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Synthesis and properties of novel glucose crosslinked hydrogels / silver nanocomposites based on heterocyclic monomers
Author
Wu, Marlene Qianyi
Supervisor
Roshan Deen G.
Abstract
Poly (N-acryloyl-N’-propylpiperazine) (AP), poly(4-acryloylmorpholine) (AM) and poly(1-vinyl-2-pyrrolidone) (VP) hydrogels were prepared by free- radical polymerization in deionized water using carbohydrate, glucose, as the crosslinking agent. Only AP gels were responsive to changes in pH and temperature and swelled best in pH 3 at 25 °C. AM and VP hydrogels were not responsive to these external stimuli due to the lack of ionizable groups and have high volume phase transition temperature contributed by their high hydrophilic character. As for temperature, AP gels shrink as temperature increased from 25 to 45 °C. Its swelling ratio dropped from 4.5 to 1. Since AM and VP gels were not stimuli responsive, their swelling ratio were consistent for all pH and temperature changes. Water sorption kinetics were studied gravimetrically with the diffusion process for all hydrogels obeying Fickian behavior. AM hydrogel displayed highest diffusion coefficient of 3.41 x 10-5 cm2 min-1 and AP gel was the lowest at 2.67 x 10-5 cm2 min-1 at Mt/M∞ ≤ 0.6. The amount of freezable and non- freezable bound water was also evaluated using differential scanning calorimetry. VP hydrogels had most water closely bound to it at 76.9% whist AP had the least bound water of 59.1%. Degradation studies of hydrogels were done at 25°C in pH 3, 7 and 11. Dissolution of gels only took place in AP gels and AM as well as VP gels shrank with mass loss over the 7 weeks. The self-reducing properties of the gels was demonstrated through silver nanoparticle fabrication in the gel matrix without using any chemical reducing agents.
Date Issued
2016
Call Number
QD400 Wu
Date Submitted
2016