Bubble Attachment to Cellulose and Silica Surfaces of Varied Surface Energies: Wetting Transition and Implications in Foam Forming

Annika E. Ketola, Wenchao Xiang, Tuomo Hjelt, Heikki Pajari, Tekla Tammelin, Orlando J. Rojas, Jukka A. Ketoja (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

Abstract

To better understand the complex system of wet foams in the presence of cellulosic fibers, we investigate bubble-surface interactions by following the effects of surface hydrophobicity and surface tension on the contact angle of captive bubbles. Bubbles are brought into contact with model silica and cellulose surfaces immersed in solutions of a foaming surfactant (sodium dodecyl sulfate) of different concentrations. It is observed that bubble attachment is controlled by surface wetting, but a significant scatter in the behavior occurs near the transition from partial to complete wetting. For chemically homogeneous silica surfaces, this transition during bubble attachment is described by the balance between the energy changes of the immersed surface and the frictional surface tension of the moving three-phase contact line. The situation is more complex with chemically heterogeneous, hydrophobic trimethylsilyl cellulose (TMSC). TMSC regeneration, which yields hydrophilic cellulose, causes a dramatic drop in the bubble contact angle. Moreover, a high interfacial tension is required to overcome the friction caused by microscopic (hydrophilic) pinning sites of the three-phase contact line during bubble attachment. A simple theoretical framework is introduced to explain our experimental observations.

Original languageEnglish
Pages (from-to)7296-7308
Number of pages13
JournalLangmuir : the ACS journal of surfaces and colloids
Volume36
Issue number26
DOIs
Publication statusPublished - Jul 2020
MoE publication typeA1 Journal article-refereed

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