Influence of an adsorbing polymer in the aging dynamics of Laponite clay suspensions

TL;DR

This study investigates how adding polyethylene oxide (PEO) affects the aging process of Laponite clay suspensions, revealing that PEO slows down aging by hindering particle arrest through surface coverage and steric stabilization.

Contribution

It provides new insights into how polymer adsorption influences the aging dynamics of clay suspensions, highlighting the role of polymer concentration in slowing down gelation.

Findings

PEO addition delays the aging process of Laponite suspensions.

Higher PEO concentrations lead to increased surface coverage and steric stabilization.

Polymer adsorption modifies the effective interactions between clay particles.

Abstract

Clay-polymer dispersions in aqueous solutions have attracted a great interest in recent years due to their industrial applications and intriguing physical properties. Aqueous solutions of bare Laponite particles are known to age spontaneously from an ergodic state to a non ergodic state in a time varying from hours to months depending on Laponite concentration. When a polymer species like Polyethylene Oxide (PEO) is added to the solution, it weakly adsorbs on clay particle surfaces modifying the effective interaction potential between Laponite particles. A dynamic light scattering study, varying polymer concentration at fixed polymer molecular weight (Mw=200.000 g/mol), has been performed in order to understand the effect of polymer on the aging dynamics of the system. The results obtained show that arresting phenomena between clay particles are hindered if PEO is added and consequently the aging dynamics slows down with increasing PEO concentration. This process is possibly due to the progressive coverage of the clay surface by polymers that grow with increasing PEO concentration and may lead to steric stabilization.