Design, Synthesis, and Self-assembly of Mesogen-Jacketed Liquid Crystalline Polymers Constructed by Hydrogen Bonding

A new type of supramolecular mesogen-jacketed liquid crystalline polymer (MJLCP) was constructed by hydrogen bonding with poly(4-vinyl pyridine) (P4VP) as the hydrogen-bonding acceptor and carboxyl-containing molecules as hydrogen-bonding donors. The formation of hydrogen bonds was proven by Fourier-transform infrared spectroscopy (FTIR) and wide-angle X-ray scattering, and the effect of molecular structures on the phase behaviors of supramolecular MJLCPs was systematically studied. The results showed that because the "jacketing" effect of hydrogen-bonding donor molecules with only one (8MP) and three benzene rings (4TP and 6TP) and relatively short alkyl-chain tails was not strong enough when they were complexed with P4VP, the complexes P4VP(4TP)x, P4VP(6TP)x, and P4VP(8MP) x are disordered at a molar complexing ratio x (between the donor and the acceptor) of 1.0. The four types of complexes P4VP(8TP)x, P4VP(10TP)x, P4VP(12MP)x, and P4VP(16MP) x undergo a transition from an disordered structure to the smectic (Sm) phase when the complexing ratio increases, and the minimum ratio for the appearance of liquid crystalline phases gradually decreases when the length of alkyl-chain tails and the rigidity of the hydrogen-bonding donor increase. Because of the high rigidity of the hydrogen-bonding donor and its long alkyl-chain tails, the P4VP(12TP) x undergoes a phase transition from disordered to the Sm phase and then to a hexagonal columnar (Colh) phase with the increase in the complexing ratio. However, if the size of the hydrogen-bonding donor molecule is too large, the formation of hydrogen bonds would be hindered, and macroscopic phase separation occurs in P4VP(8PP)(x) even when the complexing ratio is very low. The use of hydrogen bonding greatly simplifies the construction of MJLCPs. The liquid crystalline phase can be flexibly regulated by controlling the structure of small molecules and the complexing ratio, which provides a new idea for the structural design of MJLCPs with complex structures. [GRAPHICS] .