A diamine with carboxyl-terminated polyethylene glycol (PEG) side chains (Lys-NH-PEG)was synthesized as chain extender for polyurethanes (PUs)

using L-lysine

ethylenediamine and PEG bis-(carboxymethyl)ether as raw materials.Further to this

a comb-like polycarbonate urethane with PEG side chains (PCU-L-P) was synthesized using Lys-NH-PEG and 4

4'-diphenylmethane diisocyanate (MDI) as hard segment

and polycarbonate diol as soft segment.Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR) were used to confirm the chemical structure of PCU-L-P

whose number-average molecular weight was about 38000 determined by gel permeation chromatography (GPC).The solution of PCU-L-P (in dimethylformamide) can be transformed into hydrocolloid stabilized by the hydrophilic PEG side chains

with a mean particle size of about 213 nm and a zeta potential of -19 mV.Model protein albumin has been successfully grafted onto the colloidal particles

indicating the reactivity of the carboxyl groups at the PEG free ends.This reactive polyurethane can be used to graft various biomolecules for improving PUs' biofunctionality.