Polypeptoids as model materials for studying the role of monomer sequence and chain shape on block copolymer self-assembly

第1部分：非技术总结在纳米尺度上形成图案的聚合物是粘合剂和下一代柔性橡胶材料的重要组成部分。能够控制下一代聚合物中的这种图案对于纳米光刻、柔性电子和生物医学等应用非常重要。与典型的聚合物分子相比，这些聚合物具有更复杂的化学结构和分子尺度的形状。这个项目的目标是了解分子化学结构和形状的复杂性如何影响其形成涉及许多分子相互堆积的模式的能力。为了做到这一点，分子的设计和研究将受到生物聚合物(蛋白质)的启发，但允许调整其形状、硬度和化学结构。本科生和研究生研究人员将在国家研究用户设施接受培训，参加地方和国家科学会议，并与研究合作者密切互动。将研究和学习结合起来，在更广泛的科学界进行互动，这是面向工业或学术界的研究生教育经验的一个组成部分。此外，PI将与UCSB科学与工程合作中心合作，将不同类型的即将到来的社区大学转学学生纳入研究小组，以缓解转学冲击并提供研究经验。在圣巴巴拉/戈莱塔中小学开展的“科学之夜”外展活动将继续在新一代学生中激起STEM领域的兴奋。第二部分：技术总结嵌段共聚物中的自组装介观结构源于不同嵌段之间的焓分离、液晶相互作用、组成以及嵌段之间尺度尺寸的不匹配之间的竞争。在克尺度合成序列特定多肽的能力提供了一个独特的机会，可以直接测试共聚物自组装的预测，这些预测表明，共聚物序列中的“嵌段性”和梯度强度都会影响链的能力，通过将单体分类到界面的首选一侧，从而将自由能降至最低。此外，通过控制序列、侧链手性和体积，链持续长度在单一化学平台上是可调节的。该平台提供了必要的构象(持续长度)控制，以探索杆和线圈之间的半柔性链形状的连续体。此外，我们还将探讨非对称性在混合自由能中贡献长程熵效应的基本作用。这个项目的目标是深入了解序列和链的形状如何影响嵌段共聚物自组装的自由能贡献。预计这一基本认识将指导半柔性和序列定义的嵌段共聚物的设计，并最终影响到有机光电子学和生物材料等各种领域。

PART 1: NON-TECHNICAL SUMMARYPolymers that form patterns on the nanometer scale are important components of adhesives and next-generation flexible and rubbery materials. Being able to control this patterning in next-generation polymers is important for applications such as nanolithography, flexible electronics, and biomedicine. These polymers have much more complicated chemical structures and molecular-scale shapes than typical polymer molecules. This project is targeted at understanding how complexity in the molecule's chemical structure and shape affects its ability to form patterns involving the mutual packing of many molecules. To do this, molecules will be designed and studied that are inspired by biological polymers (proteins) but allow for tuning of their shape, stiffness, and chemical structure. Undergraduate and graduate student researchers will be trained at national research user-facilities, participate in local and national scientific meetings, and interact closely with research collaborators. Combining both research and learning to interact in the broader scientific community comprises an integral part of the educational experience for graduate students bound for either industrial careers or the academic world. Furthermore, the PI will partner with the UCSB Center for Science and Engineering Partnerships to incorporate a diverse cadre of incoming community-college transfer students into the research group to both ease transfer shock and provide research experience. A robust program of "Science Night" outreach activities at Santa Barbara/Goleta elementary and middle schools will continue to generate excitement in STEM fields among a new generation of students. PART 2: TECHNICAL SUMMARYEquilibrium self-assembled mesostructures in block copolymers arise from the competition between enthalpic segregation of dissimilar blocks, liquid crystalline interactions, composition, and the mismatch in scaling dimensions between blocks. The ability to synthesize sequence-specific polypeptoids at gram scale presents a unique opportunity to directly test predictions of copolymer self-assembly that suggest both 'blockiness' and gradient strength in a copolymer sequence impacts the chain's ability to minimize free energy by sorting monomers to the preferred side of the interface. Furthermore, the chain persistence length is tunable on a single chemical platform by controlling the sequence, side chain chirality, and bulkiness. This platform provides the conformational (persistence length) control necessary to explore the continuum of semiflexible chain shapes between the rod and coil limits. In addition, the fundamental role of asymmetry in contributing long-range entropic effects to the free energy of mixing will be explored. The goal of this project is to develop a deep understanding of how sequence and chain shape impact the free energy contributions to block copolymer self-assembly. It is expected that this fundamental understanding will guide the design of semiflexible and sequence-defined block copolymers and ultimately impact fields as diverse as organic optoelectronics and biomaterials.