Patent Application: US-201013509630-A

Abstract:
the invention provides a tetrazole - containing polymer of intrinsic microporosity comprising or more subunits , wherein one or more of the subunits comprise one or more tetrazolyl moieties . in one embodiment , a polymer of intrinsic microporosity was modified using a “ click chemistry ” cycloaddition reaction with sodium azide and zinc chloride to yield new pims containing tetrazole units . polymers of the present invention are useful as high - performance materials for membrane - based gas separation , materials for ion exchange resins , materials for chelating resins , materials for superabsorbents , materials for ion conductive matrixes , materials for catalyst supports or materials for nanoparticle stabilizers .

Description:
dimethyfacetamide ( dmac ), n - methylpyrrolidone ( nmp ), toluene , methanol ( meoh ), potassium carbonate ( k 2 co 3 ), sodium azide ( nan 3 ), zinc chloride ( zncl 2 ), methylamine ( 40 wt % in h 2 o ), diisopropylamine , n , n - diisopropylethylamine and chloroform ( chcl 3 ) were purchased from sigma - aldrich and used as received . 5 , 5 ′, 6 , 6 ′- tetrahydroxy - 3 , 3 , 3 ′, 3 ′- tetramethylspirobisindane ( ttsbi , sigma - aldrich ) was purified by crystallization from methanol . tetrafluoroterephthalonitrile ( tftpn , matrix scientific ) was purified by vacuum sublimation at 150 ° c . under inert atmosphere . the structures of the polymeric materials were fully characterized using nuclear magnetic resonance ( nmr ) spectroscopy at different temperatures . nmr analyses were recorded on a varian unity inova ™ spectrometer at a resonance frequency of 399 . 961 mhz for 1 h and 376 . 276 mhz for 19f . 1 h and 19 f nmr spectra were obtained from samples dissolved in cdcl 3 or dmso - d 6 using a 5 mm pulsed field gradient indirect detection probe . the solvent signals ( cdcl 3 1 h 7 . 25 ppm ; dmso - d 6 1 h 2 . 50 ppm ) were used as the internal references . an external reference was used for 19 f nmr : cfci 3 0 ppm . molecular weight and molecular weight distributions were measured by gpc using ultrastyragel ™ columns and thf as the eluent at a flow rate of 1 ml / min . the values obtained were determined by comparison with a series of polystyrene standards . ftir spectra were recorded on thermo scientific ftir microscope ( model nicolet 6700 ) with film samples at 8 cm − 1 resolution over the 400 - 4000 cm − 1 range . each sample was scanned 64 times . polymer thermal degradation curves were obtained from thermogravimetric analysis ( tga ) ( ta instruments , model q - 5000ir ). the tga furnace is equipped with an interface for mass spectrometer detection of the off - gasses released from the polymer decomposition . polymer samples for tga were initially heated to 150 ° c . ( or 120 ° c . for pilim tga curves ) under nitrogen gas and maintained at that temperature for 1 h for moisture removal and then heated to 600 ° c . at 10 ° c ./ min ( or at 5 ° c ./ min for pilims ) for degradation temperature measurement . a mass spectrometer ms model thermostar ™ from pfeiffer vacuum was used to detect gas driven off from thermally degraded samples in the tga instrument . glass transition temperatures ( t g ) were observed from differential scanning calorimetry ( dsc ) ( ta instruments model 2920 ), and samples for dsc were heated at 10 ° c ./ min under a nitrogen flow of 50 ml / min , then quenched with liquid nitrogen and reheated at 10 ° c ./ min for the t g measurement . dense polymer films for gas permeability measurements were prepared from 1 - 2 wt % pim solutions in chloroform , nmp or dmac . solutions of pim - 1 and tetrazole - modified pims were filtered through 0 . 45 μm polypropylene filters and then poured into glass or teflontm petri dishes in a glove box at room temperature ( for chcl 3 ) or 80 ° c . ( for nmp or dmac ) and allowed to evaporate slowly for 1 day . the membranes were soaked in methanol and dried in a vacuum oven at 120 ° c . for 24 h , or were soaked in boiled water and dried naturally and then in a vacuum oven at 120 ° c . for 24 h . the resulting membranes with thickness in the range of 70 - 90 μm were bright yellow ( for pim - 1 ) or brown yellow ( tz - pims and pilims ) and flexible . permeability coefficients ( p ) of n 2 , o 2 , and co 2 were determined at 25 ° c . at a feed pressure of 50 psig and atmospheric permeate pressure using the constant - pressure / variable - volume method . the permeation flow was measured using a bubble flow meter , with the exception of co 2 , which was measured by a mass flow meter ( agilent adm 2000 ). p was calculated by using a following equation : where dv / dt is the permeate - side flow rate , and t is the operation temperature ( k ). the membrane effective area was 9 . 6 cm 2 ( tz - pims ) or 0 . 78 cm 2 ( pilims ). a literature procedure was employed to prepare pim - 1 ( du 2008a ). the m n was 70 , 000 da , with a pdi of 2 . 3 for comparative experiments with tz - pims . the m n was 86 , 000 da , with a pdi of 2 . 