Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. II. Reactions of ȮH radicals with amino acids

The reaction of ?H radicals with a number of aliphatic amino acids has been studied by entrapping the resultant radicals as end groups of poly(methyl methacrylate) that have been detected and estimated by the sensitive dye partition technique. The rate constants of the reaction (in mol^?1 L S^?1) of 7 amino acids at 25°C and at pH 1.00 have been determined as 8.33 × 10⁸ for glycine, 2.56 × 10⁹ for β-alanine, 2.01 × 10⁹ for β-alanine, 3.99 × 10⁹ for 4-amino butyric acid, 7.56 × 10⁹ for (1+) valine, 1.42 × 10¹⁰ for (1?) leucine, and 5.98 × 10¹⁰ for 6-amino caproic acid. Glycine, α-alanine, β-alanine, and 4-amino butyric acid produced radicals that underwent deamination and incorporated only carboxyl-bearing end groups in the polymer. The other amino acids, leucine, valine, and 6-amino caproic acid, produced at least two types of radicals, radicals that underwent deamination and those that remained intact, and incorporated in the polymer both carboxyl- and amine-bearing end groups but in different amounts. The latter type of radicals were about 29% from 6-amino caproic acid, 23% from leucine, and 18% from valine. The change of pH from 0.80 to 2.72 did not produce any significant change in the end group profile of the polymer obtained, indicating no appreciable change in the rate of the reaction of ?H radicals with the simplest amino acid glycine in the pH range studied.     

Viscosity Molecular Weight Determination of Polyadenylic Acid

Abstract

In this study viscosity measurements of polyadenylic acid (PolyA) in aqueous solution were carried out under different conditions. In the absence of any additives, the polymer degraded during flow through the capillary of a viscometer or when standing still. Degradation during the former was more severe. The degradation of polyadenylic acid can be prevented by addition of an electrolyte such as KCl to increase the ionic strength. However, in this case the deviation from linearity was still considerable at most ionic strength values. The best fit to the Huggins and Kraemer equations was obtained using a Tris–EDTA buffer solution with a final pH of 7.65. Estimation from intrinsic viscosity and weight-average molecular weight values gave k and α as 2.04 × 10^?5 and 0.89 from the equation η = kM ^α. The difference between Huggins (k ₁) and Kraemer (k ₁′) constants was close to 0.50 for all measurements.     

Glucose Oxidase-dextran Conjugates with Enhanced Stabilities Against Temperature and pH

Multipoint covalent bonding of glucose oxidase (EC 1.1.3.4) to hydrophilic natural polymer dextran and optimization of procedures to obtain, with enhanced temperature and pH stabilities, were studied. Purified enzyme was conjugated with various molecular weight dextrans (17.5, 75, and188 kD) in a ratio of 20:1, 10:1, 1:1, 1:5, 1:10, 1:15, and 1:20. After 1 h of incubation at pH 7, the activities of purified enzyme and conjugates were determined at different temperatures (25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, and 80°C), and the results were evaluated for thermal resistance. Increases in temperature from 25°C to 50°C did not change the activities of the conjugates. The conjugate, which was prepared with 75 kDa dextran in a molar ratio of 1:5, showed the highest thermal resistance and even the activity still remains at 80°C at pH 7.0. This conjugate also displayed activity in a wide pH range (pH 4.0–7.0) at high temperatures. Conjugate, which was synthesized with 75 kDa dextran in a molar ratio of 1:5, appears to be feasible and useful for biotechnological applications.     

Preparation of Proton Conductive Inorganic-Organic Hybrid Films Using Epoxycyclohexylethyltrimethoxysilane and Orthophosphoric Acid

Proton conductive inorganic-organic hybrid films, which show high proton conductivity at temperatures higher than 100°C with low humidification, have been prepared from epoxycyclohexylethyltrimethoxysilane (EHTMS), 3-glycidoxypropyltrimethoxysilane, and orthophosphoric acid by the sol-gel method. Self-supporting, flexible, and brownish transparent films with a thickness ranging from 150 to 300 μm were obtained. Differential thermal analyses and thermogravimetric measurements revealed that the films were stable up to about 200°C. Ionic conductivity of the films increased with an increase in the content of phosphoric acid in the films. The films with a molar ratio of P/Si = 1.75 retained a high conductivity of about 6 × 10^?4 S cm^?1 even after holding for 150 h under 0.7% relative humidity at 130°C. The conductivity of the films increased with an increase in the relative humidity and was about 1 × 10^?2 S cm^?1 under 20% relative humidity at 130°C.     

