Synthesis of polysiloxanes with pendant methoxy‐substituted aromatic fragments

Abstract

The synthesis of new polysiloxanes was performed via hydrosilylation reactions of polymethylhydrosiloxane with 4-allyl-1-methoxybenzene and 4-allyl-1,2-dimethoxybenzene in the presence of Karstedt's catalyst {Pt 2 [(VinSiMe 2 ) 2 O] 3 } and platinum hydrochloric acid (0.1M solution in tetrahydrofuran). The hydrosilylation reactions were carried out at 608C. The molar ratio of BSiÀ ÀH groups to the allylic compound was 1 : 1.2. The synthesized oligomers were characterized with 1 H-NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and gel permeation chromatography. In the presence of platinum hydrochloric acid, not all active BSiÀ ÀH bonds took part in hydrosilylation, and because of this, gelation took place and the molecular masses of the extracted parts increased 7-8 times; in contrast to this, in the presence of Karstedt's catalyst, all active BSiÀ ÀH bonds participated in hydrosilylation, and an increase in the molecular masses did not occurs. The influence of substituted methoxy groups on the glass-transition temperatures was studied.

Organosilicon – Organic Hybrid Polymers and Materials

“…The hydrosilylation of styrene, ␣-methylstyrene, phenylacetylene [107,108] allyl methoxybenzene and allyl dimethoxybenzene [109], in the presence of Karstedt's catalyst and H 2 PtCl 6 in THF, showed that Karstedt's catalyst is more efficient in the reactions examined.…”