Synthesis of Three Novel Silane-Based Carboxylic Acids for Application in Methacrylated Epoxy-Based Oligomers and Their Ability to Improve the Properties of UV Curable Hybrid Coatings

Abstract

Improvement of thermal stability of silicone-based coatings was the main objective of this study. In this study bromoacetic acid (BAA) was reacted with 3-(mercaptopropyl) trimethoxy silane (MPTS) and trimethoxy silyl propyl thioacetic acid (TSTA) was produced. Also, bromoacetic acid (BAA) was reacted with 3-(triethoxysilyl) propylamine (APTS) and triethoxysilyl propylamino acetic acid (TSPA) was synthesized. Finally, from a reaction between trimellitic anhydride (TMA) and APTS, trimellitylimidopropyl triethoxysilane (TMIS) resulted. Compounds containing carboxylic acids and trimethyl silane were obtained in all of these reactions. Furthermore, hybrid coatings based on methacrylated bisphenol A epoxy (MBAE) and the synthesized carboxylic acids were obtained by photopolymerization. Polycarbonate substrates were utilized for preparation of the transparent hybrid films. Then the solvent resistance, hardness and gel content, as well as the adhesion of the coatings, were measured as physical and mechanical properties. According to the obtained results, these properties of the hybrid coatings were improved with the increase in alkoxysilanes and sol–gel precursor contents. The surface morphology was characterized by scanning electron microscopy (SEM). The results showed that silica particles were not dispersed homogenously at the molecular level in the hybrid system. Also, the thermogravimetric analysis results indicated that alkoxysilanes enhanced the thermal oxidative stability of the hybrid coatings.