Preparation of a Thermoplastic Lignin-Based Biomaterial through Atom Transfer Radical Polymerization

Abstract

Graft copolymerization of styrene onto kraft lignin (KL) was achieved by atom transfer radical polymerization (ATRP) using a fully substituted lignin-based macroinitiator (KLM). The number average of molecular mass (Mn) of polystyrene copolymer graft side-chains was achieved by varying the ratio of the DMF: water solvent system from 5:0 to 1:4. A Mn of up to ∼206,000 was obtained using a DMF/water ratio of 3:2 (v/v). However, as the Mn increased, the overall ATRP became less controlled. In addition, the thermal properties of the lignin-g-polystyrene copolymers improved significantly with increasing Mn of polystyrene copolymer side-chains.