Patent Application: US-23062608-A

Abstract:
polymers and copolymers of formula i : in which m is typically 30 to 500 and n is 0 to 500 ; ar is for example , 1 , 2 - phenylene , 1 , 3 - phenylene , 1 , 4 - phenylene , or 2 , 6 - pyridylene ; ar 2 and ar 3 are selected from various bivalent aryl and heteroaryl groups ; and x is for example , the bivalent so 2 or co . have high temperature properties which make them useful as films , matrices in carbon fiber reinforced composites and high performance adhesives ; processes for preparing the polymers and copolymers employ a novel c — n coupling reaction .

Description:
in the preparation discussed supra in the background of the invention , of poly ( arylene ether benzimidazole ) s and poly ( n - arylenebenzimidazole ) s 21 , 22 both nh and oh groups are present in the monomers but only the oh reacts under the conditions used . surprisingly , it has now been found that , under similar conditions , but at higher temperatures , to those used for the preparation of poly ( arylene ether benzimidazole ) s and poly ( n - arylenebenzimidazole ) s , the nh group in benzimidazoles will undergo a c — n coupling reaction with activated halides to give novel polymers of high molecular weight , of the invention , as illustrated in the example below . accordingly , one aspect of the invention relates to a process which comprises the reaction step at a temperature of no less than 160 ° c ., as described above . the process of this aspect of the invention is typically performed at a temperature of at least about 170 ° c . and typically at a temperature up to 320 ° c ., such as at least about 180 ° c . or about 190 ° c ., such as at about 200 ° c . or 210 ° c . higher temperatures may be required depending on the halogen , in the starting compound , for example when the halogen is cl , higher temperatures are typically required than for the corresponding reaction where the halogen is f . the halogen may be selected from the group consisting of br , cl , i , and f , and more typically is selected from the group consisting of f and cl . preferably , if x is so 2 or co , the halogen will be f , so as to avoid the higher temperatures required for other values of halogen , especially cl . in the case where x is so 2 or co , and the halogen is cl , the reaction is typically carried out at a temperature of 250 ° c . to 320 ° c ., in diphenylsulphone or benzophenone as solvent . the process is suitably carried out in the presence of a base , such as k 2 co 3 and further typically comprises the use of a solvent such as sulfolane or other aprotic dipolar solvents , or diphenylsulphone or benzophenone . the size of the polymer synthesized , as known to the skilled person , may vary depending on stoichiometries and concentration . suitably , in the process of this aspect of the invention , m is an integer between 1 and 10 , 000 , and preferably 1 to 1000 , and more preferably m is 30 to 500 . in general the properties of the polymer depend on the total chain length and in particular the end to end distance . the terminal groups of the polymer will typically be nh groups of the benzimidazole , or cyclics may form . a further aspect of the invention relates to a process which comprises the reaction step : at a temperature of no less than 160 ° c ., as described above . the process of this latter aspect of the invention is typically performed at a temperature of at least about 170 ° c . and typically at a temperature up to 320 ° c ., such as at least about 180 ° c . or about 190 ° c ., such as at about 200 ° c . or 210 ° c . higher temperatures may be required depending on the halogen , in the starting compound , for example when the halogen is cl , higher temperatures are typically required than for the corresponding reaction where the halogen is f . the halogen may be selected from the group consisting of br , cl , i , and f , and more typically selected from the group consisting of f and cl . preferably , if x is so 2 or co , the halogen will be f , so as to avoid the higher temperatures required for other values of halogen , especially cl . in the case where x is so 2 or co , and the halogen is cl , the reaction is