Solid-state NMR Characterization of Polymers

Wang, FF (Wang, Fen-fen) 1Sun, PCA (Sun, Ping-chuan) 1

ACTA POLYMERICA SINICA, 2021, 52(7): 840-856

DOI 10.11777/j.issn1000-3304.2020.20254

Abstract

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.