Design of Mixed-Graft Block Copolymers for Emerging Applications

第一部分：非技术概述有机聚合物由于其多样的性质和易加工性而被广泛用作功能或结构材料。虽然对于开发具有一种以上独立可调性质的单一聚合物材料用于制造下一代电子和能源设备存在巨大需求，但科学挑战仍然存在。该项目旨在引入接枝共聚物-含有多个侧链的聚合物主链的分子-作为合成平台，以实现有机材料，其中几种性能的依赖性是解耦的。此类性质的实例包括离子/电子传导性、纳米结构和机械性质。通过具有不同化学组成和可精确控制的结构参数的接枝共聚物的独特分子结构，能够独立地调节多种性质。 调整这些聚合物的主链长度开辟了一条道路，不仅能够形成超小的纳米畴间距，而且实现理想的热机械性能和可加工性。 所提出的材料与新兴应用密切相关，如电子皮肤和软机器人组件。 本项目的总体目标是开发可加工和机械兼容的聚合物材料，其具有可独立调节和定向的离子和电子电导率。混合接枝嵌段共聚物（mGBCPs）由两种或两种以上类型的功能聚合物侧链接枝在一个线性骨架将被设计和合成，以实现这一目标。不同的侧链的mGBCP的不相容性导致相分离，以形成有序的纳米结构与骨干作为界面。负责不同导电性质的各种各样的侧链官能团分别富集在不同的纳米畴中。导电相的取向可以通过定向自组装技术来调节，并且纳米畴的尺寸主要由侧链长度控制。调节mGBCP的主链长度开辟了一条不仅能够形成超小纳米畴间距而且能够实现期望的热机械性能和可加工性的途径。该项目解决了经典线性嵌段共聚物应用中的一个重大挑战，由于其相互组成的依赖性，其本体性质和纳米结构无法独立调整。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。

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.