CAREER: Toward Photocontrol of Conjugated Polymer Emission: Modulation of Fluorescence Properties in Photochromic Poly(p-phenylenevinylene) Derivatives

在化学系有机和大分子化学项目的支持下，威廉玛丽学院的Elizabeth J. Harbron教授将开发光致发光（PL）聚合物，其荧光和发射颜色可以通过垂坠基团的光激活异构化来调节。这些材料的潜在应用包括光开关和记忆存储。本文将合成几种新型光致变色聚对苯乙烯（PPV）衍生物，并在溶液和薄膜中进行研究。研究的第一个领域将是衍生物，其中从聚合物主链的能量转移选择性地发生到只有一种形式的垂坠光色素。因此，当光色素处于一种形式时，PPV将以未淬灭的强度发射，而当光色素处于谐振形式时，由于有效的能量传递，PPV将不发射。这种聚合物将促进荧光信号的真开/关读取，也将使聚合物薄膜中的全光学写入/读取/擦除循环成为可能。进一步的研究将集中在通过光致光色素排列控制发射强度，这将在单分子水平上进行研究。时间分辨荧光技术将用于研究所有的光致变色PPV衍生物，以研究PPV链内激子迁移和能量转移到悬垂的光致变色受体之间的相互作用。不同光致变色侧链的测量结果将用于确定最佳光开关聚合物所需的PPV和侧链能量特性的组合。在有机和大分子化学计划颁发的CAREER奖的支持下，Harbron教授将研究简单的、可综合使用的材料，以提供对开关现象过程的基本理解，并通过光学测量和实验提供真正的好处。提议的活动的更广泛的影响主要是在聚合物，有机合成和光物理的本科生训练。Harbron教授将继续让本科生研究人员参与项目，并在ACS期刊上发表文章。她还提议为高中生开设暑期课程。

With the support of the Organic and Macromolecular Chemistry Program in the Chemistry Division, Professor Elizabeth J. Harbron of the College of William and Mary will develop photoluminescent (PL) polymers whose fluorescence and emission color can be modulated by light-activated isomerization of pendant groups. Potential suggested applications for these materials include photo switching and memory storage. Several new photochromic poly (p-phenylenevinylene) (PPV) derivatives will be synthesized and studied in solution and film. The first area of investigation will be a derivative in which energy transfer from the polymer backbone occurs selectively to only one form of the pendant photochrome. Thus, PPV will emit with unquenched intensity when the photochrome is in one form and will not emit when the photochrome is in its resonant form due to efficient energy transfer. This polymer will facilitate true on/off reading of a fluorescence signal and will also enable all-optical write/read/erase cycles in polymer films. Additional studies will focus on control of emission intensity through photoinduced photochrome alignment, which will be studied on the single molecule level. Time-resolved fluorescence techniques will be employed to study all photochromic PPV derivatives to investigate the interplay between exciton migration within the PPV chain and energy transfer to pendant photochromic acceptors. The results of measurements with different photochromic side chains will be used to identify the combination of PPV and side chain energetic characteristics required for an optimal photoswitch polymer.. With the support of this CAREER award from the Organic and Macromolecular Chemistry Program, Professor Harbron will work with materials that are simple, and synthetically accessible to provide a fundamental understanding of the processes involved in switching phenomena with the real benefit being provided by the optical measurements and experiments. Broader impacts of the proposed activity are primarily the training of undergraduates in polymers, organic synthesis, and photophysics. Professor Harbron will continue getting undergraduate researchers involved in projects and in publishing in ACS journals. She has also proposed summer course for high school students.