Novel Polymer Clay-Based Nanocomposites: Films with Remarkable Optical and Water Vapor Barrier Properties

• Published in: Macromolecular materials and engineering Vol. 301; no. 7; pp. 836 - 845
• Main Authors: Murima, Douglas, Pfukwa, Helen, Tiggelman, Ineke, Hartmann, Patrice C., Pasch, Harald
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01-07-2016; John Wiley & Sons, Inc
• Subjects: Barriers; Clay (material); Copolymers; Latex; Montmorillonite; morphology; Nanocomposites; Optical properties; Styrenes; transparency; Water vapor; water vapor barrier properties
• ISSN: 1438-7492; 1439-2054
• DOI: 10.1002/mame.201600080

The impact of varying the copolymer composition of styrene–co‐butyl acrylate copolymers on the dispersion of montmorillonite (MMT) clay and the effect thereof on the transparency and water vapor barrier properties of the resultant films is assessed. The hybrid latexes containing MMT clay concentrations of 10–30 wt% are prepared using miniemulsion polymerization. The morphology of the resultant latexes shows that the MMT particles are predominantly adhered onto the surface of the latex particles. However, the transparency of the films suggests a fair dispersion of the MMT platelets in the matrix. The thickness‐normalized light transmittance for copolymers with 40 and 50 mol% styrene only decreases from 70% in the neat films to 50% in the nanocomposite films containing 30 wt% clay. The best optical properties are observed for the copolymers with 30 mol% styrene, in which the light transmittance only decreases from 85% (unfilled film) to 60% in the nanocomposite films containing 30 wt% clay. Overall, the water vapor barrier properties are much higher in the copolymer films with 30 mol% styrene due to the unique morphological organization of MMT platelets in the matrix.
Hybrid latexes of styrene–butylacrylate copolymers and montmorillonite clay with concentrations of 10–30 wt% clay are prepared and investigated as barrier coatings. The composite films exhibit high optical transparency and excellent water vapor barrier properties. Copolymer films containing 30 mol% styrene are superior to other materials.