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

Four amino acid-bearing acrylamides, N -acryloyl-l-threonine (AThrOH), N -acryloyl-l-glutamic acid (AGluOH), N -acryloyl-l-phenylalanine (APheOH), and N -acryloyl-l, l-diphenylalanine (APhePheOH), were selected for copolymerization with n -butyl acrylate ( n BA) to develop amino acid-based self-healable copolymers. A series of copolymers comprising amino acid-bearing acrylamides and n 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( n BA- co -AGluOH) with suitable comonomer compositions and molecular weights ( n BA : AGluOH = 82 : 18, M n = 18 300, M w / M n = 2.58) exhibited good mechanical properties (modulus of toughness = 17.3 MJ m -3 ) and self-healing under ambient conditions. The multiple noncovalent bonds of P( n BA- co -AGluOH)s were also efficient in improving the optical properties with an enhanced refractive index and good transparency.