Hyperbranched aryl polycarbonates derived from A₂B monomers versus AB₂ monomers

Abstract

Abstract Hyperbranched aryl polycarbonates were prepared via the polymerizations of A 2 B and AB 2 monomers, which involved the condensation of chloroformate (A) functionalities with tert ‐butyldimethylsilyl‐protected phenols (B), facilitated by reactions with silver fluoride. The polymerization of the A 2 B monomer gave hyperbranched polycarbonates bearing fluoroformate chain ends, which were hydrolyzed to phenolic chain‐end moieties and further elaborated to tert ‐butyldimethylsilyl ether groups. The polymerization of the AB 2 monomer gave tert ‐butyldimethylsilyl ether‐terminated hyperbranched polycarbonates. The polymerizations were conducted at 23–70 °C in 20% acetonitrile/tetrahydrofuran in the presence of a stoichiometric excess of silver fluoride for 20–40 h to afford hyperbranched polycarbonates with weight‐average molecular weights exceeding 100,000 Da and polydispersity indices of typically 2–3. The degrees of branching were determined by a reductive degradation procedure followed by high‐performance liquid chromatography. Alternatively, the degrees of branching were measurable by solution‐state 1 H NMR analyses and agreed with the statistical 50% branching expected for the polymerization of A 2 B and AB 2 monomers not experiencing constructive or destructive electronic effects on the reactivity of the multiple functional groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 823–835, 2002; DOI 10.1002/pola.10167