About

Muzhou Wang is an Associate Professor of Chemical and Biological Engineering at Northwestern University. He holds a Ph.D. in Chemical Engineering from the Massachusetts Institute of Technology and a B.S. in Chemical Engineering from the California Institute of Technology. His research focuses on understanding the fundamental processes that govern the self-assembly of nanostructured polymers and other soft materials, which are prevalent in applications ranging from household items to organic electronic devices and biomaterials. Wang's group employs advanced optical microscopy techniques to observe materials below the optical resolution limit, enabling real-time, in situ monitoring of polymer morphology evolution. His work emphasizes developing new polymeric materials, with particular attention to biomaterials and biohybrid molecules, contributing to the advancement of polymer science through innovative characterization methods.

Research topics

• Computer Science
• Materials science
• Physics
• Composite material
• Artificial Intelligence
• Nanotechnology
• Process engineering
• Optics
• Mechanical engineering
• Biological system
• Engineering
• Physical chemistry
• Polymer science
• Thermodynamics
• Mathematics
• Chemical physics
• Chemistry
• Polymer chemistry
• Geometry

Selected publications

• Real-Time Visualization of Single Polymer Conformational Change in the Bulk State during Mechanical Deformation

  Physical Review Letters · 2025-04-09 · 5 citations

  articleSenior author

  Although polymers are most often used within bulk materials, investigating their conformations and dynamics has long been a challenging endeavor in this configuration, particularly under external forces. Addressing this, we utilize single-molecule localization microscopy as a powerful imaging tool to visualize bottlebrush poly(n-butyl acrylate) chains in the bulk state under spherical indentation, quantitatively describing changes in behavior of single polymer chains. We compare these experiments to displacement fields determined analytically and confirmed through finite element analysis. This study pioneers visualizing polymer conformational changes in their native environment in situ, offering transformative insights into polymer behavior and dynamics.

  PublisherDOI

• Extreme Dependence of Dynamics on Concentration in Highly Crowded Polyelectrolyte Solutions

  ChemRxiv · 2024-05-08 · 1 citations

  preprintOpen accessSenior author

  Charge carrying species, such as polyelectrolytes, are vital to natural and synthetic processes that rely on their dynamic behavior. Through single-particle tracking techniques, the diffusivity of individual polyelectrolyte chains and overall system viscosity are determined for concentrated polylysine solutions. These studies show experimental scaling dependences much stronger than theoretical predictions for both neutral polymers and polyelectrolytes and draw into question whether power law based scaling theories are appropriate to describe concentrated charged systems. Similar trends are observed in concentrated solutions prepared at various pH and counterion conditions. These hindered system dynamics appear universal to polyelectrolyte systems and are attributed to the large effective excluded volumes of polyelectrolyte chains inducing glassy dynamics. The framework of the Vrentas Duda free volume theory is used to compare polyelectrolyte and neutral systems. Supported by this theory, excluding counterion mass from total polymer mass results in all environmental conditions collapsing onto a common trendline. These results are applicable to crowded biological systems, such as intracellular environments where protein mobility is strongly inhibited.

  PublisherOA PDFDOI

• Extreme dependence of dynamics on concentration in highly crowded polyelectrolyte solutions

  Science Advances · 2024-07-03 · 18 citations

  articleOpen accessSenior authorCorresponding

  Charge-carrying species, such as polyelectrolytes, are vital to natural and synthetic processes that rely on their dynamic behavior. Through single-particle tracking techniques, the diffusivity of individual polyelectrolyte chains and overall system viscosity are determined for concentrated polylysine solutions. These studies show scaling dependences of D ~ c −6.1 and η ~ c 7.2 , much stronger than theoretical predictions, drawing the applicability of power law fits into question. Similar trends are observed in concentrated solutions prepared at various pH and counterion conditions. These hindered system dynamics appear universal to polyelectrolyte systems and are attributed to the large effective excluded volumes of polyelectrolyte chains inducing glassy dynamics. The framework of the Vrentas-Duda free-volume theory is used to compare polyelectrolyte and neutral systems. Supported by this theory, excluding counterion mass from total polymer mass results in all environmental conditions collapsing onto a common trendline. These results are applicable to crowded biological systems, such as intracellular environments where protein mobility is strongly inhibited.

