Simple green synthesis of polyborosiloxanes as environmentally-safe, non-halogenated flame retardant polymers

A novel class of boron-containing siloxane copolymers (polyborosiloxanes) was synthesized by simple environmentally friendly methods. A boron containing monomer, specifically phenylboronic acid (PBA), and imide forming monomers, specifically aromatic dianhydrides 4,4′-oxydiphthalicanhydride (Oxy) and 1,1,4,4-tetracarboxylicphenyldianhydride (DAH), were employed to make terpolymers with propylamino-terminated polydimethylsiloxane (A12-PDMS). The terpolymer synthesis was carried out using various PBA : Oxy and PBA : DAH compositions ranging from 0 : 1 to 1 : 0 mole ratios. The thermal and flame retardant properties of the novel polymers were investigated. Intermediate ratios of both PBA : Oxy and PBA : DAH resulted in optimal thermal stability and flame retardancy. These novel terpolymers are promising candidates as environmentally-safe, non-halogenated alternatives to traditional flame retardant polymers.