Textured Frozen Polymer Droplets

Ice templating provides a means of generating textures with a well-defined topography. While typically executed with colloids, our research explores using polymers to manipulate the morphology and texture of frozen droplets. Our experiments indicate that frozen polymer droplets' macroscopic shape and texture vary with the molecular weight and polymer concentration under unidirectional freezing conditions. Distinctly, a white cloudy halo forms along the freezing direction upon freezing, delineating two droplet zones exhibiting different freezing behaviors and suggesting phase separation occurring. Concomitantly, detailed in-situ microscopic observations revealed that the roughening of the freezing front also depends on polymer concentration and molecular weight, suggesting a connection between the microscopic roughness of the freezing front and the macroscopic roughness of the frozen droplet. By combining polymer physics and heat transfer, our findings offer novel strategies for ice templating and microstructure fabrication.