RUI: Orientational Relaxation of Chromophore Order in Nonlinear Optical Block Copolymers

技术：用于光学信号处理的非线性光学材料扩展到聚合物，它提供了比传统晶体材料更大的组成灵活性。聚合物中的光学功能是通过将发色团与透明聚合物主体混合并对材料进行电极化以诱导生色团的非中心对称有序化来实现的。到目前为止，研究主要局限于均聚物宿主，它们为调节发色团微环境提供了有限的选择。实现稳定偶极有序化的另一种有前景的方法是选择性地将生色团包裹在嵌段共聚物的一个区域中。本项目以PS-b-P4VP嵌段共聚物为模型体系，通过二次谐波产生和偏振吸收光谱实验，详细测量了嵌段共聚体中发色团的极化诱导有序参数和极化后取向弛豫时间。我们将使用共价键合和氢键键合的方法来研究键合模式对取向弛豫的影响。这个模型系统将有助于探索通过适当选择嵌段共聚体系，极化和弛豫的不同要求可以在多大程度上解耦。非技术：非线性光学材料是基于互联网的通信的光纤数据传输等应用所不可或缺的。传统的材料是结晶的，在制造成本和最终带宽能力方面都是有限的。聚合物材料是一种在设计和成本上提供灵活性的替代材料，但它们在已部署设备中的长期稳定性尚未完全确定。一个有希望的聚合物类别是嵌段共聚物，它是化学上不同的聚合物在纳米尺度上的有效有序组合。这项研究将利用基于激光的实验来测量具有用于电信设备的潜力的嵌段共聚材料的长期稳定性。该项目将在德鲁大学一个强有力的跨学科研究项目中雇用物理和化学本科生。这将为他们提供薄膜表征、激光和相关光子技术方面的宝贵经验，所有这些都是高科技行业和研究生培训计划所需要的。学生还将受益于与包括约翰·霍普金斯大学和威斯康星大学在内的主要研究机构的合作者进行互动。

TECHNICAL:Nonlinear optical materials for applications in optical signal processing is extended to polymers, which offer greater compositional flexibility than conventional crystalline materials. Optical functionality in a polymer is incorporated by blending a chromophore with a transparent polymer host and electrically poling the material to induce a noncentrosymmetric ordering of chromophores. Research to date has largely been confined to homopolymer hosts, which offer limited options for tuning the chromophore micronenvironment. A promising alternate approach to achieving stable dipolar ordering is to selectively encapsulate the chromophore in one domain of a block copolymer. In this project, second harmonic generation and polarized absorption spectroscopy experiments will be used to make detailed measurements of the poling-induced order parameter and the post-poling orientational relaxation times of chromophores encapsulated in block copolymer domains, using the PS-b-P4VP block copolymer as a model system. Covalent and hydrogen-bonding schemes for selective chromophore encapsulation will be used to investigate orientational relaxation as a function of bonding mode. This model system will help probe to what extent the disparate requirements for poling and relaxation can be decoupled through appropriate choice of block copolymer system.NON-TECHNICAL:Nonlinear optical materials are integral to applications such as fiber optic data transmission for Internet-based communication. Traditional materials are crystalline, which are limited both in cost of fabrication and ultimate bandwidth capability. Polymeric materials are an alternative that offer flexibility in design and cost, but their long-term stability in deployed devices has not been fully established. One promising polymer category is that of block copolymers, which are effectively ordered combinations of chemically distinct polymers on the nanoscale. This research will utilize laser-based experiments to measure the long-term stability of block copolymer materials that have the potential for use in telecommunications devices. The project will employ physics and chemistry undergraduates in a vigorous interdisciplinary research program at Drew University. This will provide them with valuable experience in thin-film characterization, lasers, and related photonic technologies, all of which are in demand by high-technology industries and graduate training programs. Students will also benefit from interacting with collaborators at major research institutions, including the Johns Hopkins University and the University of Wisconsin.