Spontaneous formation of microporous poly(lactic acid) coatings

[Display omitted] •Microporous poly(lactic acid) (PLA) coatings were prepared by spin-coating process.•Influence of substrate, solvent, concentration and humidity were investigated.•Depending on conditions PLA coatings with pore sizes from 1 to 7 μm were obtained.•Average pore size increased with increasing PLA concentration and humidity. Microporous poly(lactic acid) (PLA) coatings with fairly homogeneous pore size and distribution were obtained through spin-coating process. Critical effects of the thermal conductivity of the substrate (copper, glass, insulated glass), solvent type (dichloromethane, chloroform and tetrahydrofuran), polymer concentration (3–15% by weight) and relative humidity of the environment (0–85% relative humidity) on the formation and topography of microporous surfaces were investigated. Characterization of the surfaces was achieved via scanning electron microscopy, white light interferometry and static water contact angle measurements. By tuning the production parameters, PLA coatings displaying microporous surfaces with uniform pore sizes and distribution were obtained. Pore sizes varied from 1 to 7 μm depending on the experimental conditions.