Synthesis and Gas-Separation Properties of New Silacyclopentane-Containing Polynorbornenes

摘要: Previously, it was shown that the presence of bulky silicon-containing substituents in monomer unit metathesis polynorbornenes hinders postmodification and, particular, exhaustive gem-difluorocyclopropanation main-chain double bonds. In order to reduce bonds shielding by substituents, a new polynorbornene with dimethylsilacyclopentane fragment unit, poly(4,4-dimethyltricyclo[5.2.1.02,6]-4-siladec-8-ene) (PNBCP), is synthesized, which silylmethyl group moved further from achieve this, 4,4-dimethyltricyclo[5.2.1.02,6]-4-siladec-8-ene (NBCP) first obtained via diene condensation 1,3-cyclopentadiene and 1,1-dichlorosilacyclopent-3-ene following methylation Si-Cl NBCP polymerized ring-opening scheme first-generation Grubbs catalyst, Cl2(PCy3)2Ru=CHPh. The polymer PNBCP yield 99–100% characterized. difluorocarbene, generated during thermolysis sodium chlorofluoroacetate, studied; conditions for replacement gem-difluorocyclopropane are found. It more active compared poly(5-trimethylsilyl)norbornene but less than unsubstituted polynorbornene. demonstrated introduction silacyclopentane into its subsequent difluorocyclopropanation lead increase gas permeability diffusion cause slight decrease ideal separation selectivities. found increases glass transition temperature 60°C makes films stable when stored air.