4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

4. BLOCK COPOLYMER MICELLES’ ZIPPER ASSEMBLYCoatings obtained from traditional methods like grafting of polymers 1 , electrodeposition 2 , or atomiclayer deposition 3are permanent in nature which prevent any further self-adjustment of thestructure or surface properties. In contrast, a responsive coating can optimize dynamically the surfacestate of materials with respect to their environment. For example, polyelectrolyte multilayers display areversible nanoporosity via a pH-induced swelling transition 4 , whereas a polyelectrolyte-based sacrificialcoating can be used in a controlled manner to ensure a continuous regeneration of the surface state 5 .However, their preparation employs an industrially fastidious and time consuming multistep strategy.Inspired by natural systems, synthetic materials having reversible connections between their constitutingobjects (molecules, macromolecules, dendrimers, particles…) demonstrate a certain dynamism leadingto potential new applications 6 . The preparation of such materials is usually based on a self-assemblystrategy with a bottom-up approach where small building blocks are assembled into larger edifices witha sharp control over local and global architecture 7 . Self-sorting constitution can be observed fromcomplex systems following “natural” selection rules 8 , but the need to target the final material propertiesis generally reached by designing the assembly stage with a predictable strategy 9 .The so called “Zipper effect” has been observed in several natural systems at all scales with anexceptional ability to form reversible assembly through a controlled zipping-unzipping process. Forexample, many transcription factors are known to contain leucine zippers 10,11 . In this case, the structureof the proteins contain a series of leucines every seven residues. This specific spacing enables the leucine -helix and to interact with a second analogous proteinfragment via hydrophobic bonds. Molecular zippers have been used alone like in the preparation of DNAzippers and tweezers 12 , reversibly opening organic tubes 13 , one dimensional molecular assemblies 14 , or incombination with layer-by-layer techniques or chemical reactions 15,16 . In polymer science, zipping hasalso been reported for example in molecularly imprinted polymers to control the access to therecognition pocket 17 , to drive a crystallization process 18,19 , or to prepare ultra-dense polymer brushes 20 .Zipper-assembly can be considered as a variant in the “self-assembly” family that combines (macro)molecular interactions and architectural cooperation 21 .103