手性金属纳米结构诱导不对称光聚合策略高效合成光学活性聚二乙炔功能材料及其手性微图案化

手性共轭聚合物具有独特的物理化学性质和功能，已成为当今高分子科学领域研究的热点之一。目前限制手性共轭聚合物材料应用的关键科学问题包括：共轭聚合物手性结构和性能的精确调控、手性功能微图案的大面积规模化精准构筑等。本申请拟以具有手性光学响应的金属纳米结构为新的手性源，发展从非手性二乙炔单体出发，利用非偏振紫外或可见光辐照，高效选择性合成光学活性聚二乙炔功能材料的新方法；揭示手性金属纳米结构在不对称光聚合反应中的诱导作用机制，精准合成具有不同宏观光学活性的聚二乙炔功能材料。本申请拟结合圆偏振光以及超手性光辐照技术，进一步提高二乙炔单体不对称光聚合反应效率和选择性，实现高光学活性聚二乙炔功能材料的可控制备。在此基础上，与传统微加工技术相结合，精确构筑具有复杂手性微纳结构的光学活性聚二乙炔功能微图案，为其在对映体选择传感、圆偏振发光器件等领域的应用提供理论基础和关键技术。

Chirality plays an important role in chemistry, materials and biology systems. In particular, the introduction of chiral nanostructure into conjugated polymer materials is expected to induce novel optical, electrical and magnetic properties, and tremendous potential application in enantioselective recognition and separation, asymmetrical catalysis, and biological medicine. However, there are several scientific challenges including the accurate chiral structural control and the precise modulation of chiraloptical properties, large-scale construction of chiral micro-patterns with tailorable optical properties and so on. Our group has been focused on the synthesis of chiral conjugated polymer materials for many years, and demonstrated the successful synthesis of chiral polydiacetylene (PDA) from achiral monomer by means of circular polarized light (CPL)-triggered asymmetric photo-polymerization. But in most cases, only a small enantiomeric excess could be obtained by above method since their anisotropy (g) factors is very small (<0.001). Meanwhile, the optical activity, enantioselective recognition ability and the circularly polarized luminescence of the prepared chiral PDA films all were low, limited their practical applications. Recently, we found that, assisted with chiral silver nanoparticles as the sole chiral source, the highly enantioselective photo-polymerization of achiral diacetylene monomer could be readily achieved upon unpolarized UV irradiation, and optical activity of PDA films strongly depended on not only the optical activity of chiral plasmonic nanoparticles but also the wavelength of the incident unpolarized UV light. On basis of above results, we will focus on the enantioselective photo-polymerization of achiral diacetylene monomer by using chiral silver or Au plasmonic nanostructures as the sole chiral source. In terms of application, we will develop a novel facial and effective approach to achieve symmetry breaking in photo-polymerization reactions by the combination with chiral plasmonic nanostructures, and inducible optical activity, enantioselective recognition ability and the circularly polarized luminescence of the resulting PDA films are estimated to be greatly enhanced due to the local surface plasmon resonance. We will study the effect of chiraloptical properties of plasmonic nanostructures, the wavelength and irradiation time on the inducible optical activity of the final PDA films and their resulting enantioselective recognition ability and circularly polarized luminescence, and explore the possible mechanism of enantioselective photo-polymerization assisted with chiral plasmonic nanostructures. It is anticipated that the optical asymmetry of the final PDA films may be further enhanced by irradiation with circularly polarized light or superchiral light. Moreover, we expect to construct programmable chiral PDA micro-patterns with tailorable circularly polarized luminescence by a modified double exposure technique, toward practically high-performance bio-sensing and chiral nanophotonics devices. Above studies may not only open the pathways for fabricating programmable micro-patterns of chiral conjugated polymer with tailorable chiraloptical properties, but also is highly valuable for deeper understanding of symmetry breaking in photochemical reaction and the origin of homochirality in living matter.