Design of Mixed-Graft Block Copolymers for Emerging Applications

第一部分：非技术合成有机聚合物因其不同的性质和易于加工而被广泛用作功能材料或结构材料。尽管开发具有一种以上独立可调性能的单一聚合物材料用于制造下一代电子和能源器件的需求很大，但科学挑战依然存在。该项目旨在引入接枝共聚物--包含由多个侧链连接的聚合物主干的分子--作为实现几种性质的依赖关系解耦的有机材料的合成平台。这种性质的例子包括离子/电子导电性、纳米结构和机械性质。接枝共聚物独特的分子结构使其能够独立调节多种性能，具有可精确控制的不同化学组成和结构参数。调节这些聚合物的主链长度不仅可以形成超小的纳米结构域间距，而且还可以实现所需的热机械性能和加工性。建议的材料与新兴应用密切相关，如电子皮肤和软机器人中的部件。第2部分：技术总结该项目的总体目标是开发可加工和机械兼容的聚合物材料，具有离子和电子导电性，可以独立调节和取向。为了实现这一目标，将设计和合成由两种或更多类型的功能聚合物侧链接枝在线形骨架上的混合接枝嵌段共聚物(MGBCP)。MGBCP不同侧链的不相容导致相分离，形成以主链为界面的有序纳米结构。导致不同导电性能的各种侧链官能团分别富含在不同的纳米结构域中。导电相的取向可以通过定向自组装技术来调节，而纳米域的大小主要由侧链长度来控制。调节mGBCP的主干长度不仅为形成超小的纳米结构域间距开辟了一条道路，而且还实现了所需的热机械性能和加工性能。该项目解决了经典线性嵌段共聚聚合物应用中的一个重大挑战，即由于主体属性和纳米结构相互依赖，无法独立调整。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYOrganic polymers have been widely adopted as functional or structural materials due to their diverse properties and facile processability. While there is great demand for developing single polymeric materials with more than one independently-tunable property for the fabrication of next-generation electronic and energy devices, scientific challenges remain. This project aims to introduce graft-copolymers -- molecules containing a polymer backbone tethered with multiple side chains -- as a synthetic platform to realize organic materials in which the dependencies of several properties are decoupled. Examples of such properties include ion-/electron-conductivity, nanostructures, and mechanical properties. The ability to independently tune multiple properties is enabled by the unique molecular architecture of graft-copolymers with diverse chemical compositions and structural parameters that can be precisely controlled. Tuning the backbone length of these polymers opens a way not only to enabling the formation of ultrasmall nanodomain spacing but also to realizing desirable thermomechanical properties and processability. The proposed materials are closely relevant to emerging applications such as electronic skin and components in soft robotics.PART 2: TECHNICAL SUMMARYThe overall goal of this project is to develop processable and mechanically compliant polymeric materials with both ionic and electronic conductivities that can be independently tuned and oriented. Mixed-graft block copolymers (mGBCPs) consisting of two or more types of functional polymeric side chains grafted on a linear backbone will be designed and synthesized to achieve this goal. The incompatibility of distinct side chains of mGBCPs results in phase-separation to form ordered nanostructures with the backbone serving as the interface. A diverse range of side chain functionalities that are responsible for different conductive properties are respectively enriched in different nanodomains. The orientation of the conductive phases can be regulated through directed self-assembly techniques, and the nanodomain sizes are controlled primarily by the side chains lengths. Tuning the backbone length of mGBCPs opens a way not only to enabling the formation of ultrasmall nanodomain spacing but also to realizing desirable thermomechanical properties and processability. This project tackles a grand challenge in the application of classic linear block copolymers in which the bulk properties and nanostructures cannot be independently tuned due to their mutual compositional dependence.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.