Nitroxide-Mediated Miniemulsion Polymerization of Bio-Based Methacrylates
Saeid Tajbakhsh, Faezeh Hajiali, Milan Marić
Abstract
Nitroxide-mediated homopolymerization and statistical copolymerization of commercially available methacrylates derived from sustainable feedstocks (isobornyl methacrylate (IBOMA) and a mixture of methacrylic esters with an average alkyl side chain length of 13 units (termed C13MA)) was conducted in organic solvent (toluene) and in dispersed aqueous media using an oil-soluble unimolecular initiator (Dispolreg 007) without any controlling comonomers in a controlled manner. IBOMA homopolymerization in emulsion at 83–100 °C revealed the optimal polymerization temperature of 90 °C giving relatively narrow molecular weight distributions (1.46 < dispersities (Đ) < 1.58) and conversion up to 83% in a relatively short time (2 h). IBOMA/C13MA statistical copolymerizations yielded copolymers with tunable glass transition temperature (Tg) prepared in emulsion (−52 °C < Tg < 123 °C) and in organic solvent (−40 °C < Tg < 169 °C). Resins made in emulsion at 90 °C proceeded up to 92.7% conversion with monomodal molecular weight distributions (M̅n up to 68,000 g mol–1 and Đ = 1.62–1.72) and were colloidally stable (24% solids and final average particle sizes of 270–481 nm). Furthermore, chain end fidelity was verified by chain extensions with IBOMA and C13MA monomers in both emulsion and organic solvent. These results constitute a readily scalable route to make polymers via nitroxide-mediated polymerization with controlled architecture using bio-based feedstocks without the hazards of bulk or homogeneous organic solvent polymerization.