γ-Irradiation Induced Synthesis of Titanium Dioxide/Poly(acrylic acid) (TiO₂/PAA) Nanocomposites and Layer-by-Layer Assembly on Glass Substrate

Adsorption and encapsulation of the nanoparticles in polyelectrolytes impart stability to the nanometal by preventing aggregation through electrostatic and steric effects. Poly (acrylic acid) (PAA) was employed as a polymer cap to anatase titania nanoparticles. Cross-linking of the polymer was done via free-radical cross-linking using gamma-irradiation. The size of the nanocomposite produced ranged from 40-120 nm. SEM images showed that excess TiO2 in solution becomes nucleation sites for aggregation. Film assembly of the synthesized nanocomposite were done by layer-by-layer deposition with PDDA. Films formed with increasing thickness (5, 10, and 15 layers) were analyzed under AFM and shown to have a thickness of 0.25 μm, 1.1μm and 3.0 μm respectively.The average film layer thickness obtained ranged from 50-200 nm per TiO2/PAA-PDDA layer where as the number of layers deposited increase, the layer thickness increase while the roughness decreases.