光解離性保護基導入による長鎖化PLAの弾性率低下を抑制する分子構造設計に関する分子シミュレーション

抄録

Previously, the authors proposed a method to endow PLA with hydrolysis-controllability by introducing o-nitrobenzyl alcohol as photo-dissociable protecting groups. This study aimed to obtain the design guideline for optimum molecular structures in the long-chain PLA generated by introducing intermediate photo-dissociable protecting groups. This would help suppress decrease in the elastic modulus of hydrolysis-controllable PLA. First, the possibility of generating long-chain PLA was discussed using a molecular orbital calculation. Based on the results, it was suggested that the reaction to generate the long-chain PLA via o-nitrobenzyl alcohol could occur depending on the combination of the reaction sites. Secondly, uniaxial tensile simulation for the long-chain PLA, whose molecular structures were deemed as “generatable”by the MO calculation, was conducted using molecular dynamics. The results suggested that the jackknife-like structure of the long-chain PLA formed by the introduction of the intermediate o-nitrobenzyl alcohol decreases the elastic modulus of PLA. Therefore, it might be necessary to select photo-dissociable protecting groups, which could in turn maintain the straight molecular structures of the long-chain PLA, in order to suppress decrease in the elastic modulus.