typically carried out at a temperature of 250 ° c . to 320 ° c ., in diphenylsulphone or benzophenone as solvent . the process is suitably carried out in the presence of a base , such as k 2 co 3 and further typically comprises the use of a solvent such as sulfolane or other aprotic dipolar solvents , or diphenylsulphone or benzophenone . the size of the polymer synthesized , as known to the skilled person , may vary depending on stoichiometries and concentration . suitably , under the process of this aspect of the invention , ( m + n ) can range from 1 to 10 , 000 wherein m must be at least 1 , preferably 1 to 1000 , and more preferably m is 30 to 500 , and n can vary from 1 to 9999 , preferably 1 to 999 , and more preferably 1 to 500 . in general the properties of the copolymer depend on the total chain length and in particular the end to end distance . the terminal groups of the polymer will typically be nh groups of the benzimidazole , or cyclics may form . advantageously , the polymers and copolymers of the present invention have very high tgs and they are very thermally stable . the t d - 5 % ( 5 % weight loss in n 2 ) for the copolymer of example 7 below is 539 ° c ., similar to the properties of polymers prepared by hergenrother et al . the molecule 4 -( 1h - benzo [ d ] imidazol - 2 - yl ) phenol has been used as an end - cap in the synthesis of poly ( arylene ether benzimidazole ) s and poly ( n - arylenebenzimidazole ) s to control the molecular weight of the polymers . 17 in this reaction it is reported that it acts as a monofunctional compound , i . e . with only the oh group entering the reaction . in the present invention it has been found , surprisingly , that 4 -( 1h - benzo [ d ] imidazol - 2 - yl ) phenol can behave as a bifunctional compound and that high molecular weight polymers ( n = 0 ) can be prepared by reaction with activated dihalides , as shown below . copolymers can also be synthesized by copolymerization with bisphenols as shown below with 4 , 4 ′- biphenol . accordingly a further aspect of the invention relates to copolymers of the formula where ar 2 , in and n are as defined above . high molecular weight copolymers are produced by copolymerizing the bisbenzimidazoles with bisphenols as shown in the example below with 4 , 4 ′- biphenol . accordingly , a further aspect of the invention relates to copolymers of the formula where ar , ar 2 , m and n are as defined supra . a further aspect of the invention relates to compounds obtainable by a process of the invention . in particular , an interesting aspect of the invention relates to polymers are of the formula i wherein in and n are as defined above and ar , ar 2 , ar 3 , and x are defined as follows : ar is a divalent radical selected from the group consisting of : ar 2 is a fused ring selected from the group consisting of : ar 3 is a divalent radical selected from the group consisting of : x is a divalent radical selected from the group consisting of : matrix assisted laser desorption ionization time - of - flight ( maldi - tof ) mass spectra were recorded on a kratos kompact maldi - iii tof mass spectrometer with the instrument set in positive reflection mode to get higher resolution . the melting points were taken on a fisher - johns melting point apparatus . ultraviolet - visible ( uv - vis ) absorption spectra were recorded on a cary 50 spectrophotometer . fluorescent spectra were taken on a fluoro max - 2 spectrophotometer . monitoring the progress of the reaction and purity of the isolated monomers was done by high performance liquid chromatography ( hplc , milton roy , cm 4000 ) with methanol as an eluent and a uv detector at 254 nm . the t g s of the polymers were obtained using a seiko 220 dsc at a heating rate of 20 ° c ./ min . the t g was taken from the midpoint of the change in slope of the baseline , while melting temperature were taken from the onset of the change in slope to a minimum of the endotherm of peak . the weight loss data were obtained from a seiko 220 tga / dta instrument at a heating rate of 20 ° c ./ min in nitrogen . inherent viscosity data were obtained with a calibrated ostwald viscometer . a water bath with a julabo ( model type pc ) heater was employed to control the temperature . a 25 ml three - necked round - bottom flask was equipped with an argon inlet , magnetic stirrer , a dean - stark trap and condenser . the flask was flushed with argon , and then charged with 1 , 3 - dibenzimidazolylbenzene ( 0 . 