Vinyl-functionalized polyborosiloxane for improving mechanical and flame-retardancy performances of silicone rubber foam composites

In this work, we first synthesized vinyl-terminated polyborosiloxane (pBS) filler, and then incorporated it into silicone rubber foam (SRF) matrix to prepare composite materials through a simple chemical dehydrogenative foaming method under ambient conditions. The pBS filler with reactive groups could form physical and chemical crosslinking networks in SRF, leading to an excellent dispersion level of pBS in the SRF matrix. Moreover, the inserted pBS could remarkably improve the mechanical and flame-retardancy properties of SRF-pBS composites. Intriguingly, the SRF-pBS6 foam containing 6 wt% of pBS possessed a uniform porous structure and balanced mechanical properties (sigma(b) = 65.4 kPa, epsilon(b) = 56.7%, compression stress 97.1 kPa), thermal conductivity (0.102 W (m K)(-1)), limiting oxygen index (29.8%) and UL-94 rating (V-0) among the prepared foams. In addition, the incorporated pBS (6 wt%) could synergistically catalyze the formation of a silicon-boron strengthened ceramic-like protective layer under fire and was capable of suppressing heat and smoke production in the SRF-pBS6 foam. The present work provides a promising way for developing high mechanical and flame-retardant polymeric foam materials with good thermal insulation. (c) 2021 Society of Industrial Chemistry.