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- Atomic force microscopy (4)
- Monolayers (2)
- Nanoparticles (2)
- AFM; V-theory (1)
- Adhesives (1)
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- Aspect ratio (1)
- Bending (1)
- Bending modulus (1)
- Colloidal nanoparticles (1)
- Colloidal probe (1)
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- DENA (1)
- Dimensionless numbers (1)
- Emulsion polymerization (1)
- Fracture strength (1)
- Indentation (1)
- Ion latexes (1)
- Membrane (1)
- Multilayers (1)
- N-alcohols (1)
- N-alkanes (1)
- Nanoparticle (1)
- Nanostructures (1)
- PEDOT fibers (1)
- Persistence length (1)
- Pseudopod-filament adhesive contacts (1)
- Pseudopods (1)
- Quaternary ammonium (1)
- Self-assembly (1)
- Semifluorinated polymer latexes (1)
Articles 1 - 9 of 9
Full-Text Articles in Physics
Mechanical Properties Of Self-Assembled Nanoparticle Membranes: Stretching And Bending, Yifan Wang, Pongsakorn Kanjanaboos, Sean P. Mcbride, Edward Barry, Xiao-Min Lin, Heinrich M. Jaeger
Mechanical Properties Of Self-Assembled Nanoparticle Membranes: Stretching And Bending, Yifan Wang, Pongsakorn Kanjanaboos, Sean P. Mcbride, Edward Barry, Xiao-Min Lin, Heinrich M. Jaeger
Dr. Sean P. McBride
Monolayers composed of colloidal nanoparticles, with thickness less than ten nanometers, have remarkable mechanical strength and can suspend over micron-sized holes to form free-standing membranes. We discuss experiments probing the tensile strength and bending stiffness of these self-assembled nanoparticle sheets. The fracture behavior of monolayers and multilayers is investigated by attaching them to elastomer substrates which are then stretched. For different applied strain the fracture patterns are imaged down to the scale of single particles. The resulting detailed information about the crack width distribution allows us to relate the measured overall tensile strength to the distribution of local bond strengths …
Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law
Viscosity Dependent Liquid Slip At Molecularly Smooth Hydrophobic Surfaces, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
Colloidal probe atomic force microscopy is used to study the slip behavior of 18 Newtonian liquids from two homologous series, the n-alkanes and n-alcohols, at molecularly smooth hydrophobic n-hexadecyltrichlorosilane coated surfaces. We find that the slip behavior is governed by the bulk viscosity η of the liquid, specifically, the slip length b∼ηx with x∼0.33. Additionally, the slip length was found to be shear rate independent, validating the use of Vinogradova slip theory in this work.
Improved In Situ Spring Constant Calibration For Colloidal Probe Atomic Force Microscopy, Sean P. Mcbride, Bruce M. Law
Improved In Situ Spring Constant Calibration For Colloidal Probe Atomic Force Microscopy, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
In colloidal probe atomic force microscopy (AFM) surface forces cannot be measured without an accurate determination of the cantilever spring constant. The effective spring constant k depends upon the cantilever geometry and therefore should be measured in situ; additionally, k may be coupled to other measurement parameters. For example, colloidal probe AFM is frequently used to measure the slip length b at solid/liquid boundaries by comparing the measured hydrodynamic force with Vinogradova slip theory (V-theory). However, in this measurement k and b are coupled, hence, b cannot be accurately determined without knowing k to high precision. In this paper, a …
Forces At Individual Pseudopod-Filament Adhesive Contacts, Govind Paneru, Prem S. Thapa, Sean P. Mcbride, David Moore-Nichols, Bruce M. Law, Bret N. Flanders
Forces At Individual Pseudopod-Filament Adhesive Contacts, Govind Paneru, Prem S. Thapa, Sean P. Mcbride, David Moore-Nichols, Bruce M. Law, Bret N. Flanders
Dr. Sean P. McBride
On-chip cellular force sensors are fabricated from cantilever poly(3,4-ethylene dioxythiophene) filaments that visibly deflect under forces exerted at individual pseudopod-filament adhesive contacts. The shape of the deflected filaments and their ∼3 nN/μm spring constants are predicted by cantilever rod theory. Pulling forces exerted by Dictyostelium discoideumcells at these contacts are observed to reach ∼20 nN without breaking the contact.
