POSS-reinforced covalent network in epoxy adhesive and its improvement in the high-temperature adhesion, toughness, and transparency

Developing epoxy structural adhesives with excellent high-temperature adhesion remains a great challenge. The incorporation of fillers can enhance the performance of epoxy adhesives, albeit at the expense of reduced high-temperature adhesion properties. Polyhedral oligomeric silsesquioxanes (POSS) is considered a promising filler for enhancing high-temperature adhesion properties due to its excellent compatibility and nano cage-structured. Herein, the rigid cage-structured was covalently introduced epoxy adhesives to improve the high-temperature adhesion properties. The introduction of 1 wt% POSS significantly increased the high-temperature (120°C) adhesion strength by 197% and toughness by 283%. The POSS-reinforced adhesive also featured excellent wide temperature adaptability, indicating that it maintained high adhesion strength at various temperatures. Furthermore, POSS drastically enhanced the transparency of epoxy adhesive by three times. It is highly anticipated that this work will open a new avenue of designing epoxy adhesives with the excellent high-temperature adhesion properties and transparency.