62 g , 2 . 0 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 51 g , 2 . 0 mmol ), cesium carbonate ( 0 . 65 g , 2 . 0 mmol ), calcium carbonate ( 0 . 20 g , 2 . 0 mmol ), sulfolane ( 2 . 5 g ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . after chlorobenzene was removed , the reaction mixture was brought up to 210 ° c . for 2 h . additional 1 ml of sulfolane was then added to dilute the solution and the reaction was kept at 210 ° c . for 6 h . when the color of the reaction system changed and the viscosity increased significantly , the reaction mixture was cooled down and diluted with 2 ml of solvent . the resulting solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was partially soluble in chloroform or dichloromethane and was redissolved . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the resulting polymer was precipitated out by pouring into methanol . the polymer was collected and dried in vacuo at 80 ° c . for 24 h . yield 90 %. the polymer was prepared in a manner similar to example 1 . the resulting polymer was not very soluble in chloroform and gave a brittle film by casting from its dmso - solution . a 25 ml three - necked round - bottom flask was equipped with an argon inlet , magnetic stirrer , a dean - stark trap and condenser . the flask was flushed with argon , and then charged with 1 , 3 - dibenzimidazolylbenzene ( 0 . 20 g , 0 . 64 mmol ), 2 , 6 - bisbenzimidazolylpyridine ( 0 . 20 g , 0 . 64 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 33 g , 1 . 3 mmol ), calcium carbonate ( 0 . 13 g , 1 . 3 mmol ), anhydrous potassium carbonate ( 0 . 20 g , 1 . 4 mmol ), sulfolane ( 2 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . the chlorobenzene was then removed , and the reaction mixture was brought up to 180 - 190 ° c . for 2 h , and then at 210 ° c . for 2 h additional . 1 ml of sulfolane was added to dilute the solution that was kept at 210 ° c . for 4 h . when the viscosity significantly increased the reaction mixture was cooled down and diluted . the resulting solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was redissolved in dmso . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the polymer was redissolved in chloroform , and reverse precipitated in methanol . the polymer was collected and dried in vacuo at 80 ° c . for 24 h . yield 90 %. the synthesis of most of the copolymers were carried out in sulfolane . the polymerization was conducted initially at 160 - 170 ° c . for 1 . 5 - 2 h to remove the water with chlorobenzene and then at 180 - 200 ° c . to effect the polymerization reaction . to a 25 ml three - necked round - bottom flask equipped with a dean - stark trap , a water condenser , a magnetic stirrer and a nitrogen inlet were added 4 , 4 ′- biphenol ( 0 . 056 g 0 . 30 mmol ), 1 , 3 - dibenzimidazolylbenzene ( 0 . 22 g , 0 . 70 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 25 g , 1 . 0 mmol ), calcium carbonate ( 0 . 15 g , 1 . 5 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), sulfolane ( 2 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with the chlorobenzene . the chlorobenzene was then removed , and the reaction mixture was brought up to 180 - 190 ° c . for 1 - 2 h . when the reaction mixture became too viscous to be stirred , an additional 2 ml of sulfolane was added to dilute the solution and it was kept at that temperature for 20 min . when the viscosity increased , the reaction mixture was cooled down , and diluted with dichloromethane . the solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the polymer was collected by filtration and dried in vacuo at 80 ° c . for 24 h . yield 97 %. to a 25 ml three - necked round - bottom flask equipped with a dean - stark trap , a water condenser , a magnetic stirrer and a nitrogen inlet were added 4 , 4 ′- dihydroxybenzophenone ( 0 . 13 g , 0 . 60 mmol ), 1 , 3 - dibenzimidazolylbenzene ( 0 . 43 g , 1 . 