About

Maya Endoh is a Research Professor in the Department of Materials Science and Chemical Engineering at Stony Brook University. She specializes in researching polymer structures using various methods such as X-ray and neutron scattering, atomic force microscopy, scanning electron microscopy, and spectrofluorometry. Her research focuses on understanding the molecular scale structure of polymeric systems, investigating the crystalline structure and orientation in nano-scale confined areas, and exploring the adsorption mechanisms and adhesion dynamics of polymeric composites. Her work also extends to the biomedical field, particularly microbial activities at polymer surfaces. Dr. Endoh holds a Ph.D. in Polymer Physics from Kyoto University, Japan, earned in 2005, along with a Master of Engineering in Polymer Chemistry (1997) and a Bachelor of Engineering in Polymer Engineering (1995) from the same institution. Her career includes positions such as Senior Research Scientist in the Department of Chemistry at Stony Brook University from 2012 to 2014, and a Beamline Scientist at NSLS, BNL from 2012 to 2013. She has been a Research Professor at Stony Brook University since 2015. Her honors include the 2024 NY State Chancellor's Award for Excellence in Adjunct Teaching and a Research Postdoctoral Fellowship for Young Scientists from the Japan Society for the Promotion of Science (JSPS). Her research aims to provide fundamental insights into polymer materials, which are valued for their lightweight, resilience, corrosion resistance, color, transparency, and ease of processing, and to contribute to current and future technological advancements.

Research topics

• Materials science
• Physics
• Nanotechnology
• Composite material
• Chemistry
• Chemical physics
• Polymer science
• Optics
• Computational chemistry
• Crystallography
• Philosophy
• Condensed matter physics
• Chemical engineering
• Engineering
• Statistical physics
• Epistemology
• Physical chemistry

Selected publications

• How Topological Polymer Loops on the Nanoparticle Surface Control the Mechanical Properties of Nanocomposites

  Macromolecules · 2025-08-21 · 3 citations

  article

  Carbon black (CB) and silica (SiO2) filled elastomers are known to be the most successful polymer nanocomposites (PNCs) in industry, where “bound rubber (BR)” (i.e., polymer chains that are physically or chemically adsorbed on the nanofiller surface) plays a critical role in their reinforcement. Here, we report a molecular-scale mechanism underlying the “BR-induced reinforcement” by integrating neutron scattering experiments and molecular dynamics simulations. Simplified non-cross-linked SiO2-filled polybutadiene (PB) and CB-filled PB reveal the critical role of topological polymer loops in the BR for the enhanced mechanical performance. The average loop size on the SiO2 surface modified with a silane coupling agent is much smaller than that on the CB surface and the loops on the SiO2 surface are densely formed, preventing interdigitation with the matrix chains. On the other hand, the larger, uncrowded loops formed on the CB surface facilitate the interdigitation with the matrix polymer chains even near the filler surface. In this way, a strong connectivity is established between a matrix and a nanofiller, resulting in an adhesive filler–polymer interface. Our findings shed light on rich and complex physics and materials design problems in PNCs, where the topological polymer structure on the nanofiller surface directly controls the macroscopic mechanical properties.

  PublisherDOI

• Structural and Dynamical Insights into the Formation Process of a Cross-Linked Polymer Network in Acrylic Adhesives During Thermal Curing

