聚(L-乳酸)薄膜内气体高速渗透通道的构筑及选择透过机制研究

生物可降解薄膜在生鲜果蔬保鲜包装中具有巨大的应用潜力，且对于环境保护和食品安全都具有重要意义。聚(L-乳酸)（PLLA）的气体透过性中等，CO2/O2透过比低，用于包装高呼吸强度果蔬时，易产生无氧呼吸或CO2中毒，导致腐败加剧。本研究利用聚硅氧烷（PSi）的柔性、高气体透过性和选择透过性的特点，制备高分子量PLLA-PSi-PLLA系列嵌段共聚物，研究嵌段组分比、PSi嵌段的取代基大小和极性以及成膜条件等对PLLA-PSi-PLLA微相分离结构的影响，分析微相分离结构对材料内部气体通道构建和力学性能的影响，阐明微相分离结构与H2O、CO2和O2等气体透过及选择透过的作用机制。本研究还将根据微相分离结构与气体透过性之间的关系，反向定制特异性气调保鲜包装膜，使其能够自动调节包装内部O2和CO2气氛比例，抑制和降低果蔬的有氧呼吸，抑制微生物的繁殖和酶反应，达到延长果蔬保鲜期的目的。

Biodegradable films have great potential in the packaging of fresh fruits and vegetables, and it is also of great significance to environmental protection and food safety. Poly(L-lactic acid) (PLLA) has a medium gas permeability and low perm-selectivity. When its was used for the packaging of fruits and vegetables with high respiratory intensity, anaerobic respiration and carbon dioxide toxicity are easy occurs, inevitably led to corrupt. In this study, polysiloxane (PSi), a kind of flexible polymers with high gas permeability and perm-selectivity, was used to synthesis a series of high molecular weight PLLA-PSi-PLLA triblock copolymers. The effect of the composition, substituent, polarity and film formation conditions on the microphase separation structure was investigated. And the effect of microphase separation structure on the mechanical property and the building of gas permeable channel was also been explored. Furthermore, the influence mechanism of microphase separation structure on the gas permeability of H2O, CO2 and O2 of films was thoroughly studied. Based on the above study, a new packaging system was established, which can adjust the inter atmosphere spontaneous by film to a low O2 and high CO2 state to restrained the respiration and propagation of microorganisms, prolonging the storage period.