The dispersion copolymerization of methyl methacrylate (MMA) with macromonomeric azoinitiator, MIM-400, as a macrocrosslinker initiated by the benzoyl peroxide (BPO)/N,N'dimethylaniline (DMA) coupled in water/ethanol (4/1, v/v) at 20 degrees C was carried out to yield PEG-b-PMMA networks with labile azo linkages in the main chain. Gel fraction, swelling ratios (q(v)) and the average molecular weights between junction points (M-c) values of the networks were investigated. Maximum gel fraction was obtained using 0.133 M MIM-400, 9.2 x 10(-2) M BPO, 2.1 x 10(-2) M DMA and 2.19 M MMA.