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

在化学系有机化学和高分子化学项目的支持下，威廉和玛丽学院的伊丽莎白·J·哈布伦教授将开发可通过侧基的光激活异构化来调节荧光和发射颜色的光致发光(PL)聚合物。这些材料的潜在建议应用包括光开关和存储器存储。合成了几种新型的光致变色聚对苯乙炔(PPV)衍生物，并在溶液和薄膜中进行了研究。第一个研究领域将是一种衍生物，其中能量从聚合物主链选择性地转移到只有一种形式的侧链光色素上。因此，当光致变色剂为一种形式时，PPV将以不熄灭的强度发射，而当光致变色剂处于其共振形式时，由于有效的能量传递，PPV将不会发射。这种聚合物将有助于荧光信号的真正开/关读取，并且还将在聚合物薄膜中实现全光写入/读取/擦除循环。更多的研究将集中在通过光诱导的光致变色排列来控制发射强度，这将在单分子水平上进行研究。时间分辨荧光技术将被用来研究所有光致变色PPV衍生物，以研究激子在PPV链中的迁移和向悬挂的光色受体的能量转移之间的相互作用。不同光致变色侧链的测量结果将用于确定最佳光致开关聚合物所需的PPV和侧链能量特性的组合。在有机化学和高分子化学项目的这一职业奖项的支持下，哈布伦教授将致力于使用简单且可合成的材料，以提供对开关现象所涉及的过程的基本了解，并从光学测量和实验中获得真正的好处。拟议活动的更广泛影响主要是对本科生进行聚合物、有机合成和光物理方面的培训。哈布伦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.