Agyapong Johnson N, Van Durme Bo, Van Vlierberghe Sandra, Henderson James H
The Bioinspired Institute, Syracuse University, Syracuse, NY 13244, USA.
Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA.
Polymers (Basel). 2023 Apr 28;15(9):2117. doi: 10.3390/polym15092117.
Wrinkle topographies have been studied as simple, versatile, and in some cases biomimetic surface functionalization strategies. To fabricate surface wrinkles, one material phenomenon employed is the mechanical-instability-driven wrinkling of thin films, which occurs when a deforming substrate produces sufficient compressive strain to buckle a surface thin film. Although thin-film wrinkling has been studied on shape-changing functional materials, including shape-memory polymers (SMPs), work to date has been primarily limited to simple geometries, such as flat, uniaxially-contracting substrates. Thus, there is a need for a strategy that would allow deformation of complex substrates or 3D parts to generate wrinkles on surfaces throughout that complex substrate or part. Here, 4D printing of SMPs is combined with polymeric and metallic thin films to develop and study an approach for fiber-level topographic functionalization suitable for use in printing of arbitrarily complex shape-changing substrates or parts. The effect of nozzle temperature, substrate architecture, and film thickness on wrinkles has been characterized, as well as wrinkle topography on nuclear alignment using scanning electron microscopy, atomic force microscopy, and fluorescent imaging. As nozzle temperature increased, wrinkle wavelength increased while strain trapping and nuclear alignment decreased. Moreover, with increasing film thickness, the wavelength increased as well.
皱纹形貌已被研究作为一种简单、通用且在某些情况下具有仿生功能的表面功能化策略。为了制造表面皱纹，一种利用的材料现象是薄膜的机械不稳定性驱动的起皱，当变形的基底产生足够的压缩应变使表面薄膜发生屈曲时就会出现这种情况。尽管已经在包括形状记忆聚合物（SMP）在内的形状变化功能材料上研究了薄膜起皱，但迄今为止的工作主要限于简单的几何形状，如平坦的、单轴收缩的基底。因此，需要一种策略，该策略能够使复杂基底或三维部件变形，从而在整个复杂基底或部件的表面上产生皱纹。在此，将SMP的4D打印与聚合物和金属薄膜相结合，以开发和研究一种适用于打印任意复杂形状变化基底或部件的纤维级形貌功能化方法。已经表征了喷嘴温度、基底结构和薄膜厚度对皱纹的影响，以及使用扫描电子显微镜、原子力显微镜和荧光成像对核排列的皱纹形貌。随着喷嘴温度升高，皱纹波长增加，而应变捕获和核排列减少。此外，随着薄膜厚度增加，波长也增加。
