Dalia G. Yablon

• PhD
• Founder at SurfaceChar

As microscopists, we often hope – and intuit – that the microstructure we measure correlates somehow to bulk properties, but this correlation is difficult to quantify. Machine learning and specifically, deep learning, is a powerful tool to establish the presence (or absence) of such correlations with its ability to flesh out relationships and trend...

AFM phase images were collected on impact copolymer samples that differ in bulk mechanical properties and microstructure. A deep learning model based on a convolutional neural net (CNN) successfully classified some combinations of ICP’s based on microstructure. A separate regression-based CNN correlated the AFM phase images with various bulk mechan...

Measuring Viscoelastic Master Curves at the Nanoscale in Polymer Composites - Bede Pittenger, Sergey Osechinskiy, Thomas Mueller, Dalia Yablon

This overview is meant to help newer microscopists decide on an appropriate high-resolution method for nanoscale and microscale materials characterization. The operating principles, capabilities, and resolution of scanning electron microscopy (SEM) and atomic force microscopy (AFM), as well as the needs for sample preparation and the constraints im...

The development of heterogeneous materials like polymer composites, blends, and multilayers are of considerable importance in the chemicals industry. Bulk viscoelastic measurements are routine in establishing structure-property relationship for these materials. However, materials R&D often produces composites that contain nano-sized portions that d...

We introduce nanoscale dynamic mechanical analysis (DMA) based on atomic force microscopy (AFM), a new mode for quantitative viscoelastic analysis of heterogeneous polymer materials at the nanoscale (AFM-nDMA). AFM-nDMA takes advantage of the exquisite force sensitivity, small contact radius, and nanoscale indentation depth of the AFM to provide dy...

The structure and mechanical properties of sub-micron features in materials are of particular interest due to their influence on macroscopic material performance and function. Atomic force microscopy has the high resolution and force control to directly probe the mechanical properties of a wide range of these materials. This application note discus...

CoreAFM: Research-Grade AFM Platform with Application Modularity - Volume 25 Issue 6 - Christian Bippes, Patrick Frederix, Paul Werten, Dalia Yablon

Quantitatively characterizing nanomechanical properties has always been a holy grail for atomic force microscopy. This application note discusses some of the industry's previous attempts at quantitative nanomechanical measurement, and introduces a method of performing contact resonance that overcomes many of the previous hurdles of the technique. I...

Scanning probe microscopy (SPM) offers many advantages in materials characterization including a resolution range from over 100 microns down to the nanoscale and beyond. In addition to its superior resolution, SPM images samples under real-world conditions such as liquid or ambient environments resulting in a very powerful and flexible tool. Now im...

A novel instrumentation approach to nanoindentation is described that exhibits improved resolution and depth sensing. The approach is based on a multi-probe scanning probe microscopy (SPM) tool that utilizes tuning-fork based probes for both indentation and depth sensing. Unlike nanoindentation experiments performed with conventional AFM systems us...

Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converter...

Zinc dialkyldithiophosphates (ZDDPs) are widely used additives in automotive lubricants which form crucial antiwear tribofilms at sliding interfaces. The mechanisms governing the tribofilm growth are not well-understood, limiting the development of replacements with better performance and catalytic converter compatibility. Using atomic force micros...

Atomic force microscopy (AFM) quantitatively maps viscoelastic parameters of polymers on the nanoscale by several methods. The loss tangent, the ratio between dissipated and stored energy, was measured on a blend of thermoplastic polymer materials by a dynamic contact method, contact resonance, and by a recently developed loss tangent measurement b...

Mechanical oscillators employ the use of resonance parameters, frequency and the quality factor Q, for the measurement of corrosion or deposition. The ability of a mechanical oscillator to measure small amounts of metal loss or deposition is not only dependent upon the mechanical design but is limited by the precision in determining the resonance f...

Atomic force microscopy (AFM) is a family of nanoscale characterization techniques that has exploded onto the overall characterization and nanotechnology field as its versatility and high resolution continue to feed a dizzying variety of disciplines from biology to physics and chemistry to engineering. This introductory chapter provides an overview...

Describes new state-of-the-science tools and their contribution to industrial R&D. With contributions from leading international experts in the field, this book explains how scanning probe microscopy is used in industry, resulting in improved product formulation, enhanced processes, better quality control and assurance, and new business opportuniti...

Bimodal Atomic Force Microscopy (AFM) is a recently developed dynamic AFM technique. Recent work [1] has shown the existence of different regimes of operation in Bimodal AFM depending on the operating conditions. The current work focuses on the effects of different operating parameters while imaging an impact copolymer blend of polypropylene (PP) a...

Scanning electron microscopy (SEM) and ion beam milling techniques are mature nanoscale measurement technologies, whereas atomic force microscopy (AFM) is a developing technology generating intense interest in the scientific community for basic research and development. These techniques have generally existed in separate worlds. This article discus...