0 for comparative experiments with pilims . pim - 1 was dissolved in nmp ( 1 - 3 g in 20 ml of solvent ). nan 3 and anhydrous zncl 2 with different mol equiv versus the nitrile groups were added , and the reaction mixture was stirred at 120 ° c . for different times according to the conversion required ( see table 1 , tz - pims4 - 7 ). after cooling to 60 ° c ., 15 ml of diluted hcl ( 1 : 10 by volume in water ) was added , and the reaction mixture was kept at this temperature for 3 - 5 h . the pims thus obtained were then precipitated into excess aqueous hcl , filtered , washed on the filter with the same hcl solution and water , and dried in vacuum at 120 ° c . pim - 1 films were immersed in mixed solvent of nmp / h 2 o ( v : v = 1 : 2 ). nan 3 ( 20 mol equiv versus the nitrile groups ) and anhydrous zncl 2 ( 10 mol equiv versus the nitrile groups ) were added . the reactions were run under different conditions as follows and as illustrated in table 1 . the conditions were : ( 1 ) 60 ° c . ultrasonic condition for 2 hours ; ( 2 ) 600 w microwave to reflux for 1 hour ; and ( 3 ) heating to reflux for 2 days . after cooling to 60 ° c ., 15 ml of diluted hcl ( 1 : 10 by volume in water ) was added , and the films were maintained at this temperature for 3 - 5 h . the pim films ( tz - pims - ultrasonic , - microwave or - heat ) thus obtained were washed with dilute hcl and water , and dried in vacuum at 120 ° c . initially , two approaches for preparing tz - pims were considered : ( 1 ) direct polycondensation of 2 , 3 , 5 , 6 - tetrafluoro - 1 , 4 - ditetrazole monomer and ttsbi ; and ( 2 ) by post - polymerization modification of nitrile groups on pim - 1 . however , the first approach was abandoned , since the attempted synthesis of the tetrafluoroditetrazole monomer by reaction of tetrafluoroterephthalonitrile with nan 3 and anhydrous zncl 2 in nmp solution at room temperature led to extremely low product yields and resulted in darkly colored side - products . the [ 2 + 3 ] cycloaddition “ click chemistry ” type post - polymerization modification has been mentioned as a possible method for the functionalization of polymeric materials ( binder 2007 ). click reactions are traditionally defined by a gain of thermodynamic enthalpy of at least 20 kcal / mol ( kolb 2001 ) leading to reactions characterized by high yields , insensitivity to solvents , tolerance to various types of interfaces , and high selectivity . microwave - assisted cycloadditions of nitriles with nan 3 was also reported as a drastic reaction condition ( shie 2007 ) for direct conversion of nitrile to tetrazoles in aqueous media . in the present work , different reaction conditions were investigated . the pim - 1 used as starting material for the click reaction was gel - free and had a high molecular weight ( e . g . m n = 70 , 000 , pdi = 2 . 3 ), which was obtained under an optimized polycondensation process ( du 2008a ). dense pim - 1 films were prepared from polymer solutions in chloroform and the resulting membranes with thicknesses in the range of 70 μm to 90 μm . scheme 2 shows possible resulting repeat units derived from different degrees of cycloadditions . polymer repeat units may contain zero , one or two nitrile groups and correspondingly have two , one or zero tetrazole groups . at first , the [ 2 + 3 ] cycloaddition reactions for nitriles on pim - 1 films were carried out by microwave or ultrasonic - assisted methods in aqueous nmp solutions . for comparison , the reaction on pim - 1 film was run in the same medium at reflux temperature for 48 h . tz - pim films were prepared from pim - 1 films under different conditions : 600 w microwave for 1 h ; 60 ° c . ultrasonic condition for 2 h and refluxing the films for 2 days . in contrast with the previous report , the microwave - assisted method was not efficient for the [ 2 + 3 ] cycloaddition modification of pim - 1 films to those containing tetrazole , since the conversion was incomplete . only about 5 - 10 % of the nitrile groups of pim - 1 films were converted to tetrazole groups , as shown by ftir and 1h nmr measurements . furthermore , only small conversions were observed among all the pim film samples obtained by microwave - assisted method , ultrasonic - assisted method or refluxing method . although [ 2 + 3 ] cycloaddition click reactions are highlighted as being effective for various types of interfaces , this was not the case with pim films , perhaps due to limited access of the reagents ( nan 3 and zncl 2 ) into the pim - 1 dense film . pim - 1 was also solution - modified by a one - pot procedure in nmp solution with different ratios of nan 3 and zncl 2 at the elevated temperature ( 120 ° c .) for reaction times of 2 - 8 d , resulting in tz - pim . in comparison to the modification of pim - 1 films , the solution method for pim - 1 in nmp was easier to control and provided higher conversion rates . when 1 mol equiv of nan 3 and zncl 2 versus nitrile groups