基于同步辐射的POSS-聚合物纳米复合材料微观结构与阻燃机理研究

Flame retardant mechanism is a key issue in the study of flame retardant materials. In this project, the flame retardant mechanism of polyhedral oligomeric silsesquioxane (POSS)-polymer nanocomposites is expected to be explored based on the multi-parameter coupling studies in the combustion of process using synchrotron radiation and other necessary means. The composition, the structure of molecular chain and the microscopic morphology of the composite materials can be controlled by changing the types of POSS substituents, the combination type and the molar ratio between the POSS and the polymer substrates, which can meet the flame retardant requirements for nanocomposites; Synchrotron radiation wide-angle X-ray diffraction (WAXS) and small-angle X-ray diffraction (SAXS) are used for the in-situ characterization of the evolution of the composite microstructure with temperature rising (before ignition); The combustion process, the combustion characteristics and the combustion products of nanocomposites are studied by using synchrotron radiation photoionization and molecular beam mass spectrometry combined with other conventional means. Based on the above research, together with analying the composition, the morphology and the microscopic structure-composition-performance coupling law in the heating process before ignition, the influences of POSS on the combustion mechanism of nanocomposites and regulation mechanism to improve the flame retardancy together with thermal stability can be investigated clearly. In this way, the flame retardant mechanism for POSS-polymer nanocomposites is expected to be found out, which can lay a foundation in theory and accumulate beneficial experience in experiment for the developments of silicon-based flame-retarded polymeric materials.

阻燃机理是阻燃材料研究的关键。本项目以多面低聚倍半硅氧烷（POSS）-聚合物纳米复合材料为研究对象，综合利用同步辐射等多种研究手段，基于燃烧全过程的多参数耦合深入研究POSS对聚合物的阻燃机理。通过调节POSS取代基的类型、POSS与聚合物基体的复合方式、比例等来控制材料的组成、分子链结构和微观形貌，实现材料阻燃要求；依据同步辐射WAXS和SAXS的实时原位表征确定复合材料的微观结构在升温条件下（受热引燃前）的演化规律；利用同步辐射单光子电离和分子束质谱，结合常规研究手段，对材料燃烧过程、燃烧特性和燃烧产物进行全面分析。综合复合材料组成、形貌以及受热引燃过程中微观结构-组成-性能的耦合对复合材料燃烧性能的改善和对热稳定性能提高的作用机制，揭示POSS-聚合物复合材料阻燃机理，为新型硅系阻燃材料的发展奠定理论上的基础和积累实验上的经验。

本项目以多面低聚倍半硅氧烷（POSS）-聚合物纳米复合材料为研究对象，综合利用同步辐射等多种研究手段，基于燃烧全过程的多参数耦合深入研究POSS对聚合物的阻燃机理。主要开展了以下三个方面的工作：（1）制备和构筑了多种POSS单体和有机修饰的POSS纳米粒子，对其结构和相关性能进行了表征分析：制备苯基POSS和氨基POSS，通过红外、核磁共振、XRD、电子显微镜等多种手段，确认了其笼型分子结构；基于“点击反应”对POSS纳米粒子进行有机修饰，有效改善了有机相容性；（2）基于功能化的POSS纳米粒子设计构筑了几种典型的POSS聚合物纳米复合材料，并对其结构和相关性能进行了必要的表征：基于苯基POSS (B-POSS)、异丁基POSS (Oib-POSS)、八乙烯基POSS（OV-POSS）以及环氧基POSS (G-POSS) ，通过熔融共混制备聚丙烯（PP）纳米复合材料，并对材料的结构和性能进行了表征。同时采用熔融物理共混和熔融反应共混两种方法制备了PP/OV-POSS纳米复合材料，研究表明物理共混制备的纳米复合材料热稳定性能优于反应共混制备的纳米复合材料，OV-POSS可以明显提高PP的热解活化能。此外，还设计发展了一种新型的压力辅助合成装置，实现了纤维状POSS-聚苯胺纳米复合材料的尺寸可控制备。（3）基于同步辐射和其他相关的表征手段，对复合材料的热稳定性能和阻燃性能进行了全面表征。利用同步辐射真空紫外光电离质谱(SVUV-PIMS)研究了膨胀阻燃PP复合材料的主要热解产物，通过对比分析，确定膨胀阻燃PP复合材料的主要热解产物，同时研究表明膨胀阻燃PP复合材料的阻燃机理属于凝聚相阻燃。综合复合材料组成、形貌以及料燃烧性能的改善和对热稳定性能提高的作用机制，揭示POSS-聚合物复合材料阻燃机理，为新型硅系阻燃材料的发展奠定理论上的基础和积累实验上的经验。