Polymer Nanospheres with Hydrophobic Surface Groups as Supramolecular Building Blocks Produced by Aqueous PISA

Abstract

A robust and straightforward synthesis of waterborne polymer nanospheres bearing the supramolecular association unit dialkoxynapthalene at their surface is presented using polymerization-induced self-assembly (PISA). A RAFT agent bearing this unit is first employed to produce poly(acrylic acid) chains, which are then chain-extended with styrene (S) to spontaneously form the nano-objects via RAFT aqueous emulsion polymerization. The particular challenge posed by the dialkoxynapthalene hydrophobicity can be overcome by the use of PISA and the deprotonation of the poly(acrylic acid). At pH = 7, very homogeneous latexes are obtained. The particle diameters can be tuned from 36 to 105 nm (with a narrow particle size distribution) by varying the molar mass of the PS block. The surface accessibility of the dialkoxynapthalene moieties is demonstrated by complexation with the complementary host cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺ · Cl^- ), highlighting the potential of the nanospheres to act as building blocks for responsive supramolecular structures.

Keywords: RAFT polymerization; emulsion polymerization; polymer nanoparticles; polymerization-induced self-assembly; supramolecular assembly.