'Pancake' vs. brush-like regime of quaternizable polymer grafts: an efficient tool for nano-templating polyelectrolyte self-assembly
Résumé
A tunable strategy, based on the combination of Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and the Layer by Layer (LbL) deposition of polyelectrolytes, was exploited to design tailor-made polyelectrolyte multilayers (PEM) with unusual nanometric features. The cornerstone of the approach is to use polyelectrolytes grafted onto a planar inorganic substrate with different chain conformations as a template for depositing PEM. More particularly, tethered poly(trimethylammonium ethyl methacrylate iodide) (PTMAEMAI) grafts provide various 3D distributions of charge due to a conformation transition of the precursor quaternizable poly(N, N-dimethylamino)ethyl methacrylate (PDMAEMA) chains from 'pancake' to brush-like regime. The change of regime was ensured through the controlled variation of the graft molecular weight using SI-ATRP. The regions made of attached-polycations may serve as preferential positively charged anchoring sites and act as structure-directing agents for the subsequent LbL self-assembly of poly(sodium 4-styrenesulfonate) (PSS)/poly(diallyldimethylammonium chloride) (PDADMAC) multilayers. We have revealed the possibility to fine manipulate (i) the interaction abilities and (ii) the topology of (PSS/PDADMAC) films through the spatial organization exhibited by the PTMAEMAI grafts. This appears as a well-suited and straightforward tool to create an adjustable nanoscale patterning of the resulting multilayers.