About

Lauren Zarzar is a Professor of Chemistry and the Associate Department Head for Graduate Education at Penn State's Eberly College of Science. She holds a B.A. in Chemistry and a B.S. in Economics from the University of Pennsylvania, as well as a Ph.D. in Chemistry from Harvard University. Her postdoctoral work was conducted at MIT. Her research focuses on dynamic materials that sense and adapt to their surroundings, which are considered to be integral components of future technologies. Her lab explores platforms involving both hard and soft materials, including direct laser writing of polymers, metals, and oxides for nano and microscale patterning, as well as reconfigurable soft materials such as emulsions and polymers with functions like tunable lenses, sensors, and triggered release. Zarzar has received numerous honors and awards, including the Penn State Faculty Scholar Medal, the Presidential Early Career Award for Scientists and Engineers, the Sloan Research Fellowship, and the Packard Fellowship for Science and Engineering, among others.

Research topics

• Nanotechnology
• Materials science
• Physics
• Chemistry
• Chemical engineering
• Thermodynamics
• Computer Science
• Chemical physics
• Engineering
• Organic chemistry
• Mechanics
• Composite material
• Optics

Selected publications

• Where Do We Go from Here?

  Accounts of Materials Research · 2026-02-27

  articleSenior author
  PublisherDOI

• Memory effects in active droplets

  ChemRxiv · 2026-01-06

  articleSenior author

  Marangoni-driven self-propelled droplets have attracted considerable attention as a platform to study active soft matter and collective behavior. The speed of active drops is generally assumed to be determined by instantaneous diameter and solubilization rate, which together dictate the spontaneously generated interfacial tension gradients across the drop surface and induce propulsion; the history of the droplet has not before been considered. Here, we report that active droplets can exhibit a type of memory wherein the temporal history of the droplet, particularly the starting diameter, influences the droplet speed. For example, two droplets of identical instantaneous diameter in the same local chemical environment can exhibit dramatically different instantaneous velocities depending upon their initial diameter. This effect is observed for a range of droplet oils and common ionic surfactants. The relationships between drop diameter, velocity, and solubilization rate were examined for several ionic and nonionic surfactants and suggest that droplet motility only is present when solubilization is interfacially limited, as opposed to diffusion limited. Oil droplets in ionic surfactant solutions also undergo a transition from motile to non-motile, where the diameter at the transitionary point depends upon initial drop diameter. We hypothesize that this memory behavior may result from an interfacial phase transition, as hinted at by observed visual deformations on drop interfaces under some circumstances. We believe this work provides insight as to how memory may be imparted in active droplet systems, highlights the importance of non-equilibrium phenomena in active materials, and offers valuable insights for the design of adaptive, dynamic droplet systems.

  PublisherDOI

• Nonequilibrium surfactant partitioning into microdroplets generates local phase inversion conditions and interfacial instability

  Soft Matter · 2026-01-01

  articleOpen accessSenior authorCorresponding

  Droplets far from equilibrium experience different compositions and local environments compared with bulk oil and water phases at equilibrium. Understanding the pathways involved in emulsion progression towards equilibrium is valuable for designing complex fluids for many purposes including coatings, food, chemical separations, active matter, and enhanced oil recovery. Here we report how microscale oil droplets, which partition nonionic surfactants and also solubilize, can follow an unexpected pathway wherein a spherical droplet transitions through an interfacial instability and dissociates. This process depends on the oil hydrophobicity, the concentration and ethylene oxide number of the surfactant, the initial droplet diameter, and the presence of neighboring droplets. We propose a mechanism based on local phase inversion that explains both the visual appearance of the droplet dissociation behavior as well as the trends in its counterintuitive dependence on specific conditions like oil and surfactant chemical structure and surfactant concentration.

  PublisherOA PDFDOI

• Uncovering Chemical Principles Governing Nanophase Formation in Ternary Solvents

  Angewandte Chemie International Edition · 2025-03-14 · 3 citations

  articleOpen accessSenior authorCorresponding

  Nanoscopic phases, such as oil-enriched pockets dispersed in water, have been observed in ternary mixtures of oil, water, and cosolvent in the absence of surfactants. Such nanophases are found across a portion of compositions within the single-phase region of the ternary phase diagram. However, the principles governing the formation of nanophases under certain conditions but not others, regarding both volumetric and chemical makeup, are unclear. Here, the nanophase behavior of ternary mixtures of water with a suite of cosolvents and oils containing strategically chosen functional groups is systematically analyzed to probe the role of intermolecular interactions. Dynamic light scattering is used to quantify the nanophase structure. It was found that stronger classes of intermolecular interactions such as H-bonding or n-Π* interactions between oil and cosolvent notably contribute to forming thermodynamically stable nanophases. Ternary mixtures in which the oil has only van der Waals interactions with the water and cosolvent do not stabilize nanophases detectable by dynamic light scattering. Aromatic groups favor nanophase formation. The most prominent structuring (highest number and largest sizes of nanophases) is found in water-rich compositions near the miscibility gap. This experimental study provides chemical insight into the chemical formulation of ternary solvent mixtures favoring nanophase formation.

