An outstanding heat-resistant hydroxyl boron–silicone oil with hyperconjugation action in backbone

Abstract

A high heat-resistant hydroxyl boron–silicone vinylidene oil (HBSVO) was synthesized by copolymerizing hydroxyl polyborosiloxane oil (HPBSO) prepolymer with fumaryl chloride. The temperature at 5% mass loss (T5), 10% mass loss (T10), and maximum decomposition rate (Tmax) of HBSVO was 515, 550, and 600 °C, respectively. The structure –Si–O–B–O–C(=O)–CH=CH–C(=O)– in the backbone of HBSVO might cause a tendency to form a five-member ring structure by hyperconjugation action between boron atom and vinylidene groups. The hyperconjugation action, which improved the heat-resistant and hydrolysis-resistant properties of HBSVO, was confirmed by UV spectroscopy, 11B-NMR, and 1H-NMR. The chemical moieties (–Si–O–B–O–C(=O)–CH=CH–C(=O)–) were also identified by Fourier transform infrared (FT-IR) and 29Si-NMR (CDCl3) spectroscopies.