The crystalline structures of ethylene-dimethylaminoethyl methacrylate copolymers as studied by solid-state high-resolution 13C NMR spectroscopy

Abstract

The crystalline structures of ethylene-dimethylaminoethyl methacrylate (EDAM) copolymers, which were either melt-quenched (mq) or isothermally crystallized (iso), were studied by solid-state high-resolution 13C NMR spectroscopy. It revealed that the crystalline structures of EDAM copolymers are greatly dependent on the comonomer content, crystallization condition and the storage time after treatment. The ratio of monoclinic to orthorhombic crystal (M/O) increases with the increase in the dimethylaminoethyl methacrylate content. Higher crystallinity and lower monoclinic content were observed for iso samples compared to the mq ones. The monoclinic crystal was found to melt at lower temperatures compared to the orthorhombic one during the heating process. The degree of crystallinity as well as the contents of monoclinic and orthorhombic crystals and the M/O value are found to increase after storage at room temperature for a month.