Complex fluid interfacial phenomena
Our group addresses problems in complex fluid interfacial phenomena. This entails fundamental investigations of the structure and dynamics of macromolecules, surfactants, and composite nanoparticles in suspension or adsorbed at solid or fluid interfaces. It supports application-driven research in environmental nanotechnology, aerosolized carriers for pulmonary drug delivery, lubrication and high efficiency emulsifiers. A recurring theme is the effort to understand phenomena that arise in realistic multicomponent mixtures that normally are not predicted from the behavior of idealized single component systems.
Faculty
A member of the faculty of Carnegie Mellon University since 1992, Robert Tilton is Chevron Professor of Chemical Engineering. He is a Fellow of the American Chemical Society and a Fellow of the American Institute for Medical and Biological Engineering.
Publications
For a current list of Professor Tilton's publications, please visit his ORCID site.
Research projects
Below, you'll find representative research projects from the Tilton Group.
Colloidal forces in polymer/surfactant mixtures
Products based on colloidal suspensions are engineered by controlling the forces that act between particles, often by addition of polymers and/or surfactants to the suspensions. We are investigating how complexation of polymers and surfactants in solution profoundly alters colloidal forces. We are particularly interested in systems where polymer/surfactant interactions that fundamentally alter the strength and range of the colloidal depletion force. See for example:
- DOI 10.1016/j.jcis.2019.06.026
- DOI 10.1021/acs.langmuir.9b02143
Marangoni transport in complex surfactant systems
Marangoni flows caused by surface tension gradients at fluid interfaces are influential in multiphase flows, often dominating the dynamics of surfactant-based complex fluids. They can be particularly important in emulsification, spreading and coating processes. We are investigating the potential for surfactant interactions in multicomponent fluids to amplify or suppress the effects of Marangoni flows and the role of the self-assembly status of the surfactant, in parallel with efforts to develop self-dispersing aerosolized drug carriers that exploit Marangoni flows to better distribute inhaled medications in the lungs. See for example:
- DOI 10.1016/j.jcis.2016.08.076
- DOI 10.1016/j.cocis.2018.01.001
- DOI 10.1016/j.jcis.2019.06.016
- DOI 10.1089/jamp.2017.1412
- DOI: 10.1016/j.jcis.2016.01.011
Interfacial engineering with responsive nanoparticulate polymer brushes
A “nanoparticulate polymer brush” is a nanoscale object consisting of a large number of polymer chains end-attached to a central core. These can be polymer-grafted nanoparticles, multi-arms star polymers or bottlebrush polymers. We have been developing such structures that perform as high efficiency emulsifiers and produce emulsions with pH- or thermally responsive stability or rheology, as well as responsive boundary lubrication agents that can be triggered to switch from high friction, adhesive contacts to non-adhesive, low friction contacts between surfaces. See for example:
- DOI 10.1002/aic.16427
- DOI: 10.1021/acs.langmuir.6b02963
- DOI 10.1016/j.jcis.2018.04.082
- DOI 10.1016/j.jcis.2014.12.047
- DOI: 10.1007/s00396-019-04585-4
Videos
Below, you'll find videos related to research from the Tilton Group.
Research Team
Diane Nelson
Post-Doctorate
- Research interests
- Droplet interfacial coalescence and solute delivery from perfluorocarbon emulsions
- Email
- dlnelson@andrew.cmu.edu
Henry Chu
Post-Doctorate
- Research interests
- Dispersion, diffusiophoresis and colloidal transport
- Email
- hcchu@andrew.cmu.edu
Bhagyashree Lele
Doctorate
- Research interests
- Synergistic and antagonistic effects of polymer/surfactant interactions on colloidal depletion forces
- Email
- blele@andrew.cmu.edu
Danish Iqbal
Doctorate
- Research interests
- Multi-responsive polyelectrolyte brush-grafted nanoparticles and thin films
- Email
- diqbal@andrew.cmu.edu
Tsung-Lin Hsieh
Doctorate
- Research interests
- Marangoni transport synergism in mixed surfactant systems
- Email
- tsunglih@andrew.cmu.edu
Yilin Zhang
Doctorate
- Research interests
- Complex copolymer architectures for agrochemical and environmental applications
- Email
- yilinz1@andrew.cmu.edu
Angela Yang
Doctorate
- Research interests
- Diffusiophoresis and super-diffusive transport of complex colloids
- Email
- angelaya@andrew.cmu.edu
Past students
Ph.D. students
- Julie L. Robeson, 1995, “Application of Total Internal Reflection Fluorescence to Probe Surface Diffusion and Orientation of Adsorbed Proteins.”
- James R. Charron, 1996, “Block Copolymer Adsorption to Phospholipid Monolayers at the Air-Water Interface.”