Influence Of Line Tension On Spherical Colloidal Particles At Liquid-Vapor Interfaces, Sean P. Mcbride, Bruce M. Law
Influence Of Line Tension On Spherical Colloidal Particles At Liquid-Vapor Interfaces, Sean P. Mcbride, Bruce M. Law
Dr. Sean P. McBride
Atomic force microscopy (AFM) imaging of isolated submicron dodecyltrichlorosilane coated silica spheres, immobilized at the liquid polystyrene- (PS-) air interface at the PS glass transition temperature, Tg , allows for determination of the contact angle θ versus particle radius R . At Tg , all θ versus R measurements are well described by the modified Young’s equation for a line tension τ=0.93 nN . The AFM measurements are also consistent with a minimum contact angle θmin and minimum radius Rmin , below which single isolated silica spheres cannot exist at the PS-air interface.
Hydrolysis Of P-Nitrophenyl Esters Promoted By Semi-Fluorinated Quaternary Ammonium Polymer Latexes And Films, Baljinder Kaur, Sean P. Mcbride, Warren T. Ford
Hydrolysis Of P-Nitrophenyl Esters Promoted By Semi-Fluorinated Quaternary Ammonium Polymer Latexes And Films, Baljinder Kaur, Sean P. Mcbride, Warren T. Ford
Dr. Sean P. McBride
Semifluorinated polymer latexes were prepared by emulsion polymerization of 2.5-25% of a fluoroalkyl methacrylate, 25% chloromethylstyrene, 1% styrylmethyl(trimethyl)ammonium chloride, and the remainder 2-ethylhexyl methacrylate under surfactant-free conditions. The chloromethylstyrene units were converted to quaternary ammonium ions with trimethylamine. In aqueous dispersions at particle concentrations of less than 1 mg mL-1 the quaternary ammonium ion latexes promoted hydrolyses of p-nitrophenyl hexanoate (PNPH) in pH 9.4 borate buffer and of diethyl p-nitrophenyl phosphate (Paraoxon) in 0.1 M NaOH at 30 oC with half-lives of less than 10 minutes. Thin 0.7-2 μm films of the latexes on glass promoted fast hydrolysis of Paraoxon …
Strong Resistance To Bending Observed For Nanoparticle Membranes, Yifan Wang, Jianhui Liao, Sean P. Mcbride, Efi Efrati, Xiao-Min Lin, Heinrich M. Jaeger
Strong Resistance To Bending Observed For Nanoparticle Membranes, Yifan Wang, Jianhui Liao, Sean P. Mcbride, Efi Efrati, Xiao-Min Lin, Heinrich M. Jaeger
Dr. Sean P. McBride
We demonstrate how gold nanoparticle monolayers can be curled up into hollow scrolls that make it possible to extract both bending and stretching moduli from indentation by atomic force microscopy. We find a bending modulus that is 2 orders of magnitude larger than predicted by standard continuum elasticity, an enhancement we associate with nonlocal microstructural constraints. This finding opens up new opportunities for independent control of resistance to bending and stretching at the nanoscale.
Fracture And Failure Of Nanoparticle Monolayers And Multilayers, Yifan Wang, Pongsakorn Kanjanaboos, Edward Barry Edward Barry, Sean P. Mcbride, Xiao-Min Lin, Heinrich M. Jaeger
Fracture And Failure Of Nanoparticle Monolayers And Multilayers, Yifan Wang, Pongsakorn Kanjanaboos, Edward Barry Edward Barry, Sean P. Mcbride, Xiao-Min Lin, Heinrich M. Jaeger
Dr. Sean P. McBride
We present an experimental investigation of fracture in self-assembled gold nanoparticle mono- and multilayers attached to elastomer substrates and subjected to tensile stress. Imaging the fracture patterns down to the scale of single particles provides detailed information about the crack width distribution and allows us to compare the scaling of the average crack spacing as a function of strain with predictions by shear-lag models. With increasing particle size, the fracture strength is found to increase while it decreases as the film thickness is built up layer by layer, indicating stress inhomogeneity in the thickness dimension.
Long Reach Cantilevers For Sub-Cellular Force Measurements, Govind Paneru, Prem S. Thapa, Sean P. Mcbride
Long Reach Cantilevers For Sub-Cellular Force Measurements, Govind Paneru, Prem S. Thapa, Sean P. Mcbride
Dr. Sean P. McBride
Maneuverable, high aspect ratio poly 3-4 ethylene dioxythiophene (PEDOT) fibers are fabricated for use as cellular force probes that can interface with individual pseudopod adhesive contact sites without forming unintentional secondary contacts to the cell. The straight fibers have lengths between 5 and 40 μm and spring constants in the 0.07-23.2 nN μm-1 range. The spring constants of these fibers were measured directly using an atomic force microscope (AFM). These AFM measurements corroborate determinations based on the transverse vibrational resonance frequencies of the fibers, which is a more convenient method. These fibers are employed to characterize the time dependent forces …