Polyoxometalate-Containing Diblock Copolymers: Synthesis, Self-Assembly and Applications

技术综述：多金属氧酸盐(POMS)是一种具有纳米尺寸的分子阴离子簇合物，近年来的一个令人兴奋的发展是，新的化学终于允许POM簇合物合理和可控地并入有机共轭体系。现在可以想象下一代含有POM的杂化材料，它提供形态控制并具有有序的微(和/或纳米)结构。这一提议实际上旨在制备前所未有的杂化两嵌段共聚物，其中一个柔性嵌段包含POM团簇作为侧链，另一个嵌段是？？共轭聚合物。一个需要仔细解决的基本问题是，附着的巨型离子团簇如何影响自组装过程，以及可能产生哪些新的形态。一个要瞄准的具体应用是太阳能电池。如果杂化棒-线圈两嵌段共聚物能够实现相分离的双连续网络，其中POM团簇聚集在一个区域，而共轭？A链段排列在另一个区域，则可以实现高效的光致电荷分离和输运。因此，这种杂化两嵌段共聚物是一种潜在的新型高效光伏材料。除了通过两嵌段共聚物自组装实现高效的电荷传输外，还明智地设计了包括向列相和盘状液晶相在内的亚相液晶顺序，以进一步改善电荷传输性能。非技术综述：能源短缺是21世纪工业化国家面临的最重要问题之一。利用太阳能电池获取太阳能是最具吸引力和环境友好的方法之一。虽然传统的基于半导体的太阳能电池已经存在了半个多世纪，但这些电池仍然过于昂贵，无法广泛应用。与传统太阳能电池相比，聚合物太阳能电池具有制造成本低、重量轻、衬底柔性好、机械性能好等优点。聚合物太阳能电池的问题一直是电能转换效率低。这一建议旨在开发概念上的新型杂化聚合物，其中接受电子的无机团簇与有机嵌段共聚物结合在一起，以促进光致电荷分离和随后的电荷传输。这些杂化聚合物不仅代表了一种可以解决基本科学问题的全新类型的材料，而且也是潜在的高效光伏材料。聚合物太阳能电池研究的突破带来的经济和社会影响是巨大的。S项目的多学科性质将为包括本科生和高中生在内的学生提供在不同领域发展智力和技术技能的充分机会。该项目还将使PI能够继续扩大其在大堪萨斯城大都市区更多代表不足和处境不利的学生的服务范围。

TECHNICAL SUMMARY: One exciting development in recent years on polyoxometalates (POMs), a fascinating type of molecular anionic cluster with sizes in the nanometer region, is that new chemistry has finally allowed the rational and controlled incorporation of POM clusters into organic ?à-conjugated systems. It is now conceivable to envision next-generation POM-containing hybrids which offer morphological control and possess ordered micro- (and/or nano-) domain structures. This proposal indeed aims at preparing unprecedented hybrid diblock copolymers with one flexible block containing POM clusters as pendants and the other block a ?à-conjugated polymer. One fundamental question to be carefully addressed is how attached ¡§giant¡¨ ionic clusters affect the self-assembly process and what new morphologies may result. One specific application to be targeted is for solar cells. If phase-separated bicontinuous networks can be realized from hybrid rod-coil diblock copolymers where the POM clusters aggregate in one domain while conjugated ?à-segments arrange in the other, efficient photoinduced charge separation and transport may be attainable. Such hybrid diblock copolymers are thus potentially new efficient photovoltaic materials. In addition to achieving efficient charge transport through diblock copolymer self-assembly, sub-phase liquid crystal order, including both nematic and discotic liquid crystalline phases, are judiciously designed to further improve charge transporting properties. NON-TECHNICAL SUMMARY: Energy shortage is one of the most important issues facing industrialized nations in the 21st century. Harvesting solar energy using solar cells is one of the most appealing and environmentally friendly approaches. While conventional semiconductor-based solar cells have been in existence for over half a century now, these cells are still too expensive for broad applications. Compared to traditional solar cells, polymer-based cells enjoy a variety of advantages such as low fabrication cost, light weight, substrate flexibility, good mechanical properties, etc. The issue with polymer solar cells has been the poor power conversion efficiency. This proposal aims at developing conceptually new hybrid polymers where electron-accepting inorganic clusters are brought together with organic block copolymers to facilitate photo-induced charge separation and subsequent charge transport. These hybrid polymers not only represent a brand new type of material on which fundamental scientific questions can be addressed, but are also potentially highly efficient photovoltaic materials. The economic and social impact of a breakthrough in polymer solar cell research is enormous. The project¡¦s multidisciplinary nature will offer students, including undergraduates and high school students, ample opportunities to develop intellectual and technical skills in a diverse area. The project will also allow the PI to continue to expand his outreach to more underrepresented and disadvantaged students in the greater Kansas City metropolitan area.