Preparation of nano boron nitride-trimethylolpropane tris (3-mercaptopropionate) grafted poly (L-lactic acid) based on click chemistry and its effect on the crystallization of poly (lactic acid)

Nano boron nitride-trimethylolpropane tris (3-mercaptopropionate) grafted poly (L-lactic acid) (BN-TTMP-PLLA) was prepared with nonmetallic organic catalyst by thiol-ene click chemistry. By orthogonal experiment and range analysis, the optimum reaction conditions of BN-TTMP-PLLA were as follows: reaction time of 2.5 h, photoinitiator addition amount of 0.04 g, TTMP addition amount of 0.9 g, and mass ratio of PLLA-AA to BN-570 of 1:1. The product was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which showed that PLLA was successfully grafted onto BN surface. Furthermore, PLA/BN-TTMPPLLA nanocomposites were prepared by melt blending with BN-TTMP-PLLA as modifier to enhance the performance of PLA. Compared with pure PLA, the impact strength and elongation at break of PLA/BN-TTMP-PLLA (0.5 wt%) nanocomposites were increased by 1.58 times and 7.34 times, respectively. Molecular dynamics simulation calculation showed that EInteraction between PLA and BN before and after functionalization decreased from -177.44 kcal/mol to -516.42 kcal/mol, which proved that intermolecular interactions between them were strengthened. In addition, PLA/BN-TTMP-PLLA (0.5 wt%) nanocomposites during melting and isothermal crystallization were studied by Rheonaut technology for simultaneous rheometry and FTIR, which demonstrated that the crystallization properties of PLA was clearly improved due to the strong hydrogen bonding effect between BN-TTMP-PLLA and PLA.

Automated summary

Nano boron nitride-trimethylolpropane tris (3-mercaptopropionate) grafted poly (L-lactic acid) (BN-TTMP-PLLA) was successfully prepared using thiol-ene click chemistry with a nonmetallic organic catalyst. The addition of BN-TTMP-PLLA as a modifier in PLA significantly improved the impact strength and elongation at break of the nanocomposites, demonstrating enhanced performance compared to pure PLA. Molecular dynamics simulation calculations showed strengthened intermolecular interactions between PLA and BN after functionalization, indicating improved compatibility. Additionally, the crystallization properties of PLA were enhanced due to the strong hydrogen bonding effect between BN-TTMP-PLLA and PLA, as observed in Rheonaut technology analysis during melting and isothermal crystallization.