Electrostatic Self-ASsembly of Soft Materials
Research in the Srivastava Lab utilizes the self-assembly of mesoscopic building blocks to engineer soft materials with real-life applications. We focus on polyelectrolyte complexation – the associative phase separation of oppositely charged polyelectrolytes. Our aim is to address the fundamental question: “How can we leverage macromolecular design to modulate the length scale of phase separation in polyelectrolyte complexes?"
Self-Assembled Polyelectrolyte Complex Networks and Hydrogels
Scaffoldings for Wet Adhesives and 3D Bioprinting Inks
We develop electrostatically self-assembled networks and hydrogels that are used as scaffolds addressing challenges in the mechanical properties of a wide range of conventional covalent-type hydrogels. This approach enables the development of interpenetrating polymer networks comprising covalent and electrostatic self-assembled networks. We have demonstrated synergic improvements in shear and tensile strengths of hydrogels while preserving the microstructure of electrostatically self-assembled networks. Our materials have proved instrumental in enhancing the performance (delivery, injection, and 3D printing) of biopolymer inks and bioadhesives in biomedically-relevant environments.
Stabilizers for Water-Air and Water-Water Interfaces
We explore fundamental questions related to the interfacial assembly of surfactants and (macro)molecules at water-air and water-water interfaces. We developed a new paradigm for membraneless stabilization of complex coacervates microdroplets, resulting in a new class of materials known as complex coacervate emulsions that rely solely on the assembly of comb polyelectrolytes at the coacervate-water interface. Our approaches have expanded the utility of complex coacervates as protein encapsulants and colloidal bioreactors.
Selected Relevant Publications:
Interfacial Stabilization of Aqueous Two-Phase Systems: A Review, C. Fick, Z. Khan, S. Srivastava* Materials Advances, Advances 4, 4665–4678 (2023). [PDF]
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]
Fundamentals of Complex Coacervates
Our group explores fundamental questions on the properties of polyelectrolyte complexes. We developed a new framework termed time-ionic strength superposition, to link the influence of salt and polyelectrolyte counterions on the flow behavior of polyelectrolyte complex coacervates. Our framework enables a facile approach to probe long-time relaxation dynamics of polyelectrolyte chains in complex coacervates. We also study the non-trivial properties and phase behavior of complex coacervates by probing the ion valency and chain lengths to determine the polymer content and rheological properties that are significant in industrial applications.
Selected Recent Publications:
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, 54, 105 (2021) [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].
Sustainable Plastics and Composites
Low-Energy and Low-Carbon-Intensity Inorganic-Organic Composites and Cements
We pursue low-energy cost, environmentally friendly approaches to produce composites that rival commercial construction materials by utilizing products obtained from the chemical recycling of plastics. To do this, we integrate naturally occuring zeolite minerals with organic molecules sources from post-consumer-use polyurethane foams (mattresses and cushions) to create organic-inorganic composites with tensile and compressive strengths exceeding cement.
Enabling Upcycling of Post-consumer Use Plastics
Our group has adopted a three-fold approach to address the pertinent issue of plastic waste. To enable the development of tailored approaches for chemically recycling plastics with varying chemical compositions, we propose inexpensive and field-employable strategies to sort post-consumer-use plastic. These strategies correlate simple observable physical properties to their complex thermomechanical and chemical properties, and inform the development and optimization of depolymerization strategies. Furthermore, we upcycle products from depolymerization reactions into fabricating high-value, high-strength organic/inorganic composites with mechanical and functional properties superior to conventionally employed materials.
Selected Relevant Publications:
Hybrid Organic–Inorganic Composites Based on Glycolyzed Polyurethane, D. Iyer, M. Gallagher, D. Simonetti, G. Sant, S. Srivastava*, ACS Sustainable Chem. Eng. 10, 17116−17123 (2022). [PDF]
Thermoresponsive Polymer-mineral Suspensions
Our group, in collaboration with the Sant Group, endeavors to unravel the foundational principles essential for expediting the development of a novel 3D-printable cementitious binder based on portlandite, enabling CO2 sequestration. To achieve this objective, our research is designed to: (i) enhance the comprehension, regulation, and optimization of the rheological properties of concentrated portlandite suspensions, thereby facilitating printability. (ii) fine-tune portlandite carbonation pathways at ambient temperatures, maximizing CO2 absorption rates to expedite carbonation kinetics, and (iii) build innovative multi-material 3D-printed metastructures distinguished by exceptional load-bearing capacity and an optimal strength-to-weight ratio.
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]