at least two types of homoblocks, selected from either PSSD, PSSB, TPES, PSS, TMPSS or PESK or selected from at least one of PSSD, PSSB, TPES, PSS, TMPSS or PESK and at least one of PPSU, PES or PSU, wherein each of the said homoblock has an identical or different molecular weight of at least 1000 and has at least 5 % of the overall weight and wherein the block copolymer has a molecular weight of at least 2000, the process steps comprising of :

(a) preparing each of the aforesaid homoblocks by heating at least one aromatic diol/dihydroxy compound with at least one aromatic dihalo compound, one of which contains at least one sulfone group, in the presence of at least one alkali optionally in at least one solvent and further optionally in the presence of an azeotropic agent,

(c) recovering the block copolymer.

2. A process as claimed in claim 1 wherein the block copolymer is recovered by washing the reaction mass to remove the salt and alkali and optionally the solvent.

3. A process as claimed in claim 1 wherein the block copolymer prepared in at least one solvent is recovered from the solvent by filtering out the salt and precipitating the block copolymer in water or MeOH or a mixture of water and MeOH and further filtering, washing and drying block copolymer.

4. A process as claimed in claim 1 wherein the block copolymer prepared in at least one solvent is recovered by filtering the salt and distilling off the solvent.

5. A process as claimed in claim 1, wherein the aromatic dihalo compound is selected from either of Dichloro diphenyl sulfone (DCDPS), 4,4' Bis (4 - chlorophenyl sulfonyl) biphenyl (CSB), Dichloro Benzophenone, Dichloro diphenyl ether, Dichloro biphenyl, Dichloro diphenyl methylene, Di Methyl dichloro diphenyl sulfone, tetra methyl dichloro diphenyl sulfone, dihalodiphenyl biphenyl, dihalo diphenoxy biphenyl, dihalo diphenyl biphenyl diether (disulfone or diketo) (C1-C6H4-C6H4-X-C6H4-C6H4-X-C6H4-C6H4-CL), C1-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-C1-, C1-C6H4-X-C6H4-C6H4-Y-C6H4-C1-, C1-C6H4-C6H4-X-C6H4-Y-C6H4-C6H4-C1-, C1-C6H4-C6H4-X-C6H4-Y-C6H4-C1, where

X = -O-, -SO2-, -CO-, -CH2-

or a combination of any two C1-C6H4-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-CL where

X = -O-, -SO2-, -CO-, -CH2- and

Y= -O-, -SO2-, -CO-, -CH2-,

and -Cl implies any halogen.

6. A process as claimed in claim 1, wherein said aromatic diol/dihydroxy compound is selected from either of Dihydroxy diphenyl Sulfone (DHDPS), Bisphenol A, Biphenol, Hydroquinone, Dimethyl Dihydroxy diphenyl sulfone, Tetramethyl dihydroxy diphenyl sulfone (TMDHDPS), Tetramethyl Bisphenol A, Tetramethyl Biphenol, Dihydroxy Diphenyl Ketone, Bis (hydroxy phenyl sulfonyl) Biphenyl (HSB), Bis (hydroxy phenyl keto) Biphenyl, Bis (hydroxy phenoxy) Biphenyl, HO-C6H4X-C6H4-C6H4-Y-C6H4-OH where

X & Y = -0-,-S02-,-C0-, -CH2- and phenyl or biphenyl rings may be having one or two methyl substitution, HO-C6H4-X-C6H4-Y-C6H4-OH, with or without methyl substitutions.

7. A process as claimed in claim 1, wherein either of said aromatic diol or said aromatic dihalo compound is equal in moles or greater than the other up to 15 mole %.

8. A process as claimed in claim 1, wherein each of said homoblock has at least 10 % of the overall weight of the block copolymer.

9. A process as claimed in claim 1, wherein each of said homoblock has at least 25 % of the overall weight of the block copolymer.

10. A process as claimed in claim 1, wherein each of said homoblock has at least 40 % of the overall weight of the block copolymer.

11. A process as claimed in claim 1 , wherein said solvent is Dimethyl acetamide (DMAc), Dimethyl Sulphoxide (DMSO), Sulfolane, N-Methyl Pyrrolydone, diphenyl sulfone, dimethyl sulfone or a mixture thereof.

12. A process as claimed in claim 1, wherein said alkali is a metal hydroxide, or a mixture of two or more metal hydroxides.

13. A process as claimed in claim 12, wherein said metal hydroxide is

NaOH, KOH or a mixture thereof.

14. A process as claimed in claim 1, wherein said alkali is a metal carbonate or a mixture of two or more metal carbonates.

