Patent Application: US-94484510-A

Abstract:
facile ways towards the integration of the regioregular polys onto carbon nanotubes , providing multifunctional materials that combine the extraordinary properties of the carbon nanotubes with those of regioregular polys , are presented .

Description:
the present invention relates to the development and characterization of new multifunctional materials ( structures 1 and 2 ) comprising regioregular poly ( 3 - alkylthiophene ) s covalently attached on single or multi wall carbon nanotubes . the structures of the materials are given below . for the purpose of the present invention , monofunctionalized regioregular poly ( 3 - alkylthiophene ) s having octyl side chain group and single wall carbon nanotubes are preferable . the first goal of this invention is the preparation of one - end functionalized regioregular poly ( 3 - octylthiophene ) having phenol as terminal group . our approach is a two - step process slightly different from an already reported procedure ( jeffries - e l , mccullough et al . 2005 ; sheina , mccullough et al . 2006 ) for the end - functionalization of regioregular poly ( 3 - alkylthiophene ) s , in order to avoid the synthesis of difunctionalized phenol terminated regioregular poly ( 3 - alkylthiophene ) s . first , we synthesized and isolated the h / br terminated rrp3ot ( 1 ) according to ( iovu , mccullough et al . 2005 ; loewe and mccullough 2000 ; miyakoshi , yokozawa et al . 2005 ). the 1 h nmr spectrum of rrp3ot ( 1 ) is presented in fig1 a , which allows the accurate determination of the molecular weight of rrp3ot ( 1 ) based on the integration of the peak at 2 . 8 ppm , assigned to the a - methylene protons of the octyl groups and the broad peak at 2 . 6 - 2 . 5 ppm , assigned to the methylene protons on the first carbon substituent ( b and b ′) on the end units . for example , the number of the repeat units n for the rrp3ot ( 1 ) is equal to 13 , corresponding to m n = 2600 . this molecular weight is lower than that obtained from the gpc measurements ( m n ˜ 4350 ). afterwards , a palladium - mediated suzuki coupling reaction ( miyaura and suzuki 1995 ) was performed between rrp3ot ( 1 ) and ( tetrahydropyranyloxy ) phenyl boronic acid ( m1 ), for the preparation of the phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ). the 1 h nmr spectrum of phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ) is depicted in fig1 b . the characteristic peaks of the tetrahydropyranyl - protecting group as well as two small doublet peaks are clearly observed at δ ˜ 7 . 4 and 7 . 1 ppm respectively , assigned to the phenyl ring . verification of the monofunctionalization of the rrp3ot ( 1 ) was also confirmed from the 1 h nmr spectrum of fig1 b . based on the peak at 1 . 9 ppm assigned to the protons of the tetrahydropyranyl group and the peak at 0 . 9 ppm assigned to the methyl protons of the octyl group , a polymerization degree of 15 repeating units was obtained for this polymer , in close proximity to the dpn = 13 obtained for the h / br rr - p3ot ( 1 ). finally , hydrolysis of phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ) with hydrochloric acid 37 % afforded the phenol - terminated rrp3ot ( 3 ) in quantitative yields . the reaction of pristine swnts in the presence of 2 - aminoethanol in dmf led to the synthesis of nanotube derivative ( 4 ) that has free hydroxyl groups in the periphery of the swnt . the direct reaction of amino derivatives onto the carbon nanotube surface has been described in the literature ( basiuk , basiuk et al . 2004 ) and is an easy method of providing functionalized carbon nanotube materials . based on the tga results of fig2 , the pristine swnt and nanotube derivative ( 4 ) present a loss of weight of about 8 % and 17 . 