UV stability of self-healing poly(methacrylate) network layers

The applicability of high-modulus poly(methacrylate) networks containing reversible Diels-Alder crosslinks as self-healing coatings for outdoor applications, like photovoltaics, is evaluated. The materials are compared before and after accelerated UV-ageing using a combination of spectroscopic techniques, as well as thermogravimetric analysis and kinetic simulations, illustrating polymer network stability. In addition, it is proven by differential scanning calorimetry that the reversibility of the Diels-Alder bonds persists after ageing. Using dynamic mechanical analysis, it is shown that all pristine and UV-aged reversible networks maintain their structural integrity between -80 degrees C and 120 degrees C, and that they exhibit self-healing of micro-defects, allowing the restoration of thermomechanical properties. Furthermore, kinetic modelling is used to simulate the thermal effect on the Diels-Alder conversion during a typical day cycle for photovoltaic modules. The modelling shows that the total Diels-Alder conversion stays high (above 77%), ensuring mechanical robustness of these materials by maintaining a high crosslink density during high temperature exposure and/or temperature cycling, hence illustrating their thermal stability and supporting the potential use of such materials in outdoor photovoltaic applications. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The applicability of high-modulus poly(methacrylate) networks with reversible Diels-Alder crosslinks as self-healing coatings for outdoor applications is evaluated. The stability of the polymer network is assessed using spectroscopic techniques, thermogravimetric analysis, and kinetic simulations before and after accelerated UV-ageing. The reversibility of the Diels-Alder bonds is confirmed by differential scanning calorimetry. Dynamic mechanical analysis demonstrates that both pristine and UV-aged reversible networks maintain their structural integrity and exhibit self-healing of micro-defects within a temperature range of -80 degrees C to 120 degrees C, restoring their thermomechanical properties. Kinetic modelling is used to simulate the effect of temperature on the Diels-Alder conversion during a typical day cycle for photovoltaic modules. The modelling results show that the total Diels-Alder conversion remains high, ensuring mechanical robustness by maintaining a high crosslink density during high temperature exposure and temperature cycling, indicating the thermal stability and potential use of these materials in outdoor photovoltaic applications.