present in pim - 1 was used , approximately 30 % of the nitrile groups were converted to tetrazole after 2 d . when the mol ratio of azide and lewis acid to nitrile was increased to 4 , approximately 50 - 60 % of the nitrile groups were converted to tetrazole in the same time period , demonstrating that the modification was more efficient with higher reagent concentrations . using the same mol excess of reagent , no unreacted nitrile groups could be observed in the ftir spectrum of the product after 8 d , indicating complete conversion to tetrazole . tz - pm6 and tz - pim7 were characterized by 1 h and 19 f nmr spectroscopy . comparative 1 h nmr spectra of pim - 1 in cdcl 3 and tz - pims ( tz - pim6 and tz - pim7 ) in dmso - d 6 are displayed in fig2 along with signal assignments derived from 2d - nmr . the intensities and the shapes of the tz - pim polymer 1 h nmr signals were monitored at different nmr probe temperatures : 23 ° c ., 50 ° c ., 80 ° c . and 100 ° c . the observed signal ( at 100 ° c .) intensity ratio for the tz - pim7 aromatic ( 6 . 73 , 6 . 19 ppm , h - 6 , 9 ) and aliphatic ( 0 . 25 - 2 . 4 ppm , h - 2 and ch 3 ) regions was exactly 4h : 16h as expected from the molecular structure . furthermore , at low temperature the intensity of all the signals in the 0 . 5 - 7 . 0 ppm area increased with increasing temperature . it is well known in nmr spectroscopy that changes in the sample temperature affect the mobility of the molecules , and hence , the intensity and shape of the signals . this is particularly noticeable with protons involved in hydrogen bonding ( exchange rate , electron density around the h nuclei ( silverstein 2005 )). the spectra of fig2 are a good example of what can happen to the intensity and shape of proton signals when h - bonding is affected by temperature changes . it is worth mentioning that the spectrum of tz - pim6 also shown in fig2 ( 100 ° c .) displayed four peaks at 6 . 92 , 6 . 73 , 6 . 35 and 6 . 19 ppm due to the shielding effects of — cn and tetrazole groups ( du 2009a ), which proves the conversion of — cn to tetrazole groups after the [ 2 + 3 ] cycloaddition click reaction . finally , the polymers were scanned for 19 f nmr signals that might arise from incomplete ladder polymer formation , but no fluorine signals were detected . the ftir spectra of the progress of reactions at 120 ° c . at different reaction times to produce tz - pim ( 4 - 7 ) are shown in fig3 . pim - 1 shows the characteristic nitrile absorption band at 2238 cm − 1 , while the absence of absorption bands in the range of 3000 to 3600 cm − 1 indicates that no n — h groups are present . after a two day [ 2 + 4 ] cycloaddition click reaction at 120 ° c ., the relative intensity of the nitrile absorption band decreased compared with other bands ( tz - pim4 and 5 ). broad absorption bands are observed in samples tz - pim 6 and 7 in the range of 3000 cm − 1 to 3600 cm − 1 , corresponding to n — h stretching vibrations with n — h ••• n bond , and in the range of 2300 cm − 1 to 2800 cm − 1 , attributed to vibrations of quaternary nitrogen atom ( vygodskii 2008 ). a narrow intense absorption near 1580 cm − 1 arises due to the stretching vibration of the n ═ n and n — h groups which implies that some of the nitrile groups were converted into tetrazole groups ( disli 2009 ). it is notable there are small new bands near 1510 cm − 1 , 1400 cm − 1 and 1100 cm − 1 , which are due to c ═ n stretching ( darkow 1997 ) and bending vibrations of the characteristic tetrazole ring , respectively . the relative height of the n ═ n stretching band increased in an observable manner and the nitrile absorption band decreased until it almost disappeared after an 8 day reaction time , indicating that nitrile groups were completely converted into tetrazole groups . the synthesized tz - pims with pendant tetrazole groups were further characterized by thermal gravimetric analysis ( tga ) and differential scanning calorimetry ( dsc ), and the results compared to the nitrile precursor pim - 1 ( fig4 ). none of the polymers have a discernable t g in the measured range of 50 ° c . to 350 ° c . the tz - pims were further characterized by tga , and the results are compared to the pim - 1 precursor . generally , nitrile - containing polymers have high thermal stability , likely due to strong dipolar interactions . in all cases , the tz - pims decompose at lower temperature compared to pim - 1 . it is observed that under nitrogen , at a heating rate of 10 ° c ./ min , tz - pims decompose thermally in two stages , the first being the degradation of the tetrazole ring ( around 170 ° c .) and the second the thermo - oxidative destruction of the polymeric residue ( approximately 488 ° c .). tz - pim7 was tested by tga - ms using 30 ml / min of he as the purge gas and a 5 ° c ./ min ramping rate . the gases released from the polymer decomposition were analyzed by ms ( mass 1 - 300 ) and correlated with the tga curve . the polymer lost 12 % weight between 