Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 47, 3142–3153 (2009)
A series of well-defined double hydrophilic double-grafted copolymers, consisting of polyacrylate backbone, hydrophilic poly(2-(diethylamino)ethyl methacrylate) and poly(ethylene glycol) side chains, were synthesized by successive atom transfer radical polymerization. The backbone, poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) comb copolymer, was firstly prepared by ATRP of PEGMEA macromonomer via the grafting-through route followed by reacting with lithium diisopropylamide and 2-bromopropionyl chloride to give PPEGMEA-Br macroinitiator
of ATRP. Finally, poly[poly(ethylene glycol) methyl ether acrylate]-g-poly (2-(diethylamino)ethyl methacrylate) graft copolymers were synthesized by ATRP of
2-(diethylamino)ethyl methacrylate using PPEGMEA-Br macroinitiator via the grafting-
from route. Poly(2-(diethylamino)ethyl methacrylate) side chains were connected
to polyacrylate backbone through stable CAC bonds instead of ester connections, which is tolerant of both acidic and basic environment. The molecular weights of both backbone and side chains were controllable and the molecular weight distributions kept relatively narrow (Mw/Mn 1.39). The results of fluorescence spectroscopy, dynamic laser light scattering and transmission electron microscopy showed this double hydrophilic copolymer was stimuli-responsive to both pH and salinity. It can aggregate to form reversible micelles in basic surroundings which can be conveniently dissociated with the addition of salt at room temperature.