Self-healing amino acid-bearing acrylamides/-butyl acrylate copolymers multiple noncovalent bonds.

Four amino acid-bearing acrylamides, -acryloyl-l-threonine (AThrOH), -acryloyl-l-glutamic acid (AGluOH), -acryloyl-l-phenylalanine (APheOH), and -acryloyl-l, l-diphenylalanine (APhePheOH), were selected for copolymerization with -butyl acrylate (BA) to develop amino acid-based self-healable copolymers. A series of copolymers comprising amino acid-bearing acrylamides and BA with tunable comonomer compositions and molecular weights were synthesized by free radical and reversible addition-fragmentation chain-transfer copolymerization. Self-healing and mechanical properties originated from the noncovalent bonds between the carboxyl, hydroxyl, and amide groups, and π-π stacking interactions among the amino acid residues in the side chains were evaluated. Among these copolymers, P(BA--AGluOH) with suitable comonomer compositions and molecular weights (BA : AGluOH = 82 : 18, = 18 300, / = 2.58) exhibited good mechanical properties (modulus of toughness = 17.3 MJ m) and self-healing under ambient conditions. The multiple noncovalent bonds of P(BA--AGluOH)s were also efficient in improving the optical properties with an enhanced refractive index and good transparency.