The synthesis of monomodal copolymers with poly(ethylene glycol) (PEG) side chains from commercial poly(ethylene glycol) methacrylates (PEGMA) by atom transfer radical polymerization (ATRP) is verified. Two hydroxy-functionalized PEGMA macromonomers (520 g/mol and 360 g/mol) were copolymerized with methyl methactylate (MMA) using various initial feed (1.5/98.5-50/50 mol.%). The copolymers P(MMA-co-PEGMA) with high degree of polymerization, e.g. 100-275 of repeating units in the backbone including 7-56 PEG side chains, were obtained. The relative reactivity ratios of PEGMA and MMA determined by the Jaacks method indicated slightly faster incorporation of macromonomer into polymeric chain than MMA (r(MMA) = 0.79; r(PEGMA) = 1.27). The polymers containing at least 17 mol.% of PEGMA units were water-soluble and exhibited clouding point at temperature in a broad range of 39-70 degrees C. The temperature-sensitive effect makes these polymers as a potential carriers in drug delivery systems. In the case of copolymers insoluble in water, a three-step procedure, including esterification to ATRP multifunctional macroinitiators, ATRP of tert-butyl methacrylate (tBMA) by grafting from, deprotection of carboxylic groups by removing tert-butyl groups, was applied to extend PEG grafts and expand the content of hydrophilic fraction (32-94 mol.%), what efficiently developed polymer solubility in polar solvents giving possibility for the future biomedical applications. (C) 2014 Elsevier Ltd. All rights reserved.