From Surfactants to Viscoelastic Capsules

Expanding Applications for Viscoelastic Surfactants

Allan Twynam BP Sunbury, England For help in preparation of this article, thanks to Curtis Boney, Ernie Brown, Steve Davies and George Hawkins, Sugar Land, Texas, USA; Jorge Gonzalez and Arthur Milne, Caracas, Venezuela; Satyaki Ray, Calgary, Alberta, Canada; and David Schoderbek, Burlington Resources Canada, Calgary. ClearFRAC, ClearPAC, CoalFRAC, FMI (Fullbore Formation MicroImager), FracCADE...

Inorganic molecular capsules: from structure to function.

The assembly of nanoscale capsules or cages using metal coordination represents one of the most interesting and challenging areas of chemical nanoscience. These high-symmetry capsules are invariably comprised of many metal–ligand components, which often selfassemble rapidly and in high yield into a single gigantic species—sometimes even protein-sized. However, the interest in these systems goes...

Higher Oligomeric Surfactants — From Fundamentals to Applications

Stable jets of viscoelastic fluids and self-assembled cylindrical capsules by hydrodynamic focusing.

We demonstrate formation of long-lived cylindrical jets of a viscoelastic fluid using hydrodynamic focusing. A solution of polyacrylamide in water is driven coaxially with immiscible oil and subjected to strong extensional flow. At high flow rates, the aqueous phase forms jets that are 4-90 microm in diameter and several centimeters long. The liquid surfaces of these jets are then used as templ...

Response and Recovery Times of Elastic and Viscoelastic Capsules in Shear Flow

Amid the recent interest in the role of membrane viscosity in the deformation of a fluid-filled capsule, we consider the role of various capsule properties (shear elasticity, membrane bending stiffness and viscosity) in determining the response and recovery times of a spherical capsule in shear flow. These times are determined by fitting exponential functions to results for the Taylor deformati...