Boron-containing phenolic–siloxane hybrid polymers through facile click chemistry route

Realization of easily processable, tough phenolic functional polymer materials is of high demand for composite applications. Herein, we report the synthesis of boron-containing phenolic–siloxane hybrid polymers through a facile copper-catalysed azide–alkyne click chemistry (CuAAC) approach. For this, phenolic resoles incorporated with boron (PFB) was propargyl-derivatized and then bridged through triazole moieties using telechelic α, ω azidated polydimethylsiloxane (AZ-PDMS). The propargylated boronated PF (PFBPr) resins exhibited high heat of reaction during thermal cure due to the prevalence of multiple reactions. PFBPr-siloxane hybrid co-polymers exhibited glass transitions in the ranges – 100 to – 75 °C and at 25–35 °C corresponding to soft segment and hard segments. Pyrolysed PFBPr-siloxane products showed mixed phase heterogeneous systems of B and SiC. Introduction of boron and silicon improved the degree of graphitization and reduced the graphite crystallite size of the carbonization products. The pyrolysed compounds of silicon and boron formed during high temperature were conducive for creating a layer of void-free graphitic ordered carbon that improved with boron and silicon content, as revealed by SEM images.