Synthesis and properties of PS-PEO core-shell amphiphilic dendrigrafts

Water-soluble amphiphilic dendrigrafts constituted of a hydrophobic polystyrene core and a hydrophilic poly(ethylene oxide) shell have been prepared via a 'grafting onto' procedure from polystyrene dendrigraft precursors. The introduction of the surrounding hydrophilic shell was achieved through cyclic trans-acetalization between ω-acetal functionalized branches of the polystyrene precursor and PEO grafts bearing a α-bis(hydroxymethyl) chain end (A2-PEO). Yields of grafting are strongly affected by the increase of the degree of polymerization of the reactive PEO grafts (respectively, 100, 87, and 38% with A2-PEO20, A2-PEO100 and A2-PEO150). However, paradoxically, only the use of A2-PEO100 or A2-PEO150 as reactive grafts affords water-soluble dendrigrafts due to higher PEO weight content (respectively, 41 and 36%). The dimensions and the shape of the PScore-PEOshell polymers were investigated in solution (THF and water) by dynamic light scattering and in the dry state by TEM and AFM.