5 % at 800 ° c ., respectively . this corresponds to the presence of one functional hydroxy - terminated group per 60 carbon atoms . decoration of the modified swnt ( 4 ) with the phenol - terminated rrp3ot ( 3 ) was accomplished by an ether bond formation in the presence of triphenylphosphine ( tpp ) and diisopropylazodicarboxylate ( diad ) ( mitsunobu 1981 ), providing the regioregular poly ( 3 - octylthiophene ) modified single wall carbon nanotube ( rrp3ot - co - swnt ) ( 5 ). the amount of the polymer chemically bonded onto nanotube derivative ( 4 ) was evaluated by tga ( fig2 ). the aminoethanol modified swnt ( 4 ) show very good thermal stability up to 800 ° c . under an inert nitrogen atmosphere , while the presence of the grafted polymer onto nanotube derivative ( 4 ) is verified by the polymer decomposition occurring in this temperature range . tga measurements demonstrated that approximately 11 wt % of the rrp3ot - co - swnt ( 5 ) is due to the polythiophene precursor . taking into account that the molecular weight of the polymer is equal to 2600 , the functionalization percentage of rrp3ot - co - swnt ( 5 ) was estimated to be approximately 0 . 12 %. a simple calculation permits a functionalization percentage of 1 . 9 % if all the hydroxyl groups of nanotube derivative ( 4 ) are connected to the phenol - terminated rrp3ot ( 3 ). this indicates that not all the hydroxyl groups of the nanotube derivative nanotube derivative ( 4 ) have reacted with the phenol group of ( 3 ), and we estimate that there is an average of one regioregular polythiophene chain per 17 aminoethanol groups . in the second synthetic route , esterification of the free phenol of ( 3 ) with 2 - chloropropionyl chloride end up with the desired regioregular poly ( 3 - octylthiophene ) macroinitiator ( 6 ). the 1 h nmr spectrum of ( 6 ) is depicted in fig1 c . the disappearance of the characteristic signals of the tetrahydropyranyl protecting group and the subsequent appearance of a multiple peak are clearly observed at δ ˜ 4 . 6 ppm and at δ ˜ 1 . 8 ppm respectively , which are assigned to the terminal proton next to the halogen atom and to methyl protons next to the terminal proton of the chloropropionyl group , respectively . verification of the polymerization degree of the rrp3ot ( 1 ) was also confirmed from the 1 h nmr spectrum of fig1 c . based on the methyl protons of the chloropropionyl group and the methyl protons of the octyl group , a polymerization degree of 15 repeating units was obtained for this polymer , similar to the dpn = 15 obtained for the phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ). one method of introducing the fullerene into polymer backbone was through atom transfer radical polymerization conditions as described in the literature ( zhou , li et al . 2000 ; chochos , gregoriou et al . 2005 ). by employing similar reaction conditions between regioregular poly ( 3 - octylthiophene ) macroinitiator ( 6 ) and swnt , we succeeded in synthesizing the regioregular poly ( 3 - octylthiophene ) modified single wall carbon nanotube ( rrp3ot - swnt ) ( 7 ). the amount of the polymer grafted onto the surface of the swnt was estimated by tga ( fig2 ). tga measurements demonstrated that approximately 15 wt % of the rrp3ot - swnt ( 7 ) is due to the polythiophene chains corresponding to a functionalization percentage equal to 0 . 