Spontaneous Formation of Oriented Lateral Wrinkles Assisted by Shrinkage Controlled Cracking

Abstract

AbstractOriented wrinkled surfaces play a vital role in the preparation of functional components. However, existing methods for the fabrication of oriented wrinkle patterns are often limited by specific equipment (e.g., high vacuum systems) and cumbersome processes. In this study, an approach utilizing shrinkage controlled cracking method is proposed to introduce prefabricated topographic patterns on flat semi‐crosslinked polydimethylsiloxane (Semi‐PDMS) substrate for modulating anisotropic release of the interlaminar lateral stresses, where the crosslinking‐induced volumetric shrinkage from the Semi‐PDMS substrate provides the driving force for developing and stabilizing oriented surface wrinkle formation; followed by thickening polydopamine (PDA) capping layer to increase the orientation degree of wrinkles. Moreover, the evolutionary mechanism of oriented wrinkles on the PDA/Semi‐PDMS composite surface are demonstrated. The materials used in the reported method are low cost and environmentally friendly, and the preparation process is simple and green without the need for extreme conditions or strong solvents, which can be scaled up to large‐scale fabrication. According to the biocompatibility, high stability, and reactivity of polydopamine, the prepared oriented wrinkles may find potential applications in electronic skin, enhancement of cell alignment, flexible and stretchable electronics, and as structured templates for surface arrays.