BROMINATION AND GAS-PERMEABILITY OF POLY(1-TRIMETHYLSILYL-1-PROPYNE) MEMBRANE

The bromination of poly(1-trimethylsilyl-1-propyne) (PMSP) was carried out by immersing a PMSP membrane in bromine water at 25-degrees-C. Th e bromine mainly reacted at the carbon-carbon double bonds in the back bone chain, and carbon-carbon single bonds were produced, which was de termined from the infrared (IR) and ultraviolet (UV)-visible analyses. The glass transition temperature of the PMSP is above 350-degrees-C, but a new endothermic peak appeared between 50 and 80-degrees-C in the differential scanning calorimetry (DSC) curves of all brominated PMSP s. The permeability for 12 gases in the PMSP membrane and its brominat ed membranes was investigated between 30 and 90-degrees-C below 1 atm. With increasing bromine content in the membrane, the permeability coe fficient for all gases decreased together with the diffusion coefficie nt, and the ideal separation factor for the industrially important gas pairs increased at 30-degrees-C. A distinct change in slopes at near the endothermic temperature determined by the DSC analysis was observe d in Arrhenius plots of the permeability coefficients in all brominate d PMSP membranes. (C) 1994 John Wiley & Sons, Inc.