Hu Shuhuan, Huang Wei, Meng Fanchao, Lam Raymond H W, Lau Denvid
Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China.
Department of Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China.
ACS Appl Mater Interfaces. 2022 Feb 9;14(5):7221-7229. doi: 10.1021/acsami.1c20282. Epub 2022 Jan 12.
Interfacial bonding integrity between different materials is critical to maintain the functionality of the entire physical system in any scale, ranging from building structures down to semiconductor transistors. For example, micro-patterned polymers embedded with conductive nanoparticles [e.g., carbon nanotubes (CNTs)] bonded with integrated circuits have been applied as many emerging chemical/biological microelectronic sensors. Nonetheless, it is challenging to measure and ensure the interfacial bonding integrity between materials for consistent and sustainable operations. Herein, we apply multiple interface characterization methods based on micro-engineering and microscopy as an integrative approach to reveal the mechanism of interfacial reinforcement by adding CNTs in a matrix material. An epoxy/CNT micro-beam is fabricated onto a silicon substrate, sandwiching a gold layer as an interfacial precrack. Superlayers of chromium are then repeatedly deposited onto the microstructure, inducing stepwise increasing stress over the materials and the corresponding micro-beam bending after detachment from the bonded interface. Accordingly, we can quantify key interfacial fracture parameters such as crack length, steady-state energy release rate, and fracture toughness. By further examining the formation and distribution of the micro-/nanostructures along the debonded interface using bright-field microscopy, 3D fluorescence imaging, and scanning electron microscopy, we can identify the underlying dominant interfacial strengthening and fracture toughening mechanisms. We further compare experimental results and theoretical predictions to quantify the interfacial bonding properties between epoxy/CNT and silicon and unveil the underlying reinforcement mechanisms. The results provide insights to develop polymer/nanoparticle composites with reinforced interfacial bonding integrity for more sustainable and reliable applications including microelectronics, surface coatings, and adhesive materials.
不同材料之间的界面结合完整性对于维持任何尺度下整个物理系统的功能至关重要，从建筑结构到半导体晶体管皆是如此。例如，嵌入导电纳米颗粒（如碳纳米管）的微图案聚合物与集成电路结合后，已被用作许多新兴的化学/生物微电子传感器。然而，测量并确保材料之间的界面结合完整性以实现一致且可持续的运行具有挑战性。在此，我们应用基于微工程和显微镜的多种界面表征方法作为一种综合方法，以揭示通过在基体材料中添加碳纳米管来增强界面的机制。在硅衬底上制备了一个环氧/碳纳米管微梁，中间夹着一层金作为界面预裂纹。然后在微结构上反复沉积铬超层，在材料上诱导出逐步增加的应力，并且在与粘结界面分离后微梁会相应地发生弯曲。据此，我们可以量化关键的界面断裂参数，如裂纹长度、稳态能量释放率和断裂韧性。通过使用明场显微镜、三维荧光成像和扫描电子显微镜进一步研究沿脱粘界面的微/纳米结构的形成和分布，我们可以确定潜在的主要界面强化和断裂增韧机制。我们进一步比较实验结果和理论预测，以量化环氧/碳纳米管与硅之间的界面结合特性，并揭示潜在的强化机制。这些结果为开发具有增强界面结合完整性的聚合物/纳米颗粒复合材料提供了见解，以用于包括微电子、表面涂层和粘合剂材料在内的更可持续和可靠的应用。
