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Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers
Published on: June 20, 2019
Asymmetric Molecular Dynamics and Anisotropic Phase Separation in the Cocrystal of the Crystalline/Crystalline
Ying Zheng1,2,3, Navin Kafle1, Derek Schwarz1
1School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio 44325-3909, United States.
Abstract:
Semicrystalline polymers are categorized as either mobile or fixed crystals, depending on chain mobility in the crystalline region. In this work, we investigate molecular dynamics and phase structure in the cocrystal consisting of fixed and mobile polymer crystals by solid-state (ss) nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that (i) the mobile component begins large amplitude motions associated with crystal-crystal transition, while fixed ones keep their rigidity in the cocrystal, and (ii) asymmetric molecular dynamics leads to nanosegregations into mobile- and fixed-rich domains in the cocrystal below the melting temperature (Tm). The observed phase separation induced by asymmetric molecular dynamics is similar to the phase separation of the miscible amorphous polymer blend; however, it is limited to two dimensions due to the parallel packing of the stems inside the cocrystal, as well as chain connectivity at the crystalline-amorphous boundary.
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