09 %. ft - ir characterization was also used to verify the introduction of the rrp3ot precursor onto the swnt surface both for materials rrp3ot - co - swnt ( 5 ) and rrp3ot - swnt ( 7 ). the spectrum of rrp3ot ( 1 ) show peaks at 2926 cm − 1 and at 2853 cm − 1 assigned to the methyl and methylene protons of the octyl side chain group ( fig3 ), while the ir spectra of materials rrp3ot - co - swnt ( 5 ) and rrp3ot - swnt ( 7 ) demonstrate similar peaks at 2926 cm − 1 and at 2853 cm − 1 , respectively ( fig3 ). the uv - vis and emission spectra of rrp3ot ( 1 ), both in solution and solid state , are shown in fig4 . the uv - vis spectra of rrp3ot ( 1 ) reveal an absorption maximum at 440 nm in solution and at 512 , 554 and 606 nm in the solid state ( fig4 a ), characteristic of the rrp3ats ( rieke 1994 ; rieke 1998 ). in addition , the photoluminescence spectra of rrp3ot ( 1 ) exhibit two electronic transitions at 572 and 620 nm in solution and at 650 and 715 nm in the solid state , respectively ( fig4 b ). the uv - vis spectra of rrp3ot - co - swnt ( 5 ) and rrp3ot - swnt ( 7 ) in the solid state are shown in fig5 a . strong evidence for the efficient incorporation of the polythiophene precursor onto the swnt ensue from the corresponding absorption spectra . although swnts do not show any absorption band between 400 and 700 nm in the solid state , the rrp3ot - co - swnt ( 5 ) and rrp3ot - swnt ( 7 ) demonstrate a broad absorption band between 400 and 700 nm assigned to the rrp3ots . furthermore , it is shown that the absorption spectra of the rrp3ots are less resolved when are integrated onto the swnt , in contrast to the regioregular polythiophene precursor . in addition , comparing the emission spectra of the rrp3ot - co - swnt ( 5 ) or rrp3ot - swnt ( 7 ) in the solid state , with those of the rrp3ot thin film , one can see that although the absorption spectra are adjusted to almost the same absorption value , the emission from the rrp3ot - co - swnt ( 5 ) or the rrp3ot - swnt ( 7 ) is totally quenched ( fig5 b ). this is a strong indication of an efficient electron transfer from the excited polythiophene chains to the swnt backbone showing that this type of modification does not disturb in a large extent the electronic properties of the swnt . the following non - limiting examples are illustrative of the invention . all documents mentioned herein are incorporated herein by reference . one of the synthetic procedures which is followed for the synthesis of the h / br regioregular poly ( 3 - octylthiophene ) ( 1 ) is given below . to a suspension of magnesium ( 4 . 72 g , 196 . 32 mmol ) in 120 ml of anhydrous diethyl ether , the octylbromide ( 29 . 6 ml ) in 30 ml of diethyl ether was added dropwise . after complete disappearance of magnesium , 3 - bromothiophene ( 20 g , 122 . 7 mmol ) and 1 , 3 - diphenylphosphinopropane nickel ( ii ) chloride ( ni ( dppp ) cl 2 ) ( 0 . 33 g , 0 . 6135 mmol ) were added . after stirring and heating for 48 h , the reaction mixture was poured into a mixture of crushed ice and diluted hcl ( 2n ) and extracted from ether . the combined ether layers were dried over mgso 4 . after removal of the solvent , the residue was purified by column chromatography using hexane as eluent . the 3 - octylthiophene was received as colorless oil ( 16 . 11 g , 67 % yield ). 1 h - nmr ( cdcl 3 ): δ = 7 . 21 ( m , 1h ), 6 . 88 ( m , 2h ), 2 . 55 ( t , 2h ), 1 . 54 ( m , 2h ), 1 . 25 ( m , 10h ), 0 . 92 ( t , 3h ). 3 - octylthiophene ( 9 . 8 g , 0 . 05 mol ) was solubilized in 30 ml of dimethylformamide ( dmf ) under argon in the dark . n - bromosuccinimide ( nbs ) ( 17 . 8 g , 0 . 1 mol ) was added portionwise . the resulting solution was stirred at room temperature under argon overnight . sodium sulfite ( na 2 so 3 ) ( 30 ml ) was then added in order to remove the impurities of succinimide , and the organic phase was extracted with diethyl ether ( 100 ml ) twice , washed with water and dried with magnesium sulfate . the solvent was removed under reduced pressure to obtain the 2 , 5 - dibromo - 3 - octylthiophene ( 15 . 