Application of SiO2 nanoparticles with double layer coverage consist of citric acid and l(+)-ascorbic acid for the production of poly(vinyl chloride)/SiO2 nanocomposite films with enhanced optical and thermal properties

Incorporation of SiO2 nanoparticles (NPs) into poly(vinyl chloride) (PVC) matrix to prepare PVC/SiO2 nanocomposites (NCs) can enhance its properties. To achieve improved properties for the NCs, NPs should be dispersed properly and be compatible within the polymer matrix. Therefore, to prevent SiO2 NPs from aggregation, surface modification of NPs was performed by citric acid (CA) and l(+)-ascorbic acid (AA) as biological and environmental friendly coating layers for the first time. This process was carried out under ultrasonic irradiation condition, which is an economical and eco-friendly tool. After that three different amounts of modified SiO2 (SiO2-CA-AA) were inserted into PVC matrix and PVC/SiO2-CA-AA NCs were prepared using solution casting method. The structures and morphology of the prepared NC films were verified by several techniques including Fourier transfer infrared, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, ultraviolet-visible (UV-Vis) spectroscopy and tensile testing. Thermogravimetric analysis confirmed the presence of about 13 wt% modifiers on the surface of SiO2. Microscopic observations showed good dispersity of SiO2-CA-AA NPs in the polymer matrix. Resulting NC films showed more flexibility than pure PVC.