Photocatalytic degradation and heat reflectance recovery of waterborne acrylic polymer/ZnO nanocomposite coating

Abstract

This work aims to clarify the photocatalytic degradation mechanism and heat reflectance recovery performance of waterborne acrylic polymer/ZnO nanocomposite coating. To fabricate the nanocomposite coating, ZnO nanoparticles (nano‐ZnO) were dispersed into acrylic polymer matrix at the various concentrations from 1 to 6% (by total weight of resin solids). The photocatalytic degradation of nanocomposite coating under ultraviolet (UV) light irradiation has been investigated by monitoring its weight loss and chemical/microstructural/morphological changes. As the topcoat layer, its heat reflectance recovery has been evaluated under UV/condensation exposure by using an artificial dirty mixture of 85 wt% nanoclay, 10 wt% silica particles (1–5 μm), 1 wt% carbon black, and 2 wt% engine oil. After 108‐cycle UV/condensation exposure, infrared spectra and weight loss analysis indicated that the maximal degradation for nanocomposite coating is observed at 1 wt% nano‐ZnO. On the other hand, after 96 hr of UV light exposure, the nanocomposite coating with1 wt% nano‐ZnO could restore effectively the reflective index of solar‐heat reflectance coating (from 58.45 to 80.78%). Finally, the photodegradation mechanism of this waterborne acrylic polymer coating has been proposed as the UV‐induced formation of CCCO conjugated double bonds. As a result, its self‐cleaning phenomenon can be achieved as the recovery of heat reflectance.

Water-Borne ZnO/Acrylic Nanocoating: Fabrication, Characterization, and Properties

“…IR analysis: The chemical changes of the coatings during the aging process were studied by IR analysis in an FT-IR spectrometer (NEXUS 670 from Nicolet, Waltham, MA, USA). The quantitative analysis of the changes in the functional groups was performed following the reported method [ 20 ]. By making the ratio of the IR absorbance at the corresponding wavenumber of the sample before ( D o ) and after ( D t ) aging cycles, the remaining functional groups were determined, expressed in Equation (2): Remaining group (%) = (D t /D o ) × 100 …”

“…However, most published works only focused on the micro-sized ZnO particles, with a very limited photocatalytic behavior in the coating system. In the case of the nanocomposite coating, their antimicrobial activity and self-cleaning ability could be achieved, with nano-ZnO being the most promising and effective photocatalyst [ 18 , 19 , 20 , 21 ]. As reported, after absorbing UV radiation, an electron of ZnO at the valence band jumps into the conduction band, creating an h + hole [ 22 ].…”

“…Under the action of weathering factors, outdoor coatings are significantly degraded [ 24 , 25 , 26 ]. The supplement of additives can increase or reduce the weathering resistance of the coatings, depending on their characteristics [ 20 , 27 , 28 , 29 , 30 , 31 ].…”

The Synergistic Effects of Sio2 Nanoparticles and Organic Photostabilizers for Enhanced Weathering Resistance of Acrylic Polyurethane Coating

“…Currently, the addition of inorganic particles/nanoparticles (at appropriate content) into the polymer substrate can enhance its property [10][11][12][13][14][15][16]. Nano-SiO 2 is the most used among the common inorganic nanoparticles.…”

Multi-Stressed Nano and Micro-Silica/Silicone Rubber Composites with Improved Dielectric and High-Voltage Insulation Properties

“…Heat dissipation, which increases due to the aging effect, is a great challenge in charge-storing devices [ 24 ]. Therefore, there is a constant need of improvement in the dielectric properties of dielectrics [ 25 ]. Different fillers have been used in dielectric polymers for enhancement of their properties.…”