Tailored Synthesis of Star and Network Poly(dimethylsiloxane)s through Electrostatic Self-Assembly and Subsequent Covalent Fixation of Telechelics Having Cyclic Onium Salt Groups

Abstract

Efficient electrostatic self-assembly and subsequent covalent fixation of macromolecules by multipoint interaction have been achieved with poly(dimethylsiloxane), poly(DMS), having five-membered cyclic ammonium salt end groups. Thus a 1-methylpyrrolidinium salt end group was introduced at a single or both chain ends of poly(DMS) (1 and 1‘, respectively). The anion-exchange reaction of 1 and 1‘ with di-, tri- and tetracarboxylates was found to take place efficiently by a simple precipitation of 1 and 1‘ into aqueous solution containing an equimolar amount of carboxylate compounds (thus ca. 10-3 M, 0.01−0.1 wt % concentration). The subsequent heat treatment of ionically-assembled products at 120 °C caused covalent fixation by the selective ring opening reaction of cyclic onium salt groups by nucleophilic attack of carboxylate anion, to produce star and model-network poly(DMS) structures in high yields.