  PublisherOA PDFDOI

• Tailoring Multibounce Reflection Interference with Microscale Refractive Interfaces

  ACS Applied Optical Materials · 2025-03-27 · 1 citations

  articleOpen accessSenior authorCorresponding

  Developing approaches to tailor iridescence generated by microscale structures is essential for applications ranging from sensors to security materials. Here, we achieve tunable iridescence by combining microscale refractory interfaces with concave microstructures to generate multibounce reflection interference. By incorporating designed refractory interfaces, we demonstrate the ability to control the distribution of illumination angles entering the structured cavity thereby modulating the resulting color and reflection efficiency. Experimental analysis of Janus droplets combined with ray tracing simulations highlight how refractory elements modify the optical paths of multibounce reflections and alter the angle-dependent coloration. Additionally, we investigate the incorporation of axion lenses that refract and focus light onto the microstructure to increase reflection efficiency while maintaining color saturation. The integration of refractory interfaces with reflective microstructure cavities provides customizable routes to tailor the structural coloration and reflection performance of multibounce reflection interference, advancing the design of high-performance optical materials.

  PublisherOA PDFDOI

• Uncovering Chemical Principles Governing Nanophase Formation in Ternary Solvents

  Angewandte Chemie · 2025-03-14 · 1 citations

  articleOpen accessSenior authorCorresponding

  Abstract Nanoscopic phases, such as oil‐enriched pockets dispersed in water, have been observed in ternary mixtures of oil, water, and cosolvent in the absence of surfactants. Such nanophases are found across a portion of compositions within the single‐phase region of the ternary phase diagram. However, the principles governing the formation of nanophases under certain conditions but not others, regarding both volumetric and chemical makeup, are unclear. Here, the nanophase behavior of ternary mixtures of water with a suite of cosolvents and oils containing strategically chosen functional groups is systematically analyzed to probe the role of intermolecular interactions. Dynamic light scattering is used to quantify the nanophase structure. It was found that stronger classes of intermolecular interactions such as H‐bonding or n –Π* interactions between oil and cosolvent notably contribute to forming thermodynamically stable nanophases. Ternary mixtures in which the oil has only van der Waals interactions with the water and cosolvent do not stabilize nanophases detectable by dynamic light scattering. Aromatic groups favor nanophase formation. The most prominent structuring (highest number and largest sizes of nanophases) is found in water‐rich compositions near the miscibility gap. This experimental study provides chemical insight into the chemical formulation of ternary solvent mixtures favoring nanophase formation.

  PublisherOA PDFDOI

• Droplets as Cell Models: Chemical Gradient-Induced Directional Filopodia Formation

  ChemRxiv · 2025-08-25

  preprintOpen access

  Cells are complex chemical systems capable of sensing and responding to environmental cues by dynamically reshaping themselves, e.g. by forming arm-like protrusions such as filopodia. Recapitulating cellular behavior in artificial systems is a longstanding goal in understanding the matter-to-life transition and designing responsive soft materials. Here, we use oil-in-water emulsions that mimic cellular environmental sensing and form directional arm-like filopodia in response to external chemical cues. Our work analyzes the step-by-step process involved in the formation of artificial filopodia, and we engineer ways to direct filopodia growth through different chemical gradients. The process is driven by asymmetric surfactant partitioning across the oil-water interface, followed by ordering at the interface to form lamellar structures, which are projected out as filopodia. We observe filopodia growing away from the source of kosmotropic anions and toward the source of chaotropic anions from the Hofmeister series. Significantly, these systems also respond to amino acid gradients, similar to cells: tryptophan gradients favor growth towards the source, while lysine and arginine gradients cause growth away from the amino acid source. Our findings open new avenues for fabricating life-like materials that sense and grow in response to environmental cues.

  PublisherOA PDFDOI

• Technology Roadmap of Micro/Nanorobots

  ACS Nano · 2025-06-27 · 68 citations

  reviewOpen access

  , the field of micro/nanorobots has evolved from science fiction to reality, with significant advancements in biomedical and environmental applications. Despite the rapid progress, the deployment of functional micro/nanorobots remains limited. This review of the technology roadmap identifies key challenges hindering their widespread use, focusing on propulsion mechanisms, fundamental theoretical aspects, collective behavior, material design, and embodied intelligence. We explore the current state of micro/nanorobot technology, with an emphasis on applications in biomedicine, environmental remediation, analytical sensing, and other industrial technological aspects. Additionally, we analyze issues related to scaling up production, commercialization, and regulatory frameworks that are crucial for transitioning from research to practical applications. We also emphasize the need for interdisciplinary collaboration to address both technical and nontechnical challenges, such as sustainability, ethics, and business considerations. Finally, we propose a roadmap for future research to accelerate the development of micro/nanorobots, positioning them as essential tools for addressing grand challenges and enhancing the quality of life.

