Preparation of UV-Curable Easy-Cleaning Coatings Based on Polydimethylsiloxane-Modified Hyperbranched Polythiourethane

Polydimethylsiloxane (PDMS)-containing hyperbranched polythiourea (PDMS-HBPTU) was synthesized using monohydroxyl-terminated polydimethylsiloxane (PDMS-OH), isophorone diisocyanate (IPDI), and trimethylolpropane tris(3-mercaptopropionate) (TMPMP) as raw materials. The PDMS-HBPTU was then added to polycaprolactone-based polyurethane acrylate (LPUA) coatings to prepare a series of easy-cleaning coatings with different mass fractions of PDMS-HBPTU. The effects of the mass fraction of PDMS-HBPTU on the wettability, light transmittance, anti-pollution properties, and wear resistance of the the coatings were systematically investigated using the optical contact angle meter, UV-Vis spectrophotometer, oil-based marker ink, and the tribometer. The results indicate that when the mass fraction of PDMS-HBPTU is 2.0%, the contact angles of water and hexadecane on the coating surface are significantly increased, while the sliding angle of water and the surface energy of the coating are reduced. Additionally, the coating maintains high light transmittance and exhibits decreased surface roughness. XPS data indicates that the PDMS segments are enriched on the coating surface, forming a low-surface-energy interface. The coating demonstrates excellent anti-staining and easy-cleaning properties against oil-based marker ink as well as common liquids such as milk, cooking oil, and beverages. After 5000 rubbing cycles with cotton cloth, the water contact angle of the coating decreases by only 6.02%, retaining good anti-graffiti performance, which highlights its excellent wear resistance. The hyperbranched structure effectively improves the compatibility between PDMS and the matrix resin. When the mass fraction of PDMS-HBPTU is 2.0%, the coating not only maintains high transmittance but also possesses excellent surface hydrophobicity/oleophobicity, easy-cleaning properties, and wear resistance, showing good prospects for practical applications.