Patent Application: US-84733901-A

Abstract:
functionalized derivatives of benzocyclobutenone of formula i and ii herein are photoreactive and may be employed in the production of a variety of self - curable polymer composition which may be employed as photoresist compositions , pressure sensitive adhesives , hot melt adhesives and sealants ; the polymer compositions may be cured or cross - linked by uv or vis radiations .

Description:
the present invention provides generally a new type of photo - crosslinker and photo - reactive polymers capable of undergoing grafting and crosslinking upon uv - vis irradiation , without using any catalysts or photosensitizers . specifically , the photochemistry based on the reaction of benzocyclobutenone with itself and alcohol is exploited , and the use of benzocyclobutenone as a latent reactive group in various polymers is developed therefrom . benzocyclobutenone is easily functionalized to give a series of benzocyclobutenone derivatives of formula ( i ) l wherein r is any electron - withdrawing and electron - donating group . preferably , r is — sh , — so 2 cl , — so 3 h , or n - substituted group , for example : the preparation of the functionalized bcbo derivatives ( i - 1 to i - 6 ) uses 5 - aminobenzocyclobutenone ( u . s . pat . no . 5 , 869 , 693 ). the functionalization is typically a reaction of 5 - aminobenzocyclobutenone with 2 - bromoethanol , acryloyl chloride , methacryloyl chloride , succinic anhydride or 3 , 5 - dinitrobenzoyl chloride . furthermore , direct chlorosulfonation of benzocyclobutenone affords 5 - chlorosulfonyl benzocyclobutenone ( i - 7 ), which can be hydrolyzed to the corresponding sulfonic acid and reduced to the thiol . compounds i - 1 and i - 2 undergo polymerization and crosslinking reaction in solution or in the solid state , as illustrated in example 1 , however useful polymerization and crosslinking reactions are not limited to those illustrated in example 1 , to yield polymeric resins upon photo irradiation at ambient temperatures . compound i - 3 is an acrylamide monomer , which is used to copolymerize with a variety of commercially available vinyl monomers to yield the corresponding photo - reactive vinyl polymers . diamine i - 6 is used to form a photo - reactive polyimide in the polycondensation of a diamine and a dianhydride . both compounds i - 4 and i - 7 can be used to react with either the hydroxy or amino groups presented in a polymer , such as poly ( 4 - hydroxy styrene ), polyvinyl alcohol and polybutyral . thus , the resulting grafted polymers contain a reactive bcbo group and can be photochemically crosslinked . the bcbo derivatives can also be taken in the following formula ii : wherein x is a polyvalent organic bridging group . preferably , x is a divalent moiety selected from the group consisting of : the above bis - bcbo derivatives are generally prepared by reacting 5 - aminobenzocyclobutenone with the corresponding diacid chloride , diisocyanate or dianhydride in solution , as described in u . s . pat . no . 5 , 869 , 693 . these bis - bcbo compounds are generally solids with high melting points and possess high thermal stability . typically , the thermal ring - opening temperatures are over 200 ° c . thus , they can be used in melt mixing ( e . g ., melt extrusion or compression ) with any hydroxy - containing polymers such as polyol , poly ( vinyl alcohol ) or polybutyral and presented in photocopy toner and as polymers for use as a pressure - sensitive adhesive that contains a small amount of the hydroxy functionality . these bis - bcbo compounds are typically photo crosslinkers for curing the above hydroxy - containing polymers , as illustrated in example 20 . using bcbo - containing vinyl monomers such as i - 3 or 5 - aminobenzocyclobutenone , bcbo can thus be incorporated into a wide spectrum of vinyl polymers as a pendent group through copolymerization with vinyl monomers or through grafting onto anhydride - containing and carboxylic acid - containing polymers via imidization transformation and acid - amine coupling reactions . thus , the bcbo - containing copolymers include those of the formulae iii - vi above . for example , i - 3 monomer can copolymerize with any commercial vinyl monomers such as styrene using aibn ( azobisisobutyronitrile ) as a radical initiator in solution . furthermore , 5 - aminobenzocyclobutenone may be grafted onto any maleic anhydride , or carboxyl acid containing commercial polymers . in addition , bcbo - containing polyimides or polyamides ( or nylons ) can also be prepared by the condensation of a diamine derived from bcbo such as i - 6 with other dianhydrides and diacids or diacid chlorides , respectively . preferably , the following bcbo - containing copolymers are prepared : the copolymers containing the bcbo moiety can be modified in bulk and at the surface through the photografting reaction of bcbo with small hydroxyl - containing molecules , oligomers and polymers . the bcbo photochemistry provides ways and means for tailoring and enhancing the bulk and / or the surface properties of existing polymers through grafting . the amount of the grafted component such as a polyol can be controlled by the bcbo content in the polymers . the bcbo content in the polymers is typically in the range of 0 . 5 mol % to 80 mol % and preferably about 5 mol %. hydrophilic , hydrophobic , and other functional units with a hydroxyl end group can be linked onto the bcbo - modified commercial polymers simply upon uv irradiation . the hydroxyl - containing functional groups , preferably , are hydrophilic poly ( ethylene glycol ) methyl ether ( any molecular weight , more preferably , low molecular weight between 550 - 2000 ), hydrophobic zonyl ® fluoroalcohol , fluorescent pyrenebutanol , azo dye disperse red - 1 , electrochromic hydroxyl - end capped naphthalene imide , and conductive hydroxyl - end capped materials . by using functional hydroxyl - containing molecules , the bulk or surface of the polymers can be selectively modified to have desirable properties attributed to the functional hydroxyl groups that are grafted on . with respect to surface grafting , the uv curing can happen selectively on the selected area of the substrate , since the location of photo grafting can be chosen through a photomask or shadow mask , as illustrated in example 13 . the substrate can be any polymer films , either hydrophilic or hydrophobic . using bcbo derivatives such as i - 3 and i - 8 , the terpolymers containing both bcbo and hydroxyl groups having the structural formulae vii - x are prepared . preferably , bcbo and oh - containing terpolymers or precursors of such terpolymers include the following , having the repeat units n and m in a range of 0 . 1 to 0 . 9 : for crosslinking in solution , the solvent used to dissolve the bcbo polymers can be any organic solvent except an alcohol and preferably is selected from tetrahydrofuiran , ethyl acetate , ether , dichloromethane , chloroform , 1 , 1 , 2 , 2 - tetrachloroethane , n , n - dimethylformamide , hydrocarbons , toluene and xylenes . the polymer concentration can be very dilute ( 0 . 5 %) to very concentrated ( 50 %). with respect to curing in the solid state , the size and thickness of polymer films can be made according to requirements , coating conditions , and uv source available . preferably , the uv curing area can be between 0 . 1 mm 2 to 15 cm 2 , the film thickness can be from 50 nanometers to 2 mm . the uv curing temperature can be as low as 77 ° k ., and as high as 250 ° c . ( or just below the thermal ring opening temperature of the bcbo group in the said polymer ). preferably , the uv curing proceeds at ambient temperatures . the wavelength of the light source varies between 250 nm to 500 nm , depending on the chemical structure of bcbo derivatives . preferably , a wavelength of 300 nm to 350 nm is selected . the uv curing time can be less than a second to a few hours , depending on the film thickness , light intensity and light dose . as shown in example 9 , photo coupling reactions of benzocyclobutenone with a variety of alcohols gives the corresponding esters in almost 100 % yield . kinetic studies indicate that the photo reaction of bcbo follows the first order kinetic . thus , the ring - opening of bcbo in the photo coupling reaction with alcohol is the rate - determining step . the same is true in the self dimerization or crosslinking reaction of bcbo in a polymer . the self - curable polymers , which contain the bcbo group or contain both bcbo and hydroxyl groups , can form crosslinked structures upon uv irradiation in solution or in the solid state . the crosslinking degree is controlled by the bcbo content in the polymers . the bcbo content in the self - curable polymers is in the range of 0 . 