In this work, a novel boehmite (BA)-embedded organic/inorganic nanocomposite coating based on cycloaliphatic epoxy oligosiloxane (CEOS) resin was prepared with UV-induced cationic polymerization. The main changes of the material behavior caused by the nanofiller were investigated with regard to the photocuring kinetics, thermal stability, and glass transition temperature (Tg). As the role of the particle surface was of particular interest, unmodified nanoparticles (HP14) and particles modified with p-toluene sulfonic acid (OS1) were incorporated into a CEOS matrix in the concentration range of 1–10 weight (wt).%. The resulting nanocomposites exhibited improved thermal properties, with Tg being shifted from 30 °C for unfilled CEOS to 54 °C (2 wt.% HP14) and 73 °C (2 wt.% OS1) for filled CEOS. Additionally, thermogravimetric analysis (TGA) showed an increased thermal stability of samples filled with the nanoparticles. Attractive interactions between boehmite and the CEOS matrix influenced the curing. Real-time infrared spectroscopy (RT-IR) experiments demonstrated that the epoxide conversion rate of the nanocomposites was slightly increased compared to the neat resin. The beneficial role of the BA can be explained by the participation of hydroxyl groups at the particle surface in the photopolymerization processes and by the complementary contribution of the p-toluene sulfonic acid surface modifier and water molecules introduced into the system with the nanoparticles.
Boehmite Nanofillers in Epoxy Oligosiloxane Resins: Influencing the Curing Process by Complex Physical and Chemical Interactions
Topolniak, I.; Hodoroaba, VD; Pfeifer, D; Braun, U., Sturm, H.
published in Materials, 2019, Vol. 12, Issue 9, 1513
BAM, Department Materials Protection and Surface Technology, Division Surface Analysis and Interfacial Chemistry and Division Nanotribology and Nanostructuring of Surfaces