Liquid crystalline polymers (LCPs) combine the attributes of liquid crystals and polymers, while discotic LCPs have been less developed in sharp contrast to their calamitic counterparts mainly due to lack of suitable discotic LCP materials. Here we successfully prepared a series of welldefined triphenylene (TP) based discotic LC polyacrylates via reversible addition−fragmentation chain-transfer (RAFT) polymerization for the first time, and through a combination of multiple analysis techniques and phase transition kinetics study, a remarkable molecular weight effect or polymer effect at a critical degree of polymerization (DP) around 20 has been disclosed. Moreover, the first proposed discrete columnar stacks (DCS) based hierarchical self-organization model accounts well for the formation and transformation of ordered hexagonal columnar lattice Col ho dominated by side-chain TP stacking and oblique columnar superlattice Col ob-s induced by compaction and ordering of polymer backbones. The in-depth understanding of their superstructures and readily achieved uniaxial alignment pave the way for the rational design and preparation of such kind of solution processable cutting-edge polymeric semiconducting materials and may boost various fascinating optoelectronic applications.

Very little is known about some fundamental issues such as the spacer length influence and molecular weight (MW) effect of discotic liquid crystalline polymers (DLCPs), despite the elucidation of such aspects are of crucial importance for their structure tuning and device performance. Here in this article, a systematic comparative study has been conducted to investigate the MW effect and especially gain a deeper insight into the spacer length influence of side-chain DLCPs based on a homologous series of well-defined discotic liquid crystalline polyacrylates with triphenylene (TP) side groups of variant spacer lengths. The series DLCPs of shorter spacers display various well-organized columnar superlattices based on multicolumn bundles organization with "coordination number" from two to six through individual discogens or discrete columnar stack (DCS)-based intracolumnar stacking modes. It is disclosed for the first time that the positive coupling effect (PCE) prevails in side-chain DLCPs, and proper coupling between discotic side groups and polymer backbone is desirable and required for achieving well-organized ordered columnar mesophases, in striking contrast with the renowned classical spacer decoupling principle directing the fruitful exploration of their side-chain calamitic counterparts for several decades. These findings are inspiring for in-depth understanding of self-assembly of aromatic interactions involved complex functional chemical and biological systems and especially opening an avenue for rational design and synthesis of well-controlled side-chain DLCPs for low-cost solution processable optoelectronic device applications.

Photoresponsive materials (PRMs) have long been a hot topic and photo‐modulated smart surface is very appealing. Particularly, liquid crystalline PRMs are able to amplify and stabilize photoinduced orientation thanks to their self‐assembling and ordering characteristics. Herein, the first pillararene‐based azobenzene liquid crystalline PRM with well‐defined structure is presented, which can avoid the usually ill‐defined composition drawback of polymer PRMs and prevent the severe H‐aggregation from suppressing or even completely blocking photoresponse in simple azobenzene derivatives. The pillar[5]arene‐based macrocyclic azobenzenes with variant length spacers show wide temperature range smectic liquid crystalline mesophases and excellent film‐formation property. The tubular pillar[5]arene macrocyclic framework provides sufficient free volume for azobenzene moieties to achieve reversible photoisomerization and photoalignment; thus, their thin films demonstrate excellent light‐triggered modulation of surface free energy, wettability, and even photoalignment‐mediated orientation of an upper layer discotic liquid crystal columnar mesophase. Such pillararene‐based azobenzene liquid crystals represent novel and promising PRMs with extensive fascinating applications.

Developing discotic columnar liquid crystals (LCs) with both high electrical conductivity and strong luminescence remains a challenge because the intracolumnar interdisc π−π stacking usually in ordered discotic columnar LCs is essential to generate charge transport pathways but normally detrimental to light emissions. We here present tricyanotristyrylbenzene-based quasi-discotic LCs upon bearing three wedge-shaped alkyl tails for addressing this issue. The resulted columnar materials displayed both high electrical conductivity and strong luminescence, especially for the ones stabilized by multivalent hydrogen-bonding interactions. Besides, an interesting thermochromic luminescence tuning behavior in a smooth manner was observed over a wide wavelength range for the hydrogen bond-stabilized columnar LCs. This study will lead to the future design and application of new multifunctional optoelectronic materials by integrating excellent conductivity and luminescence tuning behaviors.

By combining the virtues of conventional linear and hyperbranched polymers, long‐chain hyperbranched polymers (LCHBPs) have attracted great attention. Therefore, a comprehensive summary of the research progress of LCHBPs is presented, with a particular focus on their synthetic strategies, unique properties, and potential applications. The synthetic methodologies are rationalized into four main classes according to their construction process or mechanism, namely ABx (x ≥ 2), A2 + Bx (x ≥ 3), AB + ABx (x ≥ 2), and self‐condensing vinyl polymerization. Some of their rheological properties, self‐assembly behavior, and stimuli‐response features are then discussed. Finally, the emergent applications including biomedicine, electrical conductivity, chemical sensing, and catalyst carrier, are outlined. It is anticipated that this review will stimulate more inspiration for advancing the development of this novel kind of LCHBP.

Triphenylene (TP) derivatives are typical and probably the most widely studied discotic liquid crystalline (DLC) materials. Through polymer analogous reactions to attach TP mesogens to the well-synthesized poly(ethylene glycol)-b-poly(2-hydroxyethyl acrylate) (PEG–PHEA) by ATRP, a series of well-defined side chain DLC diblock copolymers PEG–poly(TPm) (m = 6 or 10) with DLC block weight fraction (f w,DLC) ranging from 37% to 90% have been successfully prepared with narrow molecular weight distribution (PDI ≤ 1.11). An intriguing microphase-separated superstructure evolution and the correlation between overall morphologies and discotic mesogenic orders as a function of f w,DLC and temperature have been demonstrated by combination of DSC, POM, and variable temperature SAXS/WAXS. Those copolymers with lower DLC contents (f w,DLC = 37% and 43%) and at lower temperatures formed lamellar structures of variant periods and underwent order–order transitions upon PEG region crystallization at 45 °C and different discotic mesophases of ND or Ncol transition at about 25 °C. For the copolymer with intermediate f w,DLC = 62%, a high temperature hexagonal packed cylinder (HPC) structure of amorphous PEG nanocylinders in the matrix of DLC was formed above 35 °C, while upon cooling below 35 °C it turned into a mixed lamellar structure with PEG region crystallization. The higher f w,DLC (67% ∼ 80%) copolymers exhibited HPC structures with the DLC matrix showing Ncol or ND mesophases. For copolymers with the highest f w,DLC around 90%, an overall ND phase was developed in sharp contrast to the ordered columnar phase formed by their corresponding DLC homopolymers, which was quite inspiring and might suggest another pathway of attaining this important nematic discotic phase through introducing a suitable copolymerized block. The better understanding of the interrelation of microstructures and discotic mesogenic orders constitutes the key basis for utilizing such type of organic semiconductor materials and could help to guide the design of complex DLC polymer materials with hierarchical structures for variant applications.

Well-prepared side-chain discotic liquid crystal polymers with shorter spacers in ordered columnar phases are fascinating and promising cost-effective, solution-processable organic semiconducting materials for various potential optoelectronic device applications.

Tunable fluorescent behaviour was achieved for hydrogen-bonded supramolecular discotic columnar liquid crystals via a fluorophore core engineered approach.