Electric Field Induced Phase Transitions of Polymer Solutions and Mixtures

电场诱导聚合物溶液和混合物的相变

• 批准号: 9310506
• 负责人: Gerald Fuller
• 金额: $ 19.75万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1997-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9310506&HistoricalAwards=false
• 关键词: Electric; Field; Induced; Phase; Transitions

9310506 Fuller The morphology and phase behavior of polymer mixtures can be influenced by the application of external fields. This research examines the manipulation of polymer mixture morphology by the use of electric fields. Preliminary results on polymer solutions are offered that demonstrate a variety of new phenomena, such as electric field-induced de-mixing and re- mixing of polymer mixtures. These results suggest the possibility of systematically controlling the interfacial properties of polymer blends, and the manipulation of their domain structure. Such control could be used in the processing of polymer mixtures to arrive at specific bulk material properties and improve interfacial mixing. The research extends these preliminary results to include polymer blends and polymer gels. In addition, both upper and lower critical solution temperature systems will be examined, since the specific shape of the phase boundary is predicted to determine whether application of an electric field will cause either de-mixing (UCST systems) or re-mixing (LCST systems). Finally, the project considers the simultaneous application of electric and hydrodynamic fields, since real processes normally include the presence of flow. Since hydrodynamic forces are also known to affect the phase behavior of polymer liquids, a nonlinear coupling of the effects of electric and flow fields would be expected. The research combines experimentation and theory. Small angle light scattering and scattering dichroism are used to measure the structure of polymer mixtures subject to external flow fields Both experiments methods provide measures of anisotropy in concentration fluctuations and can be used in situ. The theoretical analysis utilizes current mean field approaches whereby the dynamics of concentration fluctuations can be expressed in terms of the relative importance of fluxes due to the external fields and relaxation mechanisms arising from osmotic forces. ***

9310506 Fuller 聚合物混合物的形态和相行为可能受到外部场的应用的影响。 这项研究研究了利用电场对聚合物混合物形态的操纵。 提供的聚合物溶液的初步结果证明了各种新现象，例如电场引起的聚合物混合物的分层和再混合。 这些结果表明系统控制聚合物共混物的界面性质以及操纵其域结构的可能性。 这种控制可用于聚合物混合物的加工，以获得特定的本体材料性能并改善界面混合。 该研究将这些初步结果扩展到包括聚合物共混物和聚合物凝胶。 此外，还将检查上临界溶液温度系统和下临界溶液温度系统，因为相界的具体形状被预测以确定施加电场是否会导致分层（UCST 系统）或重新混合（LCST 系统） ）。 最后，该项目考虑了电场和流体动力场的同时应用，因为实际过程通常包括流动的存在。 由于已知流体动力也会影响聚合物液体的相行为，因此预计电场和流场的影响会出现非线性耦合。 该研究结合了实验和理论。 小角度光散射和散射二色性用于测量受外部流场影响的聚合物混合物的结构。这两种实验方法都提供了浓度波动中各向异性的测量，并且可以在原位使用。 理论分析利用当前的平均场方法，浓度波动的动态可以用由于外部场和渗透力引起的弛豫机制引起的通量的相对重要性来表达。 ***