Biobased Lactones—Exploring Their Free-Radical Polymerization and Polymer Properties
M. A. Mousa, Helena Bergenudd, Anna Larsson Kron, Eva Malmström
Abstract
Herein, we report the free-radical polymerization of the biobased α-methylene-γ-butyrolactone and α-methylene-γ-valerolactone, either into homopolymers or together with fossil-based (meth)acrylate monomers, methyl acrylate and methyl methacrylate in different ratios. The polymerization was thermally initiated by 2,2′-azobisisobutyronitrile or lauroyl peroxide to investigate their effect on the polymerization behaviors. Polymerizations were monitored by monomer conversion, and the final polymers were characterized with respect to molecular weight, composition, glass transition temperature, and thermal degradation. NMR showed significant differences in conversion rates of each monomer in the copolymerizations which suggest differences in reactivity ratios, sometimes to such an extent that the polymers exhibited a substantial compositional drift as corroborated by assessed thermal properties. Tailored Tg's and increased thermal stability were achieved by copolymerizing the lactones and the (meth)acrylates.