Combination of “living” nitroxide-mediated and photoiniferter-induced “grafting from” free-radical polymerizations: From branched copolymers to unimolecular micelles and microgels

摘要: Abstract We report on solution properties of lightly grafted copolymers composed polystyrene (PS) backbone (degree polymerization PS backbone, N b = 95 ) and variable length poly(tert-butyl methacrylate) P(tBuMA) side chains chains, sc 14 – 222 at fixed number grafting sites n = 11 polydispersity index (Mw/Mn) ranging from 1.05 to 2.63. Synthesis these graft is based a novel synthetic route [Gromadzki D, Makuska R, Netopilik M, Holler P, Lokaj J, Janata et al. Eur Polym J 2008;44:59–71] involving two independent controlled/“living” mechanisms, namely nitroxide-mediated radical (NMP) for the synthesis photoinduced “grafting from” iniferter process building branches. The viscosity-related contraction factors g ′ 1 confirmed high degree branching studied copolymers. Dilute solutions in non-selective solvent (THF), examined by dynamic light scattering (DLS), small-angle X-ray (SAXS) viscometry, revealed transition comb-like conformation through wormlike-star microgel architecture under increasing monomeric units chains. These data were further supported structure R η / h obtained measurements extrapolated infinite dilution. Persistence lengths samples exhibiting topology larger compared linear THF suggesting stiffening main chain with size attached Unimolecular micelles detected DLS SAXS selective grafts, tert-amyl alcohol.