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Hybrid fluorescent liquid crystalline composites: directed assembly of quantum dots in liquid crystalline block copolymer matrices
摘要： Hybrid ?uorescent liquid crystalline (LC) composites containing inorganic quantum dots (QDs) are promising materials for many applications in optics, nanophotonics and display technology, combining the superior emission capability of QDs with the externally controllable optical properties of LCs. In this work, we propose the hybrid LC composites that were obtained by embedding CdSe/ZnS QDs into a series of host LC block copolymers of di?erent architectures by means of a two-stage ligand exchange procedure. The ABA/BAB triblock copolymers and AB diblock copolymers with di?erent polymerization degrees are composed of nematogenic phenyl benzoate acrylic monomer units and poly(4-vinylpyridine) blocks, which are capable of binding to the QD surface. Our results clearly show that the spatial distribution of QDs within composite ?lms as well as the formation of QD aggregates can be programed by varying the structure of the host block copolymer. The obtained composites form a nematic LC phase, with isotropization temperatures being close to those of the initial host block copolymers. In addition, the in?uence of the molecular architecture of the host block copolymers on ?uorescence properties of the obtained composites is considered. The described strategy for the QD assembly should provide a robust and conventional route for the design of highly ordered hierarchical hybrid materials for many practical applications.
关键词： liquid crystalline block copolymer matrices,ligand exchange procedure,fluorescence properties,CdSe/ZnS QDs,nematic LC phase,Hybrid ?uorescent liquid crystalline composites,quantum dots
更新于2025-09-23 15:19:57
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Orientation and Morphology Control of Liquid Crystalline Block Copolymer Thin Film by Liquid Crystalline Solvent
摘要： The critical challenge to engineer the morphological structures in the strongly phase segregated block copolymer thin film is to overcome the preferential wetting of the blocks at interface and direct the self-assembly process. Herein, we utilize surface activity and selective solvation of a nematic (N) liquid crystalline (LC) solvent, 5CB, to facilely alter the LC anchoring and the orientation of the nano-phase separated structures of the smectic-nematic (S-N) LC block copolymer thin film. For the neat S-N diblock copolymer thin film, the nano-structures are parallel aligned. In contrast, with continuous introduction of 5CB into the system, the orientations of the characteristic nano-structures and the morphologies of the LC thin film can be consequently changed, yielding the perpendicularly oriented lamellar or cylindrical structures with the feature size below 10 nm. The homeotropic alignment of the 5CB nematics near the air interface plays a critical role to induce this unique behavior in the S-N/5CB systems, which offers an opportunity to fine-tune the interfacial structures and the morphological patterning in the block copolymer thin film.
关键词： Thin film,Self-assembly,5CB,Liquid crystalline block copolymer,Nano-structures
更新于2025-09-10 09:29:36