聚丁二酸丁二醇酯微孔发泡成核机理研究

In recent years, exploitation on the functional microcellular polymer foam had attracted extensive attention. However, the existing classical nucleation theory could not characterize quantificationally on the microcell nucleation mechanism, which also could not reveal the essence of heterogeneous nucleation induced by CO2 local enrichment from micro- and nanoscale. In this project, fluorinated polyhedral oligomeric silsesquioxane (F-POSS) was selected as the nucleation agent, the theoretical and experimental investigations on microcell nucleation in poly (butylene succinate) (PBS) will be conducted. In the theoretical aspect, a three-dimensional density functional theory containing multi interactions and multi interfaces will be constructed to quantitatively describe the dispersion of F-POSS in PBS, and confirm the mesostructure as well as the nucleation evolution and the nucleation optimum condition of various cells in different conditions. In the experimental aspect, the PBS foaming process in different conditions will be conducted; the preparation of microcellular PBS foam with a low pressure drop could be achieved, and some of experimental results are employed to examine the reliability of theoretical prediction. The effect of nanoscale rough and orderly distribution of F-POSS on the surface of PBS on the micromechanism as well as regulate and control mechanism of cell nucleation will be clarified, from micro molecular effect to mesostructure of various interfaces then to macroscopic property. As a result, a theoretical model about the inhomogeneous microbubble nucleation of PBS induced by local enrichment of interfacial CO2 will be constructed for the ongoing investigations, which possess important scientific significance.

近年来，开发功能性聚合物微孔泡沫受到广泛关注。但关于微孔成核机理，现有经典成核理论很难定量表征，无法从纳微尺度揭示CO2局部富集诱导的非均相成核本质。本项目以氟化聚倍半硅氧烷（F-POSS）为成核剂，选取聚丁二酸丁二酯（PBS）微孔成核过程为研究对象展开理论和实验研究。理论研究方面，构建一套包含多作用、多界面的三维密度泛函理论，定量表征F-POSS在PBS中的分散，确定不同条件下不同气泡的介观结构和成核演变过程及最佳条件。实验研究方面，考察不同条件下的PBS发泡过程，在理论指导下，实现较低压力降条件下PBS的“可微发泡性”，部分实验结果用于检验相关理论模型。本项目特色是从微观分子作用推演到各种界面的介观结构再到宏观性质，阐明F-POSS在PBS表面形成的纳尺度粗糙与有序分布对界面CO2富集诱导的气泡非均相成核微观机理和调控机制，形成一套关于PBS非均相微孔成核的理论模型，具有重要科学意义。

近年来，将微孔发泡和可生物降解特性结合起来，开发出性能优异、环境友好、应用广泛的功能性聚合物微孔泡沫材料，已引起越来越广泛的关注。要实现可生物降解聚合物的超临界CO2微孔发泡，需要加入高效的成核剂，以降低成核能垒，从而显著增加泡孔密度，降低泡孔尺寸。主持人在基金（51703004）的支持下，结合北京市自然科学基金青年基金与北京市青年拔尖人才计划等项目的资助，通过构建新的统计力学理论模型，对三氟丙基聚倍半硅氧烷（F-POSS）/PBS微孔发泡成核过程展开了研究。理论方面，针对PBS发泡过程中F-POSS分散、F-POSS周围CO2局部高度富集、非均相气泡成核三个关键科学问题展开了理论研究，建立了三套理论预测模型。试验方面，围绕PBS复合材料发泡开展了三个方面的研究：1、采用等温结晶诱导的方法，成功制备了PBS/F-POSS微孔泡沫；2、成功制备了高绝热PBS/纤维素纳米晶泡沫；3、成功制备了PBS/甲壳素纳米晶开孔泡沫。现已超额完成任务书约定的所有内容：建立了相关理论模型3套，已发表SCI论文18篇，其中，SCI论文16篇，中文核心期刊2篇，申请发明专利2件，培养研究生7名。