Suppression of coffee ring effect in high molecular weight polyacrylamide droplets evaporating on hydrophobic surfaces

Raghuram, GKS and Bansal, L and Basu, S and Kumar, A (2021) Suppression of coffee ring effect in high molecular weight polyacrylamide droplets evaporating on hydrophobic surfaces. In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 612 .

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Abstract

In this work, we experimentally report the concentration and molecular weight dependence of the deposit patterns of polyacrylamide (PAM) droplets on hydrophobic surfaces. We find that with an increase in non-dimensional concentrations c/c* ranging from 0.16 (dilute) to 66.66 (semi-dilute entangled) there is a gradual transition from ring to non-ring patterns. However, with a decrease in the molecular weight of the polymer by one order, the coffee ring formation was not suppressed for the reported range of concentration. We attribute these results to the role played by the critical overlap concentration (c*) and diffusion coefficient of polymer along with the evaporation modes. The present study focuses on the drying of pure polymer droplets instead of the widely studied coffee ring effect in drying of droplets with rigid solid phase colloidal particles. We believe that these experimental findings would be of immense insight in applications such as inkjet printing, surface coatings, paints and detection assays in biotechnology for tuning polymer deposit patterns as a function of polymer molecular weight and concentration. © 2020 Elsevier B.V.

Item Type:	Journal Article
Publication:	Colloids and Surfaces A: Physicochemical and Engineering Aspects
Publisher:	Elsevier B.V.
Additional Information:	Copyright to this article belongs to Elsevier B.V.
Keywords:	Deposits; Drops; Molecular weight; Polymers; Sols; Surface chemistry, Colloidal particle; Gradual transition; High molecular weight; Hydrophobic surfaces; Overlap concentration; Polyacrylamide(PAM); Polymer molecular weight; Surface coatings, Hydrophobicity
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	29 Jan 2021 07:35
Last Modified:	29 Jan 2021 07:35
URI:	http://eprints.iisc.ac.in/id/eprint/67588

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