Light Controlled 3D Crystal Morphology for Droplet Evaporative Crystallization on Photosensitive Hydrophobic Substrate.

Controlling crystal morphology is crucial in analytical chemistry and smart materials synthesis, etc. However, flexible manipulation of 3D crystal morphology still remains challenging. Herein, we present a novel and facile light strategy for droplet evaporative crystallization to manipulate macroscopic crystal morphology on photosensitive hydrophobic substrate possessing photothermal conversion property. We demonstrate that the spherical coronal shell and alms bowl-like crystal skeletons can be achieved on smooth photosensitive hydrophobic substrate, depending on the salt concentration. Rough photosensitive hydrophobic substrate further creates a bubble-assisted light strategy, by which a cylindrical shell-like crystal skeleton with a directionally controllable cavity is achieved. Amazingly, the proper additive endows droplet evaporative crystallization to form a closed crystal skeleton with the solution wrapped inside. The present study provides new ideas for designing a novel optical droplet microfluidic platform for controlling crystal morphology.