Materials World Network: Controlling Properties of Polymers in Thin Films

这个材料世界网络汇集了世界上关于聚合物薄膜实验表征的专业知识（美国波士顿大学和德国弗赖堡弗赖堡大学分别研究薄膜应力和粘弹性）和受限聚合物动力学和结构的计算机模拟（查尔斯·萨德隆研究所，斯特拉斯堡，法国），以寻求一个统一的图片的可能性，可以解释所有不寻常的性质观察到的聚合物薄膜的日期（即动力学、残余应力和热膨胀率），同时试图将这些性质与其中的（不平衡的）聚合物结构以及产生它们的制造和/或后制造工艺相关联。通过建立这种结构-性能和加工-性能关系，该网络的目标是最终制定一种可以预测，设计和调整聚合物薄膜性能的策略。由于据称导致不寻常性能的聚合物膜的结构是亚稳态的并且随时间变化，因此使用聚苯乙烯的交联共聚物来冻结结构，从而冻结它们的性能。本研究主要由几个已发表的实验和Reiter（来自德国的PI）和de Gennes提出的模型指导，该模型描述了快速溶剂蒸发产生的非平衡聚合物网络结构如何解释负热膨胀性。该计划的结果预计将证实这一模型，并进一步扩大其相关性的动态行为的电影。由此产生的，更全面的模型将提供一个关键的平台上的结构性能和加工性能的关系，可以描绘和/或formulated.Applications的聚合物薄膜是广泛的。该计划的成功导致了一个简单的策略，设计和制造聚合物薄膜与预谋的热膨胀和/或动态性能。拥有这样的能力大大提高了我们的杠杆作用，以适应这些材料在成本效益的方式不断变化的要求，其性质的应用程序采用它们。六名博士生在该计划中接受培训，为他们提供了一个很好的培训基地，在学术上具有挑战性和技术相关的问题，有关旋涂聚合物薄膜的不寻常性能。该网络的成员受益于该方案的国际背景。特别是，除了频繁的视频会议外，博士生之间还定期举行会议和物理交流。该计划积极吸引本科生和高中生参与。该奖项由DMR聚合物计划和DMR特别计划办公室共同资助。

This Materials World Network brings together world-expertise on the experimental characterizations of polymer films (Boston University, USA and Universität Freiburg, Freiburg, Germany on the film stress and viscoelasticity, respectively) and computer simulations on the dynamics and structure of confined polymers (Institut Charles Sadron, Strasbourg, France) to seek for the possibility of a unified picture that can account for all the unusual properties observed of polymer films to date (namely the dynamics, residual stress and thermal expansivity), and at the same time attempt to relate these properties to the (out-of-equilibrium) polymer structures therein as well as the fabrication and/or post-fabrication processes producing them. By establishing such structure-property and processing-property relations, the Network aims to ultimately institute a strategy that can predict, design and tune the properties of polymer films. Because the structures of the polymer films that allegedly cause the unusual properties are metastable and change with time, a cross-linkable copolymer of polystyrene are used to freeze-in the structures and whereby their properties. This research is largely guided by several published experiments and a model conjectured by Reiter (the PI from Germany) and de Gennes portraying how a non-equilibrated polymer network structure engendered by rapid solvent evaporation could explain negative thermal expansivity. The results of this program are expected to substantiate this model, and additionally expand its relevance to the dynamical behaviors of the films. The resultant, more encompassing model will provide a pivotal platform upon which the structure-property and processing-property relations can be portrayed and/or formulated.Applications of polymer films are widespread. Success of this program leads to a simple strategy to design and fabricate polymer films with premeditated thermal expansion and/or dynamical properties. Having such ability significantly enhances our leverage to adapt these materials in a cost effective manner to the ever-changing demands on their properties by the applications employing them. Six PhD students are trained in this program, providing them an excellent training ground in the academically challenging and technologically relevant problem concerning the unusual properties of spin-coated polymer films. Members of the Network benefit from the international setting of the program. In particular, there are regular meetings and physical exchange between the PhD students besides frequent video conferences. This program actively engages undergraduate and high-school student participants. This award is jointly funded by the DMR Polymers Program and the DMR Office of Special Programs.