170 ° c . and 300 ° c . during that same period of time the ms signals for masses 14 , 28 and 29 increased , peaked and then decreased . those significant signals are typical of nitrogen gas being detected by the ms . when the heating rate was higher than 10 ° c ./ min , explosive decomposition of the polymer was observed between 170 ° c . and 300 ° c . all the evidence indicate that the first decomposition product is n 2 by extrusion from tetrazole groups prokudin 1996 ). furthermore , the about 12 % weight loss for tz - pim7 at the first stage is close to the about 15 % calculated weight loss that would occur from complete tetrazole decomposition , which is further evidence for the presence of tetrazole structures on the main chains . a higher ratio of nitrile groups in tz - pims results in a smaller observed weight loss from the first decomposition stage . in summary , the pim - 1 was thermally more stable than the tz - pims , however , all tz - pims still show good thermal stability , even after complete conversion of nitrile to tetrazole groups by the [ 2 + 3 ] cycloaddition reaction . the solubility of the tz - pims was distinctly different when compared to pim - 1 . pim - 1 is readily soluble in tetrahydrofuran ( thf ), dichloromethane ( ch 2 cl 2 ), chloroform ( chcl 3 ), but insoluble in polar aprotic solvents such as dimethylformamide ( dmf ), dimethylacetamide ( dmac ) and n - methylpyrrolidone ( nmp ). after the [ 2 + 3 ] cycloaddition reaction at 120 ° c . for 2 days , the resulting tz - pim5 was no longer soluble in ch 2 cl 2 and chci 3 , but it was still partly soluble in thf . with extended cycloaddition reaction , thf was a non - solvent and dmf , dmac and nmp were good solvents for the tz - pim6 and 7 , indicating that the tz - pims still have good solvent processability . dense tz - pims films were prepared from polymer ( tz - pim4 and 5 ) solutions in dmac and the thickness of the resulting membranes was in the range of 70 μm to 90 μm . tz - pim5 films were darker in color when compared to fluorescent yellow pim - 1 films . with extended reaction times and high tetrazole content in the tz - pims , the films became more brittle , possibly due to additional rigidity and hydrogen bonding . however , flexible films for gas transport testing could readily be cast from dmac solutions of tz - pim4 and tz - pim5 . gas permeabilities and selectivities of tz - pims obtained under different reaction conditions follow a trade - off relationship , similar to that observed for many glassy or rubbery polymers . in general , higher permeability is gained at the cost of lower selectivity and vice versa . pure - gas permeability coefficients ( p ) for o 2 , n 2 and co 2 were measured on polymer dense films of pim - 1 and tz - pim1 - 3 prepared by film modification and tz - pim4 - 5 prepared by solution modification using the [ 2 + 3 ] cycloaddition reaction with sodium azide . higher tetrazole content tz - pim6 - 7 could not be measured due to film brittleness . a summary of the p values and ideal selectivities for various gas pairs are shown in table 2 . gas permeability and selectivity of pim - 1 are known to be very sensitive to film preparation conditions and pre - treatment ( budd 2008 ). consequently , there is variation between the previously reported permeability data and the present data for pim - 1 as shown in fig5 and fig6 . it is likely that this difference arises from the post - treatment protocol for the membranes . different from previous work , the tz - pim membranes were boiled in water first ( with hcl , ph = 4 - 5 ), in order to remove nmp . after several washes in water , they were soaked in methanol and then allowed to dry naturally . finally , the membranes were dried in a vacuum oven for 24 h by gradually increasing the temperature from ambient to 120 ° c . for comparison , a pim - 1 membrane was treated identically . the o 2 / n 2 selectivities for pim - 1 are above the robeson upper bound ( robeson 1991 ), with expected “ trade - off ” behavior between permeability and selectivity as shown in fig5 . tz - pim3 exhibited o 2 / n 2 and co 2 / n 2 selectivity similar to pim - 1 , with lower selectivities observed for tz - pim1 - 2 . these results are consistent with the results of 1 h nmr and ftir which indicate the click reaction conducted on the pim - 1 film was not effective under various heterogeneous conditions . however , tz - pim4 and tz - pim5 show extraordinary gas transport properties which are above the robeson upper bound ( robeson 2008 ) for the o 2 / n 2 and co 2 / n 2 gas pairs . compared with pim - 1 , the tz - pim series shows higher selectivity for gas pairs such as o 2 / n 2 and co 2 / n 2 , with a corresponding decrease in permeability . selectivity coupled with high permeability even combines to exceed the robeson upper - bound ( robeson 2008 ) for the o 2 / n 2 and co 2 / n 2 gas pair . thus , tz - pims are particularly useful in membranes for oxygen enrichment or carbon dioxide separation . molecular modeling analysis using hyperchem ™ 7 . 