Wooh Sanghyuk, Lee Soojin, Lee Yunchan, Ryu Ji Ho, Lee Won Bo, Yoon Hyunsik, Char Kookheon
The National Creative Research Initiative Center for Intelligent Hybrids, The World Class University Program for Chemical Convergence for Energy and Environment, School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Republic of Korea.
School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Republic of Korea.
ACS Nano. 2016 Oct 25;10(10):9259-9266. doi: 10.1021/acsnano.6b03044. Epub 2016 Sep 22.
Cracks observed in brittle materials are mostly regarded as defects or failures. However, they can be a valuable tool when implemented in a controlled way. Here, we introduce a strategy to control the crack propagation of mesoporous micropatterns (prisms and pyramids), which leads to the isolation of well-defined microstructures. Mesoporous micropatterns were fabricated by the soft imprinting technique with wet TiO nanoparticle (NP) pastes, followed by sintering to remove organic components. Since the volume of the paste significantly shrinks during the sintering step, stress is localized at the edge of micropatterns, in good agreement with finite element method simulations, creating well-defined cracks and their propagation. It was demonstrated that the degree of stress localization is determined by the thickness of residual layers, NP size, and heating rate. After controlled crack propagation and delamination of microparticles from the substrates, mesoporous microwires and microparticles were successfully produced and functionalized from the isolated mesoporous prisms and pyramids. The method proposed in this study for controlled crack manipulation and delamination opens a door for straightforward and economical fabrication of well-defined mesoporous microparticles.
在脆性材料中观察到的裂纹大多被视为缺陷或失效。然而，当以可控方式实现时，它们可以成为一种有价值的工具。在此，我们介绍一种控制介孔微图案（棱柱和棱锥）裂纹扩展的策略，这会导致形成明确的微观结构。介孔微图案通过使用湿的TiO纳米颗粒（NP）糊剂的软压印技术制造，随后进行烧结以去除有机成分。由于糊剂的体积在烧结步骤中显著收缩，应力集中在微图案的边缘，这与有限元方法模拟结果高度吻合，从而产生明确的裂纹及其扩展。结果表明，应力集中程度由残余层厚度、NP尺寸和加热速率决定。在控制裂纹扩展以及微粒从基底分层之后，成功地从分离出的介孔棱柱和棱锥制备并功能化了介孔微丝和微粒。本研究中提出的用于控制裂纹操纵和分层的方法为直接且经济地制造明确的介孔微粒打开了一扇门。
