Characterization of plasma polymers from tetramethylsilane,octamethylcyclotetrasiloxane, and methyltrimethoxysilane

The products in inductively coupled plasma excited in organosilicic compounds were studied on chemical structures by spectroscopic methods. Plasma-polymerized tetramethylsilane (PA) contains not only Si? CH₃ groups but also Si? H groups on IR and ²⁹Si-NMR analyses. ¹³C-NMR spectrum of PA reveals that the crosslinked structure of PA is mainly constructed of Ch₂ and CH groups. Plasma-polymerized octamethyleyclotetrasiloxane (PD₄) is composed of Si? CH₃ and Si? O groups. ¹³C- and ²⁹Si-NMR spectra of PD₄ point out the highly preservation of the structural units similar to the monomer. These data of PD₄ suggest that PD₄ is formed from the ring-opening polymerization by cleavages of Si? O bonds. ¹³C-NMR spectrum of polymethyltrimethoxysilane] (PT) indicates the existence of CH₃? O groups, meanwhile its ²⁹Si-NMR analysis concludes that PT is chiefly composed of the structural units similar to the monomer. The surface analyses by XPS of PA, PD₄ and PT suggest that these organosilicic plasma polymers resemble their starting materials.