Synthesis, structure and thermogravimetric analysis of alpha,omega-telechelic polydimethylsiloxanes of low molecular weight [Supplementary Material]

Abstract

A series of a,w-telechelic polydimethylsiloxanes (PDMS), with predetermined molecular weights of about 2500 g mol^-1, was synthesized by siloxane equilibration reaction. Syntheses were performed using octa­methylcyclotetrasiloxane (D₄) and various disiloxanes: hexame­thyl­disiloxane (HMDS), tetramethyldisiloxane (TMDS), 1,3-divinyl­tetramethyl-disiloxane (DVTMDS), 1,3-bis(3-carboxypropyl)tetra­methyldisil­oxane (DCPTMDS) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (DAPTMDS). The role of disiloxane was to introduce terminal functional groups at the end of polymer chains and to control molecular weight of the polymers. Polymers with trimethyl, hydrido, vinyl, carboxypropyl and aminopropyl end-groups were obtained in this way. The structure of a,w-telechelic PDMSs was confirmed by NMR and IR spectroscopy. Molecular weights of the polymers were determined by ¹H NMR, gel-permeation chromatography(GPC) and viscometry of dilute solutions. Thermogravimetric analysis(TGA) in nitrogen and air showed that the type of terminal groups significantly influences thermal and thermo-oxidative stability, as well as the degradation mechanism of a,w-telechelic PDMSs.