Glass transition and polymer dynamics in silver/poly(methyl methacrylate) nanocomposites

Synthesis of Moringa oleifera coated silver-containing nanocomposites of a new methacrylate polymer having pendant fluoroarylketone by hydrothermal technique and investigation of thermal, optical, dielectric and biological properties

Firstly, silver nanoparticles were synthesized by green synthesis method from Moringa oleifera extract. Nanocomposites containing newly synthesized methacrylate polymer, poly 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) and Ag nanoparticles from M. oleifera in different mass ratios (1, 3, and 5 wt%) were synthesized using the hydrothermal method. The morphological and structural properties of the materials have been examined by SEM, FTIR, UV, TGA, and XRD techniques. The activation energies (E_a) related to thermal decomposition of the nanocomposites were estimated by the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods by using non-isothermal TGA experiments. The thermal stability, glass transition temperature (T_g), and the thermal decomposition activation energy (E_a) values of nanocomposites were increased by increasing the Ag nanoparticles amount on the composite. The dielectric constant (ε'), the dielectric loss factor (ε″) and ac conductivity of neat PFPAMA and nanocomposites were also measured for the frequency range of 100 Hz to 2 kHz at 25 °C. It was seen that the frequency dependence of the dielectric constant and dielectric loss factor decreased with increasing frequency. The biological activities of nanocomposites against gram-positive (Staphylococcus aureus), gram-negative (Escherichia coli) bacteria and Candida krusei yeast were also tested. The antibacterial effect increased against both bacterial species as the amount of Ag nanoparticles from M. oleifera in the nanocomposites increased. In addition, the wound healing properties of nanocomposites were investigated by the scratch wound test.

Segmental dynamics and physical aging of polystyrene/silver nanocomposites

We report the complicated variation trend of calorimetric T_g and physical aging in PS/Ag nanocomposites, despite the invariant segmental dynamics with increasing silver nanoparticle loading.