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Synthesis of hyperbranched polymethylvinylborosiloxanes and modification of addition‐curable silicone with improved thermal stability
Author(s) -
Li Lizhi,
Zhao Jingbo,
Li Hao,
Zhao Tong
Publication year - 2013
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3070
Subject(s) - thermal stability , chemistry , silicone , condensation polymer , diglyme , polymer chemistry , catalysis , thermal decomposition , diimide , ceramic , gel permeation chromatography , chemical engineering , nuclear chemistry , organic chemistry , solvent , polymer , molecule , perylene , engineering
This paper reports a non‐catalyzed environmentally friendly method of synthesizing hyperbranched polymethylvinylborosiloxanes (PMVBSs) and their use to improve the thermal stability of normal addition‐curable silicones (ACSs). PMVBSs were synthesized by the direct polycondensation of dimethoxymethylvinylsilane with boric acid at 80–130°C in 1,4‐dioxane or diglyme. They were characterized by gel permeation chromatography; FT‐IR; 1 H, 13 C, 29 Si and 11 B NMR; and TGA. PMVBSs were composed of Si―O―Si and Si―O―B bridges with some unreacted B―OH groups remaining, and had a ceramic yield up to 65.97% at 900°C. PMVBS‐modified ACSs (PBS‐ACSs) were prepared by curing the PMVBSs with hydrogen‐containing silicone oil under Karstedt (platinum divinyltetramethyldisiloxane) catalysis . Thermal stability of PBS‐ACSs was characterized by TGA in N 2 or air, and ceramic yields as high as 76.7% were obtained. Gas decomposition during the ceramization of PBS‐ACSs was examined by TG/mass spectroscopy. The SiBOC ceramics formed were characterized by FT‐IR, Raman, 29 Si and 11 B magic angle spinning NMR and elemental analysis. This method provides a valuable way to improve the thermal stability of ACSs. Copyright © 2013 John Wiley & Sons, Ltd.