Professor of Chemical Engineering
112F Goessmann Lab
B.Ch.E. with distinction, summa cum laude, University of Delaware, 1995
Ph.D., Princeton University, 2000
Awards and Recognitions
Invited participant, NSF/AAAS Workshop on Diversity in Nanoscience Fields (2011)
UMass CVIP Technology Development Award (2010)
Invited Participant, NAE Frontiers of Engineering Education Symposium (2009)
UMass Program Outreach Innovation Award (2008)
UMass College of Engineering Outstanding Junior Faculty Award (2005)
UMass College of Engineering Outstanding Teaching Award (2004)
National Science Foundation CAREER Award (2003)
Dupont Young Professor Award (2002)
3M Nontenured Faculty Award (2002)
Current Focus of Research
Our research focuses on complex fluids, which can be defined as solutions and gels containing surfactants, polymers, and colloidal particles. These "soft materials" have been investigated for a wide variety of applications, including paints, coatings, adhesives, cosmetics, skin and eye care products, and food additives. More recently, solutions of surfactants and polymers have been investigated as potential drug delivery agents and models for biomembranes.
Rheology and Phase Behavior of Associative Polymer Solutions
Associative polymers have groups that tend to aggregate in solution, eventually building up a network structure. This structure imparts interesting viscoelastic properties to the solution. We are currently investigating aqueous micellar solutions of diblock polymers that contain hydrophobic groups on the ends of the hydrophilic blocks. The micelles can thus be modeled as "sticky" soft spheres. The strength of attraction in these systems can be tuned via a simple post-polymerization reaction. We use rheology, light scattering, and neutron scattering to examine the solution properties and structure, both at rest and under shear. We also perform mean field calculations to further elucidate the structure of the micelles and compute an intermicellar potential. This theoretical intermicellar potential can be related to the solution microstructure and phase behavior and thus can be directly compared to our experimental results.
Polymeric Materials for Cell Encapsulation
In collaboration with the Roberts lab, we are initiating a new program to develop and characterize polymeric materials for cell encapsulation applications. Potential applications include bioreactors for the production of mammalian cell proteins, in vitro studies of drug metabolism, disease treatment through implantation of encapsulated cells, and the production of pharmaceuticals and plant-derived products from plant cell cultures. Our interdisciplinary approach, combining faculty in Chemical Engineering, Polymer Chemistry, and Plant Biology, focuses on hydrophobically modified biopolymers that form hydrogels. These hydrogels must be optimized with regards to biocompatibility, mechanical integrity, oxygen diffusion, and nutrient transport to ensure cell viability.
Solubilization of Bioactive Molecules in Surfactant Mesophases
In rational drug design, micelle-water partition coefficients serve as a quantitative measure of solute hydrophobicity. They are used as estimates of how easily a drug will cross the cell membrane and can sometimes be directly correlated with bioactivity. Our lab uses NMR techniques to study the partitioning of pharmaceuticals into micelles and vesicles. We focus on classes of drugs that are known to operate in the cell membrane, such as local anesthetics, anti-inflammatory agents, and inhalation anesthetics. We also use dynamic light scattering and fluorescence measurements to study the kinetics of uptake and release of these systems from surfactant assemblies. Our main goals are to study the effects of vesicle size and solution ionic strength. We also wish to investigate differences in partitioning between micelles and vesicles.
Elasticity and Shear-Induced Structures in Lamellar Phases
We use various scattering techniques to measure the elastic constants of surfactant lamellae and protein-containing membranes. These properties are related to the membrane topology and hence have implications for the surfactant phase behavior and formation of shear-induced structures. We are particularly interested in the formation of "onions," multilamellar vesicles that can cause an increase in the solution viscosity and impart a significant amount of elasticity to the system. We investigate the effect of counterion size and charge, as well as added polymer, on the membrane bending constant and formation of onions.
S. Choudhary, S. R. Bhatia. “Rheology and Nanostructure of Hydrophobically Modified Alginate (HMA) Gels and Solutions.” Carbohydrate Polymers 2012, 87, 524-530.
E. Saffer, G. N. Tew, S. R. Bhatia. “Poly(lactic acid)-poly(ethylene oxide) Block Copolymers: New Directions in Self-Assembly and Biomedical Applications.” Current Medicinal Chemistry 2011, 18, 5676-5686.
N. B. Raikar, S. R. Bhatia, M. F. Malone, D. J. McClements, M. A. Henson. “Predicting the Effect of Homogenization Pressure on Emulsion Drop Size Distributions.” Industrial and Engineering Chemistry Research 2011, 50, 6089-6100.
S. K. Agrawal, N. Sanabria-Delong, S. K. Bhatia, G. N. Tew, S. R. Bhatia. “Energetics of Association in Poly(lactic acid)-based Hydrogels with Crystalline and Nanoparticle-Polymer Junctions.” Langmuir 2010, 26, 17330–17338.
A. Banerjee, M. Arha, S. Choudhary, R. S. Ashton, S. R. Bhatia, D. V. Schaffer, R. S. Kane. “The Influence of Hydrogel Modulus on the Proliferation and Differentiation of Encapsulated Neural Stem Cells.” Biomaterials 2009, 30, 4695-4699.
