Investigation of the Structures and Dynamics of Fluoropolymers Using Novel Methods of Solid-state ^<19>F NMR Spectroscopy.

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Various spectroscopic techniques using ^<19>F magic angle spinning (MAS) and ^1H【double arrow】^<19>F cross polarization (CP)/MAS nuclear magnetic resonance (NMR) spectroscopy were developed to explore new methodology for the analysis of structure and molecular mobility of functional fluoropolymers in the solid state. Novel ^<19>F NMR methods, such as a selective observation of the crystalline domain of polymers whose mobility does not much differ from the amorphous domain, an estimation of the characteristic local mobility in the amorphous polymers, an appraisal method for estimating interatomic H-F distances, etc. were developed in addition to the analysis of CP dynamics in a multi-spin system consisting of highly abundant nuclei and various methods for measuring magnetic relaxation times. Such ^1H【double arrow】^<19>F CP/MAS techniques were applied for (1)polyvinylidene fluoride (PVDF) exhibiting distinct polymorphism and (2)polyvinylfluoride (PVF) whose phase structure has not been c … More larified yet. I)The degrees of crystallinity and structural isomerism were estimated from the intensity of each signal, II)the conformations of the main chain were determined from ^<19>F chemical shifts (resonant positions), III) the difference in molecular mobility among polymorphs and between crystalline/amorphous domains, and the F-H interatomic distances were investigated from the magnetic relaxation measurements and the analysis of ^1H【double arrow】^<19>F CP dynamics, and IV)the gradual changes in conformation of the crystalline domains at elevated temperatures were clarified by the variable temperature (VT) measurements. Subsequently, derivative NMR techniques were applied for (3)Cytop that is an amorphous perfluoropolymer, a crystalline (4)ethylene/tetrafluoro-ethylene copolymer (ETFE), (5)vinylidene fluoride/trifluoroethylene copolymer (P(VDFITrFE)) that exhibits very high ferroelectricity, (6)miscible blends of PVDF/PMMA, (7)polychlorotrifluoroethylene (PCTFE) having high weatherability, (8)immiscible blends of PCTFE/PVDF, and (9)fluorine-containing aromatic polyimides applicable for optical waveguide circuits. This series of research has shown that ^<19>F MAS and the ^1H【double arrow】^<19>F CP/MAS NMR methods are very useful and promising for the analysis of structures and motility of functional fluoropolymers. Less