Paper Number
GS25 

Session
Gels and Self-Assembled Systems

Title
Hydrogel materials as rheometer tooling for the transient delivery of additives during mechanical rheometry

Presentation Date and Time
October 11, 2017 (Wednesday) 4:35

Track / Room
Track 4 / Crestone A

Authors (Click on name to view author profile)

1. Ma, Tianhui M. (University of Michigan, Ann Arbor, Chemical Engineering)
2. Szakasits, Megan (University of Michigan, Ann Arbor, Chemical Engineering)
3. Kao, Peng-Kai (University of Michigan, Ann Arbor, Chemical Engineering)
4. Van Epps, J. Scott (University of Michigan, Ann Arbor, Emergency Medicine)
5. Solomon, Michael J. (University of Michigan, Ann Arbor, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Tianhui M. Ma¹, Megan Szakasits¹, Peng-Kai Kao¹, J. Scott Van Epps², and Michael J. Solomon^1
1Chemical Engineering, University of Michigan, Ann Arbor, Ann Arbor, MI 48105; ²Emergency Medicine, University of Michigan, Ann Arbor, Ann Arbor, MI 48105

Speaker / Presenter 
Solomon, Michael J.

Text of Abstract
Mechanical rheology is widely applied to study self-assembled soft matter; however, the transient rheological properties of these materials are often sensitive to additives in a way that is difficult to study. It is therefore of interest to study the transient rheology of self-assembled materials as such additives diffuse into the material and generate microstructural and physicochemical changes. We have developed rheometer tooling comprised of a porous hydrogel that allows us to dose solvents and other additives to materials as their mechanical response is measured. We synthesize a disposable hydrogel rheometer plate through photopolymerization of an aqueous polymer solution. We control the precision of the tooling by fixing the mold to a five-axis optomechanical stage, which controls the pitch, yaw, and translational position of the tool relative to its rotational axis. We demonstrate the performance of the tooling by measuring viscoelastic properties of aqueous polyethylene oxide (PEO) solutions and comparing the values to those obtained using standard fixtures. We further offer examples of self-assembled and gel soft matter that demonstrate that the tooling can be used to study the kinetics of material property variation due to the diffusion of molecular additives though the hydrogel plate. The examples addressed include solutions of colloids, polymers, and proteins, with additive dosing that includes salts, surfactants, and enzymes.