0 software reveals that the interchain distance of the polymer is not extensively altered by introducing tetrazole groups into the pim . tetrazole groups insert into the free volume spaces between the zigzag main chains , which may have an effect on interchain space filling . in addition , strong interchain hydrogen bonds may act to rearrange the chains , building up a network structure to increase the rigidity of polymer chains , which would lead to lower permeability and higher selectivity . this hypothesis is in good agreement with the observation that tz - pim5 forms a gel in dmf solution . the intrinsic intermolecular force of these tz - pims is expected to be independent of processing . the amount of hydrogen bonding network structures can be controlled by the amount of nan 3 and reaction time . thus , post - modification of pim - 1 by various cycloaddition conditions is a convenient method to adjust or tune the gas permeability and selectivity . the post - polymerization modification of nitrile - containing pim - type materials via a [ 2 + 3 ] cycloaddition click reaction with inorganic azide is an alternative and convenient approach for accessing structurally new pims . optimal results were obtained when the reaction was carried out at 120 ° c . for 2 - 8 d using a ratio of the reagents — cn : nan 3 : zncl 2 equal to 1 : 4 : 2 . partial and full cycloaddition in tz - pim results in markedly better solubilities in protic solvents than the starting materials , the tz - pims being soluble in alkaline aqueous solutions , while maintaining good processibility . all the tz - pims exhibited lower thermal stability compared with pim - 1 , the first degradation loss resulting from nitrogen extrusion from the tetrazole ring , but all tz - pims were nevertheless quite thermally stable . tz - pim4 and tz - pim5 membranes in particular had good mechanical properties for gas permeability testing , and showed evident decreases in o 2 , n 2 and co 2 permeabilities and corresponding significant increases in pure - gas selectivities against n 2 with increasing tetrazole content . both tz - pim4 and tz - pim5 had co 2 / n 2 and o 2 / n 2 gas pair performance exceeding the 2008 robeson upper - bound limit ( robeson 2008 ). in a manner similar to example 1 , pim - 1 was reacted with trimethylsilyl azide ( tms - n 3 ) in the presence of copper ( i ) bromide ( cubr ) in nmp at 80 ° c . for 2 days to form a tetrazole - containing pim . the — cn : tms - n 3 : cubr ratio was 1 : 1 . 5 : 1 . 5 . a possible general mechanism for the reaction of tms - n 3 with a nitrile is suggested by us and referenced in jin 2008 . the reaction was followed by ftir and the ftir compared to that of pim - 1 and to that of the product of a pim1 - nan 3 reaction . pim - 1 shows the characteristic nitrile absorption band at 2238 cm − 1 , while the absence of absorption bands in the range of 3000 cm − 1 to 3600 cm − 1 indicate no n — h group is present . after a two day reaction of pim - 1 with trimethylsilyl azide at 80 ° c ., the relative intensity of the nitrile absorption band decreased . the ftir spectrum of pim - 1 - trimethylsilyl azide is almost same as the one coming from pim - 1 - nan 3 . broad absorptions bands are observed in the range of 3000 cm − 1 to 3600 cm − 1 , which likely correspond to n — h stretching vibrations with n — h ••• n bond , and in the range of 2300 cm − 1 to 2800 cm − 1 , suggesting vibrations associated with quaternary nitrogen atom . a narrow intense absorption near 1580 cm − 1 arises due to stretching vibrations of the n ═ n and n — h groups , which imply that some of the nitrile groups were converted into tetrazole groups . it is notable there are small new bands near 1510 cm − 1 , 1400 cm − 1 , 1100 cm − 1 , which are due to the c ═ n stretching and bending vibrations of the characteristic tetrazole ring , respectively . compared to pim - 1 , the solubility of resulting polymer is quite poor in chcl 3 . however , it can be readily dissolved in nmp , dmf , dmac , which strongly suggests that the [ 2 + 3 ] cycloaddition reaction occurred . the tga results ( fig7 ) compared to pim - 1 and pim - 1 - nan 3 showed that pim - 1 - trimethylsilyl azide and pim - 1 - nan 3 first decomposed between 160 ° c . and 250 ° c ., suggesting degradation of the tetrazole ring ( around 160 ° c .). pim - 1 - benzyl azide is prepared in a manner similar to example 7 except that benzyl azide is used instead of tms - azide and the temperature is 120 ° c . different from pim - 1 and pim - 1 - nan 3 ( polymer with tetrazole groups produced from pim - 1 and nan 3 ), the solubility of pim - 1 - benzyl azide is quite poor in ccl 3 , thf , methanol , acetone , nmp , dmf and dmac , which suggests a [ 2 + 3 ] cycloaddition reaction occurred . after a two day reaction of pim - 1 at 120 ° c . with benzyl azide and cubr , the relative intensity of the nitrile absorption band decreased in ftir spectrum . a narrow