arXiv subjects

Alesya Mikhailovskaya

Publications and source records attributed to Alesya Mikhailovskaya.

3 recordsLinked to original sources

arXiv2021

Probing non-affine expansion with light scattering

In disordered materials under mechanical stress, the produced deformation can deviate from the affine one already in the elastic regime. The nonaffine contribution was observed and characterized in numerical simulations for various systems. However, low amplitude of nonaffinity and its local character makes the experimental study challenging. We present a novel method on the based on a phase compensation of the wave scattered from a dilated amorphous material using fine wavelength tuning of the optical probe beam. Using a glass frit as a sample, we provide complete reversibility of the material deformation which enables to confirm the occurrence of nonaffinity in the elastic regime. We develop a model for the coupled effect of the thermal expansion/contraction of the material and the dilatation of the incident wavelength which allows us to estimate the magnitude of the nonaffine displacement and the spatial extent of its correlation domain.

cond-mat.soft↗

arXiv2018

Adsorption dynamics of hydrophobically modified polymers at an air-water interface

Using surface-tension measurements, we study the brush-limited adsorption dynamics of a range of amphiphilic polymers, PAAH-$α$-$\textrm{C}_n$ composed of a poly(acrylic acid) backbone, PAAH, grafted with a fraction $α$ of alkyl moieties, containing either $n=8$ or $n=12$ carbon atoms, at pH conditions where the PAAH backbone is not charged. At short times, the surface tension decreases more sharply as the degree of grafting increases while at long times, the adsorption dynamics becomes logarithmic in time and is slower as the degree of grafting increases. This logarithmic behavior at long times indicates the building of a free-energy barrier which grows over time. To account for the observed surface tension evolution with the degree of grafting we propose a scenario, where the free-energy barrier results from both the deformation of the incoming polymer coils and the deformation of the adsorbed brush. Our model involves only two fitting parameters, the monomer size and the area needed for one molecule during adsorption and is in agreement with the experimental data. We obtain a reasonable value for the monomer size and find an area per adsorbed polymer chain of the order of 1nm$^2$, showing that the polymer chains are strongly stretched as they adsorb.

cond-mat.soft↗

arXiv2017

Spatially-resolved measurements of micro-deformations in granular materials using DWS

This article is a tutorial on the practical implementation of a method of measurement of minute deformations based on multiple scattering. This technic has been recently developed and has proven to give new insights on the spatial repartition of strain in a granular material. We provide here the basics to understand the method by giving a synthetic review on Diffusing Wave Spectroscopy and multiple scattering in granular materials. We detail a simple experiment using standard lab equipment to pedagogically demonstrate the implementation of the method. Finally we give a few examples of measurements that have been obtained in other works to discuss the potential of the method.

cond-mat.soft↗