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

Abstract

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.

Nucleating Agents to Enhance Poly(L-lactide) Crystallization and Melting Behavior of Modified Poly(L-lactide)

“…According to the frontier orbital theory, a smaller energy gap between LUMO and HOMO often means that the electron transition from HOMO to LUMO becomes easier, implying that the PLLA's HOMO electron easier flows to NCAPH's LUMO, especially when PLLA and NCAPH are melt blended, under this circumstance, PLLA and NCAPH have high molecular activity. Additionally, according to NCAPH's electron density (Figure 2), the intermolecular interaction is presumed to occur at N-H of NCAPH and C=O of PLLA, which is proved by other research group [48].…”

Bio‐Based Copolyester PEIFT: Enhanced Hydrophilicity, Rigidity, and Applications in Nanofibers

“…G ' of PEIT‐20 and PET sharply increase at 165 and 215 °C, respectively, which may be attributed to crystallization. [ 27 ]…”

Superior heat‐resistant polylactide/poly(butylene succinate) blend fibers via in‐situ reactive compatibilization

“…Generally, the crystallinity and thus heat resistance of PLA fibers can be enhanced by using PLA of high optical purity as raw materials, combined with high‐speed spinning and intensive hot‐drawing processes 10 . Alternatively, the use of fibrillar nucleating agents including organic molecules and stereocomplex polylactide (sc‐PLA) provides an effective strategy to simultaneously enhance the crystallization rate and heat resistance 11–15 . For instance, fibrillar tetramethylenedicarboxylic dibenzoylhydrazide (TMC‐306) as a nucleation template has proven effective in improving the crystallization of PLA, leading to PLA fibers with superior heat resistance 11,12 .…”

“…organic molecules and stereocomplex polylactide (sc-PLA) provides an effective strategy to simultaneously enhance the crystallization rate and heat resistance. [11][12][13][14][15] For instance, fibrillar tetramethylenedicarboxylic dibenzoylhydrazide (TMC-306) as a nucleation template has proven effective in improving the crystallization of PLA, leading to PLA fibers with superior heat resistance. 11,12 Addition of a small amount of poly(D-lactide) (PDLA) has also shown a similar effect, ascribed to the formation of nanofibrillar sc-PLA.…”