  PublisherDOI

• Effects of Composition and Cure Parameters on the Mechanical and Optical Properties of Silicone/Methacrylate Hybrid Elastomers

  Macromolecules · 2024-08-29 · 5 citations

  article

  Hybrid silicone–organic materials offer an alternative formulation for tough, silicone based elastomers. While such systems can be synthesized using a simple UV-copolymerization scheme between end-functional polydimethylsiloxane (PDMS) and methacrylate monomers, the unique morphologies of the resulting materials complicate the establishment of clear structure–property relationships. In this work, we study the effects of composition and cure parameters on the mechanical and optical properties of PDMS/polymethacrylate hybrid elastomers. We observed that differences in the mixing thermodynamics between methacrylate and silicone components lead to hybrid materials with substantially different properties. Based on the observed trends, we further argue that both increases in UV curing intensity and PDMS chain length reduce the graft density in these hybrids, leading to shared changes in stiffness, extensibility, and transparency. Lastly, we characterize the linear and nonlinear viscoelasticity of these networks to relate the presence of mechanical dissipation to improved toughness.

  PublisherDOI

• <i>In Situ</i> Investigations of Microstructure Formation in Interpenetrating Polymer Networks

  Macromolecules · 2024-02-28 · 6 citations

  articleSenior authorCorresponding

  Interpenetrating polymer networks (IPNs) represent an effective strategy for compatibilizing immiscible polymers to enhance the mechanical properties of the final material. While it has been established that the macroscopic properties are dependent on the microstructure, it is unknown why various microstructures are formed in IPNs because the microstructure is often trapped in a nonequilibrium state. To explore this, we conducted a study to establish a relationship between polymerization kinetics and microstructure formation in polydimethylsiloxane/poly(methyl methacrylate) (PDMS/PMMA) IPNs. By manipulating the UV curing intensity, we observed three distinct morphologies: isolated PMMA-rich spheres within a PDMS matrix with a monomodal domain size distribution, spheres with a bimodal size distribution, and a clustered domain microstructure. To investigate the different phase separation mechanisms, we correlated in situ small-angle X-ray scattering (SAXS) to track microstructure formation and Fourier transform infrared spectroscopy (FT-IR) to track polymerization kinetics. Based on our findings, we propose that the monomodal sphere microstructure formed via spinodal decomposition. The positions of the domains are kinetically trapped in the PDMS network, preventing macrophase separation. Similarly, the clustered domain microstructure also arises from spinodal decomposition, but increased mobility within the PDMS matrix enables domains to aggregate after network percolation. In contrast, the bimodal spherical morphology is attributed to a combination of nucleation and growth, and spinodal decomposition. We postulate that these different mechanisms are dictated by changes in the PMMA molecular weight during polymerization. Through the examination of polymerization kinetics and microstructure formation, we have proposed multiple mechanisms that explain the microstructure formation in IPNs.

  PublisherDOI

• HaloTag display enables quantitative single‐particle characterisation and functionalisation of engineered extracellular vesicles

  Journal of Extracellular Vesicles · 2024-07-01 · 9 citations

  articleOpen access

  Extracellular vesicles (EVs) play key roles in diverse biological processes, transport biomolecules between cells and have been engineered for therapeutic applications. A useful EV bioengineering strategy is to express engineered proteins on the EV surface to confer targeting, bioactivity and other properties. Measuring how incorporation varies across a population of EVs is important for characterising such materials and understanding their function, yet it remains challenging to quantitatively characterise the absolute number of engineered proteins incorporated at single-EV resolution. To address these needs, we developed a HaloTag-based characterisation platform in which dyes or other synthetic species can be covalently and stoichiometrically attached to engineered proteins on the EV surface. To evaluate this system, we employed several orthogonal quantification methods, including flow cytometry and fluorescence microscopy, and found that HaloTag-mediated quantification is generally robust across EV analysis methods. We compared HaloTag-labelling to antibody-labelling of EVs using single vesicle flow cytometry, enabling us to measure the substantial degree to which antibody labelling can underestimate proteins present on an EV. Finally, we demonstrate the use of HaloTag to compare between protein designs for EV bioengineering. Overall, the HaloTag system is a useful EV characterisation tool which complements and expands existing methods.

