Biomimetic triblock and multiblock copolymers containing l-Phenylalanine moieties showing healing and enhanced mechanical properties

Triblock and multiblock copolymers of methyl acrylate containing short blocks of the hydrogen bonding monomer N-acryloyl-l-phenylalanine were prepared via reversible addition-fragmentation chain transfer polymerization in two steps using a bifunctional trithiocarbonate for the triblock copolymer and a polyfunctional trithiocarbonate for the multiblock copolymer. The polymer materials were investigated via tensile testing showing that the hydrogen bonding monomer induces a pronounced increase in toughness. The toughness of the material is further enhanced when going from triblock to multiblock topology. Both types of copolymer display a very strong healing effect, with the samples' toughness (which is increased by drawing) becoming even larger after breaking and healing. Already, a very small content of only 0.1 mol % of N-acryloyl-l-phenylalanine improves the mechanical properties of these thermoplastic elastomers significantly. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2809-2819