Controlling topological defects in liquid crystals (LCs) is an essential element in the development of areas such as directed self-assembly and micropatterning materials.

Chiral nematic liquid crystals (CLCs), with a unique helix structure, have attracted immense recognition over the last few decades owing to the abundant presence in natural phenomena and their diverse applications. However, the optical properties of CLC are usually hindered by the abundance of the so-called fingerprint domains. Up to now, studies have worked on controlling the in-plane orientation of the lying helix through surface rubbing and external stimuli. It remains challenging to achieve a steady and uniform lying helical structure. Here, by varying the surface anchoring strength, a uniform lying helical structure with long-range order is achieved as thermodynamically stable state without any external support. Poly (6-(4-methoxy-azobenzene-4’-oxy) hexyl methacrylate) (PMMAZO)—a liquid crystalline polymer—is deposited onto the silicon substrate to fine-tune the surface anchoring. By changing the grafting density of PMMAZO, both pitch size and morphology of the lying helical structure can be controlled. As the grafting density increases, the enhanced titled deformation of helical structure suppresses the pitch size of CLC at the same cell thickness; as the cell thickness increases, the morphology transition from long-range order stripes to small fingerprint domains is facilitated.

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It has been shown that controlling the morphology and composition of Pt-based nanocrystals can effectively enhance catalytic properties. We report a detailed study on the impact of using co-reducing agents in the galvanic replacement reaction (GRR) between Ag shell templates and Pt precursors to better control the morphology, composition, and resulting performance of the fabricated Pt-based catalysts. Mesoporous silica-supported silver shell-coated gold nanodumbbell nanostructures (AuNDB@Ag@mSiO2) are synthesized via reducing silver ions which have penetrated through the mSiO2 layer and then be deposited on the surface of the AuNDBs. These are used as templates and the morphology and optical properties of these templates can be adjusted by altering the amount of Ag+ in the depositing condition. The mSiO2 layer shows some flexibility and does not influence the silver shell formation on the surface of AuNDBs. Additionally, the thickness of the silver shell of the template and the strength of the reducing agent used in the GRR impact the morphology, composition, and catalysis performance of the resulting Pt-based catalysts. A plausible mechanism on those observations is studied and discussed.

The three-dimensional nanostructure of blue phase liquid crystals (BPLCs) are becoming the spotlight of soft matter research in electro-optic devices, sensors, photonic crystals, and 3D lasers. The polymerization of the...