Fabrication of pore-selective carboxyl group functionalized polyimide honeycomb-patterned porous films using KOH humidity

Carboxyl group functionalization in honeycomb-patterned porous (HCP) films was obtained by breath figure process using polyimide (PI) which can react with KOH humidity at the polymer solution/aqueous alkali droplet interface to form carboxyl groups. PI containing CO-NR2 imide ring group reacts with KOH for imide ring-cleavage reaction by interfacial reaction. In order to obtain pore-selective carboxyl group functionalized PI HCP films, we have suggested a new strategy introducing KOH humidity with time interval after using initial water humidity during breath figuring process. The carboxyl group functionalized pores can be applied to obtain ordered microarray of biological and inorganic materials, which have potential applications in biosensors, separations, medical biology, etc. [Display omitted] •A new strategy was developed for the pore selective carboxyl functionalization.•Polyimide reacts with KOH humidity to form carboxyl functionalized porous films.•Pore functionalization was enhanced by delayed introduction of KOH humidity.•Reactive carboxyl pores can be used as a template for further functionalization.•Silver functionalized porous polyimide films by ion-exchange self-metallization.