In this chapter, the authors discuss their present understanding regarding tapping phase contrast mechanism in polymers and the enhancements of tapping phase, force modulation, and pulsed force mode atomic force microscopy (AFM). They discuss the recent innovations, developments, and applications of several AFM methods on polymers, including force?...

This chapter discusses the artifacts and challenges associated with phase imaging. Phase can play a critical diagnostic role in controlling topographic imaging. It is well established in the scientific literature that an oscillating atomic force microscopy (AFM) tip interacting with a sample surface can be bistable. Artifacts induced by bistability...

Bimodal atomic force microscopy (AFM) is a recently developed technique of dynamic AFM where a higher eigenmode of the cantilever is simultaneously excited along with the fundamental eigenmode. The effects of different operating parameters while imaging an impact copolymer blend of polypropylene (PP) and ethylene-propylene (E-P) rubber in bimodal m...

One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material p...

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The storage modulus and loss modulus of blends of polypropylene/polystyrene and polyethylene/polystyrene have been mapped quantitatively with contact resonance atomic force microscopy. Contact resonance spectra were collected in Dual AC Resonance Tracking (DART) mode, in which the phase and amplitude are monitored at two discrete frequencies, resul...

The storage modulus (E′) and loss modulus (E″) of polyolefin blends have been mapped on the nanoscale with contact resonance atomic force microscopy (CR-FM), a dynamic contact mode of atomic force microscopy (AFM). Modulus values measured on various components within a blend of polyethylene, polypropylene, and polystyrene compared favorably with ex...

An expression for loss tangent measurement of a surface in amplitude modulation atomic force microscopy is derived using only the cantilever phase and the normalized cantilever amplitude. This provides a direct measurement of substrate compositional information that only requires tuning of the cantilever resonance to provide quantitative informatio...

We demonstrate the accurate nanoscale mapping of near-surface loss and storage moduli on a polystyrene-polypropylene blend with contact resonance force microscopy (CR-FM). These viscoelastic properties are extracted from spatially resolved maps of the contact resonance frequency and quality factor of the AFM cantilever. We consider two methods of d...

Nanoscale characterization of a number of different properties of surfaces and interfaces includes topography, electrostatic and magnetic fields, material properties, tribological properties, piezoresponse, and surface potential. All these properties can be studied in flexible environments with minimal sample preparation and in ambient and liquid e...

We report on a technique that simultaneously quantifies the contact stiffness and dissipation of an AFM cantilever in contact with a surface, which can ultimately be used for quantitative nanomechanical characterization of surfaces. The method is based on measuring the contact resonance frequency using dual AC resonance tracking (DART), where the a...

Atomic force microscopy (AFM) is a powerful technique with broad applications to characterization of surfaces, primarily used for nanoscale quantitative topographic measurements and qualitatively distinguishing between material properties on the surface. We describe recent advances in our capabilities to quantify nanoscale mechanical measurements o...

The presence of toluene and xylene is sensed via surface stress induced deflection of microcantilevers functionalized with self-assembled monolayers (SAMs). Monolayers are formed on gold coated cantilevers using alkanethiols, mercaptanols, and aromatic thiols. These coatings create a variety of chemical functionalities at the cantilever surface, wh...

Adsorption and desorption kinetics of thin film formation on metal surfaces has been directly monitored in real-time by optically measuring the deflection of activated atomic force microscope microcantilevers. Microcantilever deflection is caused by stress generated during the formation of an adsorbate layer on one side of the microcantilever. In t...

Sensing applications in the petroleum industry pose unique challenges due to high viscosity and high refractive index of hydrocarbon fluids, which render many fluid-based techniques impractical. Real-time observation of adsorption, desorption, and competitive adsorption processes of long chain functionalized hydrocarbons onto activated cantilevers...

This experimental–theoretical paper presents a reconstruction algorithm that enables the measurement of viscosity from the experimental resonance spectrum of a microcantilever immersed in the fluid under study. An analytical, closed-form solution of the equation of motion, including damping and internal friction, for the microcantilever frequency r...

Rational formulation of lubricants requires an understanding of additive interactions that impact anti-wear film qualities such as thickness, topography and friction. In an effort to understand the complex additive interactions responsible for formation of anti-wear and friction-reducing films, atomic force microscopy (AFM) in conjunction with Rama...

A new and direct approach to verify surface heterogeneity as the microscopic origin of contact-angle hysteresis is demonstrated. IR-visible sum-frequency-generation spectroscopy (SFG) was used to selectively probe the molecules at the interface of an alkyl-side-chain polymer [poly(vinyl n-octadecyl carbamate-co-vinyl acetate)] with water. The spect...

We demonstrate a new and direct approach to verify surface heterogeneity as the microscopic origin of contact-angle hysteresis. IR-Visible sum-frequency-generation spectroscopy was used to selectively probe the molecules at the interface of an alkyl side-chain polymer with water. The spectra indicate that in contact with water, the polymer surface...

