A5081394467- Force Microscopy Techniques and Applications
- Mechanical and Optical Resonators
- Supramolecular Chemistry and Complexes
- Carbon Nanotubes in Composites
- Molecular Junctions and Nanostructures
- Polymer composites and self-healing
- Supramolecular Self-Assembly in Materials
- Cellular Mechanics and Interactions
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Polymer Surface Interaction Studies
- Crystallography and molecular interactions
- Advanced Sensor and Energy Harvesting Materials
- Photochromic and Fluorescence Chemistry
- Hydrogels: synthesis, properties, applications
- Wireless Communication Networks Research
- Polymer crystallization and properties
- Synthetic Organic Chemistry Methods
- Advanced Polymer Synthesis and Characterization
- Porphyrin and Phthalocyanine Chemistry
- Advanced Chemical Physics Studies
- biodegradable polymer synthesis and properties
- Spectroscopy and Quantum Chemical Studies
- Luminescence and Fluorescent Materials
- Polymer Nanocomposites and Properties
Duke University
2016-2025
Center for Child and Family Health
2008-2024
North Bristol NHS Trust
2023
Southmead Hospital
2023
University Hospitals Bristol NHS Foundation Trust
2022
University Hospitals Bristol and Weston NHS Foundation Trust
2022
Massachusetts Institute of Technology
2000-2022
State Key Laboratory of Polymer Physics and Chemistry
2022
Changchun Institute of Applied Chemistry
2022
Hokkaido University
2021
Specific metal-ligand coordination between bis-Pd(II) and Pt(II) organometallic cross-linkers poly(4-vinylpyridine) in DMSO defines a three-dimensional associative polymer network. Frequency-dependent dynamic mechanical moduli of series four different bulk materials, measured across several decades oscillatory strain rates, are found to be quantitatively related through the pyridine exchange rates on model Pd(II) complexes. Importantly, mechanism ligand networks is same solvent-assisted...
Covalent mechanochemistry within bulk polymers typically occurs with irreversible deformation of the parent material. Here we show that embedding mechanophores into an elastomeric poly(dimethylsiloxane) (PDMS) network allows for covalent bond activation under macroscopically reversible deformations. Using colorimetric mechanophore spiropyran, can be repeated over multiple cycles tensile elongation full shape recovery. Further, localized compression used to pattern strain-induced chemistry....
Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes various optoelectronic devices. One important application of AgNW is the touch screens. However, performances screens still limited by large surface roughness and low electrical optical conductivity ratio random network electrodes. In addition, although perception writing force on screen enables a variety different functions, current technology relies complicated capacitive...
Forced Open Traditionally, the study of reaction chemistry has relied on random encounters between molecules to initiate proceedings. Heating and stirring increase power frequency such but provide little finer control. Very recently, chemists have learned how reactions more directly by embedding precursors in backbone a polymer large enough manipulate with shear forces. Lenhardt et al. (p. 1057 ) applied this technique cyclopropyl ring-opening reaction. When strained triangular carbon rings...
Current activity in, and future prospects for, the incorporation of mechanochemically active functional groups ("mechanophores") into polymers is reviewed. This area research treated in context two categories. The first category development new chemistry service material science, through design synthesis mechanophores to provide stress-sensing and/or stress-responsive elements materials. second reverse—the architectures that efficiently transmit macroscopic forces targeted molecules order...
Longer and stronger; stiff but not brittle Hydrogels are highly water-swollen, cross-linked polymers. Although they can be deformed, tend to weak, methods strengthen or toughen them reduce stretchability. Two papers now report strategies create tough deformable hydrogels (see the Perspective by Bosnjak Silberstein). Wang et al . introduced a toughening mechanism storing releasable extra chain length in part of double-network hydrogel. A high applied force triggered opening cycling strands...
Having a compact yet robust structurally based identifier or representation system is key enabling factor for efficient sharing and dissemination of research results within the chemistry community, such systems lay down essential foundations future informatics data-driven research. While substantial advances have been made small molecules, polymer community has struggled in coming up with an system. This because, unlike other disciplines chemistry, basic premise that each distinct chemical...
The mechanically accelerated ring-opening reaction of spiropyran to a colored merocyanine provides useful method by which image the molecular scale stress/strain distribution within polymer, but magnitude forces necessary for activation has yet be quantified. Here, we report single molecule force spectroscopy studies two isomers. Ring opening on time tens milliseconds is found require ∼240 pN, well below that previously characterized covalent mechanophores. lower threshold combination low...
Biological tissues are multiresponsive and functional, similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic have applications force-responsive colorimetric sensors robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a nanoparticle-in-micropore (NP-MP) architecture porous polymers, which enhances the mechanosensitivity stretchability of...
The mechanical properties of covalent polymer networks often arise from the permanent end-linking or cross-linking strands, and molecular linkers that break more easily would likely produce materials require less energy to tear. We report cyclobutane-based mechanophore cross-linkers through force-triggered cycloreversion lead are up nine times as tough conventional analogs. response is attributed a combination long, strong primary strands cross-linker scission forces approximately fivefold...
The spiropyran mechanophore (SP) is employed as a reporter of molecular tension in wide range polymer matrices, but the influence surrounding environment on force-coupled kinetics its ring opening has not been quantified. Here, we report single-molecule force spectroscopy studies SP five solvents that span normalized Reichardt solvent polarity factors (ETN) 0.1–0.59. Individual multimechanophore polymers were activated under increasing at constant 300 nm s–1 displacement an atomic...
Nucleophilic displacement reactions (the SN2 reaction) of ions in the gas phase are a prototypical reaction system that allows study dynamics, mechanisms, and structure-energy relations. This article reviews aspects kinetics (especially applicability statistical rate theory), relation structure reactivity, effects small numbers solvent molecules on compares behavior ionic with solution.
Louis Kahn, der Architekt des Salk Institute in La Jolla, sagte einmal:1 „Ein ganz gewöhnlicher, ordinärer Backstein möchte mehr sein als er ist“. Man stelle sich vor, das träfe auch auf Moleküle zu. Wir wissen, dass sie aggregieren können und es tun; bilden komplexe Strukturen erhalten dabei neue Eigenschaften – Funktionen, die man bei Untersuchung einzelnen Komponenten nicht sieht. Dieser Aufsatz beschäftigt mit Molekülaggregaten einer bestimmten Art, solchen, andere oder weniger...
A new folder: The electropositive CH groups of diaryl triazoles interact favourably with chloride, leading to anion-induced helical folding in aryl triazole oligomers. Triazoles thus provide an alternative conventional protic hydrogen bonds and coordination complexes as functional components anion receptors. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z800548_s.pdf or from author. Please note: publisher not responsible...
Hold on tight: The dynamics, rather than thermodynamics, of reversible cross-links are the primary determinants bulk viscosities in a family supramolecular networks. This result comes from study which series structurally similar pincer complexes (see picture, OTf=CF3SO3−) that have different ligand-exchange dynamics is used to cross-link poly(4-vinylpyridine). Supporting information for this article available WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z500026_s.pdf or author....
When gem-dichlorocyclopropane (gDCC) copolymers derived from polybutadiene are subjected to ultrasonication, the gDCCs undergo ring opening form 2,3-dichloroalkenes. The reactivity is not observed in low-molecular-weight (6.5 kDa) or side-chain gDCCs, consistent with mechanically induced due elongational strain of polymers sonication flow fields. openings occur several hundred times more frequently than polymer chain scission, and cis-coupled slightly likely react their trans isomers....