Bridging Gelation Kinetics with Architecture and Mechanical Properties of Soft Polymer Networks
Polymer networks are essential in engineering and biomedical applications, such as elastomers in rubber tires, dampers, and seals; hydrogels in contact lenses and superabsorbent diapers; and pressure-sensitive-adhesives (PSAs) in labels, band-aids, and double-sided tapes. These soft, tough materials feature elastic moduli E ranging from 1 kPa to 1 MPa and can sustain large deformations near pre-existing defects or cracks.
However, at high temperatures or water concentrations, polymer networks readily fracture, limiting their use in applications such as water purification membranes, hydrogels for artificial prosthetics and drug delivery, solid polymer electrolytes for energy conversion and storage devices, and electro-adhesives for advanced manufacturing. Under these conditions, the polymer segmental dynamics facilitate ion or small-molecule transport, but the networks become prone to stress concentrations, damage localization, and fracture.
We aim to unravel design rules for polymer networks that remain soft and tough at high temperatures or water concentrations, leveraging recent advances in controlled polymerization methods, reactive Monte Carlo simulations, and polymer mechanochemistry to bridge gelation kinetics, network architecture (i.e., topology), and bulk mechanical properties.
Key Publications:
Dookhith, A. Z.; Zhang, Z.; Ganesan, V.; Sanoja, G. E. Impact of Reversible Deactivation Radical Copolymerizations (RDRPs) on Gelation, Phase Separation, and Mechanical Properties of Polymer Networks. Macromolecules 2024, 57 (18), 8698–8711. https://pubs.acs.org/doi/10.1021/acs.macromol.4c00905
Dookhith, A. Z.; Zhang, Z.; Ganesan, V.; Sanoja, G. E. Designing Soft and Tough Multiple-Network Elastomers: Impact of Reversible Radical Deactivation on Filler Network Architecture and Fracture Toughness. Soft Matter 2025, 21 (20), 4029–4042. https://doi.org/10.1039/D5SM00045A.
Toward a Multi-Scale Picture of Adhesion in Soft Polymer Networks
A wide range of soft, tough materials has recently emerged, enabling advances in healthcare, energy, and manufacturing applications, including artificial prosthetics, wearable electronics, and soft robotics. However, understanding the deformation and adhesion of these materials remains challenging because energy dissipation ahead of an interfacial crack (i.e., peel front) arises from processes spanning multiple length and time scales. These mechanisms include viscoelastic dissipation associated with interchain friction and damage arising from reversible or irreversible bond scission.
We aim to develop a multiscale understanding of adhesion by unraveling the interplay between viscoelasticity and damage ahead of interfacial cracks. To this end, we leverage recent advances in polymer mechanochemistry together with more conventional surface chemistry and mechanical testing to measure damage. Such measurements can, in turn, inform the molecular design of soft materials for emerging and increasingly demanding applications, such as wearable electronics, soft robotics, and materials based on reversible or bio-derived bonding motifs, as well as guide the development of predictive cohesive zone models.
Key Publications:
Arrowood, A.; Frazier, J.; Ciccotti, M.; Sanoja, G. E. From Molecular Damage and Viscoelasticity to Interfacial Fracture in Soft Polymer Networks: Insights from Mechanochemistry. Proc. Natl. Acad. Sci. 2025, 122 (37), 1–8. https://doi.org/10.1073/pnas.2509322122.
Co-Designing the Mechanical and Transport Properties of Membranes
Freshwater scarcity is an increasingly prevalent issue worldwide. Ultrafiltration (UF) membranes could play an important role in the solution but remain limited by a trade-off between their mechanical and transport properties. Their conventional manufacturing process, nonsolvent-induced phase separation, leads to kinetically arrested structures with a broad distribution of pores, which influence both the hydrodynamic resistance to water flow and the stress concentrations around the pores.
We aim to provide a molecular rationale for co-designing the mechanical and transport properties of UF membranes by leveraging solution self-assembly of block copolymers and architectures capable of delocalizing stress in bulk. If successful, our work should inform the molecular design of advanced UF membranes for emerging and increasingly demanding separations.
Key Publications:
Mann, A. N.; Wamble, N. P.; Kuehster, L.; Landsman, M. R.; Arrowood, A. J.; Su, G. M.; Lynd, N. A.; Freeman, B. D.; Sanoja, G. E. SAN-Based Block Polymers as a Platform for Manufacturing Strong Isoporous Membranes. Macromolecules 2025, 58 (19), 10901–10913. https://doi.org/10.1021/acs.macromol.5c01452.
Co-designing the mechanical and transport properties of polymer membranes for olefin/paraffin gas separations
Olefins such as ethylene and propylene are essential building blocks for plastics and other everyday materials. Because current industrial processes for olefin/paraffin separation, such as cryogenic distillation, are highly energy-intensive, membranes are a promising lower-energy separation method to produce olefins in the quantities demanded by modern society with a lower carbon footprint. For these membranes to be employed in industrial settings, they must be mechanically robust to withstand stresses during processing and service, in addition to being highly permeable and highly selective for the lowest operating and capital costs.
We aim to understand the relationship between membrane mechanical properties and gas transport properties to build an understanding of the effect of membrane design on lifetime and separation abilities. We develop various polymer platforms which are capable of dissipating energy and delocalizing stress to toughen the membrane but maintain desirable transport properties. A molecular level understanding of the relationship between mechanical and transport properties will enable the design of tough, permeable, and selective membranes for olefin/paraffin and other gas separations.
Interplay Between Molecular-Scale Damage and Viscoelasticity in Polymer Melts: A Molecular Picture of Melt Fracture
High-rate processing methods such as extrusion, injection molding, and blow molding are central to polymer manufacturing. Under these conditions, entangled polymer melts deformed at rates exceeding their relaxation times exhibit melt fracture, limiting their reuse. Despite its technological importance, the molecular origins of melt fracture remain poorly understood, in part due to challenges in applying well-defined tensile deformations to melts and in quantifying energy dissipation at fracture surfaces
We aim to address these limitations by utilizing recent advancements in controlled polymer synthesis and mechanochemistry, thereby allowing us to tune the number of entanglements per chain and correlate this change in architecture to damage. These results establish a molecularly informed framework linking deformation rate, chain dynamics, and damage accumulation in entangled polymer melts, providing new insight into the mechanisms governing melt fracture that can inform industrial plastic recycling.