  Macromolecules · 2025-07-24 · 3 citations

  articleCorresponding

  Many modern adhesives, sealants, and coatings rely on the controlled transition from a liquid to a solid state by forming a three-dimensional cross-linked polymer network, often referred to as curing. The curing process, which is initiated by the mixing of reactive components or an external trigger, defines the structure of a network and further controls the final mechanical properties of cured materials. However, the curing mechanism is not fully understood yet due to the lack of experimental tools capable of directly probing the structure and dynamics of a network over relevant time- and length scales. In this paper, we report the curing process of a commercial two-component methyl methacrylate (MMA) adhesive using in operando X-ray photon correlation spectroscopy (XPCS), a method that closely simulates the target manufacturing environment of the adhesive. The results are then integrated with those obtained by rheology, differential scanning calorimetry (DSC), and transmission electron microscopy to establish the structure–dynamics–process–property relationship. The XPCS results identify four distinct stages in the curing process after the mixing, extrusion, and deposition of the acrylic adhesive: (i) At a cure time (or “aging time”, tage) of less than 1 min, nanodomains of polymerized MMA are formed within a liquid monomeric MMA matrix. The average size is several nm and remains constant over tage, while the dynamics of the nanodomains are slowed down with tage due to an increase in the viscosity of the MMA matrix. (ii) After tage > 1 min, the size of the nanodomains increases with tage until the gel point (= 6.3 min after mixing as determined by rheology). The dynamics of the nanodomains also increase due to the heat generated by the exothermic reaction. (iii) At the gel point, the nanodomains begin to interconnect each other, resulting in a network structure with a characteristic length of about 100 nm. This characteristic network size does not change for the rest of the curing process up to tage = 500 min. The dynamics of the network structure, however, show a rapid slowing down with tage up to tage ≈ 12 min, corresponding to the onset of vitrification (as determined by rheology). (iv) At tage > 12 min, when the DSC and rheology data can no longer provide meaningful information, the XPCS data show a further slowing down of the network dynamics associated with vitrification. Our results provide rich and complex insights into the physics and material design of thermosets in commercially relevant processes, which are essential for future industrial applications.

  PublisherDOI

• Real-time tracking of curing process of an epoxy adhesive by X-ray photon correlation spectroscopy

  Frontiers in Soft Matter · 2024-04-09 · 5 citations

  articleOpen access

  Introduction: Cross-linkable polymers are in widespread use in a variety of industries because of their thermomechanical toughness, chemical resistance, and adhesive strength. But traditional methods to characterize these materials are insufficient for fully capturing the complex chemical and physical mechanisms of the crosslinking reaction. In this study, in situ X-ray photon correlation spectroscopy (XPCS) was used to investigate the crosslinking kinetics of a two-component epoxy resin adhesive. Materials and methods: With XPCS, we tracked the temporally resolved dynamics of silica filler particles, which served as probes of the internal dynamics of the thermoset network and allowed us to study the crosslinking process. The epoxy was cured isothermally at 40 °C and 80 °C to study the effects of curing temperature on the epoxy’s crosslinking reaction. XPCS results were compared to dielectric analysis (DEA) results, to demonstrate the similarities between a traditional technique and XPCS, and highlight the additional information gained with XPCS. Results and discussion: The epoxy resin was found to be highly sensitive to temperature. The epoxy samples exhibited different relaxation processes depending on isothermal cure temperature, indicating a complex relationship between applied temperature and the development of stress/relaxation conditions associated with formation of the thermoset network. Heating to the isothermal temperature setpoint at the start of curing promoted gelation, but the vitrification process was not completed during the isothermal curing stage. Instead, cooling the sample to room temperature facilitated the final vitrification process. This paper contextualizes this epoxy’s results within the broader field of thermoset study via XPCS, and advocates for XPCS as a fundamental technique for the study of complex polymers.

  PublisherOA PDFDOI

• Impact of Irreversible Adsorption on Molecular Ordering and Charge Transport in Poly(3-hexylthiophene) Thin Films on Solid Substrates

  ACS Applied Materials & Interfaces · 2024-10-05 · 2 citations

  article

  We investigate the irreversible adsorption of poly(3-hexylthiophene) (P3HT) polymer thin films on silicon dioxide/silicon (SiO2/Si) substrates during thermal annealing at a temperature below the melting temperature (Tm) but far above the glass transition temperature (Tg), i.e., Tg ≪ T = 170 °C < Tm, and its effect on their crystalline ordering and charge transport properties. It was found that short-time annealing enhances the molecular ordering of P3HT films, while prolonged thermal annealing gradually disrupts the crystalline structures and reduces the overall crystallinity of the film. Concurrently, thermal annealing at this temperature facilitates the slow irreversible adsorption of P3HT chains at the polymer-solid interface, resulting in the formation of a 1.7 Rg-thick (∼18 nm thick) adsorbed layer on SiO2/Si substrates that is fully amorphous and contains a large fraction of loosely adsorbed chains. We postulate that such irreversible adsorption is responsible for the reduced crystalline packing of P3HT at the polymer-solid interface at Tg ≪ T < Tm, which further disrupts the molecular ordering of the entire 46 nm thick P3HT film by a long-range perturbation effect. Electrical measurements using an organic field-effect transistor (OFET) device reveal that the enhanced charge carrier mobility of P3HT films correlates with an optimized annealing time at Tg ≪ T < Tm, which achieves a balance between maximizing molecular ordering and minimizing the impact of irreversible chain adsorption. These findings provide new insights into the underlying mechanism of thermal annealing in tailoring the structure and property of conjugated polymer thin films prepared on solid substrates.

