Srivastava Lab


Electrostatic Self-ASsembly of Soft Materials

Research in our group utilizes molecular design and self-assembly of mesoscopic building blocks to engineer novel soft materials with unique combinations of features desired for real-world applications. Our work focuses on first-principle studies of the influence of various non-covalent intermolecular interactions on the structure and properties of molecular self-assembly. The overarching theme of our research is to understand and modulate natural and artificial self-assembly to create smart materials.

Fundamentals of Complex Coacervates

Polyelectrolyte complex coacervates are unique polymer-rich materials that are versatile yet poorly understood. Our works aims on creating a fundamental understanding of the phase behavior, structure, kinetics and rheology of these materials, with a special emphasis on the role of small ions in influencing the phase behavior and properties of the complexes. To this end, we envision elucidating the effects of various system parameters in our studies, including polymer architecture, length and charge density, small ion nature and concentration, and solvent effects.

Selected Recent Publications:

Influence of Divalent Ions on Composition and Viscoelasticity of Polyelectrolyte Complexes, D. Iyer,# V. M. S. Syed,# S. Srivastava*, Journal of Polymer Science, 59, 2895 (2021). [PDF]

Effect of Solvent Quality on the Phase Behavior of Polyelectrolyte Complexes, L. Li, A. M. Rumyantsev, S. Srivastava,* S. Meng, J. J. de Pablo* and M. V. Tirrell*, Macromolecules, 54, 105 (2021). [PDF]

Time−Ionic Strength Superposition: A Unified Description of Chain Relaxation Dynamics in Polyelectrolyte Complexes, Vaqar M. S. Syed, Samanvaya Srivastava*, ACS Macro Letters, 9, 1067 (2020). [PDF]

Macromolecules, 53, 7835 (2020) [PDF]; Macromolecules 51, 2988 (2018) [PDF]; Soft Matter 14, 2454 (2018) [PDF]; Advances in Chemical Physics 161, 499 (2016) [PDF].

Charge-Driven Self-Assemblies

Electrostatic interactions drive self-assembly in unique ways. Micelles of diverse morphologies, multi-component droplets, and hybrid structures thus formed can spontaneously partition a variety of charged molecules, big and small, including small ions, nucleic acids (DNA, RNA), proteins, and enzymes. Research in our group endeavors to understand and harness these processes to create efficient micro- and nano-scale encapsulants and biomolecular reactors.

Selected Relevant Publications:

Comb Polyelectrolytes Stabilize Complex Coacervate Microdroplet Dispersions, S. Gao,# S. Srivastava*, ACS Macro Letters 11, 902 (2022). [PDF]

Salt Weakens Intermicellar Interactions and Structuring in Bulk Solutions and Foam Films, C. Ochoa, S. Gao,# S. Srivastava,* and V. Sharma*, Langmuir 38, 11003 (2022). [PDF]

Foam film stratification studies probe intermicellar interactions, C. Ochoa, S. Gao,# S. Srivastava,* and V. Sharma*, Proceedings of the National Academy of Sciences, 118, e2024805118 (2021). [PDF]

Protein–Polyelectrolyte Complexes and Micellar Assemblies, S. Gao,^ A. Hokar,^ and S. Srivastava*, Polymers, 11, 1097 (2019). [PDF]

Partitioning and Enhanced Self-Assembly of Actin in Polypeptide Coacervates, P. M. McCall,^ S. Srivastava,^ S. L. Perry, D L. Kovar, M. L. Gardel, and M. V. Tirrell, Biophysical Journal 114, 1636–1645 (2018). [PDF]

Multifunctional Micelles & Hydrogels

Micelles and hydrogels form upon nanoscale phase separation. Driven by hydrophobic interactions, polyelectrolyte complexation and other non-covalent intermolecular interactions (and combinations thereof), these materials are employed in a range of biomedical applications including theranostic agents, vehicles for drug and gene delivery and tissue sealants, adhesives, and growth-supporting scaffolds. Our research focuses on inferring the role of molecular architecture and driving forces on the nanoscale as well as bulk structure and properties of these materials, intending to create modular materials design platforms to serve emerging biomedical applications.

Selected Relevant Publications:

Polyelectrolyte Complex-Covalent Interpenetrating Polymer Network Hydrogels, D. Li,# T. Göckler,# U. Schepers, S. Srivastava*, Macromolecules 55, 4481 (2022). [PDF]

Structure, Morphology, and Rheology of Polyelectrolyte Complex Hydrogels Formed by Self-Assembly of Oppositely Charged Triblock Polyelectrolytes, S. Srivastava,* A. E. Levi, D. J. Goldfeld, and M. V. Tirrell*, Macromolecules, 53, 5763 (2020). [PDF]

Gel Phase Formation in Dilute Triblock Copolyelectrolyte Complexes, S. Srivastava, M. Andreev, A. E. Levi, D. J. Goldfeld, J. Mao, W. T. Heller, V. Prabhu, J. J. de Pablo, and M. V. Tirrell, Nature Communications 8, 14131 (2017). [PDF]

Molecular Engineering Solutions for Therapeutic Peptide Delivery, H. Acar, Jeffrey. M. Ting, S. Srivastava, J. L. LaBelle, and M. V. Tirrell, Chemical Society Reviews 46, 6553 (2017). [PDF]

Polyelectrolyte Complexation, S. Srivastava and M. V. Tirrell, Advances in Chemical Physics 161, 499 (2016). [PDF]

Sustainable Plastics and Composites

Research in our group focuses on the design of a new family of composites wherein zeolites (and other cementitious materials) are compounded with organic materials sourced from recycled plastics to create robust composites. Our approach harnesses solution-controlled phase aggregation – wherein inorganic zeolitic constituents are bridged and joined by ductility-enhancing and fracture-resisting polymer compositions – to enable hybrid microstructure design and modulation of compressive and flexural strength of the composites.

Selected Relevant Publications:

Ultrafast Stiffening of Concentrated Thermoresponsive Polymer-mineral Suspensions, S. B. Kandy, I. Mehdipour, N. Neithalath, A. Kumar, M. Bauchy, E. Garboczi, S. Srivastava, T. Gaedt, G. Sant, Materials & Design 221, 110905 (2022). [PDF]

Temperature-induced aggregation in portlandite suspensions, S. B. Kandy, I. Mehdipour, N. Neithalath, M. Bauchy, E. J. Garboczi, S. Srivastava, T. Gaedt, and G. N. Sant, Langmuir, 36, 10811 (2020). [PDF]

Dispersing Nano- and Micro-sized Portlandite Particulates via Electrosteric Exclusion at Short Screening Lengths, J. Timmons,^ I. Mehdipour,^ S. Gao, H. Atahan, N. Neithalath, M. Bauchy, E. Garboczi, S. Srivastava*, and G. Sant*, Soft Matter, 16, 3425 (2020). [PDF]