Synthesis and evaluation of novel acrylic and ester-based polyols for transparent polyurethane coating applications

In the current study, the primary focus was concentrated on the synthesis and evaluation of two types of polyol systems namely acrylic and ester-based polyol (AP and EP) which can be further used as a component for the development of polyurethane coating. Both the polyols were synthesized with variable monomer compositions. The acrylic-based polyol was obtained by free-radical polymerization of monomers like Hydroxyethyl methacrylic 2-Hydroxyethyl acrylic, Isobornyl methacrylic, Butyl acrylic, Methyl methacrylic, Methacrylic acid, and Styrene in presence of di-tert-butyl peroxide (initiator). Besides, the ester-based polyols were synthesized by the esterification of stearic acid with the help of trimethylolpropane in the presence of oxalic acid or hexahydro-4-methylphthalic anhydride. The hydroxyl value of each polyol system was calculated in accordance with the ASTM D4274-99 standard and then the configuration and chemical structure were confirmed by FTIR and 1H NMR spectroscopy. The molecular weight distribution was confirmed by performing GPC whereas decomposition behavior was studied by TGA analysis. Higher hydroxyl value results in better performance of the polyols and AP- 1 and EP- 1 were found to be the most favorable systems to be used forward for the synthesis of polyurethane. Furthermore, PU coating was formulated and a preliminary study was conducted at various AP and EP concentrations, and their optical, mechanical and morphological properties were evaluated in order to validate the uses of polyols in PU coatings. This optimization was found to be true and in agreement with other characterization results.