In this paper

[2

6-dimethyl-1

4-phenylene oxidel was modified by trimethyl chlorosilane and triphenyl chlorosilane

and a serfes of silyl-substituted PPO were synthesized. The gas transport behavior in polymeric membrane were studied with changes of group and ratio of substitution. It is found that gas permeability in trimethyl silyl-substituted PPO rises and selectivity decreases

but both decrease in triphenyl silyl-substituted PPO with increasing the ratio of substitutions.Because trimethyl silyl-substitited PPO have similar gas solubility but various diffusivity

difference between gas permeability is mainly caused by gas diffusion coefficient. From relationship between gas permea-bility and polymeric chemical structure

gas diffusion process may be increased in polymer if bulky free groups are introduced into polymeric side chain.