4 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 51 g , 2 . 0 mmol ), calcium carbonate ( 0 . 22 g , 2 . 2 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), sulfolane ( 2 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . the chlorobenzene was then removed , and the reaction mixture was brought up to 180 - 190 ° c . for 1 - 2 h . when the reaction mixture became too viscous to be stirred , an additional 2 ml of sulfolane was added to dilute the solution that was kept at that temperature for 20 min . when the viscosity was increased , the reaction mixture was cooled down and diluted with dichloromethane and then the solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the polymer was collected by filtration and dried in vacuo at 80 ° c . for 24 h . yield 95 %. to a 25 ml three - necked round - bottom flask were added 2 -( 4 - hydroxyphenyl ) benzimidazole ( 0 . 15 g , 0 . 71 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 36 g , 1 . 4 mmol ), calcium carbonate ( 0 . 22 g , 2 . 2 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), sulfolane ( 1 . 5 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . the chlorobenzene was then removed , and the reaction mixture was brought up to 180 - 190 ° c . for 1 - 2 h . the resulting mixture was analyzed by hplc and maldi - tof mass spectrometry . the maldi - tof - ms spectrum showed the product was oligomeric with all the oh & amp ; nh groups reacted . 4 , 4 ′- biphenol ( 0 . 13 g , 0 . 71 mmol ) and cesium carbonate ( 0 . 19 g , 0 . 58 mmol ) were added and the reaction mixture was brought up to 180 - 190 ° c . for 1 h . when the reaction system became too viscous to be stirred , an additional 2 ml of sulfolane was added to dilute the solution and it was maintained at 180 ° c . for 0 . 5 h . when the viscosity increased , the resulting mixture was cooled down and diluted with dichloromethane and the solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the polymer was collected and dried in vacuo at 80 ° c . for 24 h . yield 95 %. a flexible thin film was cast from its chloroform - solution . tg 251 ° c ., tga - 5 % weight loss at 532 ° c . to a 25 ml three - necked round - bottom flask equipped with a dean - stark trap , a water condenser , a magnetic stirrer and a nitrogen inlet were added bpa ( 0 . 16 g , 0 . 71 mmol ), 2 -( 4 - hydroxyphenyl ) benzimidazole ( 0 . 15 g , 0 . 71 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 36 g , 1 . 4 mmol ), calcium carbonate ( 0 . 22 g , 2 . 2 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), cesium carbonate ( 0 . 19 g , 0 . 58 mmol ), sulfolane ( 1 . 5 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . the chlorobenzene was then removed . the reaction mixture was brought up to 180 - 190 ° c . for 1 h . when the reaction mixture became too viscous to be stirred , an additional 2 ml of sulfolane was added to dilute the solution and it was kept at that temperature for 30 min . when the viscosity increased , the reaction mixture was cooled down and diluted with dichloromethane and the solution was poured into 200 ml of methanol and 2 ml of acetic acid to precipitate out the polymer . the resulting polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the fibrous polymer was collected and dried in vacuo at 80 ° c . for 24 h . yield 97 %. a good film was cast from its chloroform - solution . tg 230 ° c ., tga − 5 % weight loss 489 ° c . to a 25 ml three - necked round - bottom flask equipped with a dean - stark trap , a water condenser , a magnetic stirrer and a nitrogen inlet there were added bpa ( 0 . 22 g , 0 . 97 mmol ), 1 , 3 - dibenzimidazolylbenzene ( 0 . 30 g , 0 . 97 mmol ), 4 , 4 ′- difluorobenzophenone ( 0 . 42 g , 1 . 9 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), cesium carbonate ( 0 . 19 g , 0 . 58 mmol ), sulfolane ( 1 . 