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Title: Modifications of Surfactant Distributions and Surface Morphologies in Latex Films Due to Moisture Exposure

Source: J. Phys. Chem B 2009, 113, 10189-10195; 2009

Author(s)Xu, Guizhen H.; Dong, Jinping; Severtson, Steven J.; Houtman, Carl J.; Gwin, Larry E.

Publication Year: 2009  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4709-4A

Abstract: Migration of surfactants in water-based, pressure-sensitive adhesive (PSA) films exposed to static and cyclic relative humidity conditions was investigated using confocal Raman microscopy (CRM) and atomic force microscopy (AFM). Studied PSA films contain monomers n-butyl acrylate, vinyl acetate, and methacrylic acid and an equal mass mixture of anionic and nonionic nonylphenol ethoxylate emulsifiers. A leveling of surfactant concentration distributions is observed via CRM after films stored at 50% relative humidity (RH) are exposed to a 100% RH for an extended time period, while relatively small increases in surface enrichment occur when films are stored at 0% RH. Use of CRM for binary mixtures containing anionic or nonionic surfactant and latex that has undergone dialysis to remove nonpolymeric components indicates that surfactant-polymer compatibility governs to a great extent surface enrichment, but not changes observed with humidity variations. AFM images show that upon drying latex coatings, surfactant and other additives collect in large aggregation regions, which protrude from film surfaces. These structures are absent at high humidity, which appears to result from lateral spreading across the polymer surface. When humidity is reduced, aggregation regions reform but appear to be smaller and more evenly dispersed, and by cycling humidity between 0 and 100% RH, interfacial enrichment can be seen to diminish. Presented results provide greater insights into the distribution behavior of surfactants in latex films and potential mechanisms for observed issues arising for these systems.

Keywords: Surface active agents; glue; adhesion; adhesives; testing; pressure-sensitive adhesives; latex; vinyl acetate; methacrylic acid; moisture; humidity; coatings; atomic force microscopy; AFM; confocal Raman microscopy; CRM; n-butyl acrylate; bond strength; bonding; nonylphenyl ethoxylate emulsifiers; moisture content; polymers; polymerization

Publication Review Process: Informally Refereed (Peer-Reviewed)

File size: 371 kb(s)

Date posted: 05/17/2010

This publication is also viewable on Treesearch:  view
RITS Product ID: 31908
Current FPL Scientist associated with this product
Houtman, Carl J.
Chemical Engineer

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