  PublisherDOI

• Spatial-Temporal Dynamics at the Interface of 3D-Printed Photocurable Thermoset Resin Layers

  ACS Applied Engineering Materials · 2023-02-13 · 5 citations

  article

  Additive manufacturing (AM) is used to fabricate polymeric materials into complex three-dimensional (3D) structures. As the 3D structure is built by sequential layer-by-layer deposition of filaments dispensed from a translating nozzle (in the case of extrusion-based printing), defects often form at the filament-filament interface. The out-of-equilibrium structural development that occurs during the printing process is difficult to directly measure by quantitative means, limiting our understanding of the physical mechanisms at play. Here, we utilize in operando X-ray photon correlation spectroscopy (XPCS) measurements with microbeam capability to probe the real-time structural evolution at the filament-filament interface during extrusion 3D printing. We investigate the solidification of a dual-cure (UV/thermal) acrylate/epoxy resin during multilayer 3D printing as a rational model by tracking the nanoscale motion of filler particles embedded in the resin. The spatially and temporally resolved dynamics (on length scales from several nm to a few hundreds of nm and time scales of 10–3 < t < 103 seconds) are measured during the deposition of a single filament as well as during the deposition of a second layer on top of the cured underlayer. The addition of a second layer introduces structural perturbations at the interface and results in accelerated interfacial dynamics compared to those of the cured underlayer. However, as time proceeds, the local dynamical heterogeneity disappears, and the evolution of the dynamics progresses uniformly within the entire interfacial region. The homogeneity across the interface results from the formation of an interpenetrated epoxy network that spans across the first and second filaments. This homogeneous interface is responsible for the isotropic tensile properties of a 3D-printed sample that are independent of print direction and nearly the same as the bulk (non-3D-printed) sample. The XPCS microrheology approach provides insight into the dynamics-process-property relationship at the printed filament interfaces.

  PublisherDOI

• Self‐assembling Process of Block Copolymers at the Solid–Polymer Melt Interface: Fundamentals and Applications

  2023-04-21

  otherOpen accessSenior author

  We present new pieces of experimental findings on the self-assembling process of block copolymers (BCPs) on nonneutral solid substrate surfaces. The key to this event is the concurrent physisorption of preferred blocks and nonpreferred blocks on the surface. We uncover two different kinds of BCP chains adsorbed on the solid surface using an optimized solvent-rinsing approach. One is the inner strongly adsorbed BCP chains in which all constituent blocks lie flat and form a two-dimensional network-like structure regardless of their chain architectures, microdomain structures, and interfacial energetics. The other is outer “loosely adsorbed BCP chains,” which form a poorly packed perpendicularly oriented microdomain structure on the substrate surface. The loosely adsorbed BCP chains act as seeds and promote poor perpendicularly oriented microdomains in a single BCP thin film. Interestingly, this substrate-field effect propagates into the film interior via chain entanglements between neighboring unadsorbed chains in the matrix and the loosely adsorbed chains up to a distance of ∼70 nm from the substrate surface. Finally, a new surface modification approach prevents the development of the undesirable substrate-field effect. We demonstrate that homopolymer chains composed of one of the constituent blocks adsorbed on the solid substrates act as a “structurally neutral” surface coating against both blocks.

