SYNOPSISCationic UV-polymerized resins, based on cycloaliphatic epoxides with aryl sulfonium salts as photoinitiators and polypropylene glycols of variable length as flexibilizers, have been investigated with respect to the network-forming reactions and the morphology of the resulting polymers. The combination of UV-curing and thermal postcure makes the chemical process complex and dependent on many variables, such as photoinitiator, exposure time, reaction temperature, and polyol components. Structure and curing of the epoxide were investigated by 13C CPMAS NMR. Morphology and domain sizes were studied by spin diffusion experiments using the novel "dipolar filter" technique for selective magnetization of mobile components.

No abstract

No abstract

No abstract

Solid‐state 13C cross‐polarization magic‐angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectra have been obtained for annealed films of poly (p‐phenylene vinylene) (PPV), prepared through the precursor route and for a deuterated PPV‐d4, poly (p‐2,3,5,6 tetradeuterophenylene vinylene). 13C CPMAS spectra of PPV are of high resolution, typically characteristic of a nearly fully crystalline structure. All four phenylene and vinylene resonances have been assigned, and for stretched films the 13C CPMAS linewidth and the quality of crystallinity are independent of the draw ratio. 13C CPMAS resolution and crystallite size (as determined by transmission electron microscopy, TEM) depend upon final annealing temperature. The greatest NMR resolution and largest crystallite size are obtained for films annealed at 300°C. The 13C CPMAS NMR spectra show the presence of phenylene ring 180° rotational jumps, and 13C CPMAS resolution is affected by rotational disorder about phenylene‐vinylene bonds. NMR data show that PPV films possess molecular motion at elevated temperatures. Enhancement of this motion during annealing may provide a means for improving the quality of PPV crystallinity.