5 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with the chlorobenzene . the chlorobenzene was then removed . the reaction mixture was brought up to 180 - 190 ° c . after heating for 3 h , the reaction mixture became too viscous to be stirred . an additional 2 ml of sulfolane was then added to dilute the solution , and the resulting mixture was kept at this temperature for an additional 30 min . the viscous solution was cooled down and diluted with dichloromethane and the solution was poured into a mixture composed of methanol ( 100 ml )/ water ( 100 ml )/ acetic acid ( 2 ml ) to precipitate out the polymer . the resulting polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials , and the polymer was precipitated out by pouring into methanol . the fibrous polymer was collected and dried in vacuo at 80 ° c . for 24 h . yield 98 %. a good film was cast from its chloroform - solution . the polymer was soluble in thf . tg 119 ° c ., tga − 5 % weight loss 545 ° c ., mn 18000 , mw 49000 , mwd 2 . 8 , η inh 0 . 38 dl / g . to a 25 ml three - necked round - bottom flask equipped with a dean - stark trap , a water condenser , a magnetic stirrer and a nitrogen inlet were added 4 , 4 ′-( perfluoropropane - 2 , 2 - diyl ) diphenol ( 0 . 32 g , 0 . 96 mmol ), 2 , 6 - bisbenzimidazoylpyridine ( 0 . 30 g , 0 . 96 mmol ), bis ( 4 - fluorophenyl ) sulfone ( 0 . 49 g , 1 . 9 mmol ), anhydrous potassium carbonate ( 0 . 28 g , 2 . 0 mmol ), sulfolane ( 1 . 5 ml ), and chlorobenzene ( 3 ml ). the mixture was heated to azeotrope off the resulting water with chlorobenzene . the chlorobenzene was then removed , and the orange colored reaction mixture was brought up to 180 - 190 ° c . after heating for 2 h , the reaction mixture became reddish , and too viscous to be stirred . an additional 2 ml of sulfolane was then added to dilute the mixture , and the resulting mixture was kept at this temperature for an additional 30 min . when the reaction mixture changed into dark red and the viscosity increased significantly , the resulting mixture was cooled down , and diluted with dichloromethane . the resulting mixture was poured into a mixture composed of methanol ( 100 ml )/ water ( 100 ml )/ acetic acid ( 2 ml ) to precipitate out the polymer . the precipitated polymer was redissolved in chloroform . the polymer solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials . the polymer was precipitated out by pouring the chloroform solution into methanol . the polymer was collected by filtration , and dried in vacuo at 80 ° c . for 24 h . strong cast films were obtained from its chloroform - solution . the polymer was soluble in thf . tg 245 ° c ., tga − 5 % weight loss 534 ° c ., mn 35000 , mw 79000 , mwd 2 . 2 , η inh 0 . 29 dl / g . all of the homopolymers and copolymers containing the benzimidazole groups strongly absorb uv light and are fluorescent as shown in table 1 . example 22 is typical of the reaction conditions used . 1 , 3 - dibenzimidazolylbenzene g , 1 . 0 mmol ), 4 , 4 ′- biphenol ( 0 . 19 g , 1 . 0 mmol ), cesium carbonate ( 0 . 20 g , 0 . 60 mmol ), potassium carbonate ( 0 . 21 g , 1 . 5 mmol ), diphenylsulfone ( 1 . 5 g ), and chlorobenzene ( 3 ml ) were charged into a 25 ml three - necked round - bottom flask equipped with a magnetic stirrer , an ar inlet , and a dean - stark trap with a condenser under ar atmosphere . the mixture was heated and stirred at 170 ° c . for 1 h to azeotrope off water . after the removal of chlorobenzene , the reaction mixture was cooled . to the cooled reaction mixture was added bis ( 4 - chlorophenyl ) sulfone ( 0 . 59 g , 2 . 0 mmol ). the mixture was heated and stirred at 280 ° c . for 0 . 5 h , and then was heated to 300 ° c . for 15 h with the frequent addition of another 1 g of diphenyl sulfone , each time the reaction system became too viscous to be stirred . the resulting mixture was cooled , quenched by addition of acetic acid , and then poured into methanol . the precipitated polymer was collected by filtration and washed with boiling methanol . the crude polymer was redissolved in chloroform . the chloroform solution was filtered through a thin layer of celite ( trademark ) to remove inorganic materials . the polymer was further purified by reprecipitation from chloroform solution into methanol . the polymer collected by filtration was washed thoroughly with boiling methanol , and dried in vacuo at 40 ° c . overnight . yield 90 %. the resulting polymer was soluble in various organic solvents such as chloroform . flexible , and transparent films were obtained by casting from its chloroform solution . the copolymer was prepared in the same manner to example 22 , except that potassium hydroxide ( 3 . 