In designing of liquid crystalline polymers, "decoupling effect" and "jacketing effect" are usually considered as two converse directions. Generally, the former is used in designing traditional side-chain liquid crystalline polymers (SCLCPs), while the latter is followed to obtain mesogen-jacketed liquid crystalline polymers (MJLCPs). The well-studied MJLCPs are based on 2-vinylterephthalic acid. However, the synthesis of 2-vinylterephthalic acid starts from the selective oxidation of 2,4-dimethylbenzoic acid and thus needs multi-step organic reactions with an overall low yield. With the two problems in mind, using the synergic effect of "decoupling effect" and "jacketing effect", we proposed to develop new MJLCPs based on 5-vinylisophthalic acid in this work. We synthesized poly[di(alkyl) 5-vinylisophthalates] (P_3,5′-m, m=4, 5, 6, m denotes the number of carbon atoms of each alkyl chain). The tail of the alkyl chain is tert-butyl, and ―(CH₂)_x― (x=0, 1, 2) is located between the tert-butyl and ester group. In the design of P_3,5′-m, the tert-butyl group is assumed to be the rigid and highly steric group, while the ―(CH₂)_x― is used as the flexible spacer. Polarized light microscope (PLM) and one-dimensional X-ray diffraction (1D XRD) results demonstrated that P_3,5′-4 and P_3,5′-6 are amorphous, while P_3,5′-5 exhibited hexagonal columnar liquid crystalline phase (Φ_H) before thermal decomposition. We consider that, compared to P_3,5′-4, the spacer of ―CH₂― in P_3,5′-5 leads to stronger motions, hence enlarging "jacketing effect" of tert-butyl groups to the main-chain, namely entropy-contributed "jacketing effect". In other words, the formation of the spuramocular column of P_3,5′-5 originates from the synergic effect of "decoupling effect" and "jacketing effect". 2D XRD results reveal that P_3,5′-5 renders three-dimensionally ordering upon being subjected to 1D mechanically shearing, indicative of wonderful ability of processing ordering. Combined XRD with molecular simulation results, it can be seen that P_3,5′-5 renders "single-chain column", different from that of P_3,5-m (m=8-18) with "double-chain column", which were synthesized previously by our group. This work offers new insights into the molecular design and industrial applications of MJLCPs, and into the manipulation of the chain-number of supermolecular columns of columnar polymers.

Jacketing effect;Decoupling effect;Mesogen-jacketed liquid crystalline polymers;Single-chain column