Transient surface patterns and instabilities at adhesive junctions of viscoelastic films

Hongbo Zeng, Yu Tian, Boxin Zhao, Matthew Tirrell, Jacob Israelachvili

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

A new kind of self-organized transient fingering pattern and instability was found to generally exist during the adhesive contact and coalescence of two polymer films in the viscous or viscoelastic state. The average radius of the patterns was found to increase with contact time following r = (r i + r o)/2 ∞t n, where r o and r i, are the outer and inner radii of the fingers, and where n varies from 0.15 to 0.3 depending on the viscoelastic properties of the materials. The surface approach rate has no effect on the appearance of the fingering patterns once it is less than some critical rate. The lifetime of the fingering patterns increases with the polymer viscosity as τ ∞ η n (n = 1.6 ±0.2), and peaks at some critical film thickness. The mechanism for the transient patterns is discussed in terms of theoriesof fluid mechanics and the molecular forces between surfaces.

Original languageEnglish (US)
Pages (from-to)8409-8422
Number of pages14
JournalMacromolecules
Volume40
Issue number23
DOIs
StatePublished - Nov 13 2007
Externally publishedYes

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