Light Driven Transport and Mechanistic Aspects of Relief Structure Formation in Azopolymer Films

拟议的研究的主要目标是进一步的光驱动聚合物的质量传输的偶氮官能化聚合物膜的新现象的系统调查，在适度的光强度和大大低于其玻璃化转变温度。 在偶氮苯功能化聚合物薄膜上实现了大调制深度（6000 A）表面浮雕光栅（SRG）的全光全息制作，无需任何预处理和/或后处理。 系统的调查，这种新的光驱动的表面变形和SRG形成过程中的各种偶氮苯官能化聚合物系统已经建立了一些关键的研究结果和结论。 这包括对这种全光学过程的基本理解，机制和识别可能的器件应用。 该过程是通过光场梯度的聚合物质量传输的结果，并且在聚合物膜表面处引发。 人们提出了许多驱动力的模型和机制。 由PI开发的梯度力模型描述了在无定形偶氮苯聚合物膜的这种独特的光加工过程中观察到的宏观行为。 该模型利用一个单一的粘弹性参数提供了机会，进一步连接实验建立的变形行为的分子水平的过程和分子结构的细节。 通过研究特定写入条件下定制大分子中的SRG过程，可以将光增塑变形层的粘弹性参数与分子结构细节相关联，这一重点进一步探索了先前NSF资助下发现的异常光驱动输运现象。 在这种全光学过程中，所需的微和nonopatterning可以进行几乎所有的聚合物与一些偶氮官能化，在适度的光强度没有任何后处理。 了解这类材料的基本物理过程可能会导致光子技术的重要设备和制造工艺。 预期所需图案的直接铭文将作为使用这种不寻常的光学和聚合物物理现象的课堂的简单和戏剧性的演示和学习工具。

The principal objective of the proposed research is to further the systematic investigation of the novel phenomenon of photodriven polymer mass transport in azo functionalized polymer films, at modest light intensities and substantially below their glass transition temperatures. All-optical holographic fabrication of large modulation depth (6000A) surface relief gratings (SRG) have been achieved on azobenzene-functionalized polymer films, without any pre- and/or post-processing. A systematic investigation of this novel photodriven surface deformation and SRG formation process in a variety of azobenzene functionalized polymer systems has established a number of critical research findings and conclusions. This includes the fundamental understanding, the mechanism and identifying possible device applications of this all-optical process. The process is a result of polymer mass transport by optical field gradients and is initiated at the polymer film surface. A number of models and mechanisms for the driving force have proposed. The gradient force model developed by the PI describes the macroscopic behavior observed in this unique photofabrication process in amorphous azobenzene polymer film. This model utilizing a single viscoelastic parameter has presented the opportunity to further connect the experimentally established deformation behavior to molecular level processes and molecular structural details. The viscoelastic parameter of the photoplasticized deformation layer can be correlated with the molecular structural details by investigating the SRG process in tailored macromolecules under selected writing conditions.The focus of this further explore the unusual light-driven transport phenomenon discovered under prior NSF funding. In this all-optical process, desired micro and nonopatterning may be carried out in practically all polymers with some azo functionalization, at modest light intensities without any post processing. Understanding the fundamental photophysical processes in this class of materials may lead to important devices and fabrication processes for photonic technologies. Direct inscription of desired patterns is expected to serve as a simple and dramatic demonstration and learning tool for the classroom using this unusual optical and polymer-physical phenomenon.