Collaborative Research: Revealing Strengthening and Toughening Mechanisms in Coconut Endocarp through Integrated Multiscale Modeling and Characterization

合作研究：通过综合多尺度建模和表征揭示椰子内果皮的强化和增韧机制

• 批准号: 2316676
• 负责人: Ning Zhang
• 金额: $ 26万
• 依托单位: Baylor University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2316676&HistoricalAwards=false
• 关键词: Collaborative; Research; Revealing; Strengthening; Toughening

Non-Technical Summary:The hard shell of the coconut, called endocarp, is a lightweight material with impressive strength, toughness, and hardness. As with many biological materials, this outstanding behavior is due to a highly complex structure. When studied at increasing magnifications, the endocarp reveals different structures at each magnification level. At the largest level, a porous network can be seen, consisting of bundles of hollow channels. Larger magnifications reveal a graded cellular structure, where larger cells are found toward the inside of the coconut, and smaller cells toward the outside. The cells themselves feature walls consisting of many layers, and each of these layers consists of tiny fibrils. Understanding comprehensively how all of these elements work together to make the coconut so strong and tough is a significant challenge, especially because of their disparity in size. This project will develop novel computer simulation techniques with the capability of treating these different elements simultaneously at the relevant sizes. This project will also develop new experimental techniques to measure and visualize directly how the different elements inside the coconut endocarp interact, to test and calibrate the computer models. This integrated computational and experimental approach will provide unprecedented insights into how the coconut’s structure gives rise to its outstanding performance. These insights and methods can then be used to engineer coconut-inspired lightweight applications that are strong and tough, for instance to improve helmets. This project will provide research opportunities to undergraduate students. For instance, computational and experimental training series will be offered to undergraduate students during the summer. Underrepresented students including female and minority students will participate in this research project. This project will also provide opportunities to students with disabilities to work on computational modeling remotely. Presentations and seminar talks will be offered to middle and high school students to attract them to participate into biomaterial research. Technical Summary:Coconut endocarp is substantially stronger and stiffer than wood, despite sharing the same major ingredients: cellulose, hemi-cellulose, and lignin. The key to this impressive mechanical performance is a sophisticated structure with many levels of structural hierarchy between the molecular scale and the macroscale. This project’s goal is to develop a rigorous understanding of the endocarp’s structure/property relationships by means of a multi-scale effort integrating novel computational and experimental techniques. A concurrent atomic-continuum (CAC) computational tool will be developed to span all relevant length scales of this materials system naturally. This approach will overcome limitations of current computational approaches, where different length scales are treated with conceptually different models that need to be interfaced. The CAC approach will be used on hierarchical materials for the first time, representing a game changing development for the materials sciences. The experimental efforts will mirror the computational work and provide characterization across all length scales. Scanning probe techniques will play a crucial role in characterizing not only the structure and mechanical properties of nano- and microscale constituents of the endocarp, but also their interfacial interactions. The outcome will be a powerful model that is calibrated and verified across multiple length scales. This model can serve as a basis to establish guidelines for bottom-up hierarchical design of synthetic cellular lightweight materials with outstanding mechanical performance, inspired by the coconut endocarp.This project is jointly funded by the Biomaterials progam (BMAT) in the division of materials research (DMR) and the Established Program to Stimulate Competitive Research (EPSCoR).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.

非技术摘要：椰子的硬壳（称为内果皮）是一种轻质材料，与许多生物材料一样，在放大倍数不断增加的情况下，其出色的性能是由于其高度复杂的结构。 ，内果皮在每个放大倍数下都显示出不同的结构，在最大放大倍数下，可以看到由成束的中空通道组成的多孔网络，更大的放大倍数显示出分级的细胞结构，其中在内部发现了更大的细胞。椰子的细胞壁由多层组成，每一层都由微小的原纤维组成，全面了解所有这些元素如何共同作用使椰子如此坚固和坚韧具有重要意义。该项目将开发新的计算机模拟技术，能够以相关尺寸同时处理这些不同的元素，从而直接测量和可视化不同元素的内部情况。椰子内果皮相互作用，进行测试和校准这种集成的计算和实验方法将为椰子的结构如何产生其出色的性能提供前所未有的见解，然后可以使用这些见解和方法来设计坚固耐用的椰子启发的轻量级应用。该项目将为本科生提供研究机会，例如，将在夏季为本科生提供计算和实验培训系列，包括女性和少数民族学生。为残疾学生提供远程进行计算建模的机会。将为中学生和高中生提供演示和研讨会讲座，以吸引他们参与生物材料研究。 技术摘要：尽管椰子内果皮的主要成分相同：纤维素、半纤维素和木质素，但它比木材更坚固、更坚硬。这种令人印象深刻的机械性能的关键是分子尺度和宏观尺度之间具有多层次结构层次的复杂结构。该项目的目标是通过以下方式对内果皮的结构/特性关系进行严格的理解。将开发一种集成新型计算和实验技术的多尺度工作，以自然地跨越该材料系统的所有相关长度尺度，这种方法将克服当前计算方法的局限性。 CAC 方法将首次用于分层材料，这代表了材料科学的改变游戏规则的发展，实验工作将反映计算工作并提供所有特性的表征。扫描长度尺度。探针技术不仅在表征内果皮纳米和微米级成分的结构和机械性能方面发挥着至关重要的作用，而且在表征它们的界面相互作用方面也将发挥重要作用，其结果将是一个在多个长度尺度上进行校准和验证的强大模型。受到椰子内果皮的启发，该模型可以作为建立自下而上的分层设计指南的基础，具有出色的机械性能的合成细胞轻质材料。该项目由材料研究部门的生物材料计划（BMAT）联合资助(DMR) 和刺激竞争研究既定计划 (EPSCoR)。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Cellulose–Hemicellulose–Lignin Interaction in the Secondary Cell Wall of Coconut Endocarp

椰子内果皮次生细胞壁中纤维素-半纤维素-木质素的相互作用

• DOI: 10.3390/biomimetics8020188
• 发表时间: 2023-05-04
• 期刊: Biomimetics
• 影响因子: 4.5
• 作者: Mazumder, Sharmi;Zhang, Ning
• 通讯作者: Zhang, Ning