固体高分辨核磁共振研究聚氧乙烯/纳米二氧化硅复合物的界面相互作用

采用固体高分辨核磁共振碳谱对聚氧乙烯(PEO)/纳米二氧化硅(Nano-SiO₂)复合物体系的相态结构、分子间相互作用和分子运动进行了研究,发现随着复合物中SiO₂含量增加,PEO结晶度明显降低,且PEO非晶区的分子运动受到明显约束,基于对PEO非晶区及SiO₂颗粒表面羟基质子的自旋-自旋弛豫行为的分析,提出了复合物的界面模型以及SiO₂与PEO之间的界面相互作用机制.

Solid-State High-Resolution 13C NMR Studies on Interfacial Interaction of PEO/Nano-SiO2 Composites

A series of nano SiO2/PEO composites with different compositions were prepared and studied by solid-state high-resolution NMR spectroscopy. The 1H spin-spin relaxation time( t2) of PEO in the composites was measured Via 1H→ 13C cross polarization. It is found that with the increase of nano-SiO2 content, the crystallinity of PEO decreases greatly while the mobility of PEO chains in the noncrystalline region of PEO decreases dramatically. A model was suggested to describe the interfacial structure of the nano SiO2/PEO composites based on the single exponential relaxation characteristic of the 1H t2 decay curve. Via 1H→ 29Sicross-polarization the dynamics of the hydroxyls lying on the surface of nano SiO2 particles was also studied. The obtained result strongly suggests that at room temperature there exists an equilibrium of forming and breaking of the hydrogen bonds between the surface hydroxyl group and the ether oxygen.