Simultaneous Identification and Quantification of Dextran 20 and Sucrose in Lyophilized Thrombin Powder by Size Exclusion Chromatography with ELSD

A rapid and accurate size exclusion chromatography method for the simultaneous identification and quantification of dextran 20 and sucrose with optical activity in the lyophilized thrombin powder was developed and validated. The assay was conducted on a Hitachi model D-2000 Elite HPLC system with a TOSOH TSKgel G3000 PWxl column (30 cm × 7.8 mm, 7 μm particle size) and an Alltech 3300 evaporative light scattering detector (ELSD). The mobile phase was acetonitrile–water (46:54, v/v) mixture delivered at a flow rate of 0.7 mL min⁻¹ at 25 °C. The ELSD was operated at a nebulizer-gas flow rate of 2.0 L min⁻¹ and drift tube temperature of 90 °C, and the gain was set at one. Afterward, method validation system for the size exclusion chromatography analysis was developed. The linear range was 0.1–1.6 and 0.1–1.0 g L⁻¹ for dextran 20 and sucrose, respectively, and the detection limits were <0.02 g L⁻¹ for dextran 20 and <0.015 g L⁻¹ for sucrose. Inter-day and intra-day variabilities showed that RSD ranged from 0.27 to 4.20%. Recovery validation showed that average recovery was between 96.00 and 103.98%. The developed analytical procedure was successfully applied to determine the contents of dextran 20 and sucrose in the lyophilized thrombin powder.

     

Molecular motion,morphology, and thermal properties of multiwall carbon nanotube/polysilsesquioxane composite

Diglycidyl ether of bisphenol A (DGEBA)‐bridged polyorganosiloxane precursors have been prepared successfully by reacting diglycidyl ether of bisphenol A epoxy resin with 3‐aminopropyltriethoxysilane. Acid‐modified and unmodified multiwalled carbon nanotube (MWCNT) were dispersed in the diglycidyl ether of bisphenol A‐bridged polyorganosiloxane precursors and cured to prepare the carbon nanotube/diglycidyl ether of bisphenol A‐bridged polysilsesquioxane (MWCNT/DGEBA‐PSSQ) composites. The molecular motion of MWCNT/DGEBA‐PSSQ nanocomposites was studied by high‐resolution solid‐state ¹³C NMR. Acid‐modification can improve the affinity between MWCNT and the polymer matrix. The molecular motion of the DGEBA‐PSSQ decreased with acid‐modified MWCNT content. However, when unmodified MWCNT was used, the molecular motion of the DGEBA‐PSSQ was increased. SEM and TEM microphotographs confirm that acid‐modified MWCNT exhibits better dispersion than unmodified MWCNT in DGBEA‐PSSQ. The dynamic mechanical properties of acid‐modified MWCNT/DGBEA‐PSSQ composites are more favorable than those of unmodified MWCNT. T_g of the DGEBA‐PSSQ decreased from 174.0 °C (neat DGEBA‐PSSQ) to 159.0 °C (1 wt % unmodified MWCNT) and 156.0 °C (1 wt % acid‐modified MWCNT). The storage modulus (at 30 °C) of the DGEBA‐PSSQ increased from 1.23 × 10⁹ Pa (neat DGEBA‐PSSQ) to 1.65 × 10⁹ Pa (1 wt % acid‐modified MWCNT). However, when unmodified MWCNT was used, the storage modulus of the DGEBA‐PSSQ decreased to 6.88 × 10⁸ Pa (1 wt % unmodified MWCNT). At high temperature, above 150 °C, storage modulus of nanocomposites was higher than that of neat polymer system. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 472–482, 2008     

Gas Chromatographic Determination of Guanidino Compounds Using Hexafluoroacetylacetone and Ethyl Chloroformate as Derivatizing Reagents

