Investigating the pH Dependence of Ultraviolet Radiation Induced Synthesis of TiO<sub>2</sub>/Poly(Acrylic Acid) Nanocomposites

Abstract

In this work, Poly(Acrylic Acid) (PAA) was employed as nanoparticle stabilizer for TiO2. Adsorption and encapsulation of nanoparticles in polyelectrolytes impart stability due to stearic and electrostatic effects. Crosslinking of the polymer through UV-Irradiation permanently encapsulates the metal as well as reinforces the polymer cage. The efficient pH and ratio of reactants were optimized then assessed through Dynamic Light Scattering (DLS) for particle size and Zeta Potential Measurements for stability in aqueous solutions. Results showed that among the various TiO2/PAA ratios, the 1:3 ratio showed minimal changes on the size and Zeta Potential values even when exposed to various pH conditions. Meanwhile at pH 5, TiO2 attained a positive surface charge, while PAA exists in its deprotonated form, thus maximizing the electrostatic interaction between the two materials. Analysis revealed that in that particular ratio and pH range, particles size and zeta-potential value of 61.79 nm and -36 mV were obtained respectively. Physical morphology of the nanocomposites was characterized through Scanning Electron Microscopy, showing agglomerates of small particles, resulting to larger particles. Further studies shall be done to utilize the potential of the polymer-coated nanoparticles in dry form.