5 mol % to 80 mol %, preferably , 5 mol %. the ratio of bcbo to hydroxyl moiety can be from 0 . 5 : 1 to 1 : 10 . preferably , the ratio is 1 : 1 to 1 : 3 . the aforementioned uv curing conditions can also be applied here . a polymer gel can be obtained from a solution of self - curable vinyl polymers , polyolefins , polyamides , and polyimides upon irradiation , indicating that these polymers can be used as photoresists to directly form patterns on the substrate . the substrate can be glass , silicon wafer , metal , mica , wood , ceramics or polymers . preferably , the substrate is glass , polymer , mica or silicon wafer . the function of the self - curable bcbo polymers can be passive and active , preferably , conductive , electrochromic , photochromic , photovoltaic , non - linear optical or magnetic . thus , the self - uv curable bcbo - containing polymers are very useful in microlithography , because of the fast and neat curing process , furthermore , there is no need for any photoinitiator , photo acid generator as currently used . the self - uv curable bcbo - containing polymers can also form a new type of uv adhesive , as illustrated in example 7 , however formation of uv adhesives is not limited to example 7 . the bcbo content in the polymers is in the range of 0 . 5 mol % to 80 mol %, preferably , 1 - 5 mol %. the ratio of bcbo to hydroxyl moiety can be from 0 . 5 : 1 to 1 : 10 . preferably , the ratio is 1 : 1 to 1 : 3 . the aforementioned uv curing conditions can also be applied here . the shear modulus of the polymer containing only 5 mol % of bcbo was determined and significantly enhanced after uv curing . the self - curable bcbo - containing polymers and oligomers , as described and demonstrated in examples 1 , 6 , 7 , 10 , 12 and 16 , can be potentially used as adhesives and sealants for microelectronics packaging and interconnection of optical fibers . the following examples are included for illustrative purposes only , and do not limit the scope of the invention or the claims . unless otherwise specified , all parts and percentages are by weight . to a solution of 5 - aminobenzocyclobutenone ( 1 . 33 g , 0 . 01 mol ) and diazabicyclo [ 2 , 2 , 2 ] octane ( 2 . 098 g , 0 . 019 mol ) in thf under nitrogen flow , was added excess of 2 - bromoethanol ( 3 . 23 g , 0 . 026 mol ) drop by drop . the reaction mixture was refluxing for about 24 hours . after the brown salt was removed by filtration , the filtrate was extracted with water several times . by chromatography using a mixture of hexane and ethyl acetate as the eluting solvent , the two products were isolated as identified by ir ( 3383 cm − 1 , and 1750 cm − 1 ) and ms spectra . benzocyclobutenone ( 2 . 36 g , 0 . 02mol ) was added slowly to a strongly stirred chlorosulfuric acid ( 3 ml ) in chloroform ( 10 ml ) solution . after the addition was done , the reaction mixture was stirred for 5 hours . then the chloroform was evaporated , and the residue was precipitated in water yielding fine pink crystals . m . p . 80 ° c . ; ir ( kbr , cm − 1 ): 1762 ; uv ( λ max , methanol ) 272 nm . to a solution of 5 - aminobenzocyclobutenone ( 1 . 064 g , 0 . 008 mol ) and triethylamine ( 0 . 89 g , 0 . 0088 mol ) in dry thf ( 15 ml ) at room temperature under nitrogen , was slowly added 3 , 5 - dinitrobenzoyl chloride ( 1 . 84 g , 0 . 008 mol ) in dry thf ( 20 ml ). the mixture was stirred at room temperature for 10 minutes , and the reaction was done indicating by tlc . the triethylamine hydrochloride was collected , and washed with acidic water and hot water . the resulting filtrate that contains the dinitro - product was rotating evaporated to yield the yellow solids ( yield : 84 . 