Polymersome Crack Film and Its Templating Function in Silica and Gold Deposition

ABSTRACT Here, we report for the first time the formation of unique self‐cracking films prepared by drop‐casting polymersomes self‐assembled from the block copolymer PEI‐b‐PPOZ, composed of polyethyleneimine (PEI) and poly(2‐phenyl‐2‐oxazoline) (PPOZ). Using optical and electron microscopy, we investigated the relation between the evolution of self‐cracking films with various substrate types and over time. We found that crack‐patterned films, interconnected by a dense, channel‐like network, are readily and efficiently generated during water evaporation under ambient conditions (20°C–27°C and 40%–50% RH). The concentration of polymersomes and the drying temperature of polymersome cast films have a significant impact on crack formation and crack density. Interestingly, the crack‐patterned films served as a catalytic template to promote the hydrolytic polycondensation of tetramethoxysilane (TMOS), resulting in silica‐coated films that preserve the original crack pattern. SEM observations before and after silica deposition confirmed that the crack films are composed of stacked spherical polymersomes. The resulting silica‐hybrid crack films exhibited enhanced solvent resistance, and the crack channels concentrated target materials via capillary effects when immersed in an aqueous solution of silver acetate. Moreover, deposition of gold on the cracked film by resistance heating evaporation afforded effectively a transparent conductive gold mesh with sheet resistance of 19.9 Ω/◻ and optical transparency of > 90%.