Abstract
The preparation, characterization and detailed physicochemical investigation on sol-gel behaviour of poly(N-isopropyl acrylamide)-chitosan-poly(Acrylic acid) [PNIPAAm-CS-PAA] based polymeric microgels prepared by free-radical polymerization are discussed in this manuscript. The redox initiator Ammonium per sulphate (APS) was used to initiate the reactions while N,N'-Methylenebisacrylamide (MBA) as a crosslinking agent. The polymeric microgels were then subjected to characterization and physicochemical study via using UV-Visible spectroscopy, infrared spectroscopy (FT-IR), laser light scattering (LLS), Ostwald viscometry, dynamic rheology and swelling measurement. The successful preparation of microgels was traced from the result of UV-Visible and FT-IR. The effect of external stimuli like temperature and pH, or both, on the behaviour of polymeric microgels was investigated through visual stability test, laser light scattering and rheological measurement. Similarly, the physicochemical behaviour of the microgels was also investigated in terms of the chemical composition of three different samples. The swelling/change in size of the microgel samples in aqueous media at different pH and temperature, in the terms of hydrodynamic radius (R-h), were drawn through LLS measurements. From the Rheological measurements, various physiochemical properties such as, elasticity, viscosity, shear stress, storage modulus, loss modulus, phase angle and complex viscosity of the microgels were deduced. From the analysis of Ostwald viscometry the flow viscosity of microgels was deduced at different pH and temperatures. It was found that various experimental variables appreciably influenced the properties of polymeric microgels.