Rheology of Polyelectrolyte Solutions: Current Understanding and Perspectives

Abstract

Polyelectrolytes with ionic groups are abundant in nature and essential in life. Counterions can be released into a solution and leave charges on polyelectrolyte chains, making the solution properties significantly different from those of electrically neutral polymers. A lot of scientific efforts have been made to elucidate the effect of electrostatic interactions on the conformation and material properties of polyelectrolyte solutions. However, unfortunately, our understanding is still far away from being perfect, and continuous efforts need to be provided by researchers from different aspects. This short review will highlight the research progress made in the past few years on the conformation and viscoelastic properties of polyelectrolyte solutions.

Determining the Molecular Weight of Polyelectrolytes Using the Rouse Scaling Theory for Salt-Free Semidilute Unentangled Solutions

“…Hence, η sp is governed by the weight-average N w , which leads to a method to determine N w as eq . The Fuoss law scaling of eq expects in the low salt limit for c * < c < c e , where c * is the overlap concentration and c e is the entanglement concentration. This Fuoss law has been observed to work reasonably well for a wide variety of polyelectrolytes and a recent model even accounts for subtle departures . Lastly, terminal modulus is the reciprocal of the steady-state compliance, which is known to have N z N z+1 / N w dependence. , Therefore, the N dependence of terminal modulus ( G = ckT / N is kT per chain for monodisperse polymers) , can be expressed as …”

“…This Fuoss law has been observed to work reasonably well for a wide variety of polyelectrolytes 26 and a recent model even accounts for subtle departures. 25 Lastly, terminal modulus is the reciprocal of the steady-state compliance, which is known to have N z N z+1 /N w dependence. 24,27 Therefore, the N dependence of terminal modulus (G = ckT/N is kT per chain for monodisperse polymers) 1,3 can be expressed as…”

DNA Hyperstructure

“…Equation describes the Bjerrum length l B = e 2 4 π ε r ε 0 K B T where e is the proton charge and has a Bjerrum length of 7.06 Å at room temperature. Given that b represents the distance between the DNA molecule’s phosphates along the DNA axial axis − and has a value of 1.7 Å, we calculate the ratio l B / b is 4.15, where this number is known as Manning fraction (ξ) and predicts an electrostatic screening when ξ > 1. When using water and AA ga , ε r is obtained using the Onsager theory (2) ε r = ε 1 φ 1 + ε 2 φ 2 where ε 1 and ε 2 are the dielectric constants for the solutions, and φ 1 and φ 2 are the fraction volumes.…”

Dilute polyelectrolyte solutions: recent progress and open questions

“…82 For experimental reviews dealing with non-dilute solutions and gels, we direct readers to ref. 14, 68 and 83–85.…”