Synthesis and investigation of properties of silaoxadihydrophenanthrene‐diphenylsiloxane fragments containing block copolymers

Abstract

ABSTRACT:The reaction of heterofunctional condensation of 1,1-dichloro-1-sila-2-oxadihydrophenanthrene with dihydroxydiphenylsilane at various ratios of initial compounds in the presence of pyridine is investigated. ␣,-Dihydroxysilaoxadihydrophenanthrene-diphenylsiloxane oligomers with various degrees of condensation are obtained. Organosiloxane block copolymers with the regular arrangement of silaoxadihydrophenanthrene-diphenylsiloxanes fragments in the main linear dimethylsiloxane chain are produced by the reaction of heterofunctional condensation of ␣,-dihydroxysilaoxadihydrophenanthrene-diphenylsiloxanes with ␣,-dichlorodimethylsiloxanes in the presence of anhydrous pyridine, as an acceptor of hydrochloric acid. Thermogravimetry, differential scanning calorimetry, gel permeation chromatography, and wide-angle X-ray analysis are carried out on the synthesized block copolymers. The microheterogeneous structure of block copolymers is observed at definite values of the length of the flexible dimethylsiloxane chain by DSC and X-ray investigation.

Preparation, characterization, and thermal properties of alt‐copoly[1,9‐decaphenylpentasiloxanylene/1,3‐bis(ethylene)permethyloligosiloxanylene]s

“…To compensate for this, there have been many attempts to incorporate phenyl or aryl siloxane moieties into PDMS. These include the introduction of arylenes into the backbone of the siloxane chain2–4 or as pendant groups 5–8. Both types of modifications improve thermal stability by increasing the activation energy for the onset of depolymerization 9.…”

“…These include the introduction of arylenes into the backbone of the siloxane chain [2][3][4] or as pendant groups. [5][6][7][8] Both types of modifications improve thermal stability by increasing the activation energy for the onset of depolymerization. 9 For example, poly(diphenylsiloxane) (PDPS) is stable up to 400 8C.…”