Synthesis of Degradable Polyacetals via an Intramolecular Phosphonium Borane Lewis Pair Catalyzed Copolymerization of Epoxides with o-Phthaladehyde

An intramolecular phosphonium borane Lewis pair (PBB-Br) was used for the copolymerization of o-phthalaldehyde (OPA) with epoxides under mild conditions. In particular, poly(OPA-alt-PO) having high molecular weight (Mn = 42.5 kg/mol) with Đ = 1.12 was generated at 25 ℃ using PBB-Br as a highly efficient catalyst. The purity of OPA, temperature and monomer/comonomer feeding ratio effects on the copolymerization were investigated. Subsequently, the degradability and thermal stability of generated polyacetals were studied. Using alcohol as chain transfer agent, random or block polyacetal-polyethers with different structures can be obtained in one-pot synthesis.