Adhesion of Morphologically Distinct Crystals to and Selective Release from Elastomeric Surfaces

This work describes the adhesion characteristics of micrometer-scale crystals to chemically functionalized, soft elastomeric supports throughout repeated cycles of tensile stress. The ability to tune the characteristics of hard/soft interfaces (e.g., those formed between silicones, such as poly­(dimethylsiloxane), and semiconductors, such as ZnO) is fundamentally important to understanding processes in biomineralization and crucial to technologies such as stretchable electronics and self-cleaning, antifouling surfaces. This study systematically examined the effect of surface chemistry, crystal morphology, the ambient environment, and the number of stress events on adhesion by monitoring the displacement and delamination of crystals from the support polymer. The crystals studied remained surprisingly well adhered, even in wet environments. These understandings were applied to the design and synthesis of surfaces that, through a process of mechanically activated, selective delamination, could generate 2D patterns of crystals from random deposits or isolate specific morphologies from mixtures. The concepts presented here could be applied to material assembly or to the separation of micrometer-scale particles useful to, for example, the analytical/forensic sciences.