Amphiphilic Block-Random Copolymer Stabilisers: Extension to Other Monomer Types

Abstract

Block-Random Copolymers (BRCs) incorporating acrylics were synthesised using nitroxide-mediated polymerisation (NMP) to form macro-stabilisers for the preparation ofpolymer latexes. These hybrids of block copolymers and random copolymers are traditionally composed of a polystyrene hydrophobic block coupled with a hydrophilic random block of styrene and acrylic acid. Their aqueous dispersions exhibit unique behaviour compared to conventional block copolymers, including being responsible for a unique nucleation mechanism in emulsion polymerisation. However, all previous work has only used styrene as the hydrophobic monomer, and only styrene emulsion polymerizations have been conducted. To explore the versatility of BRCs for the polymerisation of monomers other than styrenics (e.g. acrylates, methacrylates), the BRC library was explored with the introduction of methyl methacrylate (MMA) and n-butyl acrylate (n-BuA) units as the hydrophobic monomers. With blocks composed of one or multiple monomers, all the BRCs were successfully dispersed in water at high concentrations (>100 g.L-1), with similar behaviour compared to previously reported for styrene-based BRCs. Semi-batch emulsion polymerisation of styrene or acrylates latexes was also performed. A hydrophobic block consisting of a n-BuA and styrene copolymer was found to be of the most interest, showing promising stability over the range of latexes polymerised