Side-chain polynorbornenes (PNBs) containing alkoxy biphenyl mesogenic side groups with a controlled number and substituted position within each repeating unit were synthesized and characterized. Various thermotropic mesophases including the smectic A (SmA) phase, the modulated smectic phase with a centered rectangular columnar lattice (Φr-c), and the hexagonal columnar (Φh) phase have been verified in this system. The influence of the number and position of alkoxy biphenyl groups on the self-assembly behavior of PNBs has been systematically studied. When increasing the number of substituted mesogenic groups, the mesophase of PNBs changes from SmA of PNB-4-CmBA to Φr-c of PNB-3,4-CmBA and Φh of PNB-3,4,5-CmBA (m = 12, 16). The self-organized structure is determined by the curvature of the interface between the aliphatic and aromatic segregated regions. With increases in the mesogenic group numbers, the interface becomes increasingly curved giving rise to structure alteration. When changing the substituent position from PNB-3,4-CmBA to PNB-3,5-CmBA (m = 12, 16), the phase structure changes from Φr-c to the amorphous phase because of the more flexible side chain. The calamitic mesogen shown here is a powerful side-chain building block to construct side-chain polymers with complex supramolecular self-assembled structures.

Herein we describe the rational design and facile synthesis of biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens with three different length methylene spacers (m = 2, 6, 11) via the combination of reversible addition–fragmentation chain transfer (RAFT) polymerization with Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) “click” chemistry. The successful cyclization was confirmed by comprehensive characterization including size-exclusion chromatography (SEC), triple detection size-exclusion chromatography (TD-SEC), Fourier transform infrared (FT-IR) and 1H NMR spectra. Subsequently, the liquid crystalline (LC) phase behaviors of the linear and cyclic polymers were investigated systematically. Both linear and cyclic polymers form the smectic phase and exhibit a similar layer periodicity. However, the cyclic ones exhibit a slightly lower mesophase transition temperature, enthalpy, entropy and smaller textures compared with their linear counterparts. Meanwhile, the smectic C (SmC) phase is preferable in cyclic polymers with a long methylene spacer (m = 11) compared with that in the linear one.

We investigated the phase behavior of a series of supramolecular polymer complexes P4VP(nCTB)x in which poly(4-vinylpyridine) (P4VP) is hydrogen-bonded with dendron-like small moleculescontaininga phenolic end group (nCTB, n = 6,10,12,14). Supramolecular lamellar and hexagonal columnar (ΦH) structures were investigated via small angle X-ray scattering (SAXS), polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The stability of the lamellar and ΦH phases is dependent on the blending ratio of nCTB per vinylpyridine unit (x), alkyl tail length (n) and thermal treatment. The P4VP(6CTB)x exhibit only a poorly ordered lamellar phase. Upon increasing x, the phase structure of the polymer complexes (n = 10, 12, 14) can transform from the lamellar to the ΦH phase. As a result of the thermal dynamic nature of hydrogen bond and the conformation changing of P4VPduring the thermal annealing, a non-reversible order-to-order transition from lamellar to ΦH phase appears when the volume fraction of the alkyl tails is 0.56–0.58.