Collaborative Research: Solution Processing with Entropy-Controlled Stratification of Architecturally-Complex Polymer Blends

各种消费产品是通过使用溶剂在表面沉积薄聚合物膜来制造的，包括防污涂层、水净化膜和电子设备。溶剂型制造工艺很有吸引力，因为它们快速、廉价、可扩展到大面积。然而，随着溶剂的蒸发，聚合物会以难以预测或控制的方式自行排列。该合作研究奖开发了新的基于溶剂的制造工艺，其中不同类型的聚合物根据其大小和形状自动分类成层。这种独特的方法可用于分离薄膜的表面和体积特性，从而允许对每个属性进行独立优化。此外，聚合物可以降解，以促进其拆卸和可回收性。因此，通过这项研究建立的原理可以促进高性能聚合物薄膜的开发，用于生物医学设备、海水淡化和过滤系统以及清洁能源设备的最终用途，这将对社会和美国经济产生重大影响。实验室研究吸引研究生和本科生，并辅以教育和推广项目，包括合作机构的本科和研究生课程的新模块；为更广泛的科学界举办短期课程和专题讨论会；向盲人和视障人士教授科学的活动；以及两所大学之间的学生交换项目。这个合作研究项目的目标是开发溶液沉积工艺，在薄膜中产生瓶刷共聚物和线性均聚物的垂直分层。该研究任务旨在验证这样一种假设，即瓶刷共聚物在汽液界面上被熵吸引，从而导致“瓶刷上顶”分层，适用于广泛的材料化学和加工条件。重要的是，通过利用这些加工过程中的熵效应，瓶刷共聚物添加剂可以合成具有“高能”极性、离子和氢键的基团。这些化学物质对于调整一系列表面和界面特性至关重要，包括润湿性、摩擦性、耐污性、粘附强度、可降解性、电导率和刺激响应性。该研究计划考察材料设计（聚合物结构、化学）和分层剖面上的加工变量（蒸发速率、扩散速率）之间的相互作用，使用现有的胶体颗粒垂直分层模型来指导实验设计。该合作包括一组瓶刷共聚物添加剂的合成和运输相关参数的表征。系统的研究计划涉及400个独立样本的制备和表征，在两个机构之间平均分配。值得注意的是，本研究建立的原理重新定义了哪些类型的聚合物具有“表面活性”，并改变了当前高分子材料表面工程的方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A variety of consumer products are manufactured by using solvents to deposit a thin polymer film on a surface, including anti-fouling coatings, membranes for water purification, and electronic devices. Solvent-based manufacturing processes are attractive because they are fast, inexpensive, and scalable to large areas. However, as the solvent evaporates, the polymers arrange themselves in ways that are difficult to predict or control. This collaborative research award develops new solvent-based manufacturing processes where different types of polymers are spontaneously sorted into layers according to their size and shape. This unique approach can be used to decouple the surface and bulk properties of the film, allowing for independent optimization of each attribute. Furthermore, the polymers can be degradable to facilitate their disassembly and recyclability. As a result, the principles established through this research can facilitate the development of high-performing polymer films for end-use applications in biomedical devices, desalination and filtration systems, and devices for clean energy, which greatly impacts society and the U.S. economy. Laboratory research engages graduate and undergraduate students and is complemented by education and outreach programs that include new modules for undergraduate and graduate courses at collaborating institutions; short courses and symposia for the broader scientific community; activities that teach science to the blind and visually impaired; and a student exchange program between the two institutions.The goal of this collaborative research project is to develop solution deposition processes that produce vertical stratification of bottlebrush copolymers and linear homopolymers in thin films. The research tasks are designed to test the hypothesis that bottlebrush copolymers are entropically attracted toward the vapor-liquid interface, leading to "bottlebrush-on-top" stratification for a broad range of material chemistries and processing conditions. Importantly, by leveraging these entropic effects during processing, the bottlebrush copolymer additives can be synthesized with "high energy" polar, ionic and hydrogen-bonding moieties. Such chemistries are critical for tuning a range of surface and interfacial properties, including wettability, friction, fouling resistance, adhesion strength, degradability, conductivity, and stimuli-responsiveness. The research plan examines the interplay between materials design (polymer architecture, chemistry) and processing variables (evaporation rate, diffusion rates) on stratification profiles, using existing models for vertical stratification of colloidal particles to guide experimental design. The collaboration consists of synthesis of a set of bottlebrush copolymer additives and characterization of transport-related parameters. The systematic research plan involves preparation and characterization of 400 independent samples, evenly split between the two institutions. Significantly, the principles established by this research redefines what types of polymers are characterized as "surface active" and transforms current approaches to surface engineering in polymeric materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.