6 mmol ) and cesium carbonate ( 0 . 40 mmol ) were used as base instead of potassium carbonate ( 1 . 5 mmol ) and cesium carbonate ( 0 . 60 mmol ). the polymerization was completed by heating at 250 ° c . for 7 h . yield 84 %. the resulting polymer was soluble in various organic solvents such as chloroform . creasable , colorless and transparent films were obtained by casting from its chloroform solution . the copolymer was prepared in the same manner to example 22 , except that potassium hydroxide ( 3 . 6 mmol ) and potassium carbonate ( 0 . 40 mmol ) were used as base instead of potassium carbonate ( 1 . 5 mmol ) and cesium carbonate ( 0 . 60 mmol ). the polymerization was completed by heating at 256 - 258 ° c . for 20 h . yield 91 %. the resulting polymer was soluble in various organic solvents such as chloroform . creasable , colorless and transparent films were obtained by casting from its chloroform solution . the copolymer was prepared in the same manner as example 24 , except that benzophenone was used as solvent instead of diphenylsulfone . the polymerization was completed by heating at 260 ° c . for 66 h . yield 99 %. the resulting polymer was soluble in various organic solvents such as chloroform . yellow , and slightly brittle films were obtained by casting from its chloroform solution . the copolymer was prepared in the same manner as example 22 , except that sulfolane was used as solvent instead of diphenyl sulfone , and that potassium hydroxide ( 3 . 6 mmol ), cesium carbonate ( 0 . 20 mmol ), and potassium carbonate ( 4 . 0 mmol ) were used as base instead of potassium carbonate ( 1 . 5 mmol ) and cesium carbonate ( 0 . 60 mmol ). the polymerization was completed by heating at 170 - 180 ° c . for 3 . 5 d . yield 93 %. the resulting polymer was soluble in polar organic solvents such as nmp . yellow , and slightly brittle films were obtained by casting from its dmac solution . 22 diphenyl 50 % 50 % sulphone 23 diphenyl 30 % 70 % sulphone 24 diphenyl 30 % 70 % sulfone 25 benzophenone 30 % 70 % 26 sulfolane 30 % 70 % examples tg (° c .) tga - 5 % (° c .) η inh ( dl / g ) 22 100 % 254 543 0 . 35 23 100 % 242 541 0 . 34 24 100 % 242 548 0 . 36 25 100 % 235 548 0 . 29 26 100 % 241 517 0 . 36 1 , 3 - dibenzimidazolylbenzene ( 0 . 62 g , 2 . 0 mmol ), cesium carbonate ( 0 . 098 g , 0 . 30 mmol ), potassium carbonate ( 0 . 25 g , 1 . 8 mmol ), sulfolane ( 1 g ), and chlorobenzene ( 3 ml ) were charged into a 25 ml three - necked round - bottom flask equipped with a magnetic stirrer , an ar inlet , and a dean - stark trap with a condenser under ar atmosphere . the mixture was heated and stirred at 170 ° c . for 1 h to azeotrope off water . after the removal of chlorobenzene , the reaction mixture was cooled . to the cooled reaction mixture was added 4 , 4 ′- difluorobenzophenone ( 0 . 44 g , 2 . 0 mmol ) and calcium carbonate ( 0 . 21 g , 2 . 1 mmol ). the mixture was heated and stirred at 215 ° c . for 2 . 5 h with the frequent addition of another 1 g of sulfolane each time the reaction system became too viscous to be stirred . the resulting mixture was cooled , quenched by addition of acetic acid , and then poured into methanol to precipitate a light yellow fiber . the precipitated polymer was collected by filtration and washed with boiling methanol . the crude polymer was purified by extraction with boiling distilled water to remove any salt . the polymer collected by filtration was washed with boiling methanol , and dried in vacuo at 40 ° c . overnight . yield 93 %. the resulting polymer was soluble in polar organic solvents such as nmp or dmac . flexible , and light yellow films were obtained by casting from its nmp solution . all the polymerizations of bisbenzimidazoles with 4 , 4 ′- difluorobenzophenone were carried out in sulfolane . the copolymerization was conducted by one - pot two - step procedures : ( 1 ) reaction of bisbenzimidazole and 4 , 4 ′- difluorobenzophenone ; ( 2 ) the reaction of bis ( 4 - chlorophenyl ) sulfone and 4 , 4 ′- biphenol . example 28 is typical of the reaction conditions used . 