Engineering Commons^™

From Dilute Polyelectrolyte Solutions To Entangled Polyelectrolyte Networks: A Study Of Sodium Carboxymethyl Cellulose In Water By Light Scattering And Rheology, Juliette S. Behra, Timothy N. Hunter, Olivier J. Cayre, Johan Mattsson

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Sodium carboxymethyl cellulose (Na CMC) is widely used in industry for its thickening and swelling properties. Applications are very broad and include pharmaceutical, food, home and personal care products as well as the paper industry, water treatment and mineral processing. Na CMC is a linear negatively charged water-soluble polymer derived from cellulose. Its behaviour in water is known to be very complex and a function of several parameters including the characteristics of the polymer itself [1] such as molecular weight and degree of substitution as well as the solution concentration and dissolution conditions [2] (e.g. addition order of the system …

Soft Matter Films Interfaced To Electronic Devices: Capacitance-Modulated Field Effect Transistors Integrating Protein Layers, Gerardo Palazzo, Luisa Torsi, Maria Magliulo, Antonia Mallardi

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Soft matter systems interfaced to an electronic device are presently one of the most challenging research activity that has relevance not only for fundamental studies but also for the development of highly performing bio-sensors.

Layers of proteins anchored on solid surfaces have small capacitance that undergoes to only minute changes as the ligand–protein complex is formed.

For properly designed systems, the protein layer represents smallest capacitance in a series of capacitors and as such dominates the overall capacitance. When such a protein layer is integrated in a Field Effect Transistor (FET) transduction is remarkably sensitive as the transistor output current …

Relative Humidity As A New Parameter In Rheological Testing, Jörg Läuger, Gunther Arnold

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Besides temperature and pressure the water content of a sample as well as the relative humidity of the ambient air are important parameter influencing the rheological behavior of many complex fluids such as for example gels, biomaterials, polymeric systems, food products, and adhesives.

The aim of this contribution is to introduce a newly designed environmental control chamber for the use with a rotational rheometer.

A combination of a modified convection oven and an external humidity generator enables to work under defined relative humidity (RH) and temperature (T) in the ranges of RH = 5 to 95 % and T = …

Passive Microrheology As A Useful Tool For Milk Gel Analyses, Roland Ramsch, Giovanni Brambilla, Mathias Fleury, Pascal Bru, Gérard Meunier

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Passive microrheology based on Diffusing Wave Spectroscopy (DWS) [1,2] is presented as a straightforward tool for the analysis of milk gel preparation. Diffusing Wave Spectroscopy consists of analysing the interferential images of light, which is backscattered by the sample. This so called speckles images, which are detected by a CCD camera, change in time due to the Brownian motion of the particles that scatter the light. The variation of the images as a function of time can be directly correlated to the viscoelastic properties of the sample. As it is an optical method, it is perfectly adapted to study the …

Non-Uniform Flow Of Colloidal Glasses And Gels: The “Shear-Gradient Concentration Coupling Instability”, J.K.G. Dhont

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

There are several types of shear-induced instabilities in soft-matter systems, like vorticity- and gradient-banding, that are by now well-understood. There is, however, an instability that can be referred to as “the Shear-gradient Concentration Coupling instability” (the SCC-instability) that has been largely ignored due to the lack of understanding of its microscopic origin, since its phenomenological description a few decades ago. This instability is due to a postulated shear-gradient induced mass flux together with a strong coupling of the stress to concentration. The origin of the shear-induced mass flux resulting from direct interactions is so far not understood, and explicit expressions …

Conference Program, Samiul Amin, Saad Khan

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

No abstract provided.

Super-Soft And Super-Elastic Dry Gels, Michael Rubinstein, William F. M. Daniel, Mohammad V. Vatankhah, Joanna Burdyńska, Krzysztof Matyjaszewski, Jaroslaw Paturej, Sergey Panyukov, Andrey V. Dobrynin, Li-Heng Cai, Thomas E. Kodger, Rodrigo E. Guerra, Adrian F. Pegoraro, David A. Weitz, Sergei S. Sheiko

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Molecular combs and bottlebrushes are a new class of polymer architecture allowing for anomalously low density of entanglements in polymer melts. The conformations and rheological properties of melts of these branched macromolecule composed of a flexible backbone and side chains densely tethered to it are investigated theoretically, experimentally and by computer simulations.^1,2 We develop the rule for dialing in the desired value of the melt plateau modulus of these molecules as low as 1000 times below the conventional values for linear polymer melts and experimentally verify the validity of our theory. The theory also predicts that elastomers made from …