6 g ) as a yellow oil in 88 % yield . 1 h - nmr ( cdcl 3 ): δ = 6 . 75 ( s , 1h ), 2 . 52 ( t , 2h ), 1 . 52 ( m , 2h ), 1 . 28 ( t , 10h ), 0 . 89 ( t , 3h ). 2 , 5 - dibromo - 3 - octylthiophene ( 7 . 08 g , 0 . 02 mol ) was dissolved in 100 ml of anhydrous tetrahydrofuran ( thf ). to this solution was added via a syringe isopropylmagnesium chloride ( 10 ml , 2 . 0 m in tetrahydrofuran ) and the mixture was refluxed for 3 h . the reaction mixture was then allowed to cool to room temperature and 1 , 3 - diphenylphosphinopropane nickel ( ii ) chloride ( ni ( dppp ) cl 2 ) ( 0 . 11 g , 0 . 0002 mol ) was added in one portion . the mixture was refluxed for another 24 h and then poured into methanol to precipitate the polymer . the polymer was filtered and then washed by soxhlet extraction with methanol , acetone , hexane and chloroform . the h / br regioregular poly ( 3 - octylthiophene ) ( 2 . 7 g ) was received from the chloroform extraction . 1 h - nmr ( cdcl 3 ): δ = 6 . 97 ( s , 1h ), 2 . 80 ( t , 2h ), 1 . 70 ( m , 2h ), 1 . 29 ( m , 10h ), 0 . 88 ( d , 3h ). 13 c - nmr ( cdcl 3 ): δ = 140 . 30 , 134 . 11 , 130 . 89 , 129 . 01 , 32 . 29 , 30 . 93 , 29 . 97 , 29 . 84 , 29 . 69 , 23 . 07 , 14 . 49 one of the synthetic procedures which is followed for the synthesis of the phenol - terminated regioregular poly ( 3 - octylthiophene ) is given below . regioregular poly ( 3 - octylthiophene ) ( 1 ) ( 1 g ), ( tetrahydropyranyloxy ) phenyl boronic acid ( m1 ) ( 1 . 211 g , 5 . 454 mmol ) and 126 mg of tetrakis ( triphenylphosphine ) palladium [ pd ( pph 3 ) 4 ] were placed together in a reaction flask . the flask was degassed and filled with argon several times . thf ( 100 ml ) and 2m na 2 co 3 ( 6 . 1 ml ) were added and the mixture was heated at reflux for 48 h under argon atmosphere . the solvent was partially removed under reduced pressure and the mixture was poured into methanol to precipitate the crude polymer . the polymer was filtered and then washed by soxhlet extraction with methanol , acetone ( in order to remove the excess of ( m1 )) and chloroform . the phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ) ( 0 . 91 g ) was collected from the chloroform extraction . 1 h nmr ( 400 mhz , cdcl 3 ): δ h 0 . 88 ( t , 45h ), 1 . 31 ( m , 120h ), 1 . 42 ( m , 30h ), 1 . 70 ( t , 30h ), 1 . 88 ( b , 2h ), 2 . 01 ( b , 2h ), 2 . 81 ( t , 30h ), 3 . 63 ( m , 2h ), 3 . 94 ( m , 2h ), 5 . 47 ( s , 1h ) 6 . 99 ( s , 15h ), 7 . 11 ( d , 2h ), 7 . 34 ( d , 2h ); gpc : m n : 4820 , pdi : 1 . 6 ; 1 h nmr : dpn = 15 , m n : 3088 . in a round - bottom flask the phenoxy - tetrahydropyranyl terminated rrp3ot ( 2 ) was dissolved in thf ( 50 ml ). the mixture was heated to reflux and then 6 drops of hcl 37 % were added . the reaction was heated overnight and then precipitated into methanol . the polymer was filtered , washed with deionized water and methanol and dried in vacuum . the phenol - terminated regioregular poly ( 3 - octylthiophene ) ( 3 ) was afforded in quantitative yield . 1 h nmr ( 400 mhz , cdcl 3 ): δ h 0 . 88 ( t , 45h ), 1 . 28 ( m , 120h ), 1 . 41 ( m , 30h ), 1 . 70 ( t , 30h ), 2 . 80 ( t , 30h ), 6 . 99 ( s , 15h ), 7 . 07 ( d , 2h ), 7 . 26 ( d , 2h ); gpc : m n : 4760 , pdi : 1 . 6 ; 1 h nmr : dpn = 15 , m n : 3004 . the reaction which is followed for the synthesis of the aminoethanol modified single wall carbon nanotube is given below . a suspension of pristine swnts ( 50 mg ) in dmf ( 50 ml ) was sonicated for 10 min and then the 2 - aminoethanol ( 3 ml , 49 . 8 mmol ) was added . the reaction mixture was stirred at 80 ° c . for 5 days , then filtered through a millipore membrane ( ptfe , 0 . 