曲面效应对纳米受限态高分子的玻璃化转变以及物理老化过程影响的固体核磁共振表征

近年来，随着微电子、光伏器件、复合材料等领域的飞速发展，人们对其中处于纳米受限态下的高分子的行为以及最终材料的稳定性给予了极大的关注。本项目拟以无定形聚苯乙烯和聚-2乙烯基吡啶为模型高分子，通过固体核磁共振研究曲面效应对受限态高分子在玻璃化转变前后的动力学行为，以及物理老化过程的影响。具体是运用固体NMR领域近年来发展的新技术，研究玻璃化转变温度梯度，在分离局域场下链段偶极相互作用强度和几何运动的变化，以及链段动力学特征时间的演化，进而获得链段堆积密度、构象熵和运动能垒等普适的描述链段动力学的微观信息。进一步，通过控制曲面（凸面或凹面，以及曲率的大小）、高分子分子量、以及高分子-基底间相互作用，来研究这些直接与凝聚态结构关联的微观参数对局域结构的影响，及其与本体行为的差别。最后将可控的微观结构参数与玻璃化转变前后的动力学行为，以及物理老化过程相关联，在分子层面上给出对机理的理解。

This proposal is the study of curvature effect on confined polymer. Atactic polystyrene (PS) and poly(2-vinyl pyridine) (P2VP) are used as model polymer under different geometry confined conditions: convex or concave surface with different curvature radius. The newly developed NMR techniques are used to study the segmental dynamics of polymer, the amplitude and geometry of segmental motions under separated local field, and the evolution of character time. Through such information at different length and time scale, we could gain packing density, active energy, glass transition temperature gradient, and conformational enthropy. So we could explore the role played by geometry factor on confined polymer around glass transition temperature and physical aging process. Finally, a molecular level mechanism is proposed by understanding the above relationships. And this work will help people understanding glass transition and physical ageing of confined polymer more deeply.