HNSE-O1-3. Hydrogels LCST
Genaro Marcial Lorza1
Faculty Mentor: Jeremy Cho, Ph.D.1
1Howard R. Hughes College of Engineering, Department of Mechanical Engineering
Hydrogels are three-dimensional polymer lattices that are absorbent and can uptake or retain a large amount of water for their size. Some hydrogels spontaneously de-swell above a specific temperature. Observation of this type of behavior has been limited to one type of hydrogel: poly(N-isopropyl acrylamide) – PNIPAM (pronounced “ny-pam”). If PNIPAM is below the lower critical solution temperature (LCST), the hydrogels are more hydrophilic (i.e. they absorb more water), in contrast, if the temperature is higher than LCST, then the gels become less hydrophilic, the hydrogels hold less water, thus, water content will be released. We designed a water bath system device using a stainless steel container and a floating glass container. The hydrogel is submerged in the small glass container. The outer container is filled with water that is connected to a magnetic drive pump that circulates water effectively as it is being heated with two 60 Watts cartridge heaters. A plexiglass lid was added to the outer container to maintain constant heating temperatures. As we increased the temperature of the water to 35°C the hydrogel sample began to deform and expand abnormally. We expected the hydrogel to contract but were unable to see this effectively since it was submerged in water. We conclude that in order to see more swelling behaviors and biodegradability LCST could be introduced to PAAm hydrogels by incorporating a controlled fraction of PNIPAM into the polymer lattice varying increments in the temperature range of 20°C and 30°C instead of 35°C.
Dr. Jeremy Cho | Howard R. Hughes College of Engineering
Genaro Marcial Lorza | Howard R. Hughes College of Engineering
Santiago Ricoy | Howard R. Hughes College of Engineering