Guanidino compounds guanidine, methylguanidine, guanidinoacetic acid, guanidinobutyric acid, guanidinopropionic acid, and guanidinosuccinic acid after derivatization with hexafluoroacetylacetone and ethyl chloroformate at pH 9 in aqueous phase, eluted, and separated from gas chromatographic column HP-5 (30 m × 0.32 mm id) with film thickness of 0.25 μm at an initial column temperature 90 °C for 2 min, followed by heating rate of 10 °C min^?1 up to 220 °C with nitrogen flow rate of 1 mL min^?1. The detection was by flame ionization detector. The linear calibration ranges of each of guanidino compounds were obtained within 1–10 μg mL^?1, and the limit of detection was within 0.014–0.19 μg mL^?1. The derivatization and gas chromatography elution and separation were repeatable in terms of retention time and peak height/peak area with relative standard deviation (RSD) (n = 4) within 1.7–2.9 % and 1.4–2.8 %, respectively. The method was applied for the determination of guanidino compounds from deproteinized serum of uremic patients and healthy volunteers, and was found in the range below the limit of quantitation (BLOQ) to 1.25 μg mL^?1 with RSD within 1.4–3.6 %, and BLOQ to 0.4 μg mL^?1 with RSD 1.3–3.4 %, respectively. A number of pharmaceutical additives did not effect the determination with RSD within ±3.1 %.     

Synthesis of 2,3,8,9-Dibenzo-5,6-(substituted)benzo-1,4-dithio-7-oxacyclonona-2,5,8-trienes and some electrophilic substitution reactions

Treatment of 5-(2-hydroxyaryl)thianthreniumyl perchlorates 1 with sodium hydride in tetrahydrofuran at reflux gave the title compounds 5 in excellent yields. For the reactivities of the compounds 5 , the selected compounds 5 were subjected under the conditions of electrophilic substitution reactions. Bromination of 5,6-{3-(2-butyl)benzo}-2,3,8,9-dibenzo-1,4-dithio-7-oxacyclonona-2,5,8-triene ( 5f ) in acetic acid at 60° afforded two bromo compounds 9 (22%) and 10 (69%), which were oxidized by m-chloroperbenzoic acid to give tetraoxides 11 (95%) and 12 (97%), respectively. Treatment of 5f with acetyl chloride in the presence of aluminum chloride in carbon disulfide at 0° gave an acetylated compound 13 (58%). Nitration of 5f with nitric acid in acetic acid at 50° gave a nitro compound 17 (15%) together with 1,4-dioxide 7e (22%) and a 5-oxide 18 (3%) whose regiochemistry has not been established. On the other hand, 5,6-(3-methylbenzo)-2,3,8,9-dibenzo-1,4-dithio-7-oxacyclonona-2,5,8-triene ( 5a ) reacted with acetyl chloride under the same conditions to give two acetylated compounds 15 (33%) and 16 (18%). The mechanism for the formation of 5 and the structural elucidation of these compounds are discussed.     

Diazotization of Methyl 3-Amino-7-Isopropyl-2-Methoxyazulene-1-Carboxylate and its 5-Isopropyl Isomer- a Convenient Synthesis of 1,2-Azulenequinone Derivatives

Methyl 3-amino-2-methoxy-7-isopropylazulene-l-carboxylate( 8a ) and its 5-isopropyl isomer ( 8b ) were synthesized by reduction of the 3-nitro derivatives ( 7a,b ) with zinc/acetic acid in excellent yields. 7a and 7b were prepared by nitration and methylation of methyl 7-isopropyl-2-hydroxyazulene-l-carboxylate ( 5a ) and methyl 5-isopropyl-2-hydroxyazulene-l-carboxylate ( 5b ), respectively. Diazotization of 8a with sodium nitrite in trifluoroacetic acid at 0 °C gave methyl 5-isopropyl-1,2-azulenequinone-3-carboxylate ( 9a ) in 91% yield. Similar reaction of 8b gave the corresponding methyl 7-isopropyl-1,2-azulenequinone-3-carboxylate ( 9b ) in 93% yield. No evidence for the formation of l-diazo-1,2-azulenequinones was obtained.     

Direct dehydration polycondensation of lactic acid catalyzed by water‐stable Lewis acids

Poly(L ‐lactic acid) (PLLA) is generally produced by ring‐opening polymerization of (S,S)‐lactide, which is prepared from dehydration polycondensation of lactic acid and successive depolymerization. Results of this study show that scandium trifluoromethanesulfonate [Sc(OTf)₃] and scandium trifluoromethanesulfonimide [Sc(NTf₂)₃] are effective for one‐step dehydration polycondensation of L ‐lactic acid. Bulk polycondensation of L ‐lactic acid was carried out at 130–170 °C to give PLLA with M_n of 5.1 × 10⁴ to 7.3 × 10⁴ (yield 32–60%). The solution polycondensation was performed at 135 °C for 48 h to afford PLLA with M_n of 1.1 × 10⁴ with good yield (90%). In no case did ¹H NMR, specific optical rotation, or DSC measurement confirm racemizations. The catalyst was recovered easily by extraction with water and reused for polycondensation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5247–5253, 2006     