S. K. Agrawal, N. Sanabria-Delong, G. N. Tew, S. R. Bhatia. “Nanoparticle-Reinforced Associative Network Hydrogels.” Langmuir 2008, 24, 13148–13154.
H. A. Baghdadi, E. C. Jensen, N. Easwar, S. R. Bhatia. “Evidence for Re-entrant Behavior in Laponite-PEO Systems.” Rheologica Acta, 2008, 47, 121-127.
S. K. Agrawal, N. Sanabria-DeLong, G. N. Tew, S. R. Bhatia. “Structural Characterization of PLA-PEO-PLA Solutions and Hydrogels: Crystalline vs amorphous PLA domains.” Macromolecules, 2008, 41, 1774-1784.
S. K. Agrawal, N. Sanabria-Delong, P. R. Jemian, G. N. Tew, and S. R. Bhatia. “Micro- to Nano-scale Structure of Biocompatible PLA-PEO-PLA Hydrogels.” Langmuir, 2007, 23, 5039-5044.
S. K. Agrawal, N. Sanabria-DeLong, J. M. Coburn, G. N. Tew, S. R. Bhatia. "Novel Drug Release Profiles from Micellar Solutions of PLA-PEO-PLA Triblock Copolymers." Journal of Controlled Release, 2006, 112, 64-71.
S. R. Bhatia, S. F. Khattak, S. C. Roberts. "Polyelectrolytes for Cell Encapsulation." Current Opinion in Colloid and Interface Science, 2005, 10, 45-51.
S. R. Bhatia. "Ultra-Small-Angle Scattering from Complex Fluids." Current Opinion in Colloid and Interface Science, 2005, 9, 404-411.
K. A. Aamer, H. Sardinha, G. N. Tew, and S. R. Bhatia (2003). "Rheological Studies of PLLA-PEO-PLLA Triblock Copolymer Hydrogels." Submitted, Biomaterials.
M. A. Crichton and S. R. Bhatia (2003). "Structure and Intermicellar Interactions in Block Polyelectrolyte Assemblies." Journal of Applied Crystallography, 36: 652-655.
S. R. Bhatia, J. Barker, and A. Mourchid (2003). "Scattering of Disk-like Particle Suspensions: Evidence for Repulsive Interactions and Large Length Scale Structure from Static Light Scattering and USANS." Langmuir, 19: 532-535.
J. E. Matthew, Y. L. Nazario, S. C. Roberts, and S. R. Bhatia (2002). "Effect of Mammalian Cell Culture Medium on the Gelation Properties of Pluronic F127." Biomaterials, 23: 4615-4619.
S. R. Bhatia and A. Mourchid (2002). "Gelation of Micellar Block Polyelectrolytes: Evidence of Glassy Behavior in an Attractive System." Langmuir, 18: 6469-6472.
S. R. Bhatia (2002). "Portfolio Assessment in Introductory Chemical Engineering Courses." Chemical Engineering Education, 36: 310-315.
H. Sardinha and S. R. Bhatia (2002). "Kinetics of Gel Formation in Polymer-Clay Dispersions." ACS Proceedings, Polymeric Materials: Science and Engineering, 87: 16-17.
J. E. Matthew, S. R. Bhatia, and S. C. Roberts (2002). "Pluronic F127 Gels as Materials for Mammalian Cell Encapsulation." Polymer Preprints 43: 769-770.
S. R. Bhatia, A. Mourchid, M. Joanicot (2001). "Block Copolymer Assembly to Control Fluid Rheology." Current Opinion in Colloid and Interface Science, 6: 471-478.
S. R. Bhatia, M. Crichton, A. Mourchid, R. K. Prud'homme, and J. Lal (2001). "Tuning Interactions Between Novel Polyelectrolyte Micelles." Polymer Preprints, 42: 326-327.
S. R. Bhatia, W. B. Russel, and J. Lal (2000). "Small-Angle Neutron Scattering Study of Associative Triblocks in Microemulsion Solutions." Journal of Applied Crystallography, 33: 614-617.
S. R. Bhatia and W. B. Russel (2000). "End-Capped Associative Polymer Chains Between Nano-Spheres: Attractions in Ideal Solutions." Macromolecules, 33: 5713-5720.
S. R. Bhatia and W. B. Russel (1998). "Rheology and Phase Behavior of Model Associative Polymer Solutions." ACS Proceedings, Polymeric Materials: Science and Engineering, 78: 206-207.
S. R. Bhatia and S. I. Sandler (1995). "Temperature Dependence of Infinite Dilution Activity Coefficients in Octanol and Octanol/Water Partition Coefficients of Some Volatile Halogenated Organic Compounds." Journal of Chemical and Engineering Data, 40: 1196-1198.
T. Adams, E. Hu, and S. Bhatia, 1996. Student Solutions Manual to Accompany Physical Chemistry by Joseph Noggle (3rd edition), Benjamin/Cummings Science, Menlo Park, CA.