Celebrating Soft Matter's 10th Anniversary: Chain configuration and rate-dependent mechanical properties in transient networks

Abstract

Numerical solution of a coupled set of Smoluchowski convection-diffusion equations of associating polymers modelled as finitely extensible dumbbells enables computation of time-dependent end-to-end distributions for bridged, dangling, and looped chains in three dimensions as a function of associating end-group kinetics. Non-monotonic flow curves which can lead to flow instabilities during shear flow result at low equilibrium constant and high association rate from two complementary phenomena: a decrease in the fraction of elastically active chains with increasing shear rate and non-monotonic extension in the population of elastically active chains. Chain tumbling leads to reformation of bridges, resulting in an increased fraction of bridged chains at high Deborah number and significant reduction in the average bridge chain extension. In the start-up of steady shear, force-activated chain dissociation and chain tumbling cause both stress overshoot and stress ringing behaviour prior to reaching steady state stress values. During stress relaxation following steady shear, chain kinetics and extension mediate both the number of relaxations and the length of time required for system relaxation. While at low association rate relaxation is limited by the relaxation of dangling chains and the rate of dangling chain formation, at high association rate coupling of dangling and bridged chains leads to simultaneous relaxation of all chains due to a dynamic equilibrium between dangling and bridged states.

Study of a Novel Gemini Viscoelastic Surfactant with High Performance in Clean Fracturing Fluid Application

“…Stimulus conditions [3,4,5,6,7] such as light, pH, temperature, and electrolyte can induce various responses of VES molecule aggregation, thus the macroscopic nature of viscoelasticity can be adjusted by changing the stimulus conditions [8]. Due to the “magical” properties of the viscoelastic surfactants, they have been welcomed in many industrial applications such as smart optical systems [9], drug delivery [10], template synthesis [11], biosensors [12] in past decades. Recently, they are introduced into the petroleum industry, applied to enhanced drag reduction [13,14,15], reservoir stimulation [16,17,18,19,20] and oil recovery [21,22].…”

Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics

“…As such, there is considerable current development in the theories of mechanical behavior of transient networks. 23 – 25 …”

A stochastic mesoscale model of transiently networked fluids

“…A non-monotone flow curve would be of interest to mimic the macroscale wormlike micellar shear banding models' behavior. Other studies [21,28,29] have considered FENE springs as opposed to Hookean springs, and [28] considered a FENE force dependent breakage, a much more abrupt cut-off of the chain stretch than our postulated breakage rates. In those studies a parameter range for which the homogeneous flow curve becomes nonmonotonic was found.…”