ESR spectra of poly(methacrylic acid) and poly(methyl methacrylate): Reinterpretation of the 9-line spectrum

The temperature dependence of the ESR spectra of poly(methacrylic acid) and poly-(methyl methacrylate) γ-irradiated at room temperature was studied between ?196°C and +25°C. The conventional 9-line spectrum was observed throughout this range with no significant spectral change, in contrast to the propagating radical ··· CH₂? °C(CH₃)COOR found in methacrylic acid monomer or barium methacrylate dihydrate irradiated at ?196°C. In addition, the irradiation of methacrylic acid monomer with a low dose at 0°C gave the same 13-line spectrum as that of the propagating radical obtained by the irradiation at ?196°C, while prolonged irradiation at 0°C gave the same conventional 9-line spectrum as that of poly(methacrylic acid) or poly(methyl methacrylate). The conventional 9-line spectrum has a much weaker 4-line component than that of the propagating radical. The difference comes from the surrounding matrix, and the conventional 9-line spectrum is well interpreted by introducing the concept of the distribution of the conformational angle in the irregular polymer matrix. From simulation of the ESR spectrum, it was found that the intensity of the 4-line component is very sensitive to the distribution, and that the observed 9-line spectrum is well reproduced assuming a Gaussian distribution (half-height width of 5–6°) around the most probable conformation which is nearly the same as that of the propagating radical, where the conformational angles of the two C? H_β bonds to the half-filled p-orbital are 55° and 65°.     

The influence of temperature and different storage conditions on the stability of supersulphated cement

The stability of Supersulphated Cement (SSC) is investigated at 95°C when subjected to relative humidities of 100, 53 and 11% of water vapour. Previously [1] investigations at 25, 50, 75°C under the same conditions of humidity reported the stability of ettringite, one of the initial hydration products. At 95°C, decomposition of ettringite, is found at all humidities and is rapid at 100% relative humidity. The hydration products of cement pastes at a water cement ratio of 0.27 were determined by thermogravimetry (TG) and X-ray diffraction (XRD). The formation of the hydragarnet, plazolite is recorded during the decomposition/dehydration process enhanced by possible carbonation. Rehydration studies on the products after storage for up to 9 months were carried out using distilled water and the samples tested for ettringite content. It is concluded that ettringite in SSC is inherently unstable at 95°C.     

Synthesis and properties of novel sulfonated polyimides containing 1,5‐naphthylene moieties

A series of novel sulfonated polyimides (equivalent weight per sulfonic acid = 310–744 g/equiv) containing 10–70 mol % 1,5‐naphthylene moieties were synthesized as potential electrolyte materials for high‐temperature polymer electrolyte fuel cells. The polycondensation of 1,4,5,8‐naphthalene tetracarboxylic dianhydride, 4,4′‐diamino‐2,2′‐biphenyldisulfonic acid, and 1,5‐diaminonaphthalene gave the title polymer electrolytes. The polyimide electrolytes were high‐molecular‐weight (number‐average molecular weight = 36.0–350.7 × 10³ and weight‐average molecular weight = 70.4–598.5 × 10³) and formed flexible and tough films. The thermal properties (decomposition temperature > 260 °C, no glass‐transition temperature), stability to oxidation, and water absorption were analyzed and compared with those of perfluorosulfonic acid polymers. The polyimide containing 20 mol % 1,5‐naphthylene moieties showed higher proton conductivity (0.3 S cm^?1) at 120 °C and 100% relative humidity than perfluorosulfonic acid polymers. The temperature and humidity dependence of the proton conductivity was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3901–3907, 2003     

Formation of fluorene and anthracene derivatives in reactions of perfluorinated 1-alkyl-1-phenyl- and 1-alkyl-2-phenyl-1,2-dihydrocylobutabenzenes with antimony pentafluoride

The reaction of perfluoro(1-methyl-1-phenyl-1,2-dihydrocyclobutabenzene) with SbF₅ at 50°C, followed by hydrolysis, gave perfluoro(1-phenylindan-1-ol), while analogous reaction at 90°C afforded perfluoro[10-methylanthracen-9(10H)-one]. Perfluoro(1-methyl-2-phenyl-1,2-dihydrocyclobutabenzene) did not undergo skeletal transformations under analogous conditions, whereas at 200°C it was converted mainly into perfluoro(9-methylfluoren-9-ol). Perfluoro(1-ethyl-2-phenyl-1,2-dihydrocyclobutabenzene) reacted with SbF5 at 200°C to form perfluoro(9-ethylfluoren-9-ol) together with perfluorinated 9,9-dimethyl- and 9-ethyl-9-methyl-1,2,3,4-tetrahydro-9H-fluorenes.     

