Photopolymerization Induced Phase Transitions & Evolution of Morphology Landscape in Holographic Polymer Dispersed Liquid Crystals and Photonic Cyrstals

光聚合诱导的相变

• 批准号: 0514942
• 负责人: Thein Kyu
• 金额: $ 33.6万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0514942&HistoricalAwards=false
• 关键词: Photopolymerization; Induced; Phase; Transitions; Evolution

TECHNICAL SUMMARY:The present award focuses on the directional mesophase ordering in mixtures of polymers and liquid crystals subjected to intensity gradient created by optical interference during fabrication of active and passive-type holographic polymer dispersed liquid crystals and photonic crystals. Photopolymerization induced phase transition is a phenomenon driven by photochemical reaction, in which directional phase ordering occurs by virtue of light intensity gradient during photo-patterning. The holographic photo-polymerization technique operates based on the principles of optical interference of multiple waves that has been applied to fabrication of holographic polymer dispersed liquid crystals and photonic crystals, as well as development of related electro-optical devices. The electro-optical switching performance and diffraction efficiency of the holographic imaging critically depends on the optimization of the two-phase structure within the stripes and/or arrays of spheres. The dynamics of structure ordering again depends not only on thermodynamics and kinetics of phase transition, but also on the confinement effect caused by the nano-size within these striations. The understanding of nano-science associated with anisotropic phase separation and diffusion within the confined nano-patterns of polymer dispersed liquid crystals based holographic films is of paramount importance for practical applications. The proposed studies entail several trust areas; (i) photopolymerization-induced phase transitions involving phase separation, crystallization, and mesophase ordering, (ii) coarse-grain modeling of non-equilibrium non-linear dynamics of polymer photonic crystal systems containing liquid crystals and conductive organic crystals, (iii) effects of thermal gradient and light intensity gradient on directional ordering, and (iv) confinement effect on microstructure development in 2-D and 3-D photonic band-gap structures.NON-TECHNICAL SUMMARY Polymeric photonic band-gap structures operate on a similar principle to that of electronic transistors or semiconductor band-gap materials, except that information is transmitted through light which is faster than electrons, and thus the development of such technology is vital to optical computers and chips for telecommunications. In addition, the proposed studies on the arrays of columnar cavities, if successful, will lead to immediate applications, e.g., (1) fabrication of the microporous contact lens would have high impact on the current market by virtue of excellent oxygen permeability. The microporous arrays, upon filling with water (i.e., tear), would perform like microlens with enhanced vision similar to the compound eyes of some insects and thus the proposed nano-porous films may be used as bio-mimetic membranes. (2) In the case of miscible polymer blends, the refractive index gradient structure can be created to produce thin flat converging lens of optical quality which has great advantageous over the existing converging lens that invariably has convex curvatures. The proposed flat converging lens may be useful for imaging where space is limited. The Principle Investigator's (PI) group will develop a web-based experimentation on holographic imaging as part of the distant-learning program of the Akron Global Polymer Academy AGPA at University of Akron. The enriched morphologies in polymer soft matter share the common origin with a variety of patterns in nature such as snow-flakes, ice crystals, metal welding, and coating growth in electrochemical deposition. Growth of snow-flake-like structures will be demonstrated in life-mode during class-room teaching; this subject matter would be of interest to students of all ages (K12) and also to the general public. The PI's group will continue their collaboration with Dr. Tim Bunning's group at Wright-Patterson Air Force Base. Although the PI's group is reasonably equipped with the holographic optical equipment (primarily Argon ion laser) and time-resolved light scattering for in-situ monitoring of the diffraction efficiency, the Air Force group is better equipped with UV laser which certainly gives added flexibility in the design and fabrication of photolithography with commercially available photo-curatives and matrix resins. The PI's group has demonstrated capability of theoretical modeling and simulation on the formation of microstructures in holographic polymer dispersed liquid crystals and photonic crystals, which is of immense interest to our counterpart at the Air Force.

技术摘要：目前的奖项着重于在制造活性和被动型全息聚合物分散液晶和光子晶体的聚合物和液晶混合物中的定向中间相排序。光聚聚合诱导的相变是由光化学反应驱动的一种现象，在该现象中，在照片造影过程中，通过光强度梯度进行方向相排序。全息光聚合技术基于多个波的光学干扰原理运行，这些原理已应用于全息聚合物分散的液晶和光子晶体的制造，以及相关的电流设备的开发。全息成像的电流切换性能和衍射效率在很大程度上取决于条纹和/或球体阵列内两相结构的优化。结构排序的动力学再次不仅取决于相变的热力学和动力学，而且还取决于这些条纹中纳米大小引起的限制效应。对基于各向异性相分离的纳米科学的理解和基于聚合物分散的基于液晶的液晶全息薄膜的纳米模式中的扩散至关重要。拟议的研究需要几个信托领域。 （i）光聚合剂诱导的相跃迁涉及相分离，结晶和中间体序列，（ii）含有液体晶体的非平衡非平衡非平衡非平衡非线性动力学的粗晶粒模型，这些动力学含有液晶和导电性有机体晶体（III）的影响和光强度梯度对台面和光强度对介质和光强度对介质的影响（III）的影响（III）（III）（III）（IIV）对介质和（IV）的影响（IV）（IV）（IV）（IV）（IV）（IV） 3-D光子带隙结构。非技术摘要聚合物光子光子带隙结构与电子晶体管或半导体带隙材料相似的原理运行，除了通过光传输的信息比电子更快，因此此类技术的开发对于电脑和芯片的开发至关重要。此外，关于柱状腔阵列的拟议研究（如果成功）将导致立即应用，例如（1）（1）微孔隐形眼镜的制造将凭借出色的氧气渗透性对当前市场产生很大影响。微孔阵列充满水（即撕裂）时，像微片一样具有类似于某些昆虫复合眼睛的视力增强的微片，因此提出的纳米孔膜可以用作生物模拟的膜。 （2）在混杂的聚合物混合物的情况下，可以创建折射率梯度结构来产生光学质量的薄扁平聚合透镜，与现有的融合透镜相比，它总是具有凸曲率的情况。所提出的平坦融合镜头可能对空间有限的成像很有用。主要研究者（PI）小组将开发基于网络的全息成像实验，这是阿克伦大学阿克伦全球聚合物学院AGPA遥远学习计划的一部分。聚合物软物质中富集的形态与自然界中的各种模式共享共同的起源，例如雪花，冰晶，金属焊接和电化学沉积中的涂料生长。在课堂教学期间，将在生命模式中展示类似雪花的结构的增长；所有年龄段的学生（K12）以及公众都感兴趣的主题。 PI的小组将继续与蒂姆·邦宁（Tim Bunning）博士在赖特 - 帕特森空军基地的小组合作。尽管PI的小组合理地配备了全息光学设备（主要是氩离子激光器）和时间分辨的光散射，可用于对衍射效率的原位监控，但空军组更好地配备了紫外线激光器，肯定会在具有商业化的照片和Matrix resins和Matrix resins的设计和制造中增加灵活性。 PI的组已经证明了理论建模和模拟对全息聚合物分散液晶和光子晶体中微观结构的形成的能力，这对我们在空军的对应物引起了极大的兴趣。