固体核磁共振技术在高分子表征研究中的应用

Solid-state NMR Characterization of Polymers

基于核自旋探针的核磁共振(NMR)波谱技术可以在非常宽广的时间和空间尺度上提供重要的微观结构和动力学信息.固体NMR已成为阐明高分子中化学键变化、链间相互作用、多尺度结构与动力学演化,及其与宏观物理化学性质关系的有力工具.本文从基础原理、实验方法与技巧、典型应用与研究进展等几方面进行简要综述.在基础原理部分介绍了化学位移各向异性和偶极相互作用等检测不同尺度信息的核自旋相互作用及其实验调控方法,魔角旋转、交叉极化和多脉冲去耦等高分辨技术,以及自旋扩散测定相区结构及复杂分子运动检测方法的原理等;在实验方法与技巧上,着重仪器精确校准、关键脉冲参数设置及仪器背景信号压制等;典型应用将聚焦于天然高分子及其复合材料的结构-性能关系、水与生物大分子间相互作用、多相高分子材料的微相分离结构、高分子中氢键相互作用和导电高分子材料等问题,介绍了固体NMR技术在上述领域的最新应用与进展.

Nuclear magnetic resonance(NMR)techniques based on the nuclear spins can provide important information on microscopic structure and dynamics in a very broad length and time scale.With the booming development of NMR theory and instruments,solid-state NMR(SSNMR)is playing an increasingly important role in the field of polymer material researches.SSNMR has gradually become a powerful tool for the characterization of structure and dynamics of macromolecules,changes of chemical bonds,interactions between polymer chains,relationships between the microstructure and macroscopic chemical/physical properties,which almost covers all areas of polymer researches and is suitable for different polymer systems including polymer solutions,melts,gels,liquid crystals,crystalline and amorphous solids,etc.SSNMR not only plays an important role in elucidating the relationship between structure and properties for polymer materials,but also is of great significance for developing the theory of polymeric condensed physics,which has given a significant impulse to the development of polymer science.In this paper,the basic principles,experimental methods and skills,typical applications and progresses in polymer science are briefly reviewed.In the section of basic principles,the nuclear spin interactions and its experimental manipulation methods for detecting information on different length scales,such as chemical shift anisotropy and dipolar interactions,high-resolution SSNMR techniques such as magic angle spinning,cross-polarization and multiple pulse decoupling,as well as the principles of spin diffusion method for measuring microdomain and interphase structures,and complex molecular motion on different time scale,are introduced.In the section of experimental methods and skills,we pay great attention to accurate calibration of the SSNMR instrument,key setting of the pulse parameter and background signal suppression of the instrument.In the section of typical applications and progresses,we focus on different topics including the structure property relationship of natural polymers and their composites,the interaction between water and biological macromolecules,the structure of microphase separation in multiphase polymer materials,the interaction of hydrogen bonds in polymers,as well as conductive polymer materials.The latest applications and progress of solid-state NMR technology in the aforementioned fields are also introduced.