The hydrogen\|bond defect of water in aqueous solution of a well\|defined poly(2\|hydroxyethyl acrylate)(PHEA) with different molecular weights and concentrations was studied by Raman spectrum analysis. The pre\|designed molecular weight of PHEAs with narrow polydispersities (<1 20) were synthesized via atom transfer radical polymerization (ATRP). It was found that in a low concentration PHEA aqueous solution(5?wt%), with the increase of molecular weight, the hydrogen bond defect increased markedly, but in a high concentration solution (25?wt%), the hydrogen bond defect was not sensitively affected by the molecular weight of PHEA. At higher temperature, the N value decreased due to the destroying of the hydrogen bond formation between water and the hydrophilic polymer chain in aqueous solutions.
