Poly[4‐bis(trimethylsilyl)methylstyrene] for an oxygen‐permeable membrane

Abstract

Synthesis and polymerization of styrene derivatives with silyl group(s) have been studied extensively' -3 ) , and the applications of silicon-containing polymers as X-ray resists4), oxygen-permselective membranes5) or flame retarders6) have also been studied.Recently, we have reported on a novel synthetic route for styrene derivatives having trimethylsilylmethyl group(s), 4-trimethylsilylmethylstyrene (SMS) and 4-bis(tri-methylsily1)methylstyrene (BSMS), using the unique nucleophilic reactivity of lithium diisopropylamide (LDA) toward 4-methylstyrene (MST)') . The polymer obtained from the above monomers8) is expected to show novel functions as a gas-permeable material. This paper communicates properties of poly(BSMS) and gas permeability of poly(BSMS) membrane. Experimental partMaterials: 4-Bis(trimethylsilyl)methylstyrene (BSMS) was prepared as reported in our previous paper'). 2,2'-Azodiisobutyronitrile (AIBN) was purified by recrystallization from methanol. Commercial toluene was purified by conventional method9). Polymerization of 4-bis(trimethylsilyl)methylstyrene (BSMS):AIBN (9,4 mg; 0,057 mmol) and BSMS (3,O g; 11,4 mmol) were filled in a glass tube. After sealing off the tube under high vacuum, the mixture was allowed to react at 60°C for several hours, then the tube was opened. The polymer obtained was dissolved in THF and then poured into methanol. The precipitate was purified by successive reprecipitations (3 x ) from THF solution into methanol. The polymer sample collected was subjected to freeze-drying with benzene to remove solvents employed.Membrane preparation: A toluene solution containing 5 wt.-Yo of the polymer was cast on a polytetrafluoroethylene sheet, and the solvent was evaporated during 24 h. For measuring the gas permeability, the polymer membrane was dried in vacuo and cut into a circular piece of 22 mm diameter. The thickness of the membrane was in the range 100-150 hm.

Trimethylsilyl‐group containing polyphenylacetylenes for oxygen and ethanol permselective membranes

“…Following this hypothesis we prepared highly ethanol-permselective membranes, which consisted of perfluoroalkyl groups at the surface and polydimethylsiloxane in the b~lk. '','~ Since trimethylsilylgroup containing polymers show high permeability7, 8 and are expected to show water repellency, they may be promising for ethanol-permselective membrane materials.…”

Synthesis and Gas-Transport Properties of Metathesis Polytricyclononenes Bearing Three Me3 Si Groups per Monomer Unit

“…High gas permeability level of these polymers was caused by the presence of spherical bulky groups (e.g., trimethylsilyl groups or trimethylgermyl groups) and rigid polymer chains which disrupt a dense polymer chain package . Bulky SiMe 3 groups were also introduced into other classes of polymers (polyacetylenes, polystyrenes, polysulfones, poly(phenylene oxide), polyolefins). In all of the mentioned polymers an increase in gas permeability was observed in comparison with non‐silylated polymers.…”

Synthesis and Characterization of Novel Polymers Containing Pendant Silyl Ether Groups

“…This permeability behavior was attributed to a high affinity of oxygen molecules to Si atoms and the relatively large free volumes between the polymers, resulting from the restricted mobility of the side chains in the repeat units [9]. Nagasaki et al reported that the oxygen permeability coefficient (pO 2 ) of the organosilicone-containing polymer membranes increased with the Si content [10,11]. The increased oxygen permeability was attributed to the empty d-orbital of Si atom, which interacts with the oxygen molecule.…”