Organosiloxane copolymers with cyclic fragments in the side chain

Abstract

Glass transition temperature of copolymers with cyclopentasiloxane fragments in side chains is decreased by the increase of methylcyclopentasiloxane fragment flexibility. The main reason for suppression of crystallization in oligo(dimethyl)methylsiloxanes is disturbance of the regular structure of linear siloxane chain at the introduction of methylsilsesquioxane units into them. The most effective method of modification of linear organosiloxane polymers is introduction of various elements or groups different by chemical origin and structure into the macromolecular chain. Introduction of different fragments into the dimethylsiloxane backbone induces changes of its physical and chemical properties. The synthesized chlororganosiloxymethylcyclosiloxanes was studied by the mass spectrometry method. The mass spectra of the compounds indicate the presence of fragments in the molecules, corresponded to definite typical structural components and do contradict with the suggested structures. Oxygen bridge substitution by ethylene group causes a slight decrease of thermal oxidative stability of copolymers.