Condensed Low-Volatile Alcohol Droplet-Directed Uniform Pore Formation on Polystyrene Films

In this work, various polystyrene (PS) films with uniform pores (0.18–1.26 μm in size) are prepared through spin‐casting polymer solutions consisting of PS, dichloromethane (CH2Cl2), and different low‐volatile alcohols (propylene glycol, diglycol, triglycol, polyethylene glycol‐200, ‐400, and ‐600). It is proposed that the formation of these uniform pores is directed by the condensed low‐volatile alcohol droplets formed during the solvent evaporation; relevant evidences are provided. Five different indexes are defined to help reveal the mechanisms of the effects of PS content and alcohol property on the aggregation tendency of the alcohol molecules and on the growth of the alcohol droplets, and thus on the pore size. A method for generating uniform pores of tunable size on polystyrene films is demonstrated. Low‐volatile alcohol droplets condensed from polymer solutions are used to template the precipitation of polystyrene. The property of the low‐volatile alcohol additive and the polystyrene concentration largely influence the film pore size.