竹材表面功能性微纳米结构仿生构建及形成机理研究

Inspired by the layerd micro-/nano- structures of shells, and the mastoid micro-/nano- structures of lotus, the hierarchical assembly of nano-building blocks were prepared on the bamboo surface. This newly prepared bamboo-based functional composites possess an integrated properties including dimensional stability, water-repellency and flame-retardency, mildew proof and decay resistance, ageing resistance, and self-cleaning behavior. The micro-/nano- structured materials, such as ZnO, TiO2, SiO2, Ag, CaCO3, and graphene, were repectively prepared on the bamboo surface using the hydrothermal mineralization and molecule assembly technique method. They would be similar to the coexistent dual micro-/nano- structures of shells and lotus. The controllable forming techniques of the coexistent dual micro-/nano- structures deposited onto the bamboo surface would be systematically investigated. The formation mechanism, characteristics, structures, and corelated functions of the interface between the bamboo surface and the micro or nanomaterials would be thoroughly studied. How the influencing factors of the dual structures coordinate would be further analyzed. The regulation technique and the formation mechanism of the bionic interface between the micro-/nano- structures and the bamboo substrate would be illuminated. It could provide scientific theories for buliding the intelligent response bamboo-based composites and represent important significance for the functional expansion and high-value developed bamboo-base materials. The assembly of nano-building blocks into bio-inspired structured functional composites on the bamboo surface is a feasile route from the micro level to learn from nature. The obtained inspiration not only offer us the novel research thought for function expansion and high-value development of bamboo but also provid a theoretical guidance and scientific technical support for the development of high-valued bamboo-based functional composites.

仿生贝壳微纳层状结构，荷叶微纳乳突结构，在竹材表面构筑有序组装的微纳米结构单元，获得集尺寸稳定、拒水阻燃、防霉耐腐、耐老化、自清洁为一体的新型竹质基功能复合材。采用水热矿化和分子组装技术在竹材表面制备ZnO、TiO2、SiO2、Ag、CaCO3、石墨烯等微纳米材料，形成具有和贝壳或荷叶相似的微纳二元共存结构，研究二元结构材料修饰表面的可控形成技术，与竹材异质界面的成型机制、界面特性及界面结构，充分挖掘界面效应；深入分析二元结构协调的影响因素，阐明竹材微纳米结构仿生界面调控工艺和形成机理，为创建智能响应性竹质基复合材提供科学理论指导，对竹材的功能拓展和高值化开发有重要意义。竹材表面功能性微/纳米结构单元仿生构建使竹材从更微观的层次师法自然，利用从生物体那里获得的启示为竹材的功能拓展和高值化开发提供新的研究思路，为发展高附加值的竹质基功能材料提供理论依据和科学技术保障。

竹材具有速生、可再生、强度高、韧性大、刚性好、易加工等特征，但又存在易吸湿变形、易虫蛀、腐朽和霉变、易光致变色、易燃烧等缺陷，而传统方法如浸渍或者机械刷涂等虽能部分解决上述问题，但依然存在涂层材料流失严重、与基体界面结合牢固性差等不足，并且不能赋予竹材新的奇异功能。本项目主要研究内容包括三大部分：微纳结构单元（ZnO、Ag、CaCO3）在竹材表面的生长工艺、多级微纳结构单元（石墨烯负载ZnO、TiO2、SiO2、Ag）的制备及协效效应以及表面遗态法软印刷SiO2、TiO2。在此过程中，充分分析揭示了微纳结构单元在竹材表面的仿生功能、界面效应和形成机理。结果发现水热法生长ZnO过程中，较适宜的生长条件为：水热温度95°C、反应时间1h、NaOH和ZnAc摩尔比20:1；生长后，制备的竹材试样具有优越的光催化活性和循环稳定性；进一步利用含氟物质在表面改性后，开发出耐久、抗腐蚀、超双疏、抗紫外和耐燃的ZnO/竹材复合材料。利用银镜反应在竹材表面生长Ag纳米粒子并利用含氟物质改性后，同时赋予了竹材疏水性和导电性。利用水热矿化法在竹材表面仿生鲍鱼壳生长层状CaCO3涂层并利用含氟物质改性后，同样可以得到超疏水、自清洁的竹材。氧化石墨烯分散液在水热处理过程中可被还原成还原氧化石墨烯，以层层堆积自组装的方式，在竹材表面通过吸附和氢键共同作用形成保护层，获得的RGOBT新型竹材具有良好的耐腐朽性能。在竹材表面生长以石墨烯网状结构载体负载的ZnO、TiO2、SiO2、Ag等纳米晶体层后，实现了防霉、抑菌、热稳定、防火、光催化活性、疏水、导电等多级功能的叠加效应。经软印刷技术合成的仿植物叶片微纳结构竹材表面，具有与原植物叶片相似的表面微观乳突结构及粗糙表面；经纳米SiO2、TiO2改性和含氟物质处理后，表现出优异的超疏水性能。表面功能化有效延长了竹材的使用寿命、增加竹材及其竹制品的附加值，使之更好的服务于人类，为竹资源高效利用的目标作出了积极尝试。