  PublisherOA PDFDOI

• Structure-Based Design of Dual Bactericidal and Bacteria-Releasing Nanosurfaces

  ACS Applied Materials & Interfaces · 2023-01-05 · 17 citations

  articleOpen accessCorresponding

  Here, we report synergistic nanostructured surfaces combining bactericidal and bacteria-releasing properties. A polystyrene-block-poly(methyl methacrylate) (PS-block-PMMA) diblock copolymer is used to fabricate vertically oriented cylindrical PS structures (“PS nanopillars”) on silicon substrates. The results demonstrate that the PS nanopillars (with a height of about 10 nm, size of about 50 nm, and spacing of about 70 nm) exhibit highly effective bactericidal and bacteria-releasing properties (“dual properties”) against Escherichia coli for at least 36 h of immersion in an E. coli solution. Interestingly, the PS nanopillars coated with a thin layer (≈3 nm thick) of titanium oxide (TiO2) (“TiO2 nanopillars”) show much improved dual properties against E. coli (a Gram-negative bacterium) compared to the PS nanopillars. Moreover, the dual properties emerge against Listeria monocytogenes (a Gram-positive bacterium). To understand the mechanisms underlying the multifaceted property of the nanopillars, coarse-grained molecular dynamics (MD) simulations of a lipid bilayer (as a simplified model for E. coli) in contact with a substrate containing hexagonally packed hydrophilic nanopillars were performed. The MD results demonstrate that when the bacterium–substrate interaction is strong, the lipid heads adsorb onto the nanopillar surfaces, conforming the shape of a lipid bilayer to the structure/curvature of nanopillars and generating high stress concentrations within the membrane (i.e., the driving force for rupture) at the edge of the nanopillars. Membrane rupture begins with the formation of pores between nanopillars (i.e., bactericidal activity) and ultimately leads to the membrane withdrawal from the nanopillar surface (i.e., bacteria-releasing activity). In the case of Gram-positive bacteria, the adhesion area to the pillar surface is limited due to the inherent stiffness of the bacteria, creating higher stress concentrations within a bacterial cell wall. The present study provides insight into the mechanism underlying the “adhesion-mediated” multifaceted property of nanosurfaces, which is crucial for the development of next-generation antibacterial surface coatings for relevant medical applications.

  PublisherOA PDFDOI

• Local conformations and heterogeneities in structures and dynamics of isotactic polypropylene adsorbed onto carbon fiber

  Polymer · 2022-11-30 · 5 citations

  articleOpen accessCorresponding
  PublisherOA PDFDOI

• Collective Nanoparticle Dynamics Associated with Bridging Network Formation in Model Polymer Nanocomposites

  ACS Nano · 2021 · 49 citations

  • Materials science
  • Chemical physics
  • Nanotechnology

  polymer-mediated bridges at high NP loadings above the percolation threshold. The NP collective relaxation times are up to 3 orders of magnitude longer than the self-diffusion limit of isolated NPs and display a rich dependence with observation wavevector and NP loading. A mode-coupling theory dynamical analysis that incorporates the static polymer-mediated bridging structure and collective motions of NPs is performed. It captures well both the observed scattering wavevector and NP loading dependences of the collective NP dynamics in the unentangled polymer matrix, with modest quantitative deviations emerging for the entangled PNC samples. Additionally, we identify an unusual and weak temperature dependence of collective NP dynamics, in qualitative contrast with the mechanical response. Hence, the present study has revealed key aspects of the collective motions of NPs connected by polymer bridges in contact with a viscous adsorbing polymer medium and identifies some outstanding remaining challenges for the theoretical understanding of these complex soft materials.

  PublisherOA PDFDOI

• Antimicrobial Surface Modification via Self-Assembled Nanopatterns of Block Copolymer Films

  Bulletin of the American Physical Society · 2021-03-19

  article
  Publisher

Frequent coauthors

• Tadanori Koga

  Division of Chemistry

  118 shared

• Daniel Salatto

  Stony Brook University

  56 shared

• Naisheng Jiang

  Liaoning Academy of Materials

  55 shared

• Zhixing Huang

  Stony Brook University

  50 shared

• Benjamin M. Yavitt

  University of Cincinnati

  48 shared

• Lutz Wiegart

  Brookhaven National Laboratory

  43 shared

• Stanislas Petrash

  39 shared

• Yuto T. Koga

  Osaka Institute of Technology

  39 shared

Labs

• Materials Science and Chemical Engineering - Maya Endoh LabPI

Education

• Other, Polymer Engineering

  Kyoto University

  1995

• Other, Polymer Chemistry

  Kyoto University

  1997

• Ph.D., Polymer Physics

  Kyoto University

  2005

Awards & honors

• 2024 NY State Chancellor's Award for Excellence in Adjunct T…
• Recipient of Research Postdoctoral Fellowship for Young Scie…