22 μm ), washed with dmf , dichloromethane and diethyl ether and dried under high vacuum affording 35 mg of the nanotube derivative ( 4 ). the reaction which is followed for the synthesis of the regioregular poly ( 3 - octylthiophene ) modified single wall carbon nanotube ( rrp3ot - co - swnt ) is given below . phenol - terminated rrp3ot ( 3 ) ( 22 mg ), the aminoethanol modified swnt ( 4 ) ( 15 mg ) and triphenylphosphine ( tpp ) ( 20 . 06 mg , 0 . 076 mmol ) were added in a previously degassed round - bottom flask . dmf ( 10 ml ) and thf ( 10 ml ) were placed in the reaction flask and sonicated for 15 min . diisopropylazodicarboxylate ( diad ) ( 15 μl , 0 . 076 mmol ) was then added in the reaction mixture and the flask was degassed and filled with argon several times . the reaction was stirred at 80 ° c . for 24 h under argon atmosphere . then , the same amount of tpp and diad was placed in the flask and the mixture allowed reacting at 80 ° c . for another 24 h under argon atmosphere . after being cooled to room temperature , the suspension was sonicated and centrifugated in order to remove any unreacted nanotube derivative ( 4 ). the solution was filtered through a millipore membrane ( ptfe , 0 . 22 μm ), and the brownish solid was washed several times with dmf , chloroform ( in order to remove any excess of phenol - terminated rrp3ot ( 3 )) and diethyl ether , affording 32 mg of the compound regioregular poly ( 3 - octylthiophene ) modified single wall carbon nanotube ( 5 ) ( rrp3ot - co - swnt ). the reaction which is followed for the synthesis of the regioregular poly ( 3 - octylthiophene ) macroinitiator ( 6 ) is given below . in a degassed round - bottom flask , 195 mg of phenol - terminated rrp3ot ( 3 ) was added and dissolved in distilled dichloromethane ( 30 ml ). the polymer solution was cooled to 0 ° c . chloropropionylchloride ( cpc ) ( 0 . 22 ml ) and distilled triethylamine ( et 3 n ) ( 70 μl ) were added in the reaction and after 10 min the mixture was heated at 80 ° c . for 24 h . then the mixture was cooled to 0 ° c . and the same amount of cpc and et 3 n were added . after 10 min the mixture was heated at 80 ° c . for 24 h . this procedure was repeated , and the final mixture was left to react at 80 ° c . for 48 h . finally an excess of meoh was added in the flask and the mixture was stirred for 1 h . the mixture was filtered , and the resulting initiator was washed with meoh repeatedly and subsequently dried affording regioregular poly ( 3 - octylthiophene ) macroinitiator ( 6 ) in quantitative yield . 1 h nmr ( 400 mhz , cdcl 3 ): δ h 0 . 88 ( t , 45h ), 1 . 28 ( m , 120h ), 1 . 41 ( m , 30h ), 1 . 70 ( t , 30h ), 1 . 84 ( dd , 3h ), 2 . 81 ( t , 30h ), 4 . 64 ( m , 1h ), 6 . 99 ( s , 15h ), 7 . 04 ( d , 2h ), 7 . 20 ( d , 2h ); gpc : m n : 4870 , pdi : 1 . 7 ; 1 h nmr : dpn = 15 , m n : 3091 . 5 . the reaction which is followed for the synthesis of the regioregular poly ( 3 - octylthiophene ) modified single wall carbon nanotube ( 7 ) is given below . the regioregular poly ( 3 - octylthiophene ) macroinitiator ( 6 ) ( 30 mg ), cubr ( 6 . 66 μmol ), and bpy ( 13 . 13 μmol ) were placed in a reaction flask , degassed and filled with argon three times . next , o - dichlorobenzene ( 8 ml ) and swnt ( 30 mg ) were added in the reaction flask and sonicated for 15 min . then , the reaction mixture was heated at 110 ° c . for 3 d . after being cooled to room temperature , the suspension was sonicated and centrifugated in order to remove any unreacted swnt . the solution was filtered through a millipore membrane ( ptfe , 0 . 22 μm ), and the brownish solid was washed several times with dmf , thf ( in order to remove any unreacted of regioregular poly ( 3 - 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