Manipulating Molecular Shapes and Phase Structures of Mesogen-Jacketed Liquid Crystalline Polymers: From Sheet-like to Rod-like Molecule and from Smectic to Columnar Phase

Aiming at manipulating the molecular shapes and phase structures of mesogen-jacketed liquidcrystalline polymers (MJLCPs) polymers, we designed a new MJLCP 1P containing the flexible "benzene-benzyl ester-benzene" units in its side-chains and another MJLCP 2P as reference containing the rigid "benzene-ester-benzene" units. 2P renders extremely stable lamellar liquid crystalline phase probably with sheet-like conformation. However, 1P forms lamellar liquid crystalline phase at the low-temperature range and columnar liquid crystalline phase at the high-temperature range, probably with sheet-like and rod-like conformations, respectively. We also proposed the mechanisms for transitions of molecular shapes and phase structures of 1P: at the low temperature range, the "benzene-benzyl ester-benzene" units mainly adopt the tans conformation and hence the side-chains behave like flexible rod-like mesogens, leading to the sheet-like molecules and their further lamellar packing; at the high temperature range, the "benzene-benzyl ester-benzene" units mainly adopt the gauche conformation and thus increases their jacketing effect on the main-chain, generating rod-like molecules and further columnar packing. In this work, through incorporating the flexible connecting units, we successfully manipulated the molecular shapes and phase structures of a MJLCP. This work will pave a way to tune molecular shapes and phase structures of side-chain liquid crystalline polymers.