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Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 428, 2013, Pages 53-59.
Reham Mohsen, George J. Vine, Natasa Majcen, Bruce D. Alexander, Martin J. Snowden.
School of Science, University of Greenwich, Chatham, Kent, United Kingdom and
EBEWE Pharma, Mondseestrasse, Unterach, Austria
Abstract
This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pH-responsive p(NIPAM)/acrylic acid (AA) microgels. Three microgels were synthesized using surfactant free emulsion polymerization technique, these are p(NIPAM), p(NIPAM)-co-AA 95:5% (w/w) and p(NIPAM)-co-AA 90:10% (w/w). Dynamic light scattering was used to study the behavior of diluted microgel dispersions (0.5%, w/w p(NIPAM)), while rheology was used to study the viscosity of 2% (w/w) p(NIPAM) dispersions. The characterization data indicate the swelling/deswelling and flocculation/deflocculation behavior of the microgels. The conditions required for flocculation were used to test the ability of the microgel dispersions to block a membrane of pore size 5 um. In 3 h, p(NIPAM), p(NIPAM) 5% AA (w/w) and p(NIPAM)10% AA (w/w) blocked the membrane (decrease the flow rate) by 96.16, 59.44 and 59.8% respectively. Thus, the controlled flocculation of microgels may be used in applications where pore blocking is important such as the treatment of dentinal hypersensitivity, given that the VPTT of p(NIPAM) is ≈34 °C, which is very close to the human body temperature.
