Structured Multistimuli-Responsive Functional Polymer Surfaces Obtained by Interfacial Diffusion of Amphiphilic Block Copolymers
Résumé
Herein, we report the preparation of structured multistimuli-responsive surfaces able to change reversibly both their chemical composition depending on the environment and their surface behavior by varying either/both the pH or/and the temperature. For that purpose, we took advantage of the surface segregation in homopolymer/diblock copolymer blends, composed of either polystyrene-block-poly(N,N'-dimethylaminoethylmethacrylate) (PS-b-PDMAEMA) or polystyrene-block-poly (N,N'-diethylaminoethylmethacrylate) (PS-b-PDEAEMA) and high molecular weight polystyrene used as a matrix. The variations of the surface composition as a function of the environment of exposure (air or water vapor) was investigated were investigated by XPS and contact angle measurements. The water-annealed surfaces contain PDMAEMA or PDEAEMA at the surface and are additionally able to respond both to pH and temperature as demonstrated by the Wilhelmy technique. Both PDMAEMA and PDEAEMA can switch from a hydrophilic state to a collapsed hydrophobic state increasing the temperature above the LCST. More interestingly, as a result of the microphase separation of the block copolymers at the interface, the surfaces of the blends exhibit structuration. Thus, either micellar structures or "donut-like" morphologies were obtained by using THF or toluene, respectively, as solvent.