The crystalline behavior of poly(L‐lactide) induced by nucleating agents with amide structure: The effect of benzamide molecule symmetry

Amide nucleating agents have been reported to be effective in promoting poly(L‐lactide) (PLLA) crystallization, while few research efforts have focused on the structure–activity relationship of the nucleating agents which is one basic issue to develop new agents. In this work, three amide nucleating agents with different symmetry were designed and synthesized to investigate the effect of the symmetry of benzamide nucleating agents on PLLA crystallization. It is found that the C3 symmetric amide structure of N, N′, N″‐tricyclohexyl‐1,3,5‐benzenetriamine (BTCA) agent can form a highly oriented structure by a triple hydrogen bond of π–π bond and benzene ring and can act as efficient nucleation sites. In addition, the strong intramolecular hydrogen bond with PLLA would further promote the crystallization of PLLA. In general, it is the self‐assembled ability and intramolecular hydrogen bonding with PLLA affects the rate and degree of PLLA crystallinity, and we find the C3 symmetric amide structure exhibits the best performance.