Search NASA⌕ Search
Home/Archive/DOE OSTI

DOE OSTI · 3015416

Microscopic Dynamics Controls Coupling and Cluster Formation in Brush Particle Solids

Li, Qiqi [Max Planck Institute for Polymer Research, Mainz (Germany)] (ORCID:0009000482299727)·Tarnsangpradit, Jirameth [Carnegie Mellon Univ., Pittsburgh, PA (United States)]·Biniek-Antosiak, Katarzyna [Adam Mickiewicz Univ., Poznan (Poland)]·Cang, Yu [Tongji Univ. (China)]·Yan, Jiajun [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000332863268)·Zhang, Jianan [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000331959882)·Matyjaszewski, Krzysztof [Carnegie Mellon Univ., Pittsburgh, PA (United States); Lodz Univ. of Technology (Poland)] (ORCID:0000000319603402)·Graczykowski, Bartlomiej [Adam Mickiewicz Univ., Poznan (Poland)]·Bockstaller, Michael R. [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000190469539)·Fytas, George [Max Planck Institute for Polymer Research, Mainz (Germany); Adam Mickiewicz Univ., Poznan (Poland); Inst. of Electronic Structure and Laser (Greece)] (ORCID:0000000325046374)
View original source ↗Read source document ↗Export metadata ↓

Abstract

Thermodynamics-based models predict the structure of polymer-grafted nanoparticles (PGNs) as well as their assembly behavior based on geometric parameters such as particle size, degree of polymerization, and density of grafted chains. The role of microscopic polymer dynamics, such as the mobility of repeat units in the melt state, in the evolution of the structure and properties remains unknown. Brillouin light spectroscopy (BLS), due to its capability to concurrently discern the local and global elastic properties of PGN assemblies, enables the probing of microscopic processes, such as brush interdigitation, sensitive to the annealing of the assembly. For poly(methyl methacrylate) (PMMA)-grafted silica (SiO 2 ) PGNs in the dry powder state and annealed above the glass transition temperature, BLS revealed fully reversible local elasticity, indicative of limited interdigitation between adjacent PGNs. This contrasts with polystyrene (PS)−SiO 2 analogs that displayed ready (and irreversible) fusion of brush layers during annealing. The retardation of brush interdigitation in PMMA-grafted systems is surprising, given the similar thermomechanical properties of both polymers, and is rationalized as the consequence of higher friction between PMMA repeats compared to PS. Microscopic dynamics thus has a profound impact on the kinetic path of structure (and property) evolution and thus should be considered during the processing of PGNs into functional hybrid materials.

Explore related subjects

chemical structurenanoparticlesorganic compoundsoscillationpolymers

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Li, Qiqi [Max Planck Institute for Polymer Research, Mainz (Germany)] (ORCID:0009000482299727), Tarnsangpradit, Jirameth [Carnegie Mellon Univ., Pittsburgh, PA (United States)], Biniek-Antosiak, Katarzyna [Adam Mickiewicz Univ., Poznan (Poland)], Cang, Yu [Tongji Univ. (China)], Yan, Jiajun [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000332863268), Zhang, Jianan [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000331959882), Matyjaszewski, Krzysztof [Carnegie Mellon Univ., Pittsburgh, PA (United States); Lodz Univ. of Technology (Poland)] (ORCID:0000000319603402), Graczykowski, Bartlomiej [Adam Mickiewicz Univ., Poznan (Poland)], Bockstaller, Michael R. [Carnegie Mellon Univ., Pittsburgh, PA (United States)] (ORCID:0000000190469539), Fytas, George [Max Planck Institute for Polymer Research, Mainz (Germany); Adam Mickiewicz Univ., Poznan (Poland); Inst. of Electronic Structure and Laser (Greece)] (ORCID:0000000325046374). 2026-01-08. Microscopic Dynamics Controls Coupling and Cluster Formation in Brush Particle Solids. https://doi.org/10.1021/acs.macromol.5c02236

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

DOE OSTI2026

2D in-Plane Ordered MXene Nanosheets Derived from (Mo 2/3 Er 1/3 ) 2 AlC Rare-Earth i-MAX for Energy Storage Applications

