Discovery and Insights into Organized Spontaneous Emulsification via Interfacial Self-Assembly of Amphiphilic Bottlebrush Block Copolymers

Since the first discovery of spontaneous emulsification, the process has remained uncontrollable for centuries leading to unstable emulsion droplets with limited uses. Herein, by in situ observation it was found that uniform water-in-oil (W/O) nanoemulsion droplets can be spontaneously formed and self-organized during solvent evaporation. Amphiphilic bottlebrush block copolymers are strongly adsorbed at the water/oil interface to stabilize the droplets, and their rod-like molecular conformation enables good control of the droplet spherical curvature. After solvent removal, solidified thin films or microparticles with hexagonal closest packed nanopore arrays are produced in one-step templated by the ordered W/O emulsions. The pore diameter is precisely tunable in a wide range (160 ≤ D ≤ 395 nm) by changing the spherical curvature of the water droplets dependent on the degree of polymerization of the bottlebrush block copolymer (BBCP) (89 ≤ DP ≤ 151). The well-ordered porous structures give rise to full-spectrum structural colors. This work provides a general method for scalable production of well-ordered porous materials with greatly reduced energy consumption.