3 %). the hydrogenation of above product in thf with 5 % of platinum oxide as a catalyst , yielding the title product in brown color ( yield : 52 %). to a solution of monomer i - 8 ( 0 . 201 g , 0 . 001 mol ) in anhydrous thf ( 6 ml ), were added methyl methacrylate ( 1 . 9 g , 0 . 019 mol ) and aibn ( 0 . 0023 g , 0 . 00015 mol ). after the solution was purged with nitrogen , the reaction vessel was sealed . the very viscous solution was formed after stirring at 60 ° c . overnight . the white polymer was then precipitated in methanol . ir : 1763 cm − 1 ( bcbo ketone ). terpolymerization of bcbo - methacrylamide monomer with butyl methacrylate , and 2 - hydroxyl - ethyl methacrylate ( feed ratio : 5 mol % bcbo , 15 mol % oh ) to a solution of monomer i - 8 ( 0 . 1005 g , 0 . 0005 mol ) in anhydrous thf ( 5 ml ), were added methyl methacrylate ( 1 . 1362 g , 0 . 008 mol ) and 2 - hydroxylethyl methacrylate ( 0 . 195 g , 0 . 0015 mol ) and aibn ( 0 . 0023 g , 0 . 00015 mol ). after the solution was purged with nitrogen , the reaction vessel was sealed . the very viscous solution was formed after stirring at 60 ° c . overnight . the white polymer was then precipitated in methanol . ir : 3434 cm − 1 ( oh ), 1760 cm − 1 ( bcbo ketone ). the title polymer was readily obtained from the conversion of 1 g of polyoctadecene - alt - maleic anhydride ( from aldrich chemical . co ., contains 50 % of maleic anhydride , and is treated at 200 ° c . for 30 min prior to use ) upon imidization with 5 - aminobenzocycobutenone ( 0 . 665 g , 0 . 005 mol ) in xylene at 140 ° c . for 3 hours . the yellow polymer was precipitated from hexane . ir : 1762 cm − 1 ( bcbo ketone , imide ), 1720 cm − 1 ( imide ). a similar reaction was done using maleic anhydride - grafted polyethylene , from dupont canada as fusabond ™, and the both bcbo polymers were low melting and could be mold into a film and then crosslinked upon uv irradiation . to a solution of i - 3 monomer ( 0 . 0935 g , 0 . 0005 mol ) in ethyl acetate ( 5 ml ), were added 2 - ethylhexyl acrylate ( 1 . 5894 g , 0 . 0086 mol ), 2 - hydroxy ethyl acrylate ( 0 . 0697 g , 0 . 0006 mol ), acrylic acid ( 0 . 0216 g , 0 . 0003 mol ), and aibn ( 0 . 009 g , 0 . 00006 mol ). after the solution was purged with nitrogen , the reaction vessel was sealed . the very viscous solution was formed after stirring at 60 ° c . overnight . the resulting yellow solution was very sticky . the polymer was coated on a glass or polyester substrate , showing ir bands at 3434 cm − 1 ( oh ) and 1760 cm − 1 ( bcbo ketone ), and then directly exposed to uv light at 300 - 350 nm with an intensity of 1000 mw / cm 2 for one minute . the cured film showed no more peak at 1760 cm − 1 ( bcbo ketone ). the shear modulus of cured sample clearly increased , compared to the initial polymer . the precursor polyimide containing pendent cooh unit was prepared from 6fda and daba ( diamino benzoic acid ) in m - cresol at 200 ° c . overnight , catalyzed by isoquinoline . to a solution of above cooh - containing polyimde ( 0 . 3 g ) in anhydrous dmf , were added dicyclocarbodiimide ( 0 . 114 g , 0 . 0006 mol ) and 5 - aminobenzocyclobutenone ( 0 . 0575 g , 0 . 0004 mol ). the reaction mixture was stirred at room temperature under argon overnight . to the resulting solution , was added 4 - amino benzylethanol ( 0 . 0822 g , 0 . 0006 mol ). then the mixture was stirred at room temperature under argon another overnight . the title polyimide in beige color was precipitated from methanol . ir ( kbr , cm − 1 ): 1778 , 1723 ; thermal ring - opening temperature : 280 - 300 ° c . the photochemical reaction of bcbo with several alcohols was first carried out as a model reaction . both bcbo and alcohols at different ratios ( 0 . 5 : 1 . 1 : 1 . up to 1 : 3 ) were placed in a sealed uv cell ( either in solution or in neat condition ), and subsequently uv irradiated at ambient temperature . the uv source is the novacure spot curing system produced by efos with a wavelength range of 300 - 350 nm and a light intensity of 1000 mw / cm 2 . the reaction was monitored by gas chromatography ( gc ). solid state uv curing of monomers i - 1 and i - 2 in example 1 a film was cast from a chloroform solution of a mixture of i - 1 and i - 2 and then uv irradiated ( 300 - 350 nm , light intensity of 500 mw / cm 2 ) for one minute . the curing reaction was monitored by ir by the disappearance of the peak at 1750 cm − 1 due to bcbo ketone . the resulting film was peeled off and found to be insoluble in chloroform . a mixture of bcbo - polystyrene containing 4 mol % of bcbo ( 0 . 