Molecular Dynamics, Phase Transition, and Structural Organization in Configurationally and Conformationally Disordered Polymer Crystal

Fast and anisotropic chain dynamics coupled with structural disorder significantly contribute to structural evolution of several semicrystalline polymers. We report a new class of structural disorder, “configurational disorder coupled with conformational flexibility (CDCF)” in polymer crystal. It is revealed that atactic-hydrogenated poly(norbornene) (hPNB) conducts slow conformational dynamics below crystal-crystal transition temperature (T_cc) and fast uniaxial chain dynamics above T_cc while isotactic (i)- and syndiotactic (s)-hPNBs do not perform such fast chain dynamics. It is for the first time demonstrated that the presence of fast chain dynamics leads to much higher crystallinity (80 %) and much longer long-period (L = 80 nm) in a-hPNB than those of s- and i-hPNBs (crystallinity of 50-55 % and L of 17-21 nm). It is concluded that CDCF plays an important role for phase transition, fast chain dynamics, and unique structural evolution in stereo-irregular polymer. .