Nanoparticles have been incorporated into polymeric coatings and composites to improve mechanical, chemical, and thermal properties of the system.  Despite research that shows greatly enhanced short-term performance with nanofillers, little information is available on either the long-term performance or surface damage under environmental stresses during the service life. This study presents recent development of methods to investigate and assess surface resiliency and service life performance of nancoatings exposed to different environmental stressors, especially ultraviolet (UV) irradiance, mechanical stresses (scratch resistance).  Test methods for charactering scratch resistance, monitoring UV degradation process and possible nanoparticle release will be demonstrated through different nanocoating systems including nanosilica/polyurethane and Graphene oxide (GO)/waterborne polyurethane. A macroscopically non-destructive performance protocol using nanoindentation methodology via a well-controlled scratch test was applied to evaluate the scratch resistance and monitor the surface mechanical property changes. For assessing surface morphological changes during UV degradation, a general approach was to use laser scanning confocal microscopy (LSCM) optical method to quickly screen the surface morphological changes of samples in multiscale, then zoom into a smaller scanning area to identify nanoparticles versus polymer features on UV-degraded surfaces using atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, AFM in Peak Force QNM mode (quantitative nanomechanical property) mapping was used to measure increases in surface modulus to validate the presence of nanoparticles (modulus higher than polymer matrix) at the surface that accompanied the surface morphological changes Finally, nanoparticle release study using a simulated rain process will be discussed.<br/>

Methods to evaluate service life performance of nanocoatings under different environmental stressors

2019 Fall National Meeting

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