15. A process as claimed in claim 15, wherein said metal carbonate is Na₂CO₃, K₂CO₃, or a mixture thereof.

16. A process as claimed in claim 1, wherein said alkali is a mixture of a metal hydroxide and a metal carbonate.

17. A process as claimed in claim 1, wherein said process steps (a) or (b) or both are carried out at a temperature between 160⁰C to 250⁰C.

18. A process as claimed in claim 1, wherein said azeotropic agent is toluene.

19. A process as claimed in claim 1, wherein said azeotropic agent is monochlorobenzene.

20. A process as claimed in claim 1, wherein said end-capping is performed using MeCl.

21. A process of preparing a block copolymer substantially as described herein with reference to the examples accompanying the specification.

22. A block copolymer comprising of at least two types of homoblocks, selected from either PSSD, PSSB, TPES, PSS, TMPSS or PESK or selected from at least one of PSSD, PSSB, TPES, PSS, TMPSS or PESK and at least one of PPSU, PES or PSU, that are linked together either directly or by a linking group to form block copolymer chains, wherein each of the homoblock has an identical or different molecular weight of at least 1000 and has at least 5 % of overall weight and wherein the block copolymer has a molecular weight of at least 2000.

23. A block copolymer as claimed in claim 22, wherein each of said homoblock has a molecular weight of 2000 to 10000.

24. A block copolymer as claimed in claim 22, wherein each of said homoblock has a molecular weight of 15000 to 50000.

25. A block copolymer as claimed in claim 22, wherein said block copolymer has a molecular weight of 5000 to 150000.

26. A block copolymer as claimed in claim 22, wherein said block copolymer has a molecular weight of 30000 to 150000.

27. A block copolymer as claimed in claim 22, wherein each of said homoblock has at least 10 % of the overall weight.

28. A block copolymer as claimed in claim 22, wherein each of said homoblock has at least 25 % of the overall weight.

29. A block copolymer as claimed in claim 22, wherein each of said homoblock has at least 40 % of the overall weight.

30. A block copolymer as claimed in claim 22, wherein said linking group is formed by reacting a diol or a dialkoxide with a dihalide.

31. A block copolymer as claimed in claim 30, wherein said diol or dialkoxide is selected from the family of aromatic dihydroxy compound.

32. A block copolymer as claimed in claim 30, wherein said dihalide is an aryl dichloride.

33. A block copolymer as claimed in claim 22, wherein said homoblocks are prepared using at least one aromatic diol/dihydroxy compound with at least one aromatic dihalo compound, one of which contains at least one sulfone group.

34. A block copolymer as claimed in claim 33, wherein the aromatic dihalo compound is selected from either of Dichloro diphenyl sulfone (DCDPS), 4,4' Bis (4 - chlorophenyl sulfonyl) biphenyl (CSB), Dichloro Benzophenone, Dichloro diphenyl ether, Dichloro biphenyl, Dichloro diphenyl methylene, Di Methyl dichloro diphenyl sulfone, tetra methyl dichloro diphenyl sulfone, dihalodiphenyl biphenyl, dihalo diphenoxy biphenyl, dihalo diphenyl biphenyl diether (disulfone or diketo)

(C1-C6H4-C6H4-X-C6H4-C6H4-X-C6H4-C6H4-CL), C1-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-C1-, C1-C6H4-X-C6H4-C6H4-Y-C6H4-C1-, C1-C6H4-C6H4-X-C6H4-Y-C6H4-C6H4-C1-, C1-C6H4-C6H4-X-C6H4-Y-C6H4-C1, where

X = -O-, -SO2-, -CO-, -CH2-

or a combination of any two C1-C6H4-C6H4-X-C6H4-C6H4-Y-C6H4-C6H4-CL where

X = -O-, -SO2-, -CO-, -CH2- and

Y= -O-, -SO2-, -CO-, -CH2-,

and -Cl implies any halogen..

35. A block copolymer as claimed in claim 33, wherein said aromatic diol/dihydroxy compound is selected from either Dihydroxy diphenyl Sulfone (DHDPS), Bisphenol A, Biphenol, Hydroquinone, Dimethyl Dihydroxy diphenyl sulfone, Tetramethyl dihydroxy diphenyl sulfone (TMDHDPS),

Tetramethyl Bisphenol A, Tetramethyl Biphenol, Dihydroxy Diphenyl Ketone, Bis (hydroxy phenyl sulfonyl) Biphenyl (HSB), Bis (hydroxy phenyl keto) Biphenyl, Bis (hydroxy phenoxy) Biphenyl, HO-C6H4X-C6H4-C6H4-Y-C6H4-OH where X & Y = -O-,-SO2-,-CO-, -CH2- and phenyl or biphenyl rings may be having one or two methyl substitution, HO-C6H4-X-C6H4-Y-C6H4-OH, with or without methyl substitutions.

36. A block copolymer substantially as described herein with reference to the examples accompanying the specification.