Swellable pH sensitive polymer particles prepared by free radical dispersion polymerization using N-isopropyl acrylamide (transduction monomer), methylene bisacrylamide (crosslinker), 2-dimethoxy-2 phenyl-acetophenone (radical initiator), N-tert-butylacrylamide, and methacrylic acid, ethacrylic acid or propacrylic acid and respond to pH have been incorporated into hydrogel membranes. When the polymer particles are dispersed in a hydrogel, there are large changes in the turbidity of the membrane as the pH of the buffer solution in contact with the membrane is varied. These polymer particles show a larger response over a narrower pH range than predicted by the Henderson-Hasselbach equation. The apparent pKa of the swellable polymer particles and their response to the ionic strength of the solution can be tuned by varying the composition of the formulation used. Proposed applications of these polymer particles include gastric pH measurements that require indwelling pH electrode systems to continuously monitor ruminal acidosis in dairy cows (pH 4 thru 7), continuous in vivo measurement of pH sensing of blood in arteries and muscles for patients suffering from tissue ischemia, and pH sensing to study gastro-esophageal reflux disease, a digestive disorder related to the retrograde movement of gastric acid into the esophagus.

Characterization of poly N-isopropyl acrylamide particles for optical sensing

248th National Meeting (2014)

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