UV protective bio-based epoxy/carbon quantum dots nanocomposite coatings: Synthesis and investigation of properties

Abstract

This research focuses on synthesis and study of the properties of castor oil-based epoxy/carbon quantum dots (COEp/CQDs) nanocomposite coatings possessing resistance against UV. First, CQDs were synthesized by pyrolysis of starch using microwave-assisted method and characterized via various spectroscopic and microscopic methods. Next, certain quantity of castor oil as a renewable resource, CQDs with different weight percentages and a curing agent were added to epoxy resin and consequently COEp/CQDs were prepared. Through findings of FTIR, photoluminescence and UV-visible spectroscopy analyses, existent functional groups and fluorescent feature of the nanocomposite coatings were confirmed. UV-vis spectroscopy approved UV resistance of the COEp/CQDs coatings. As concentration of CQDs increased in resin matrix, UV absorption was maximized. The morphology and uniform dispersion of CQDs in the coatings matrix were verified by FESEM analysis. Results of TGA, pull-off adhesion strength and tensile tests, and DMTA analysis proved adding CQDs to the resin matrix led to progress of thermal endurance, adhesion strength, mechanical and viscoelastic properties of the synthesized coatings including an increase in storage modulus and Tg.

Carbon quantum dots (CQDs)-modified polymers: a review of non-optical applications

“…The last zone at 370 to 450 °C had weight loss related to the complete decomposition of the coatings, where the CQDs were separated from the COEp chains. 100 The thermal resistance of the COEp/CQD coatings increased as the CQDs loading was increased in the COEp resin. The weight loss of the optimized COEp/CQD nanocomposite coating was reduced by 17.5-53.5% as compared with that of the pure COEp coating at 370-450 °C.…”

“…In the second step, 3 wt% of the synthesized CQDs was incorporated into COEp to fabricate a COEp/CQDs coating on steel via a film applicator at 70 °C for 20 min. 100 The thermal resistance capabilities with respect to the weight loss of the pure COEp and COEp/CQD coatings were tested using TGA. Weight loss of both the COEp and COEp/CQD coatings occurred in three temperature zones.…”

Green fluorescent unsaturated polyester/graphitic carbon nitride quantum dots nanocomposites: Preparation and study of UV-resistance, mechanical and viscoelastic properties

“…UV-C holds the highest energy and could be absorbed by common polymer coatings, yet regarding the potential hazards of the UV radiation, protective coatings to UV which absorb UV not only from the UV-C but also attract all the UV spectra from UV-B and UV-A, are greatly required. 46,47 To analyze the protective function of UP and UP/CNQDs exposed to UV rays in the whole range of UV, absorbance spectra of all the samples were evaluated. Figure 6(b) depicts UV-visible absorbance curves for all the samples.…”

“…Fluorescent polymers with favorable mechanical properties could be used in a variety of applications including synthesis of resistant nanocomposites to UV rays, anti-spoofing materials, electronic and optical scanners, coding and so on. 31 In the current study, in the beginning, CNQDs were synthesized by pyrolysis of citric acid and extra urea using microwave-assisted method. Next, unsaturated polyester resin was mixed with 0.25, 0.5, 0.75 wt% CNQDs, and UP/ CNQDs nanocomposites were prepared.…”

“…Fluorescent polymers with favorable mechanical properties could be used in a variety of applications including synthesis of resistant nanocomposites to UV rays, anti-spoofing materials, electronic and optical scanners, coding and so on. 31…”