Synthesis and characterization of a novel hydroxy terminated polydimethylsiloxane and its application in the waterborne polysiloxane–urethane dispersion for potential marine coatings

α‐Butyl ω‐ N , N ‐dihydroxyethyl aminopropylpolymethylhydrosiloxane (PDMS), a monotelechelic polydimethylsiloxane with a diol‐end group, which is used to prepare siloxane–urethane dispersion, was successfully synthesized. Then, novel silicone‐based polyurethane (PU)‐dispersion was prepared by the addition polymerization of hexamethylene diisocyanate, to PDMS, polyethylene glycol (PEG) and dimethylol propionic acid. The goal of this study was to explore the potential use of polysiloxane–urethane in marine coatings in order to boost the flexibility, adhesion, erosion and foul‐release property with respect to PDMS/PEG ratio (PDMS wt%). The PDMS was characterized by Fourier‐transform infrared (FT‐IR), proton nuclear magnetic resonance and carbon‐13 nuclear magnetic resonance spectroscopic techniques. The results showed that each step was successfully carried out and the targeted products were synthesized in all cases. The structural elucidation of the synthesized waterborne PU and waterborne polysiloxane–urethane (WBPSU) was carried out by FT‐IR spectroscopic technique. Thermal properties of the resins were studied by using thermogravimetric analysis and differential scanning calorimetry. The antifouling property of the coatings was investigated by the immersion test under a marine environment for 90 days. The fouled area was calculated for all the samples, and the fouled area (%) decreased with increasing PDMS content. After 90 days, the lowest fouled area (6%) was observed in the sample using WBPSU2 (PDMS 4.48 wt%) among all of the samples. Copyright © 2012 John Wiley & Sons, Ltd.