Effect of acrylic acid feed contents of microgels on catalytic activity of silver nanoparticles fabricated hybrid microgels

Authors: ZAHOOR HUSSAIN FAROOQI, SHANZA RAUF KHAN, ROBINA BEGUM, FARAH KANWAL, AHSAN SHARIF, EJAZ AHMED, SHUMAILA MAJEED, KIRAN EJAZ, AYSHA IJAZ

Abstract: We synthesized poly(N-isopropylacrylamide-co-acrylic acid) microgels with 1, 3, 5, and 7 mol percentage of acrylic acid. Silver nanoparticles were fabricated inside these microgels at room temperature. Pure microgels were characterized by Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Hybrid microgels were characterized by UV-Visible spectroscopy. The size of the silver nanoparticles increased with an increase in the content of acrylic acid. Catalytic activity of these hybrid microgels was investigated using UV-Visible spectrophotometry. Induction time decreased from 8.8 to 2.6 min and the value of apparent rate constant decreased from 0.226 to 0.109 min^{-1}, when the content of acrylic acid was increased from 1 to 7 mol %. This decrease in induction time was due to decrease in the surface area of nanoparticles present within the microgels with an increase in the feed contents of acrylic acid. The decrease in the value of apparent rate constant was due to an increase in the size of nanoparticles fabricated within the microgels with an increase in mol percentage of acrylic acid. The linear relation between apparent rate constant and feed contents of acrylic acid can be used for quantitative analysis of contents of acrylic acid present in polymer microgels.

Keywords: Microgels, nanoparticles, hybrid microgel, catalytic activity

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