15 g ) and ch 3 ( och 2 ch 2 ) n oh ( peg - oh from aldrich chemicals , mw = 550 , 1 g ) in chloroform was placed in an uv cell , and subsequently uv irradiated at 300 - 350 nm ( light intensity of 500 mw / cm 2 ) for 30 minutes . the reaction mixture was then poured into water or methanol . the resulting solution was centrifuged , filtered and extracted overnight with water or methanol in a soxhlet extractor , to yield slightly yellow peg - containing polystyrene . ft - ir and nmr proved the formation of peg units through the reaction of bcbo with peg - oh . ir : 1730 cm − 1 ( ester ), 1109 cm − 1 ( ether ). the bcbo - polyoctadecene prepared in example 6 was first coated on commercial 0 . 2 mm thick polyethylene ( pe ) film , followed by coating with peg - oh ( mw = 550 ) and uv irradiation at 320 to 350 nm ( light intensity of 500 mw / cm 2 ) for 1 min at ambient temperature . an excess of peg - oh on the surface was washed away with methanol . atr - ir ( intensity of peak at 1762 cm − 1 decreased , and that of peak at 1721 cm − 1 increased ) and xps ( 286 . 4 ev due to c — o from peg - oh , 289 . 2 ev due to c ═ o from ester formed ) confirmed the formation of peg units on pe surface . since the peg - grafted pe films have a hydrophilic surface , the dye - stain test was performed on the peg - grafted pe surface . the hydrophilic peg was coated on bcbo - pe surface , and then uv irradiated at 320 - 350 nm through a photomask ( light intensity of 500 mw / cm 2 ). after the excess of peg was washed away with water and methanol , the pe film surface was sprayed with a 0 . 5 wt % aqueous solution of 3 , 3 ′- diethylthiadicarbocyanine iodide . it could be clearly seen that only the area that was uv irradiated and hence grafted with peg on the film is colored in blue distinctly , implying the location of photo grafting . the chloroform solution of the polyimide prepared in example 8 was placed into an uv cell , then uv irradiated ( 320 - 350 nm , light intensity of 500 mw / cm 2 ) without a photoinitiator or a catalyst at ambient temperatures for a few minutes and the transparent gel was readily formed . the chloroform solution of this polyoctadecene prepared in example 6 was placed into an uv cell , then uv irradiated ( 320 - 350 nm , light intensity of 500 mw / cm 2 ) without a photoinitiator or a catalyst at ambient temperatures for a few minutes and the transparent gel was readily formed . the 140 nm - thick polyimide film was obtained by spin - coated on a silicon wafer substrate from 1 wt % tetrachloroethane solution . after uv curing ( 320 - 350 nm , light intensity of 500 mw / cm 2 ) through a contacted photomask , the polyimde in the uv irradiation area was crosslinked and thus insoluble . whereas , the polyimde in the non - uv irradiation area could be washed away with chloroform . the pattern is already visible . for further investigation scanning electron microscopy ( sem ) photograph was taken after a 10 nm film of gold was vacuum deposited onto the pattern . the sem picture shows the shapes of the polyimide materials as dark lines whereas the silicon wafer surface appears white . the pattern edge is well recognizable and , taking the rather simple patterning conditions into account , well developed . to a solution of succinic anhydride ( 0 . 618 g , 0 . 0063 mol ) in dry diethyl ether ( 15 ml ) was added the 5 - aminobenzocyclobutenone ( 0 . 798 g , 0 . 006 mol ) in one portion at room temperature . the white solids were formed immediately . after stirred for 10 - 15 minutes , the resulting amic acid was collected by filtration and dried in air ( yield 86 %). ir ( kbr , cm − 1 ) 1756 . to a solution of 5 - aminobenzocyclobutenone ( 2 . 556 g , 0 . 0192 mol ) in anhydrous thf ( 10 ml ) at room temperature under nitrogen , was added triethylamine ( 2 . 