intense absorption near 1580 cm − 1 arose . this is indicative of a stretching vibration of the n ═ n and n — h groups , which implies that some of the nitrile groups were converted into tetrazole groups . the tga results ( fig8 ) compared to pim - 1 and pim - 1 - nan 3 showed that pim - 1 - benzyl azide and pim - 1 - nan 3 first decomposed between 160 ° c . and 250 ° c ., suggesting degradation of the tetrazole ring ( around 160 ° c .). pim - 1 - acetamidobenzensulfonyl azide is prepared in a manner similar to example 8 except that 4 - acetamidobenzensulfonyl azide is used instead of benzyl azide . after a two day reaction of pim - 1 with 4 - acetamidobenzenesulfonyl azide and cubr at 120 ° c ., the relative intensity of the nitrile absorption band decreased in the ftir spectrum . broad absorption bands were observed in the range of 3000 cm − 1 to 3600 cm − 1 , which likely correspond to n — h stretching vibrations with n — h ••• n bond . a narrow intense absorption near 1700 cm − 1 arose , which suggests the presence of — hnco — groups in the polymer . the tga results ( fig9 ) compared with pim - 1 and pim - 1 - nan 3 showed that product of reaction of pim - 1 and 4 - acetamidobenzenesulfonyl azide first decomposed over 200 ° c . this suggests the degradation of the tetrazole ring . however , this substituted ring appears to more stable than pim - 1 - nan 3 . poly ( ionic liquid ) s with intrinsically microporous structures ( pilim - 1 , pilim - 2 and pilim - 3 ) were prepared from tetrazole - pim ( tz - pim - 50 , pim - 1 with 50 % nitrile groups converted into tetrazole groups ) with different amines in methanol at reflux temperature . thus , the tetrazole - containing pim having 50 % conversion of nitrile to tetrazole ( tz - pim - 50 ) was first prepared from pim - 1 solution . pim - 1 was dissolved in nmp ( 1 - 3 g in 20 ml of solvent ). nan 3 ( 4 equiv vs . nitrile groups ) and anhydrous zncl 2 ( 2 equiv vs . nitrile groups ) were added , and the reaction mixture was stirred at 120 ° c . for 5 days . after cooling to 60 ° c ., 15 ml of dilute hcl ( 1 : 10 by volume in water ) was added , and the reaction mixture was kept at this temperature for 3 - 5 h . the tz - pim - 50 thus obtained was then precipitated in excess of the same aqueous hcl solution , filtered , washed on the filter with the hcl solution and water , and dried in vacuum at 120 ° c . the pilims were prepared from tz - pim - 50 as follows . 0 . 005 mol tz - pim - 50 was dissolved in 50 ml methanol together with 0 . 015 mol amine ( methylamine , diisopropylamine or n , n - diisoprpoylethylamine ). the mixture was stirred at ambient temperature overnight , and then reprecipitated in water three times . the resulting pilims were dried in 80 ° c . vacuum oven for 2 days . the 1 h - nmr spectra ( fig1 ) show exact structures of the pilims prepared in example 9 . the 1 h - nmr signal intensities and the shapes of the tz - pim - 50 and pilim - 1 - 3 polymers were monitored at 100 ° c . nmr probe temperatures . the observed peak intensity ratio of tz - pim - 50 for the aromatic ( 6 . 2 - 6 . 8 ppm ) and aliphatic ( 0 . 3 - 2 . 4 ppm , ch 2 and ch 3 ) regions was exactly 4h : 16h as expected from the molecular structure . for pilim - 1 , except the similar aromatic and aliphatic regions , which integration was 4h : 16h , there was an additional signal at around 3 . 3 ppm corresponding to n — ch 3 , which integration was 3h . furthermore , the shoulder signal at around 6 . 8 - 7 . 2 ppm arising from — nh protons changed shape with increasing temperature . it is well - known in nmr spectroscopy that changes in the sample temperature affect the mobility of the molecules , and hence , the shape of the signals . this is particularly evident with protons involved in hydrogen bonding ( exchange rate , electron density around the h nuclei ), while other aromatic and aliphatic protons are often left unchanged . a drop of d 2 o was added into the nmr tube and its immediate effect was observed in the 1 h - nmr spectrum . the — nh protons exchanged with the deuterium nuclei , proving the presence of labile protons from the — nh groups . for pilim - 2 , compared to tz - pim - 50 , the aromatic ( 6 . 2 - 6 . 8 ppm ) and aliphatic ( 0 . 3 - 2 . 4 ppm , ch 2 from pim main chain , ch 3 from main chain and n — ch ( ch 3 ) 2 ) regions was 4h : 24h . the sharp signal around 3 . 4 ppm ( m ) corresponds to n — ch , with an integration of 2h . in addition the small shoulder peak around 6 . 8 - 7 . 2 ppm arises from — nh protons . for pilim - 3 , integration of the aromatic ( 6 . 2 - 6 . 8 ppm ) and aliphatic ( 0 . 3 - 2 . 4 ppm , ch 2 from pim main chain , ch 3 from main chain and n — ch ( ch 3 ) 2 ) regions was 4h : 27h , and there are two sharp signals ( 2h , n — ch 2 , d , 2 . 9 ppm and 2h n — ch , m , 3 . 5 ppm ). there is no obvious signals around 6 . 8 - 7 . 2 ppm area , which suggests that hydrogen bonded — nh protons doesn &# 39 ; t occur . ftir data shows an absorption band at 2238 cm − 1 in pim - 1 ( mn , 86 , 000 , pdi = 2 . 