Stephanie Lam
| PhD, Chemical Engineering, 2014 North Carolina State University M.S., Chemical Engineering, 2011 North Carolina State University B.S., Chemical Engineering, 2009 State University of New York at Buffalo Curriculum Vitae |  |
Research Focus: Formulation and Characterization of Responsive Biopolymer Foams
It has been known since the early 20th century that the addition of particles which partially wet both a hydrophobic and hydrophilic phase can result in the formation of very stable foams and emulsions. However, only recently has interest been renewed in such systems as a result of their potential for applications in food, cosmetics, commercial products, and water remediation. Most researchers have been focusing on identifying the characteristics of particles which make them good foam and emulsion stabilizers, and in the development of Pickering systems stabilized by inorganic particles. While this research is important, there is a lack in effort to engineer particles from biological materials for use in these systems, which would broaden the applications of particle stabilized foams. My project focuses on the formulation and characterization of particles generated from biologically derived materials for foam and emulsion stabilization. I am currently studying two foam systems, which are stabilized using biologically-derived materials.
Magnetically Responsive Pickering Foams
The first system at focus is a magnetically responsive foam stabilized by particles made from hydrophobically modified cellulose. This foam system can be stable for weeks in the absence of a magnetic field, but can also be collapsed on demand through the application of a gradient field. Magnetic responsiveness was imparted to the system through the use of carbonyl iron particles. The response of the foam to an applied magnetic field was evaluated as a function of foam age, correlated with the evolution of foam viscoelastic properties, and a mechanism explaining the collapse process of the foam was proposed.
Figure 1: (a) SEM micrograph of HP-55 & carbonyl iron complex. Scale bar = 30 µm. (b) Schematic of the procedure for making magneto-pickering foam.
Lignin Particles for Foam Stabilization
The second foam system at focus is a biodegradable foam that is stabilized using particles generated from a form of lignin. We found particles that were reformed through an aqueous shear process to be able to stabilize foams better than the lignin in its normal form. The effect of the reformation process on particle morphology and change in solubility are being investigated.
Figure 2: Micrographs of non-reformed (a,c) and reformed (b,d) particles. Micrographs a and b are taken in normal light microscopy, while images c and d were taken in fluorescence mode.
Publications