  PublisherDOI

• Nanophase Structuring in Simple Ternary Solvents Mediates Reaction Kinetics

  Chem · 2025-03-28

  preprintOpen accessSenior author

  Solvents play a critical role in chemical reactivity. Ternary solvent systems—such as combinations of water, a water-miscible polar organic solvent, and a water-immiscible oil—have been shown to organize into nanophase-structured domains. However, the influence of these nanophases on reaction kinetics remains largely unexplored. In this study, we investigate how nanophase structuring within ternary solvents impacts the kinetics of strain-promoted azide-alkyne click reactions. Ternary solvents were designed to either promote or suppress nanophase structuring, with dynamic light scattering being used to assess nanoscale domain formation. High-throughput UV-Vis kinetic analysis revealed that hydrophobic reactants exhibited significantly enhanced reaction rates within ternary solvents, beyond the hydrophobic effects induced within water-containing binary solvents. Rates were elevated for ternary compositions within a small, specific region of the ternary phase diagram expected to contain oil-in-water nanophases. This kinetic enhancement effect was removed when hydrophilic reactants were used or when nanophase stability was reduced. These findings suggest that the structure of ternary solvent nanophases can be harnessed to modulate reaction kinetics and have influence beyond that of the bulk solvent properties like the polarity or water-induced hydrophobic interactions between reagents. This insight has broad implications for solvent design in synthetic chemistry, biocatalysis, and prebiotic chemistry, offering insight into controlling chemical reactivity in complex, multicomponent solvent systems.

  PublisherOA PDFDOI

• Synergistic diffraction and multibounce reflection interference within single iridescent microstructures

  Newton · 2025-04-15

  preprintOpen accessSenior author

  <h2>Summary</h2> Multibounce reflection interference produces structural coloration due to interference between light rays that travel along different paths of total internal reflection in microscale cavities. As feature dimensions decrease, a ray-based framework may become inaccurate as contributions from wave-based phenomena, such as diffraction, become increasingly important. We employ Fourier plane microscopy to collect angle-resolved interference spectra from individual 10-μm-scale microstructures and reveal how edge diffraction, synergistically coupled with multibounce total internal reflection, contributes to far-field interference. Hemicylinders, particularly those with lower contact angles, exhibit interference signatures that cannot be fully explained by the conventional multibounce ray-based framework but align with full-wave simulations. By collecting angularly resolved interference spectra from selected regions within isolated hemicylinders, we identify the contributions from light entering and exiting along different paths. We develop an extended ray model that incorporates edge diffraction and use experiments to guide estimation of the relative intensity contributions of diffracted ray trajectories.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Dynamic Manipulation of Micro-scale Liquid-Liquid Interfaces within Complex Droplets for Tunable Optics

  NSF · $182k · 2018–2022

• PFI-TT: Fabrication of color-shifting coatings containing reflective microstructures

  NSF · $300k · 2020–2023

• CAREER: Laser-Induced Solvothermal Synthesis for the Direct-Write, Microscale Additive Processing of Metals and Oxides

  NSF · $534k · 2021–2027

Frequent coauthors

• Timothy M. Swager

  Massachusetts Institute of Technology

  27 shared

• Caleb H. Meredith

  Pennsylvania State University

  22 shared

• Joanna Aizenberg

  Harvard University

  21 shared

• Alexander Castonguay

  Pennsylvania State University

  20 shared

• Seong Ik Cheon

  Pennsylvania State University

  17 shared

• Bryan Kaehr

  Sandia National Laboratories

  14 shared

• Julia A. Kalow

  Northwestern University

  14 shared

• Pepijn G. Moerman

  Eindhoven University of Technology

  14 shared

Education

• PhD, Chemistry, Chemistry and Chemical Biology

  Harvard University

  2013

• BA, Chemistry, Chemistry

  University of Pennsylvania

  2008

• BS, Economics, Wharton School

  University of Pennsylvania

  2008

Awards & honors

• Penn State Faculty Scholar Medal
• Presidential Early Career Award for Scientists and Engineers
• Simons Foundation Pivot Fellowship
• Camille Dreyfus Teacher-Scholar Award
• Penn State Eberly College of Science Distinguished Mentoring…