1 , 3 - dibenzimidazolylbenzene ( 0 . 43 g , 1 . 4 mmol ), cesium carbonate ( 0 . 068 g , 0 . 21 mmol ), potassium carbonate ( 0 . 17 g , 1 . 3 mmol ), sulfolane ( 1 g ), and chlorobenzene ( 3 ml ) were charged into a 25 ml three - necked round - bottom flask equipped with a magnetic stirrer , an ar inlet , and a dean - stark trap with a condenser under ar atmosphere . the mixture was heated and stirred at 180 ° c . for 1 h to azeotrope off water . after the removal of chlorobenzene , the reaction mixture was cooled . to the cooled reaction mixture was added 4 , 4 ′- difluorobenzophenone ( 0 . 32 g , 1 . 5 mmol ) and calcium carbonate ( 0 . 15 g , 1 . 5 mmol ). the mixture was heated and stirred at 220 ° c . for 3 . 5 h with the frequent addition of another 1 g of sulfolane each time the reaction system became too viscous to be stirred . the resulting mixture was cooled . to the cooled resulting mixture was added 4 , 4 ′- biphenol ( 0 . 11 g , 0 . 60 mmol ), cesium carbonate ( 0 . 029 g , 0 . 090 mmol ), potassium carbonate ( 0 . 075 g , 0 . 54 mmol ), sulfolane ( 0 . 5 g ), and chlorobenzene ( 2 ml ). the mixture was heated and stirred at 180 ° c . for 1 h to azeotrope off water . after the removal of chlorobenzene , the reaction mixture was cooled . to the cooled reaction mixture was added bis ( 4 - chlorophenyl ) sulfone ( 0 . 16 g , 0 . 54 mmol ). the mixture was heated and stirred at 215 ° c . for 3 h with the frequent addition of another 1 g of sulfolane each time the reaction system became too viscous to be stirred . the resulting mixture was cooled , quenched by addition of acetic acid , and then poured into methanol to precipitate a light yellow fiber . the precipitated polymer was collected by filtration and washed with boiling methanol . the crude polymer was purified by extraction with boiling distilled water to remove any salt . the polymer collected by filtration was washed with boiling methanol , and dried in vacuo at 40 ° c . overnight . yield 95 %. the resulting polymer was mostly soluble in chloroform , and completely soluble in polar organic solvents such as dmac . creasable and light yellow cast films were obtained by casting from either its chloroform - solution or dmac solution . the polymer was prepared in a manner similar to example 28 . yield 92 %. the resulting polymer was soluble in polar organic solvents such as dmac . creasable and light yellow cast films were obtained by casting from either its chloroform solution or dmac solution . tg (° c .) tga - 5 % (° c .) ηinh ( dl / g ) 30 30 % 27 % 259 554 0 . 28 the procedure for the copolymer from 1 , 3 - dibenzimidazolylbenzene ( example 32 : 20 mole %) is typical . to a three - necked round - bottom flask equipped with a magnetic stirrer , a dean - stark trap , a condenser , and a nitrogen inlet were added 4 , 4 ′- difluorobenzophenone ( 0 . 44 g , 2 . 0 mmol ), hq ( 0 . 18 g , 1 . 6 mmol ), 1 , 3 - dibenzimidazolylbenzene ( 0 . 12 g , 0 . 40 mmol ), potassium carbonate ( 0 . 25 g , 1 . 8 mmol ), cesium carbonate ( 0 . 098 g , 0 . 30 mmol ), calcium carbonate ( 0 . 21 g , 2 . 1 mmol ), diphenyl sulfone ( 2 g ), and chlorobenzene ( 3 ml ). the mixture was heated and stirred at 170 ° c . for 1 h to azeotrope off water under nitrogen atmosphere . after the removal of chlorobenzene , the mixture was carefully brought up to 180 - 200 ° c . for 1 h , then heated at 230 - 250 ° c . for 0 . 5 h , and finally heated at 300 - 313 ° c . for 1 h , with the frequent addition of another 1 g of diphenyl sulfone , each time the reaction system became too viscous to be stirred . the viscous reaction mixture was cooled , and quenched by addition of acetic acid . the reaction mixture was ground into fine powder in a blender with methanol . the fine powder was boiled in a mixture of methanol / water ( 3 / 1 v / v ) for 1 h . the powder collected by filtration was boiled in acetone for 1 h . these extraction procedures were repeated twice . the resulting powdery polymer was washed with 5 % hcl aqueous solution , with distilled water , and finally with acetone . the polymer was dried in vacuo at 40 ° c . for 24 h . yields 94 - 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