Preparation and Antifouling Properties of Silicon-Modified Waterborne Polyurethane Coatings

Silicone can be used to improve the antifouling properties of polyurethane (PU) coatings. A series of uniform and stable nano-scale waterborne PU were prepared by using toluene diisocyanate (TDI), polycaprolactone diol (PCL2000) and hydroxy-terminated polydimethylsiloxane (PDMS) as the main raw materials. Fourier transform infrared spectrometer (FT-IR), dynamic light scattering (DLS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarizing microscope (PM) were used to test the structures and properties of the material.Subsequently, the coatings with different PDMS mass fractions (w(PDMS) were painted on the panels and immersed in the river. The practical antifouling levels of the materials were tested. Results showed that the thermal stability of the film increased with the increase of w(PDMS). While the surface free energy (γ), gradually decreased to 13.87 mJ/m². PDMS reduced the glass transition temperature (T_g) of the material, and enhanced the water resistance of the coatings. Besides, the addition of silicon oil effectively reduced the elastic modulus (E) of the coatings. Correlation (between the theory that the adhesion of pollutants on antifouling coating is positively relevant to the square root of the product of the elastic modulus of the coating and the surface energy and the actual antifouling level (coatings actually immersed in water) was explored. Results showed that the PDMS-modified PU had excellent antifouling performance, and the actual antifouling effect of the coating was consistent with the calculation results of the theoretical reference value \sqrt\gamma \cdot E .