Effect of soft segment composition on the physical properties of nonionic aqueous polyurethane containing side chain PEGME

Abstract

AbstractIn this study, a series of nonionic waterborne polyurethanes containing side chain poly(ethylene glycol) monomethyl ether (PEGME) were synthesized using 4,4‐methylene bis(isocyanatocyclohexane), the nonionic dispersing center produced by isophorone diisocyanate, N‐diethanol amine, and PEGME, and a series of soft segments [polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), and polycaprolactone (PCL)] with a different molecular weight. The solution properties of the polyurethane (PU) dispersions, thermal properties of the PU casting films, and the water vapor permeability (WVP) of the PU coated fabrics were investigated. Our results show that the surface tension of PU dispersion and its contact angle to untreated nylon fabric are higher for the ether‐based PU dispersion than for the ester‐based PU dispersion, with a sequence of PEG‐PU ≫ PTMG‐PU ≫ PPG‐PU ≫ PCL‐PU. Both the surface tension and the contact angle between PU dispersion and nylon fabric increase upon increasing the Mw of the soft segment. As for the thermal property of PU film, the Tgs of PCL‐PU is the highest, followed by PEG‐PU, PTMG‐PU, and PPG‐PU, and the Tgs decreases with the increase in the length of the soft segment. The Tms follows the order: PEG‐PU ≫ PCL‐PU ≫ PPG‐PU ≫ PTMG‐PU, and the Tms increases upon increasing the soft segment length. As regard to PU coated fabric, the trend of WVP is PEG‐PU ≫ PTMG‐PU ≫ PPG‐PU ≫ PCL‐PU, which increases with the increasing the soft segment length. With regarding to application for the coating, the Coated‐PU with PEG‐PU has an excellent WVP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007