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Abstract :
[en] To answer the increasing demand for long-lasting antibacterial polymeric coatings, this thesis explores a straightforward synthetic approach to cationically charged nanogels by cobalt-mediated radical cross-linking copolymerization (CMRCcP), thus expanding previous works on the cobalt-mediated radical polymerization of poly(ionic liquid)s, or PILs. This method involves a vinyl monomer and a divinyl cross-linker, in presence of a complex of Cobalt(III) playing the role of both the initiator and the controlling agent.
The syntheses of globular nanogels were first investigated under mild conditions, using a mono- and a divinyl co-monomer with similar reactivities. CMRCcP was implemented on either neutral (vinyl acetate (VAc) and divinyl adipate (DVA)) co-monomers, or hydrophilic (bromide-containing) ionic liquid co-monomers. Control over each polymerization was ascertained, and dormant cobalt-carbon chain-ends could be re-activated to form “second-generation” nanogels. CMRCcP of N-vinyl-3-ethyl imidazolium bromide (VEtImBr) and 1,13-divinyl-3-decyl diimidazolium bromide (DVImBr) was achieved in water at 30 °C, leading to hydrophilic poly(VEtImBr-co-DVImBr) nanogels. The antibacterial activity of these cross-linked structures was investigated, and an effect of architecture is detected.
The hydrophobic pendants of these PIL-based nanogels were synthesized via direct CMRCcP in ethyl acetate, using bis(trifluromethanesulfonyl)imide (NTf2-) counter anions. An array of these poly(VEtImNTf2-co-DVImNTf2) nanogels was then investigated as possible coatings for porous patterned surfaces. Thin films of hydrophobic PIL-based nanogels were also evaluated in ionic conductivity tests. “Second-generation” nanogels exhibited better ionic conductivity, and were able to form better organized porous patterned surfaces than “first-generation” nanogels.
Different cross-linked architecture were approached, using a mono- and a divinyl co-monomers of completely different reactivities: synthesizing poly(VEtImBr-co-DVA) nanogels met limited success, while copolymerizing VAc and DVImBr yielded too low conversion. A two-step arm-first process was implemented to form star-like poly(VEtImNTf2-co-DVImNTf2) nanogels with PVAc arms.
