Orientation and Morphology Control of the Liquid Crystalline Block Copolymer Thin Film by Liquid Crystalline Solvent

Structure, Properties, Preparation, and Application of Layered Titanates

As a typical cation-exchangeable layered compound, layered titanate has a unique open layered structure. Its excellent physical and chemical properties allow its wide use in the energy, environmental protection, electronics, biology, and other fields. This paper reviews the recent progress in the research on the structure, synthesis, properties, and application of layered titanates. Various reactivities, as well as the advantages and disadvantages, of different synthetic methods are discussed. The reaction mechanism and influencing factors of the ion exchange reaction, intercalation reaction, and exfoliation reaction are analyzed. The latest research progress on layered titanates and their modified products in the fields of photocatalysis, adsorption, electrochemistry, and other applications is summarized. Finally, the future development of layered titanate and its exfoliated product two-dimensional nanosheets is proposed.

Liquid-Crystalline Polymers: Molecular Engineering, Hierarchical Structures, and Applications

Liquid-crystalline polymers (LCPs) are a unique class of soft materials that combine liquid crystal and polymer characteristics. This perspective highlights recent advances of LCPs on the aspects of molecular engineering, hierarchical structures, and emerging applications. The strategy of sequence control in polymer synthesis has been introduced to tailor the primary structures of LCPs as well as their phases and orders. By incorporating mesogenic motifs rich in shape, order, and interaction into LCPs, novel bulk and interfacial structures on hierarchical scales are anticipated. The intrinsic features and fascinating properties of LCPs enable them to find potential applications in emerging areas including integrated circuits, lasing, environment, and energy, implying compelling opportunities for LCPs in fundamental science and transformative technologies.

Cholesteric Liquid Crystalline Polyether with Broad Tunable Circularly Polarized Luminescence

Strong circularly polarized luminescence (CPL) with high purity and broad tunability was achieved in a new type of polyether-based cholesteric liquid crystalline (CLC) copolymers comprising chiral cholesteryl, nematic mesogens, and cross-linkable moieties. The phase boundary diagram of the copolymers was constructed, wherein the CLC phase in a wide composition and temperature window down to room temperature was achieved. Furthermore, reflection colors across the infrared and visible light regions can be continuously tuned by altering composition or temperature, which can be further fixed in the flexible CLC elastomer by photo-cross-linking. Introducing achiral dyes in the CLC thin films can generate strong CPL with distinct handedness and high dissymmetry factors (g_lum). Particularly, the left-handed full-color CPL is obtained by selective circularly polarized scattering in the spectral region outside the band gap of the CLC thin film, and the right-handed CPL with g_lum up to -1.05 is achieved within the band gap of the CLC thin film following the selective circularly polarized reflection mechanism. This type of CPL active material is expected to have potential applications in liquid crystal display and photonics.

100th Anniversary of Macromolecular Science Viewpoint: Opportunities for Liquid Crystal Polymers in Nanopatterning and Beyond

Liquid-crystal polymers (LCPs) integrate at a molecular level the characteristics of two important material classes, i.e., liquid crystals (LCs) and polymers. As a result, they exhibit a wide variety of intriguing physical phenomena and have useful properties in various settings. In the nearly 50 years since the discovery of the first melt-processable LCPs, there has been a remarkable expansion in the field encompassing the development of new chain architectures, the incorporation of new classes of mesogens, and the exploration of new properties and applications. As engineering materials, LCPs are historically best known in the context of high strength fibers. In a more contemporary study, the pairing of LC mesophase assembly with block copolymer (BCP) self-assembly in LC BCPs has resulted in a fascinating interplay of ordering phenomena and rich phase behavior, while lightly cross-linked networks, LC elastomers, are extensively investigated as shape memory materials based on their thermomechanical actuation. As this Viewpoint describes, these and other examples are active areas of research in which new, compelling opportunities for LCPs are emerging. We highlight a few selected areas that we view as being potentially significant in the near future, with a particular emphasis on nanopatterning. Here, the ability to readily access small feature sizes, the fluidity of the LC mesophase, and LC-based handles for achieving orientation control present a compelling combination. Opportunities for LCPs are also presented under the broad rubric of "beyond nanopatterning", and we discuss relevant challenges and potential new directions in the field.