Chemical Engineering - Cooperative Education
Bachelor of Science
Date of Graduation
Double Network hydrogels are three dimensional networks of a soft, mechanically tough material that have been used for drug delivery, agriculture, adhesives, and other widely applicable uses. Using the one-pot method, a single hydrogel can be produced in 3 hours as opposed to the once demonstrated three days. It has been found that with a first, physically cross linked network and a second, chemically cross linked, hybrid double network hydrogels exhibit high mechanical properties and are freeshapeable. Agar is a thermoreversible organic molecule with a triple helix structure that provides an excellent first network that organizes into aggregate bundles once cooled to room temperature (after heated to 100 Celsius) to reform its hydrogen bonds and absorbs 20-30x its weight in water. AM is a long polymer that readily dissolves in water to form a second, chemically crosslinked network (with photoinitiator HMP) that wraps and forms more hydrogen bonds. Photocrosslinker, methylenebisacrylamide, activated with UV light organizes and increases chemical bonding of AM polymer chains with agar helices to increase the tensile stress/strain of a hydrogel without needing to alter the agar/AM ratio. These gels can achieve maximum tensile stress at 1.02 MPa, a tensile strain at 11.44 mm/mm, and an elasticity modulus of 234 kPa, whereas gelatin/PAAm gels achieve a tearing tensile stress of 0.268 MPa, a tensile strain of 40.69 mm/mm, and E =84 kPa. Agar/PAAm show promise of being a tough double network hydrogel, and have their mechanical strength increased by using photocrosslinker MBAA.
Dr. Jie Zheng
Jeske, Madelyn, "Increasing Mechanical Properties of a Double Network Hydrogel from Polyacrylamide and Agar with Methylenebisacrylamide as a Photocrosslinker" (2019). Williams Honors College, Honors Research Projects. 848.