The absorbance and fluorescence spectra of Nile Red (NR) were examined in a series of nonpolar solvents comprising linear alkanes and a range of poly alpha olefins (PAO). These solvents span a 1000-fold range in viscosity and possess very similar dielectric constants and refractive index properties. A high-energy double peak with vibronic structure...

The molecular structure of polymer surfaces in aqueous environments is central to several important chemical, physical, and biological areas of interest such as polymeric coatings and adhesives, membrane formation, micellar self-assemblies, biocompatibility of polymeric implants, and even protein folding. In this work, we have used IR visible sum-f...

This paper presents a new, general reconstruction algorithm that enables modeling of the experimental resonance spectrum of a prismatic microcantilever in a viscous fluid. A closed-form solution is obtained for the microcantilever frequency response from the equation of motion with fluid damping and internal friction terms, which allows direct calc...

Scanning tunneling microscopy (STM) is used to investigate the adsorption on graphite of two-solute mixtures from phenyloctane solvent at room temperature. The first mixture is composed of the co-solutes hexadecanoic acid (HA) and 2-Br-hexadecanoic acid (2BrHA), while the second mixture is composed of co-solutes tetracosanoic acid (TA) and octadeca...

Self-assembled monolayers (SAMs) composed of 15-hydroxypentadecanoic acid and 16-hydroxyhexadecanoic acid are investigated with scanning tunneling microscopy (STM) at the solution−graphite interface. The observed packing structures of these two molecules on the surface are dramatically different and reveal different intermolecular bonding arrangeme...

We present experimental results on dry friction, which are consistent with the hypothesis that the stick-slip mechanism for energy release is described by self-organized criticality. The data, obtained with an Atomic Force Microscope set to measure lateral forces– examines the variation of the friction force as a function of time – or sliding dista...

The structural distortion of high-generation poly(amidoamine) (PAMAM) dendrimers at the liquid/solid interface was investigated in situ using tapping mode atomic force microscopy (AFM). With a substantial compression along the surface normal but minor lateral expansion, isolated PAMAM dendrimers at the water/mica interface exhibit dimensions simila...

Gestapelte Moleküle: Porphyrin-Nonamer-Anordnungen stapeln sich durch Selbstorganisation zu dreidimensionalen Aggregaten (siehe Schema: „L“=L-förmiges Porphyrin (Eckstück), „T“=T-förmiges Porphyrin (Seitenstück), „+“=kreuzförmiges Porphyrin (Zentrum)). Die Größe der Aggregate auf Oberflächen kann von einem einzelnen Nonamer bis zu 50 nm hohen Stape...

Nature repeatedlydemon strates exquisite control over the molecular forces that underpin the veryexistence of life. Inspired bynature , the synthetic introduction of specific molecular interactions to guide the association of matter is an overarching theme in current nanoscale materials and device design.[1] The technological and functional advanta...

Manipulation of the self-assembly of chiral 2-bromohexadecanoic acid by templates composed of coadsorbed achiral molecules has been investigated at the liquid−solid interface using scanning tunneling microscopy (STM). The template formed by the odd-numbered saturated fatty acid heptadecanoic acid induces coadsorption of R-2-bromo-hexadecanoic acid...

Tessellation of nine free-base porphyrins into a 3 x 3 array is accomplished by the self-assembly of 21 molecular entities of four different kinds, one central, four corner, and four side porphyrins with 12 trans Pd(II) complexes, by specifically designed and targeted intermolecular interactions. Strikingly, the self-assembly of 30 components into...

STM has been used to study racemic 2-bromohexadecanoic acid and a mixture of this chiral molecule with achiral hexadecanoic acid physisorbed at a liquid-solid interface. Racemic 2-bromohexadecanoic acid segregates into enantiomerically pure domains on a graphite surface. The absolute chirality of individual molecules can be directly determined from...

Self-assembly of molecules on surfaces is fundamentally a process whereby individual molecules, separated in the gas or liquid phase, fonn ordered arrays on a surface. The driving forces for these self-assembly processes are the attractive and repulsive interactions among the molecules themselves and between the molecular assemblies and the surface...

The self-assembly of mixtures of hexadecanoic acid with (R)-2-Br-hexadecanoic acid and hexadecanoic acid with (S)-2-Br-hexadecanoic acid have been investigated on graphite at the liquid−solid interface using scanning tunneling microscopy (STM). The STM study of a chirally pure species provides an unambiguous assignment of geometric configurations f...

The effects of electric fields during the assembly of CdSe nanoparticle arrays from solution was investigated. A pair of Au-on-Si electrodes was submerged in a solution of CdSe nanoparticles in heptamethylnonane solvent and voltages of the order of 1000 V were applied to the electrodes. Two kinds of electrodes were used: flat electrodes and electro...

The self-assembly of a mixture of hexadecanoic acid with racemic (R)/(S)-2-bromohexadecanoic acid has been investigated using scanning tunneling microscopy. When this mixture is physisorbed onto the basal plane of graphite, hexadecanoic acid controls the resultant two-dimensional structure. By self-assembling on a graphite substrate into two distin...