  PublisherOA PDFDOI

• Diffusive Trends in Concentrated Oppositely-Charged Polyelectrolyte Solutions and Onset of Glassy Dynamics

  ACS Macro Letters · 2024-08-19 · 2 citations

  articleSenior authorCorresponding

  We utilize single particle tracking studies to investigate the diffusion of polylysine through concentrated matrices of cationic polylysine and anionic polyglutamic acid with no added salts. These studies show that diffusivity has a strong apparently exponential dependence on concentration in crowded systems that does not appear to be a function of the charge sign. These trends are consistent in both single-phase systems prepared at concentrated conditions and polymer-rich coacervate phases formed from dilute phase-separating systems. The likely origin of this behavior is the onset of glassy dynamics spurred by a decrease in plasticization by water and the large excluded volume associated with charge-bearing species. This effect can be contextualized through free volume-based theories such as the Vrentas-Duda model. Overall, we obtain dynamic behavior that is distinctly different from behavior observed in more dilute systems and warrants further investigation.

  PublisherDOI

• Extreme Dependence of Dynamics on Concentration in Highly Crowded Polyelectrolyte Solutions

  ChemRxiv · 2024-02-12 · 1 citations

  preprintOpen accessSenior author

  Charge carrying species, such as polyelectrolytes, are vital to natural and synthetic processes that rely on their dynamic behavior. Here, we utilize single molecule methods to probe this dynamic behavior using polylysine as a model polyelectrolyte. Through single-particle tracking techniques, the diffusivity of individual polyelectrolyte chains and overall system viscosity are determined for concentrated polylysine solutions. These studies show experimental scaling dependences much stronger than theoretical predictions for both neutral polymers and polyelectrolytes and draw into question whether power law based scaling theories are appropriate to describe concentrated charged systems. Similar dependences are observed in concentrated solutions prepared at a variety of pH and counterion conditions. Hindered system dynamics are attributed to contributions from monomeric friction and the large effective excluded volume of polyelectrolyte chains leading to glassy dynamics. These forces restrict the movement of polymers through the sample and their effects are seen over a wide range of concentrations. The framework of the Vrentas Duda free volume theory is used to compare polyelectrolyte and neutral systems. Supported by this theory, when the mass associated with the counterions is excluded from the total polymer mass diffusive scaling across environmental conditions collapses onto a common trendline. Overall, these results are applicable to behavior in crowded biological systems, such as intracellular environments where the mobility of proteins is strongly inhibited.

  PublisherOA PDFDOI

• Investigating the effects of the local environment on bottlebrush conformations using super-resolution microscopy

  Nanoscale · 2023-12-21 · 4 citations

  articleOpen accessSenior authorCorresponding

  that more closely follows theoretical predictions. For the more flexible chains in both systems, we reach the edge of our resolution limit and cannot visualize the entire contour of every chain. We bypass this limitation by discussing the aspect ratios of the features within the super-resolution images.

  PublisherOA PDFDOI

• Single-molecule Optical Microscopy Reveals New Polymer Insights at the Nanoscale

  Microscopy and Microanalysis · 2023-07-22

  article1st authorCorresponding

  Journal Article Single-molecule Optical Microscopy Reveals New Polymer Insights at the Nanoscale Get access Muzhou Wang Muzhou Wang Northwestern University, Evanston, IL, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 29, Issue Supplement_1, 1 August 2023, Page 93, https://doi.org/10.1093/micmic/ozad067.039 Published: 22 July 2023

  PublisherDOI

Recent grants

• CAREER: Visualizing single-chain conformation and dynamics of bottlebrush polymers in the bulk state

  NSF · $629k · 2020–2026

Frequent coauthors

• James M. Marr

  Grand Valley State University

  17 shared

• Bradley D. Olsen

  Massachusetts Institute of Technology

  16 shared

• Jeffrey W. Gilman

  National Institute of Standards and Technology

  15 shared

• Zhe Qiang

  University of Southern Mississippi

  14 shared

• Kenneth R. Shull

  Northwestern University

  14 shared

• Mingbo Wu

  12 shared

• J. Alexander Liddle

  11 shared

• Jeremy M. Beebe

  Dow Chemical (United States)

  11 shared

Labs

• Wang LabPI