0 ) that is assigned to nitrile groups , while the absence of absorption bands in the range of 3000 cm − 1 to 3600 cm − 1 indicates that no n — h group is present . ftir spectra ( fig1 ) of tz - pim - 1 and the pilims prepared in example 9 show that in tz - pim - 50 , pilim - 1 , pilim - 2 and pilim - 3 , the absorption bands and their intensities are quite similar . the relative intensity of the nitrile absorption band in these polymers decreased to half ( compared with pim - 1 , the integration is about 50 %). broad absorption bands are observed in the range of 3000 cm − 1 to 3600 cm − 1 , corresponding to n — h stretching vibrations with n — h ••• n hydrogen bonding , and in the range of 2300 to 2800 cm − 1 , attributed to vibrations of quaternary nitrogen atom ( vygodskii 2008 ). a narrow intense absorption near 1580 cm − 1 arises due to stretching vibrations of the n ═ n and n — h groups which imply that some of the nitrile groups were converted into tetrazole groups ( disli 2009 ). it is notable there are small new bands near 1510 cm − 1 , 1400 cm − 1 , 1100 cm − 1 , which are due to the c ═ n stretching ( darkow 1997 ) and bending vibrations of the characteristic tetrazole ring , respectively . pim - 1 , tz - pim - 50 , pilim - 1 , pilim - 2 and pilim - 3 have no glass transition temperatures before 350 ° c . and dsc data show that they are amorphous . the tga results compared to the nitrile - based precursor pim - 1 ( fig1 ) showed that pilim - 1 , pilim - 2 and pilim - 3 decomposed at lower temperatures . it is observed under nitrogen , at a heating rate of 5 ° c ./ min , that pilims decompose thermally in two stages , the first being the degradation of the tetrazole ring ( around 160 ° c .) and the second the thermo - oxidative destruction of the polymeric residue ( around 488 ° c .). around 11 %, 18 % and 21 % weight loss for pilim - 1 , pilim - 2 and pilim - 3 at the first stage is close to 50 % of the calculated result of complete decomposition of these poly ( ionic liquids ) ( 23 . 8 % 38 . 2 % and 42 . 5 %, respectively ), which is further proof of different ionic liquids with tetrazole structures present on the main chains . the solubility of pilim - 1 , pilim - 2 and pilim - 3 was similar to tz - pim - 50 , but distinctly different when compared to pim - 1 . pim - 1 is readily soluble in tetrahydrofuran ( thf ), dichloromethane ( ch 2 cl 2 ), chloroform ( chcl 3 ), but insoluble in polar aprotic solvents such as dimethylformamide ( dmf ), dimethylacetamide ( dmac ), and n - methylpyrrolidone ( nmp ). tz - pim - 50 was insoluble in thf , ch 2 cl 2 and chci 3 , but readily soluble in dmac and nmp . pilim - 1 , pilim - 2 and pilim - 3 were also soluble in dmac and nmp . when comparing tz - pim - 50 , pilim - 1 , pilim - 2 and pilim - 3 , gel forms more readily for dmf solutions of tz - pim - 50 and primary amine ( pilim - 1 ), due to strong hydrogen bonding while pilim - 3 exhibits the least gel formation . by visual observation , the degree of swelling of these polymers in chloroform increased in the order of pilim - 1 , pilim - 2 and pilim - 3 and in methanol increased in the order of pilim - 3 , pilim - 2 and pilim - 1 . these interesting phenomena also indicate that tetrazole ionic liquids having different amine cations on the main chain change the solubility of the polymers . specific surface area of pilim particles was measured by bet . s bet was 0 . 29 m 2 / g . gas transport properties were measured at 100 psig . the permeabilities and selectivities of pilim - 1 , pilim - 2 and pilim - 3 follow a trade - off relationship . in general , higher permeability is gained at the cost of lower selectivity and vice versa . pure - gas permeability coefficients ( p ) were measured on polymer dense films of pim - 1 , pilim - 1 , pilim - 2 and pilim - 3 for o 2 , co 2 and n 2 . a summary of these p values and ideal selectivities for various gas pairs is shown in table 3 . gas permeability and selectivity of pim - 1 are known to be very sensitive to film preparation conditions and pre - treatment ( budd 2008 ). there is variation between the previously reported permeability data and the present data for pim - 1 as shown in fig1 and fig1 . the post - treatment protocol for the membranes results in differences in gas permeabilities . because pilims swell in methanol to a certain degree , all pilims membranes were only treated in boiling water ( with hcl , ph = 5 ), in order to remove nmp and traces of salt , then allowed to dry naturally . finally , the membranes were dried in a vacuum oven for 24 h by gradually increasing the temperature from ambient to 120 ° c . for comparison , pim - 1 membrane was treated identically . the o 2 / n 2 selectivities for pim - 1 are close to the robeson upper bound ( robeson 1991 ), with expected “ trade - off ” behavior between permeability and selectivity as shown in fig1 . the pilims exhibit lower gas permeabilities but higher selectivity compared to pim - 1 above the 1991 robeson upper bound ( robeson 1991 ), even closer to the 2008 robeson upper bound ( robeson 2008 ). furthermore , the pilims show extraordinary gas transport behavior , placing it above the 2008 robeson upper bound ( robeson 2008 ) for co 2 / n 2 gas pairs ( fig1 ). from the viewpoint of molecular modeling analyses by using hyperchem ™ 7 . 