EAGER: Confined Self Assembly of Fully Conjugated Rod-Rod Diblock Copolymers in Nanofibers

EARLY概念探索性研究资助（EAGER）提供资金，研究完全共轭的棒-棒二嵌段共聚物在纳米纤维中的受限自组装。纳米纤维将通过一种称为静电纺丝的工艺制造，该工艺使用强电场来拉长和细化聚合物溶液射流，从而形成具有近纳米级直径（50-500 nm）的纤维。棒-棒嵌段共聚物联合收割机将棒状聚合物的液晶有序化（在1-10 nm的长度尺度下）和螺旋-螺旋嵌段共聚物的微相分离（在10-100 nm的长度尺度下）的物理学与形成分级有序材料的潜力相结合。溶剂蒸发速率和拉伸变形（在静电纺丝过程中）对自组装结构在两个长度尺度的影响将被研究。纳米纤维中的组装将使用透射电子显微镜以及小角度和广角X射线散射进行表征。将进行溶液浇铸膜中自组装的类似研究作为参考。如果成功，这项工作将为高效有机太阳能电池的设计提供新的活性材料。特别地，共轭聚合物嵌段（具有适当的电子性质）的自组装将在太阳能电池的光吸收活性层中提供电子供体和电子受体材料的周期性界面。这将确保有效产生光电流所必需的结合电子和空穴（在光激发时产生）的及时解离。将完全共辄的棒-棒二嵌段共聚物限制在纳米纤维内将具有两个益处。首先，它将提供开发一类新材料的机会，即有机半导体的可穿戴织物。 其次，在静电纺丝过程中的强拉伸变形和快速溶剂蒸发与纳米纤维中的物理圆柱形限制相结合，将提供获得在平衡系统或膜中可能不可能的新型自组装结构的途径。

This EArly-concept Grant for Exploratory Research (EAGER) provides funding to study the confined self assembly in nanofibers of fully conjugated rod-rod diblock copolymers. Nanofibers will be fabricated via a process called electrospinning that uses a strong electric field to elongate and thin a polymer solution jet enabling the formation of fibers with near nanoscale diameters (50-500 nm). Rod-rod block copolymers combine the physics of liquid crystalline ordering of rod-like polymers (at the length scale of 1-10 nm) and microphase-separation of coil-coil block copolymers (at length scale of 10-100 nm) with the potential of forming hierarchically ordered materials. The effects of solvent evaporation rate and extensional deformation (during electrospinning) on self assembly structures at both length scales will be studied. The assembly in nanofibers will be characterized using transmission electron microscopy as well as small and wide angle x-ray scattering. Similar studies on self assembly in solution-cast films will be conducted as reference. If successful, this work will provide a novel active material for the design of high efficiency organic solar cells. In particular, self assembly of conjugated polymeric blocks (with appropriate electronic properties) will provide periodic interfaces of electron donor and electron acceptor materials in the light absorbing active layer of solar cells. This will ensure timely disassociation of bound electron and hole (created on photo-excitation), necessary to produce photocurrent efficiently. Confining fully conjugated rod-rod diblock copolymers within nanofibers will have two benefits. First, it will provide the opportunity to develop a new class of materials, namely, wearable fabrics of organic semiconductors. Secondly, the strong extensional deformation and fast solvent evaporation during electrospinning combined with the physical cylindrical confinement in nanofibers will provide access to novel self assembled structures that may not be possible in equilibrium systems or films.