Wojciech K. Czerwinski

Siloxane-urethane membranes for removal of volatile organic solvents by pervaporation

Abstract Aqueous dispersions of siloxane-urethane copolymers (polysiloxaneurethanes) containing 0–49% of siloxane moieties were synthesized by the modified prepolymer-ionomer method. The properties of the dispersions were determined. Dense membranes were prepared from those dispersions by crosslinking with a multifunctional aziridine derivative. The structure of the obtained membranes was investigated by FTIR, solid state 13 C NMR, 29 Si NMR and DSC. Prepared membranes were tested in vacuum pervaporation of the following water-organic mixtures: water- tert -butyl methyl ether (1.8% wt. MTBE) and water-butyl acetate (0.25% wt. BuAc) at a temperature of 313 K. It was found that pervaporation properties of the polysiloxaneurethane membranes depended on the content of siloxane moieties. The best separation and transport properties were observed for the membrane containing 49% of siloxane groups. For this membrane separation factor a was equal to 750 and 1370 for water-MTBE and water-BuAc mixtures, respectively. The ratio of organic to water partial molar fluxes ( J org/ J water) was 2.8 and 0.5, respectively. This membrane was highly hydrophobic, thus the measured flux of pure water was about half of that for the membrane with a lower content of siloxane moieties.

Ozonization of electronic conducting polymersI. Copolymers based on poly[3-nonylthiophene]

Abstract The ozonization of a group of new conducting copolymers based on 3-nonylthiophene and 2-substituted-3-ethylthiophene was investigated. The reaction products have been studied using solid state 13 C NMR, and FTIR spectroscopy. Polymers ozonized were laboratory made copolymers: poly[3-(2-(9-anthrylcarboxy)ethyl)thiophene-co-3-nonylthiophene] ( P[AET-co-3NT] ), poly[3-(2-acetoxyethyl)thiophene-co-3-nonylthiophene] ( P[AcET-co-3NT] ), poly[3-(2-hydroxyethyl)thiophene-co-3-nonylthiophene] ( P[HET-co-3NT] ). Chemical and electrical stability of the polymers in ozonized air, was investigated. These properties are important due to potential application of such polymers as a electroactive components in manufacturing of light emitting diode devices (LEDs). Ozone present in the troposphere is one of the strongest oxidizing agents acting on polymeric materials, especially those having unsaturated bonds. The results of this research indicate that there are no significant changes in chemical structure of P[AcET-co-3NT] after ozone treatment. But in the case of P[AET-co-3NT] and P[HET-co-3NT] significant changes in conjugated bonds system were observed. In consequence electrical properties of polymers changed. Additionally it was found that ozonization causes distinct deterioration of optical properties.

The influence of polychromatic UV-irradiation on new thiophene copolymers

Abstract Three new thiophene-based copolymers, characterising the electrical conductivity and photosensitivity, were obtained in a four-step reaction. The acrylic or methacrylic substituents as well as nonyl or pentyl side groups were incorporated into thiophene rings. All thiophene copolymers were then exposed to UV-irradiation in air atmosphere and in room temperature using polychromatic high-pressure mercury lamp. The process of photooxidative degradation was monitored by FT-IR and UV–VIS spectroscopy. It was found that these polymers undergo chain scission, oxidation and decomposition in side groups with different efficiency. The decrease of conjugated double bonds amount, influencing the conducting properties, was also observed. It was concluded that copolymer containing methacrylic substituent was less photostable than that with acrylic one. The type of alkyl group (pentyl or nonyl) in copolymers has no significant influence on their photodegradation.

Rates of Copolymerization

Binary copolymerizations have been investigated for more than 40 years. Relations between monomer feed and copolymer composition were developed in the early 1940s by Alfrey, Goldfinger, Mayo, Lewis and Wall. In comparison with the many thousands of binary systems described in the literature since then using the so-called copolymerization equation and by reactivity ratios, there are rather few investigations of the kinetics and the rates of binary free-radical copolymerizations. The copolymerization of ternary monomer systems has received even less attention until now; the number of publications describing ternary polymerizations is not much higher than a hundred. Most authors primarily discussed problems concerning the composition of terpolymers and there is little information about the rates of ternary copolymerizations.1