- Edward S. Pagac, 1997, “Colloidal Forces in the Presence of Polymers and Surfactants.”
- Michelle Lourette Sun, 1999, “Coadsorption of Strongly Interacting Proteins and Surfactants.”
- Joon-Hyung Kim, 1999, “Pyrene Solubilization in Micelles and Polymer-Surfactant Complexes.”
- Eric Tsung, 2000, “A Novel Total Internal Reflection Fluorescence Assay for the Catalytic Activity of Adsorbed Enzyme Monolayers.”
- Stephanie Butler Velegol, 2000, “Tuning Interfacial and Bulk Self-Assembly of Ionic Surfactants via Counterions and Non-Binding Polyelectrolytes”
- Alan Braem, 2001 “Colloidal and Interfacial Phenomena in Polymer/Surfactant Mixtures”
- Derek Berglund, 2003, “Tuning Adsorption via Polymer-Surfactant Complexation.”
- Susan Daly DiPasquo, 2004, “The Effect of Polyethylene Glycol Modification of Proteins on Adsorption Mechanisms.”
- Hao Zhao, 2005, “Electrohydrodynamic Patterning and Separation of Colloids or Cells”
- Jason Hamm, 2005, “Redispersion of Polymer Coated Colloidal Aggregates with Changing Solvent Quality”
- Marvi Matos, 2006, “Electroosmotic Mass Transport Control in Polyacrylamide Gels via Embedded Silica Nanoparticles”
- Jessica Tucker, 2006, “Novel Extracellular Matrix Mimics: Applications in Drug Delivery and protein-Receptor Binding”
- Navid Bin Saleh,(Civil & Environmental Engineering), 2007, “An Assessment of Novel Polymeric Coatings to Enhance Transport and in Situ Targeting of Nanoiron for Remediation of Non-Aqueous Phase Liquids (NAPLs)”
- Kevin Sirk, 2007, “Polyelectrolyte Surface Modification of Reactive Iron Nanoparticles”
- Andy Kusumo, 2008, “High Capacity Polyelectrolyte Brushes for Tuning Protein Adsorption”
- Tanapon Phenrat, 2008 (Civil & Environmental Engineering) “Effect of Polymeric Surface Modification on Nano-Sized Zero Valent Iron (NZVI) Aggregation, Transport of Concentrated NZVI Dispersions in Porous Media, and Reactivity with Trichloroethylene”
- Hye-Jin Kim, 2009 (Civil & Environmental Engineering) “Transport, reactivity and fate of polyelectrolyte modified zero valent iron nanoparticles used for groundwater remediation in heterogeneous porous media”
- Jit Kang Lim, 2009, “Hybrid Magnetic Plasmonic Nanoparticles”
- Trishna Saigal, 2011, “Development of Novel Pickering Emulsifiers using Polymer Grafted Nanoparticles”
- Sheetal S. Pai, 2011, “Adsorption of Poly(Ethylene Glycol) Conjugated Proteins to Biomaterials used in Delivery”
- Teresa L. Kirschling, 2011, “Interactions of Microbial Communities with Engineered Nanoparticles in Environmental Systems”
- Stacy M. Wirth, 2013, “Impacts of Silver Nanoparticles on Bacterial Biofilms”
- Adam Canady, 2013 “Adsorption of poly(ethylene glycol) conjugated proteins to oil/water interfaces relevant to drug delivery”
- Stacey M. Louie, 2014 (Civil & Environmental Engineering) “Characterization and modeling of macromolecules on nanoparticles and their effects on nanoparticle aggregation”
- Amsul Khanal, 2014 (Biomedical Engineering) “Spreading of surfactant-laden aerosols on entangled polymer solution subphases”
- John K. Riley, 2016, “Friction control by adsorption of polymer brush nanoparticles”
- Ramankur Sharma, 2016, “Surfactant-induced Marangoni transport on liquid surfaces”
- Alex Bertuccio, 2017, “Metal species and surfactant impact on bacterial populations and community behavior”
- Amy Stetten, 2017 (Physics) “Capillary and transport phenomena of liquid drops spreading on miscible liquid subphases”
- Brittany Nordmark, 2018 “Efficacy of Moringa oleifera proteins as coagulants in a sustainable sand filter for drinking water treatment”
- Yun-Ru Huang, 2018 “Interfacial activity of star polymers at fluid interfaces”
- Steven Iasella, 2019 “Effect of surfactant escape on surface transport of hydrophobic solutes during aqueous solution spreading on miscible complex fluid subphases”
Former postdoctoral researchers
- Nitin Kumar, Ph.D. City College of New York, 2001-2003; Nonionic surfactant adsorption and wetting phenomena
- Gunnar Duner, Ph.D. KTH Royal Institute of Technology, 2013 – 2016; Marangoni transport at the oil/water interface
