Surface-induced Self-Assembly of Amphiphilic Block Copolymers into Functional Bilayer Thin Films.

An scalable method for the fabrication of symmetric and asymmetric BC bilayers on solid support of any type, shape and size is proposed, in order to overcome the specific limitations of currently available techniques (notably Langmuir-Blodgett (LB) deposition and polymersome vesicle fusion (VF)). We demonstrated that this fabrication process is viable by developing a proof of concept on silicon wafers, flat and macro-scopic substrates that allow the use of a wide range of complementary state-of-the-art techniques to precisely characterize the different steps of the assembly. This type of assembly, however, is potentially possible on colloidal objects, as showed by preliminary results. The proposed fabri-cation method was done using polystyrene-block-poly(acrylic acid) block copolymer and consists of two steps: i) the formation of a monolayer of BCs by the establishment of non-covalent interactions between the substrate and the hydrophilic blocks in a non-selective solvent ii) the controlled addition of a selective solvent (water) which triggers the assembly of the second layer through hydrophobic interactions between the free and previously adsorbed hydrophobic blocks resulting in the formation of a self-assembled bilayer of BCs on a solid support. A final rinsing step allows to eliminate the excess of aggregates (micelles) generated in the solution during the second step. BC monolayers and bilayers on solid supports were obtained and characterized using various surface characterization techniques. The ability of these bilayers to encapsulate hydrophobic actives of interest for specific applications has also been highlighted using gold nanoparticles (AuNPs). Finally, the possibility to form asymmetric bilayers was demonstrated on a PS-b-PAA/PS-b -poly(vinyl pyridine) (PS-b-P2VP) system.