强韧轻质无机多级结构体系的仿生设计与构筑

Developing a general strategy to lightweight hierarchical materials with combined strength and toughness complemented by distinctive qualities is a challenging issue facing today’s inorganic community. Biominerals such as bones are known for their toughness and strength yet lightweight in addition to a fascinating set of structure-enabled functionalities. Bone derives its resistance to fracture with a multitude of dissipative deformation and toughening mechanisms from crosslinked networks based on both weak interactions and chemical bonding while the lightweight is attributed to the high porosity of the sophiscated architecture. Inspired by the principle found in biominerals like bones, the current project is intended to develop a synthetic pathway to lightweight hierarchical materials with combined strength and toughness by the rational organization of different building blocks through corporative assembly and mineralization (Scaffolding strategy). Considerable attention will be given to the design of scaffolding templates where the choice of building blocks allowing energy dissipation while retaining the structural integrity in face of shock is the key, and to the modulation of porosity and the degree of mineralization. Sacrificial bondings and confined mineralization are essential parameters determining the strength and toughness, and the porosity of the materials, which will be studied systematically in-depth. The research will be carried out using functional inorganics including TiO2 and SnO, and the strategy will be extended to other inorganic systems to examine the feasibility so as to deliver a versatile scaffolding strategy for the rational organization of lightweight, strong and tough hierarchical materials for advanced appliations.

强韧轻质无机多级结构功能材料的设计与定向构筑是具有科学意义和社会价值的重要命题，将推动能源存储和转化、环境治理、生物医学及航空等战略领域的发展。目前，该领域的研究工作在国际上仍处在初级阶段。本项目在前期工作基础上，以仿生为指导思想，以建立强韧轻质多级结构的普适性框架模板构筑策略为核心创新点。选择高性能无机质（TiO2, SnO等）为靶向体系，围绕目标性能（强韧、轻质、功能性、多级结构），深入系统探索构筑中的化学问题，包括框架模板的设计与目标性能之间的关系及调控规律，自组装与共组装的协同效应，以及多级结构特征的调控方法与规律等。建立框架模板的设计规则，实现多级结构的强韧性和密度的调控。将获得的方法推广到其它无机体系，拓展框架模板策略的普适性。开发系列新型强韧轻质无机多级结构功能材料，为能源存储和转化等战略领域提供优异的材料选择。为实现定向构筑强韧轻质无机多级结构功能材料提供科学依据。

强韧轻质功能材料的精准构筑有益于推进能源、环境、生物医学及柔性传感器件的发展。建立多层次跨尺度强韧轻质结构的构筑规则、构筑方法、利用可持续原料实现定向构筑具有科学意义和社会价值。本项目利用纳米纤维素氢键组装体的三维网络柔性结构与表面羟基的选择性矿化能力，建立了具有一定普适意义的多层次跨尺度强韧结构的构筑规则，成功构筑了系列强韧轻质纳米纤维素基无机复合材料；展示了多尺度能量耗散与界面成键的有机结合是实现强韧结构的重要环节。进一步拓展这一设计规则，我们利用纳米纤维素自组装螺旋结构，通过共组装，成功构筑出系列纳米纤维素基膜材料，展示优异的刚性和韧性以及机械响应性手性光学性质。本项目的研究成果为先进材料的定向构筑提供了一种可持续性构筑基元和构筑规则。