Tailoring the properties of waterborne polyurethanes by incorporating different content of poly(dimethylsiloxane)

Abstract

A series of novel waterborne polyurethanes (WBPUs) was synthesized using α,ω-dihydroxypropyl poly(dimethylsiloxane) (PDMS), isophorone diisocyanate (IPDI), 2,2-bis-(hydroxymethyl) propionic acid (DMPA) and triethylamine (TEA). Different DMPA/PDMS molar ratio (from 0.2 to 0.7) and fixed –NCO/–OH molar ratio of 1.7, has been applied for the synthesis of six different WBPU films, without utilization of chain extension step during the synthesis. The structure of the prepared WBPUs was examined and confirmed by FTIR and NMR spectroscopy. The particle size of the prepared WBPU dispersions and molecular weight of WBPU films decrease with increasing DMPA content. In order to investigate the effect of the DMPA/PDMS ratio on thermal, mechanical and morphological properties, as well as the water resistance of the prepared WBPUs, diverse experimental techniques, such as thermogravimetric analysis, dynamic mechanical analysis, tensile tests, X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water contact angle measurements have been carried out. This research has shown that the incorporation of PDMS in WBPUs led to the appearance of microphase separation and provided surface hydrophobicity, good thermal and mechanical properties, which allow application of these WBPUs as coatings for various purposes.