Phase Behavior of Phasmidic Mesogen-Jacketed Liquid Crystalline Polymers Displaying Chain Bundling

This is the authors' abstract. We don't add key points for this paper.

Phasmidic mesogens generally consist of a long rod core and two dendronized end-groups possessing three alkyl tails. Mesogen-jacketed liquid crystalline polymers (MJLCPs) represent an important class of shape-persistent polymers. Here, we synthesized two phasmidic molecules (MS- n, n = 8, 12, where n is the carbon number of each alkyl tail). More importantly, using MS- n as side chains, we synthesized two families of phasmidic MJLCPs (PE- n and PNB- n ) for the first time. The side-chain grafted density of the PE backbone is about twice that of the PNB backbone. MS- n ( n = 8, 12) can form a hexagonal Φ phase (Φ H ). From n = 8 to 12, phase structures (molecular shapes) of PE- n and PNB- n change from smectic (ribbon-like) to Φ H (cylinder-like). For their Φ H s, we conducted a comparative analysis of molecular packing among phasmidic molecules, phasmidic MJCLPs, and previous MJLCPs. The result shows that PE-12 and PNB-12 form a double-chain and four-chain column, respectively, whereas most previous MJLCPs render a single-chain column. The single-chain versus multichain packing behavior of MJLCPs was theoretically predicted. This work provides a strategy for manipulating molecular sizes, shapes, packing, and phase structures of side-chain polymers through combined side-chain and main-chain molecular engineering.