Dense compounds of C,H, N,and O atoms: Nitramine derivatives of diimino- and dioxodecahydro-1 h,5h-diimidazo-[4,5-b:4′,5′-e]pyrazine

Guanidine condensed with 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine 1 to give 2,6-diiminodecahydro-1H,5H-diimidazo[4,5-b:4′,5′-e]pyrazine 3 isolated as the tetrahydrochloride salt. nitric acid (100%) at −40°C converted the bisguanidine 3 to 2,6-dinitrimino-4,8-dinitrodecahydro-1H,5H-diimidazo[4,5-b:4′,5′-e]- pyrazine 8 isolated as a dihydrate, whereas nitration by nitronium tetrafluoroborate at 0° to 25°C afforded 2,6-diimino-4,8-dinitrodecahydro-1H,5H-diimidazo[4,5-b:4′,5′-e]pyrazine 9 isolate as the monohydrated bistetrafluoroborate salt, and treatmetn with nitric acid (100%) and acetic anhydride or phosphorus pentoxide converted the bisguanidine 3 to 2,6-dioxo-1,3,4,5,7,8-hexanitrodecahydro-1H,5H-diimidazo[4,5-b:4′,5′-e]pyrazine 4 , also obtained from the tetra N-nitro compound 8 · 2 H₂O and from the dinitramine 9 · 2 BHF₄ · H₂O after similar treatment. The cis-syn-cis- configuration of the tricyclic bisurea 4 and bisguanidine 9 was confirmed by X-ray crys-tallographic analysis. Nitrosation by nitrous acid or by dinitrogen tetroxide converted the bisguanidine 3 to a hydrated 2,6-dinitrosimino-4,8-dinitrosodecahydro-1H,5H-diimidazo[4,5-b:4′,5′-]pyrazine 10 · 2.5 H₂O, whereas treatment with nitrosonium tetrafluo-roborate afforded the bistetrafluoroborate salt of 4,8-dinitroso derivative 11 · 2 BHF 4 . The nitrosamines 10 and 11 were converted to the tetranitro compound 8 · 2 H₂O on treatment with nitric acid (100%) at −40°C. Treatmnt with fluoroboric acid etherate in acetonitrile converted nitroimino groups in compound 8 · 2 H₂O and nitrosimino groups in compound 10 · 2.5 H₂O to imino groups in compounds 9 · 2 BHF₂ · H₂O and 11 · 2 HBF₄ respectively.     

Reactions of tetrasulfur tetranitride with bromomethyl ketones. One pot synthesis of 3,5-diaroyl- and 3,5-diacyl-1,2,4-thiadiazoles

Reactions of tetrasulfur tetranitride (S⁴N⁴) with aryl and alkyl bromomethyl ketones 1 in chlorobenzene at reflux temperature gave 3,5-diaroyl- and 3,5-diacyl-1,2,4-thiadiazoles 2 in 17-60% yields. No 1,2,5-thiadiazoles were detected. By heating of the two reactants at 115° without the solvent were also obtained 2 in 5-13% yields. Hydrolysis of 2 with sodium hydroxide in a mixture of ethanol, ethyl acetate, and water (v:v, 4:2:1) at 75° to 85° afforded the heretofore inaccessible 3-aroyl- and 3-acyl-1,2,4-thiadiazoles 3 in 17-79% yields.     

Whiskers. VII. Homo- and copolyesters of 6-hydroxythioxanthone-2-carboxylic acid

6-Hydroxythioxanthone-2-carboxylic acid (HTCA) was prepared from commercial dimethylnitroterephthalate via 2-(4'-hydroxythiophenyl) terephthalic acid. HTCA was acetylated and polycondensed in an inert reaction medium at 350 or 400°C. An insoluble and infusible, highly crystalline polyester was obtained, which did not form whisker-like crystals. Furthermore, copolyesters with 4-hydroxybenzoic acid (4-HBA) were synthesized and whiskers were obtained at a molar ratio of 1 : 9 (in favor of 4-HBA). A meltable, nematic copolyester was prepared by cocondensation of silylated 6-acetoxythioxanthone-2-carboxylic acid and silylated 4-acetoxybenzoic acid in bulk. © 1994 John Wiley & Sons, Inc.     

