Polymer Bulletin, Vol.78, No.3, 1275-1291, 2021
Rheological investigation of the viscoelastic thixotropic behavior of synthesized polyethylene glycol-modified polyacrylamide hydrogels using different accelerators
The present work is mainly focused on the synthesis and comprehensive rheological investigation of uniform and large macroporous polyethylene glycol-modified polyacrylamide hydrogels [PEG-m-P(AAm)] through free radical polymerization using different accelerators (ascorbic acid (AsA), thermal activation (60 degrees C) andN,N ',N '',N"'-tetramethyl ethylenediamine (TEMED)). The synthesis and surface morphology of the hydrogels were confirmed by FTIR and SEM techniques. Rheological investigation was carried out to determine the effect of accelerator nature on the rheological parameters and pseudo-plastic behavior of polymer hydrogels. A decline in viscosity with the increase in shear rate confirms the non-Newtonian pseudo-plastic behavior of hydrogels. From the creep-recovery study, the least strain (0.2) and creep compliance (2 x 10(-2) Pa-1) for the thermally activated synthesized polymer hydrogel show more elastic property than the hydrogels synthesized by AsA and TEMED having strain values of 0.6 and 2.2, respectively. The thixotropic character of the hydrogels was found by the hysteresis loop test. The hydrogels prepared via AsA (998.825 Pa s(-1)) showed greater thixotropic behavior, followed by thermal activation (652.857 Pa s(-1)), and TEMED (531.9 Pa s(-1)) respectively. The hydrogels synthesized by different routes attained a completely different morphology, which can be applicable for specific applications. The obtained results verify that these materials may be used for the removal of potentially toxic materials, as a carrier for bioactive compounds and in cosmetic industry.