Spatio-Temporal Emergence of Morphological Patterns in Liquid Crystalline Polymer and Rigid-Rod Polymer Systems during Solidification

液晶聚合物和刚性棒聚合物体系在凝固过程中形态模式的时空出现

• 批准号: 0209272
• 负责人: Thein Kyu
• 金额: $ 30万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0209272&HistoricalAwards=false
• 关键词: Spatio; Temporal; Emergence; Morphological; Patterns

The present proposal entails experimental and theoretical elucidation of (i) dynamics of hollow fiber (or nano-tube) formation during solidification of main chain liquid crystalline polymers (MCLCP) and/or rigid-rod polymer solution, (ii) dynamics of nano-porous membranes of monomeric mesognes during pattern polymerization, (iii) dynamics of microfibril formation during dry-jet spinning, and (iv) hybrid-composites. The well-established time-dependent Ginzburg-Landau TDGL (Model C) will be applied in conjunction with the advection term for the tracking of solvent evaporation and flow. The physical significanace of all parameters pertaining to the governing non-linear reaction-diffusion equations will be clarified, and their predictive capabilitieis will be demonstrated. The dynamics of pattern formation will be investigated by comparison with the recent experimental observations made in dry-jet and/or electro-spinning. Recognizing the possible control of domain morphology and improved understanding of mesogenic interactions, the proposed study will be extended to microporous membranes and nano-composites. The theoretical scheme proposed here demonstrates the spation-temporal evolution of the order parameters (such as density, concentration and orientation fluctuations) based on the local free energy and non-local gradient (diffusive) terms. The numerical simulation further illustrates the emergence of the local internal structures during solidification. Moreover, this methodology can applied to elucidating the microfibrillation dynamics in spinning of semicrystalline polymers and hydrogen bonding systems.It is encouraging to discern unique morphological features encompassing (i) nano-tube formation, (ii) concentric rings/spiral-breakup leading to microfibrillation and (iii) viscous fingering patterns. The observed phenomenon of spiral breakup is one of the most debated topics in the no-linear dynamics of excitable media and biological systems. Furthermore, it clearly demonstrates a new approach to the decades-old problem of predicting morphology development in solution-spun fibers such as rough skin/core structures, collapsed kidney shape morphology, and microfibrils. This methodology has potential for modern technological applications including electro-spinning of nano-fibers/tubes, microporous membranes through pattern photopolymerization induced phase separation, and nano-hybrid composites. It is anticipated that these microporous membranes have widespread applications usch as fuel cell membranes, filtration, and drug delivery. Furthermore, some of the simutaion programs have been written in C++ and can be shown on live-mode with the aid of an LCD projector. Such interactive programs are proven to be useful for classroom teaching and demonstration to the public.

本提案需要在凝固主链液晶聚合物（MCLCP）和/或刚性杆聚合物溶液（II）纳米------在模式聚合过程中单体膜的多孔膜，干式旋转过程中微纤维形成的动力学（iii）动力学，以及（iv）杂交材料。 公认的时间依赖性的金茨堡 - landau TDGL（C）将与跟踪溶剂蒸发和流动的跟踪术语结合使用。 将阐明与管理非线性反应扩散方程有关的所有参数的物理显着性，并将证明其预测性capabilitieis。 与最近在干射流和/或电旋转中进行的实验观察结果相比，将研究模式形成的动力学。 认识到可能控制域形态的控制并提高了对中源相互作用的理解，拟议的研究将扩展到微孔膜和纳米复合材料。 这里提出的理论方案证明了基于局部自由能和非本地梯度（扩散）项的阶参数（例如密度，浓度和方向波动）的暂时性演变。 数值模拟进一步说明了固化过程中局部内部结构的出现。 此外，这种方法可以应用于阐明半稳定聚合物和氢键系统旋转中的微纤维化动力学。 （iii）粘性指法图案。 观察到的螺旋分裂现象是令人兴奋的媒体和生物系统无线性动力学中最讨论的主题之一。 此外，它清楚地证明了一种新的方法，即预测溶液纤维中形态发展的历史学问题，例如粗糙的皮肤/核心结构，崩溃的肾脏形态形态和微纤维。 该方法具有现代技术应用的潜力，包括通过模式光聚合引起的相位分离的纳米纤维/管，微孔膜和纳米杂交复合材料。 预计这些微孔膜具有广泛的应用，用作燃料电池膜，过滤和药物输送。 此外，某些Simutaion程序已用C ++编写，可以在LCD投影仪的帮助下显示在Live Mode上。 事实证明，这种互动程序可用于课堂教学和向公众展示。