Synthesis of degradable polyacetals via an intramolecular phosphonium bisborane Lewis pair catalyzed copolymerization of epoxides with o‐phthaladehyde

Abstract An intramolecular phosphonium bisborane Lewis pair ( PBB‐Br ) was used for the copolymerization of o ‐phthalaldehyde (OPA) with epoxides under mild conditions. In particular, poly( o ‐phthalaldehyde‐ alt ‐propylene oxide) termed as (poly(OPA‐ alt ‐PO)), having high molecular weight ( M n = 42.5 kg/mol) with Đ = 1.12 was generated at 25 °C 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. The cooperation of the two boron centers plays a pivotal role in boosting the activity of copolymerization of OPA and PO.