0 software , the interchain distance of the polymer is not extensively changed by introducing ionic liquid groups into the pim . all the ionic liquid groups are likely situated in the spaces between the zig - zag main chains , which might have an effect on interchain space filling . in addition , the data from table 3 showed that larger volumes of amine led to lower gas permeabilities , suggesting that the ionic liquid acts as interchain filling material . thus , changing cations or anions in the poly ( ionic liquid ) s of intrinsic microporosity is a simple method to adjust or tune the gas permeability and selectivity . thus , intrinsically microporous poly ( ionic liquid ) s are polymeric materials , in which gas selectivity coupled with permeability combines to be close to or exceed the robeson upper bound for o 2 / n 2 and co 2 / n 2 . these characteristics combined with s bet and co 2 absorption properties provide polymers that are exceptionally promising as absorbents and membrane separation materials . in real gas mixtures ( e . g . co 2 / n 2 or co 2 / ch 4 ), the separation factor from a mixed gas is typically lower than the permselectivity measured from single gas permeation measurement owing to plasticization and / or competitive sorption effects . in mixed gas separation , co 2 molecules can swell the polymer matrix , causing the permeability of the slow gas ( e . g . n 2 ) to increase beyond its pure gas permeability , which results in reduced selectivity . in the present invention , surprisingly , the mixed co 2 / n 2 selectivities in tz - pims are higher than single gas selectivity data . when the co 2 concentration in mixtures are increased from 10 to 40 mol %, the mixed gas selectivity ( see table 4 ) are higher than the pure gas selectivity , assuming a pore - blocking mechanism , whereby the co 2 sorbed preferentially in tz - pims hinders the transport of n 2 . n 2 sorption isotherms at 77 k by brunauer - emmett - teller ( bet ) for tz - pim9 ( 100 % conversion of nitrile to tetrazole ) are similar to common glassy polymers having low free volume elements , and totally different from those in pim - 1 as shown in fig1 a . the bet surface area in tz - pim9 is about 30 m 2 g − 1 , which is a typical value for common glassy polymers such as polyimides ( 15 - 30 m 2 g − 1 ), and is markedly smaller than the bet surface area for pim - 1 ( 700 m 2 g − 1 ). in sharp contrast , the amount of co 2 sorption at 273 k in tz - pim9 is higher than that in pim - 1 at low pressure ranges ( see fig1 b ), indicating that tz - pims have better affinity for co 2 molecules than pim - 1 . this is likely mainly due to the tetrazole groups in tz - pims which enhance both sorbing capability and solubility - selectivity toward any other gases . by improving chemical affinity as well as microporosity , tz - pims can sorb co 2 molecules more favorably in their empty cages than n 2 molecules . in addition , strong interchain interactions in tz - pims provides rigid frameworks that help prevent polymer swelling caused by co 2 molecules . thus , the present invention provides new microporous polymers having both intrinsic microporosity and co 2 - philic functional groups , resulting in remarkable gas transport properties combined with high selectivity over the current limitation of common organic polymers . currently , economically practical co 2 capture processes are industrially important for air purification and environmentally important for reduction of carbon dioxide &# 39 ; s effect on global warming . differing from other well - established membrane gas separations , highly permeable , selective co 2 separations using polymeric membrane materials are still challenging because polymeric membranes suffer from low co 2 flux and low selectivity particularly in gas mixtures . the presently described route to tune polymer properties for effective co 2 separations and excellent processibility improves their potential utility for industrial co 2 separation applications using polymeric gas separation membranes . the contents of the entirety of each of which are incorporated by this reference . aronson j b . 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( 2000 ) angew chem int ed . 39 , 3772 - 3789 . other advantages that are inherent to the structure are obvious to one skilled in the art . the embodiments are described herein illustratively and are not meant to limit the scope of the invention as claimed . variations of the foregoing embodiments will be evident to a person of ordinary skill and are intended by the inventor to be encompassed by the following claims .