736 g , 0 . 0271 mol ) in thf ( 5 ml ). then the temperature was cooled down to 0 ° c ., acryloyl chloride ( 2 . 97 g , 0 . 0328 mol ) in thf ( 10 ml ) was added to the solution drop and drop . the resulting yellowish solution was allowed to warm up and stirred at room temperature overnight . the reaction solution was diluted with diethyl ether ( 50 ml for 0 . 23 g ) and washed with diluted hydrochloric acid three times . removal of the solvent and subsequent recrystallization of the residue ethanol / cyclohexane afforded the pure amide product as a beige crystalline solid ( 87 % yield ). ir ( kbr , cm − 1 ) 3357 , 2923 , 1760 , 1660 ; uv ( λ max , methanol ) 320 nm . the bis - bcbo compounds can react with polyols under uv irradiation to form crosslinked structure . typically , the compound in formula ii in which x is diaminobutane is dissolved in chloroform or tetrahydrofuran with polyols or polybutyral . then the solution was uv irradiated at 300 - 350 nm . the ir spectra showed the disappearance of peak at 1760 cm − 1 due to bcbo ketone , and the appearance of a new peak at 1720 cm − 1 due to the newly formed ester bond . the uv irradiation on the concentrated solution ( 20 %) caused the formation of gel . the solid film was cast from the aforementioned solution as described in example 19 or made by mixing polymer and bis - bcbo powder and then melt compression ( the chosen temperature should not be higher than the ring - opening temperature of this compound , hence the low melting point bis - bcbo is preferred ). the solid film was uv irradiated , and was not soluble in aforementioned solvent any more . the bcbo - containing nylon 66 ( 0 . 5 mol % feed ratio of bcbo ) was made as follows : to a 100 ml three - necked flask , were added hexamthylenediamine ( 0 . 915 g , 0 . 005 mol ), diamino - bcbo i - 6 as illustrated in example 3 ( 0 . 133 g , 0 . 0005 mol ) and triethylamine ( 0 . 7575 g , 0 . 0075 mol ) in 10 ml of n , n - dimethylacetamide ( dmac , 10 ml ). to this stirring solution at room temperature under nitrogen , was added rapidly adipoyl chloride ( 0 . 522 g , 0 . 0045 mol ) in 5 ml of dmac . the reaction mixture was stirred for a few hours , then precipitated in hexane . the resulting solids were washed with diluted acidic water to afford brown power . ir ( kbr , cm − 1 ) 3303 , 2934 , 1762 , 1637 . the presence of bcbo in nylon 66 was also confirmed by differential scanning calorimetry . the first dsc trace of bcbo - nylon 66 displayed an exothermic peak at about 220 ° c . to modify nylon 66 having the bcbo moiety , commercial poly ( 4 - hydrostyrene ) was used . bcbo - containing nylon 66 and poly ( 4 - hydrostyrene ) were mixed and grounded . the samples were hydraulically pressed into a film and then uv irradiated at 300 - 320 nm . the curing process was monitored by ir . after uv cure , the excess of poly ( 4 - hydrostyrene ) was washed away using acetone . the ir spectrum of bcbo - nylon 66 showed a peak at 1762 cm − 1 due to the bcbo &# 39 ; s ketone group . with the increment of uv curing time , this peak decreased gradually then nearly disappeared . the bcbo ring opening was also confirmed by differential scanning calorimetry ( dsc ) studies . the first dsc trace of bcbo - nylon 66 displayed an exothermic peak . nevertheless , no such peak was found in the first run of cured nylon samples . thermal analysis showed that the cured nylons had similar melting points as those of linear polymers . however , tga curves displayed a significantly change of heat resistance for cured nylons . the copolymerization and terpolymerization of bcbo monomers i - 3 or i - 8 with vinyl monomers were carried out in vacuum at 60 ° c ., using aibn as an initiator . the monomer concentrations were 2 mol / l approximately and solvent was dry thf . the solution was stirred at 60 ° c . for about 24 hours . the reaction mixture was successively precipitated into hexane or methanol until no more monomers left and finally dried under vacuum . specific procedures are in example 4 , example 5 and example 7 . characterizations of selected bcbo - 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