Polymerization of isobutylene induced by RF-plasma-generated ClxSi+ silylium ions

Isobutylene was polymerized by Si2Cl6-RF-plasma-generated silylium ions. Initiation is due to ClxSi+ in-situ adsorbed on frozen isobutylene surfaces at liquid nitrogen temperature. The polymerization of isobutylene occurs in the absence of counterions. According to survey and high resolution ESCA spectra, silicon is present in the resulting polymers, which suggests initiation by ClxSi+.FT-IR, H-1- and C-13-NMR spectroscopies, CC-MS, high resolution pyrolysis MS, as well as FAB and PI-MS analyses indicate that plasma-polymerized isobutylenes are linear oligomers of broad molecular weight distribution. DTA-TG analyses substantiate the conclusion that the average molecular weight of plasma-polymerized isobutylene is low. The findings demonstrate the usefulness of RF-plasma for generating silylium ions and silylium ions-mediated cationic polymerization. The possibility of producing novel polyisobutylene/polysiloxane block copolymers is suggested.