General Strategies Toward Mechanically Robust Biobased Polymers and Composites

非技术总结近年来，来自可再生自然资源的可持续聚合物由于其对可持续经济和社会的重要性而获得了很大的发展势头。天然聚合物，如纤维素、半纤维素、木质素、淀粉、蛋白质和甲壳素，已用于复合材料、塑料、生物燃料和其他应用。从分子生物质如植物油、松香酸、萜烯、萜类化合物和呋喃中合成聚合物的开发是一个快速增长的领域。然而，与占主导地位的石油化学衍生的对应物相比，在商业市场中增加生物基聚合物的组分存在许多越来越大的挑战。为了促进可持续发展和国家繁荣，该项目将通过设计基于将大分子包裹在来自自然资源的聚合物上的一般策略来开发下一代可再生聚合物，以改善其物理性能，特别是解决涉及各种生物质的劣质机械性能的关键障碍。 一个中心目标是了解如何通过超分子相互作用的大分子链包装决定这些材料的热和机械性能，并建立结构-性能关系。技术概述来自自然资源的可持续生物基聚合物正面临着许多引人注目的挑战。 其中，许多聚合物的机械性能较差，这主要是由于它们固有的低链缠结（因此，它们具有非常高的链缠结分子量）。大分子结构和组成在决定这些性质中起着至关重要的作用。计划中的研究旨在提供一种经济，稳健和通用的方法来提高生物基聚合物的机械性能。其核心思想是通过超分子相互作用将大体积的生物基聚合物与柔性和高度缠结的大分子包裹起来。拟议研究的总体目标是同时最大限度地利用生物质，并通过引入最低水平的大分子包裹，使生物基大体积聚合物在应力下具有高拉伸强度和理想的伸长率。该项目包括通过平行努力开发大分子工程方案：（1）含有庞大生物质的聚合物，如脂肪酸，树脂酸，异山梨醇，愈创木酚，蒎烯，tulipalin和葡萄糖;和（2）基于木质素和纤维素纳米晶须的生物复合材料。 一个重要的目标是了解如何通过超分子相互作用的大分子链包装决定这些材料的热和机械性能，并建立明确的结构-性能关系。计划中的研究项目旨在探索潜在的变革性概念，通过最大限度地使用具有增强热机械性能的生物基聚合物来解决可持续性问题。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。

NON-TECHNICAL SUMMARYSustainable polymers from renewable natural resources have gained much momentum in recent years given their importance to a sustainable economy and society. Natural polymers, such as cellulose, hemicellulose, lignin, starch, proteins, and chitin, have been utilized in composites, plastics, biofuels and other applications. The development of synthetic polymers from molecular biomass, such as plant oils, rosin acids, terpenes, terpenoids, and furan, is a fast-growing area. However, there are many mounting challenges in increasing the component of biobased polymers in the commercial market, in contrast with dominant petrochemical-derived counterparts. To promote sustainability and national prosperity, this project will develop next-generation renewable polymers by designing general strategies based on wrapping of macromolecules on polymers from natural resources to improve their physical properties, especially addressing critical hurdles on inferior mechanical properties involving a variety of biomass. A central goal is to understand how macromolecular chain wrapping via supramolecular interactions dictates thermal and mechanical properties of these materials and to establish structure-property relationships.TECHNICAL SUMMARYSustainable biobased polymers from natural resources are facing a lot of compelling challenges. Among them, many polymers suffer inferior mechanical properties, largely due to their inherent low chain entanglements (thus, they have very high chain-entanglement molecular weight). Macromolecular architectures and compositions play vital roles in dictating these properties. The planned research is aimed to provide an economical, robust, and general approach to enhance mechanical properties of biobased polymers. The central idea is to wrap bulky biobased polymers with a flexible and highly entangled macromolecule via supramolecular interactions. The overall goal of the proposed research is to simultaneously maximize the use of biomass and enable biobased bulky polymers with high tensile strength and desirable elongation under stress by incorporating minimal levels of macromolecular wrapping. This project includes the development of macromolecular engineering protocols through parallel efforts on: (1) polymers containing bulky biomass such as fatty acid, resin acid, isosorbide, guaiacol, pinene, tulipalin, and glucose; and (2) biocomposites based on lignin and cellulose nanowhiskers. An essential goal is to understand how macromolecular chain wrapping via supramolecular interactions dictates thermal and mechanical properties of these materials and to establish clear structure-property relationships. The planned research program seeks to explore potentially transformative concepts to address sustainability issues by maximizing the use of biobased polymers with enhanced thermomechanical properties.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.