Straightforward functionalization of breath figures: Simultaneous orthogonal host–guest and pH-responsive interfaces

Herein, we report the design and preparation of multireversible smart porous surfaces combining two different abilities. On the one hand, either neutral or negatively charged surfaces can be formed by formation/disruption of host–guest complexes. On the other hand, these surfaces have the capability of alternating negatively and positively charge upon complexation of a polycation. Moreover, these two functionalization steps were demonstrated to be reversible so that the initial surface can be recovered and employed again. For this purpose, first, a copolymer was prepared by polymerization of two different monomers, i.e. styrene (S) and a styrene modified with cyclodextrin (SCD) by click chemistry. Blends of this copolymer and polystyrene were employed to fabricate porous surfaces with controlled pore sizes and chemical distribution by the breath figures technique. More precisely, the cyclodextrin (CD) moieties, specifically located inside the holes of the surface, interact reversibly with adamantane end-terminated poly(acrylic acid) chain (Ada-PAA85). The latter served to establish electrostatic interaction with a polycation (poly-l-lysine, PLL), leading to positively charged surface. These interactions, both host–guest and electrostatic, can be inverted obtaining again the original surface, proving the full reversibility of the system.

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