MXenes have become one of the most versatile families of two-dimensional (2D) materials due to their high conductivity, hydrophilicity, and remarkable electrochemical performance. This has stimulated intense efforts to design and synthesize MXenes, including structurally unique in-plane ordered 2D MXenes called i-MXenes. Here, we have synthesized the quaternary rare earth (RE)-based i-MAX phase (Mo 2/3 Er 1/3 ) 2 AlC using an arc melting method, and the corresponding 2D i-MXene was then obtained through a LiF/HCl soft etching process. Literature studies have shown that Al and the RE element are etched out during the etching process, leading to the formation of pure vacancy-ordered Mo1.33C 2D i-MXene. However, our investigation reveals that upon exposure to a fluorine solution, the i-MAX phase forms RE fluoride impurities, which are challenging to remove through HCl−DI water washing and persist in the final product, resulting in impure Mo 1.33 C@Er i-MXene. These results were confirmed by various characterizations such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning transmission electron microscopy. Although the Mo 1.33 C@Er electrode showed a 24-fold increase in specific capacitance compared to its parent i-MAX phase, it still exhibited a high charge-transfer resistance arising from the insulating nature of RE fluoride byproducts, which adversely influence the overall capacitance behavior of the synthesized 2D Mo 1.33 C@Er i-MXenes. This study contributes to identifying pathways for the preparation of pure 2D i-MXenes from RE-based i-MAX phases and developing improved synthesis methods. With additional process optimization, the 2D i-MXene holds a strong potential for electrochemical energy storage applications. Additionally, the electronic structures of Mo 1.33 C were theoretically studied using first-principles density functional theory calculations, which revealed that pristine Mo 1.33 C is metallic, and this metallic nature is preserved even with −O, −F, and mixed functionalization.

chemical structure↗
DOE OSTI2025

Rare Earth Element-Induced Condensation of the Block V of the Repeats-in-Toxin Domain from CyaA from Bordetella pertussis for Separations

Rare earth elements (REEs) are critical for the development of a range of new technologies. However, the current industrial separation processes of these metals from natural sources, recycled materials, and industrial effluents involve the large consumption of organic solvents, resulting in a sizable environmental footprint. We aim to exploit the high affinity of the block V peptide of the repeats-in-toxin (RTX) domain of the adenylate cyclase protein from Bordetella pertussis for the separation of REEs. This peptide selectively binds with lanthanide (Ln) cations and can undergo Ln-induced phase separation, which can be used in bioseparation processes. Here, we evaluated the self-assembling structures of complexes of the RTX domain peptide folded in the presence of Ln 3+ cations. Size distribution and surface potential measurements of complexes were taken to understand the Ln-induced changes in the complexed peptide. Transmission electron microscopy imaging was used to explore the structures of complexes, while anomalous small-angle X-ray scattering measurements were used to determine the distribution of Ln 3+ ions within the protein-based macrostructures. In the presence of excess Ln 3+ , we observed the formation of coral-like cylindrical structures comprised of Ln 3+ -RTX complexes, with approximately eight trivalent metals per peptide within the nanosized assemblies. These findings provide new insights into the structural organization of assembled RTX domains and their ability to coordinate with REEs, forming nanosized, metal-rich structures that naturally condense, providing a proof-of-concept for protein-based separation processes of these critical materials.

chemical structure↗
DOE OSTI2025

Higher Dimensionality in the Mg–Co–B System: Synthesis and Structure of Incommensurate Composite Mg 1+ε Co 4 B 4

Guided by high-temperature in situ X-ray diffraction, the discovery and synthesis of Mg 1+ε Co 4 B 4 (ε ≈ 0.272) using a MgH 2 hydride precursor is reported, along with a detailed crystal structure description and measurement of magnetic properties. The mismatch in lattice periodicities between Mg and Co–B substructures places Mg 1+ε Co 4 B 4 in the family of incommensurate composite crystals and prompted structural refinement in a (3 + 1)-dimensional model. The structure of Mg 1+ε Co 4 B 4 (P4 2 /ncm(00γ)s00s, a = 6.75847(7) Å, c = 3.94007(8) Å, q = (0, 0, 1.2721(3))) was refined from neutron powder diffraction and high-resolution powder X-ray diffraction data and confirmed by scanning transmission electron microscopy and electron diffraction. Mg 1+ε Co 4 B 4 is isostructural to Nd 1+ε Fe 4 B 4 and several related ternary borides with 0.07 ≤ ε ≤ 0.17, with Mg occupying the rare-earth site. Satellite reflections in the electron diffraction patterns hinted at positional modulation of the transition metal–boron substructure by Mg atoms, but this could not be refined from the neutron or X-ray diffraction data. Low-temperature magnetic measurements show no indications of long-range magnetic ordering or superconductivity down to 5 K. DFT calculations confirmed the absence of a magnetically ordered ground state and the stability of a 5:4 supercell (ε = 0.25) relative to the fully commensurate structure. Neutron diffraction and synthesis from elemental Mg demonstrated that Mg 1+ε Co 4 B 4 is not a hydrogen-stabilized phase. Mg 1+ε Co 4 B 4 represents the second compound reported in the Mg–Co–B system and the first superspace symmetry model of a Nd 1+ε Fe 4 B 4 -type incommensurate composite compound refined from powder diffraction data.

chemical structure↗