Preparation of UV-curable waterborne poly(thiourethane-urethane) acrylate based on thiol-click chemistry

New strategies for synthesizing click chemical reactions have been studied and widely used in the synthesis of functional polymers. In this paper, based on thiol-click chemistry, thiocarbamate bonds and thioether bonds were introduced into the polymer skeleton, and then pentaerythritol tetraacrylate (PETTA) was introduced into the system to form an interpenetrating network structure (IPN). A new type of waterborne poly(thiourethane-urethane) acrylate (WPTUA) coating with strong toughness, high hardness, and rapid curing was obtained. Under the condition of an organotin catalyst, a WPTUA composite dispersion was prepared by using isophorone diisocyanate and polycarbonate diol as monomers, 2-dimethylol propionic acid as a hydrophilic chain extender, trimethylolpropane tris(3-mercaptopropionate) (TMPMP) and PETTA. The molecular structures of intermediate waterborne poly(thiourethane-urethane) (WPTU), WPTUA oligomers and UV-cured polymers were investigated by FTIR spectroscopy and Raman spectroscopy. The effects of the content of TMPMP and PETTA on the properties of WPTUA, including dispersion stability, thermal properties, mechanical properties, water resistance, hardness, and toughness, were investigated. It is found that when the WPTUA dispersion has 16 wt% TMPMP and 28 wt% PETTA, the prepared films have high hardness, significant water resistance and good thermal stability for coating applications on delicate substrates, such as paper, plastic and wood.