Synthesis and mechanical performance characterization of nanocomposite scrolls closely mimicking sponge spicules

在该项目的第二阶段，将进一步发展先前建立的卷轴制造方法，以产生密集的内部卷轴，包括紧密连接的薄片和填充的中心核心，紧密模仿自然（海绵）针状体的建筑。在此基础上，充分发挥仿生学的潜力，实现卷轴的最大力学性能，将机械柔韧性与高强度、高韧性有效结合。通过在基板上手动滚动或自滚动过程获得的卷轴内的自由空间的填充，应通过低温化学浴沉积二氧化钛纳米颗粒来完成。通过适当调整组成层的数量和厚度比、内涡旋直径、二氧化钛颗粒的结晶度和密度，以及通过合成后退火调整含水量，可以获得最佳的力学性能。此外，为了进一步接近天然针状体，计划加入纤维素纳米纤维，其柔软的机械特性有望提高机械柔韧性，其定制的表面电荷密度和长度使其成为接近理想的二氧化钛纳米颗粒成核位置。结合对人工针状体微/纳米尺度结构的详细分析，将确定其机械性能的主要机制，并将其与天然针状体进行对比。作为并行追求的另一个目标，将详细探讨两种不同类型的基于滚动的执行器。执行器应分别根据环境湿度的变化和受控的静电电荷进行操作。主要目标是确定执行器的性能，包括其工作寿命，作为最相关参数的函数，包括片层的数量和连通性，卷轴的内径和宽度，以及所实施的纤维素纳米纤维的数量。

In the second period of this project, the previously established scroll fabrication approach shall be further developed to yield scrolls whose dense interior, comprising intimately connected lamellas and a filled central core, closely mimics the architecture of natural (sponge) spicules. On this basis, the full potential of biomimetics shall be exploited to achieve maximum mechanical performance of the scrolls, effectively combining mechanical flexibility with high strength and toughness. Filling of the free space within scrolls obtained by manual scrolling on a substrate or a self-scrolling process shall be accomplished through low temperature chemical bath deposition of titania nanoparticles. Best mechanical properties shall be achieved via suitable adjustment of the number and thickness ratio of the constituent layers, the inner scroll diameter, the crystallinity and density of the titania particles, as well as the water content adjusted by post-synthesis annealing. Moreover, in order to further approach natural spicules, it is planned to incorporate cellulose nanofiber, whose soft mechanical character is expected to promote mechanical flexibility, and whose tailored surface charge density and length renders them into close-to-ideal nucleation sites for the titania nanoparticles. Combined with a detailed analysis of the micro-/nanoscale structure of the artificial spicules, the major mechanisms of mechanical performance will be identified and contrasted with those operative in their natural counterparts. As another objective to be pursued in parallel, two different types of scroll-based actuators shall be explored in detail. The actuators shall operate based upon changes of humidity of the environment and controlled electrostatic charging, respectively. A major goal is to determine the actuator performance, including their operational life time, as a function of the most relevant parameters, including the number and connectivity of lamellas, the inner diameter and width of the scrolls, as well as the amount of implemented cellulose nanofibers.