Dense compounds of C,H, N,and O atoms: II [1]. Nitramine and nitrosamine derivatives of 2-oxo- and 2-iminooctahydroimidazo-[4,5-d]imidazole

The 4,6-dinitroso derivative 11 was obtained (83%) by the nitrosation of 2-oxooctahydroimidazo[4,5-d]-imidazole 1 as the dihydrochloride and was converted to the 4,6-dinitro derivative 12 [66%] by treatment with nitric acid (100%, -40°C) and to the 1,4,6-trinitro derivative 13 (66%) and the 1,3,4,6-tetranitro derivative 2 (86%) by treatment with nitric acid (100%) in acetic anhydride at 0–5°C and 10–25°C respectively. Similar treatment with nitric acid (100%) in either acetic or trifluoroacetic anhydride at 0–25°C converted the trinitro compound 13 to the tetranitro compound 2 (86%). The dinitramine 12 was also obtained (43%) from the diamine 1 by nitration with nitric acid (100%, -40°C). A reaction between 2-nitrimino-5-iminooctahydroimidazo[4,5-d]imidazole 7 as a hydrochloride salt (from an acid catalyzed condensation between 4,5-dihydroxy-2-nitriminoimidazolidine 6 and guanidine) and nitric acid (100%, -40°C) gave the 2,5-dinitrimino derivative 14 (85%) isolated as a monohydrate. The nitrate salt 7 · HNO₃, isomeric with 14 · H₂O, was obtained from the corresponding hydrochloride 7 · HCl and silver nitrate. Both nitrimines 7 and 14 gave 1,3,4,6-tetranitro-2,5-dioxooctahydroimidazo[4,5-d]imidazole 15 (66% and 59%) by treatment with nitric acid (100%) in acetic anhydride.     

Effect of side‐chain length on the electrospinning of perfluorosulfonic acid ionomers

The effect of the side‐chain length (short side chain and long side chain, SSC and LSC, respectively) of perfluorosulfonic acid (PFSA) ionomers on the properties of nanofibers obtained by electrospinning ionomer dispersions in high dielectric constant liquids has been investigated with a view to obtaining electrospun webs as components of fuel cell membranes. Ranges of experimental conditions for electrospinning LSC and SSC PFSAs have been explored, with a scoping of solvents, carrier polymer and PFSA ionomer concentrations, and carrier polymer molecular weight. Under optimal conditions, the electrospun mats derived from SSC and from LSC PFSA show distinct fiber dimensions that arise from the different chain lengths of the respective ionomers. Enhanced interchain interactions in SSC PFSA with low equivalent weight compared to LSC PFSA result in a considerably lower average fiber diameter and a markedly narrower fiber size distribution. The proton conductivity of nanofiber mats of SSC and LSC PFSA with equivalent weights of 830 and 900 g mol^?1, respectively, are 102 and 58 mS cm^?1 at 80°C and 95% relative humidity. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis of nonlinear optical polymers with large photoconductive sensitivity and transparency

Novel nonlinear optical (NLO) chromophore, 2-{3-[2-(4-methylsulfonylphenyl)vinyl]carbazol-9-yl}ethanol was synthesized and subsequently reacted with methacryloyl chloride to give a photoconducting NLO monomer ( M1 ). 2-Methylacrylic acid 2-[3-(diphenylhydrazonomethyl)carbazol-9-yl]ethyl ester ( M2 ) was also synthesized as a comonomer to enhance the carrier mobility of the NLO polymer. Photoconducting NLO polymers, P1 and P2 were obtained by the copolymerization of Ml with methyl methacrylate and M2 , respectively. These polymers were well soluble in organic solvents and showed glass transition at 177 °C and 196 °C, respectively. Polymer films of P1 and P2 were optically clear, and were transparent at wavelengths longer than 420 nm. The electro-optic coefficient (r₃₃) of poled P1 films was measured to be ∼5 pm/V at 632.8 nm. The photoconductive sensitivities of P1 and P2 were 6.2 × 10⁻¹⁴ S·cm⁻¹/mW·cm⁻² and 5.6 × 10⁻¹¹ S·cm⁻¹/mW·cm⁻².