Hydrophilicity,crystallinity and electrostatic dissipating properties of poly(oxyethylene)-segmented polyurethanes

Plaques of poly(oxyethylene)-segmented polyurethanes prepared from isophorone diisocyanate (IPDI) and polyethylene glycol (PEG) were used to probe the structure/property relationships with regard to hydrophilicity, crystallinity and electrostatic dissipating (ESD) ability. The prepared urethane polymers or oligomers consistently exhibited lower surface resistivities than their corresponding PEG-1000, 2000 and 8000 starting materials. The magnitude of the decrease in surface resistivity (ohm/sq) was correlated with heat of crystallinity, measured by differential scanning calorimetry. Surface resistivity as low as 10^7.5 ohm/sq for PEG-1000/IPDI polyurethane, a decrease by 2.5 orders of magnitude from pure PEG-1000, was observed and attributed to the differences in crystallinity. Polyurethanes containing PEG, polypropylene glycol (PPG) and mixed PEG/PPG were also prepared for comparison. The mixed PEG/MDEA (N -methyl diethanolamine) polyurethanes further demonstrated the importance of the nature and mobility of the hydrophilic groups for lowering the polymer surface resistivity. To account for these observations, an electron conducting mechanism via association and mobility of the hydrogen-bonded water molecules with hydrophilic poly(oxyethylene) groups is suggested. © 1999 Society of Chemical Industry