Single-Step Application of Polyelectrolyte Complex Films as Oxygen Barrier Coatings

Jiaying Li, Gerard Van Ewijk, Derk Jan Van Dijken, Jasper Van Der Gucht, Wiebe M. De Vos*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Polyelectrolyte complex (PEC) films such as polyelectrolyte multilayers have demonstrated excellent oxygen barrier properties, but unfortunately, the established layer-by-layer approaches are laborious and difficult to scale up. Here, we demonstrate a novel single-step approach to produce a PEC film, based on the use of a volatile base. Ammonia was used to adjust the pH of poly(acrylic acid) (PAA) so that direct complexation was avoided when it was mixed with polyethylenimine (PEI). Different charge ratios of homogeneous PEI/PAA solutions were successfully prepared and phase diagrams varying the concentration of ammonia or polyelectrolyte were made to study the phase behavior of PEI, PAA, and ammonia in water. Transparent ∼1 μm thick films were successfully deposited on biaxially orientated polypropylene (BOPP) sheets using a Meyer rod. After casting the films, the decrease in pH, caused by the evaporation of ammonia, triggered the complexation during drying. The oxygen permeation properties of films with different ratios and single polyelectrolytes were tested. All films displayed excellent oxygen barrier properties, with an oxygen permeation below 4 cm3·m-2·day-1·atm-1 (<0.002 barrer) at the optimum ratio of 2:1 PEI/PAA. This ammonia evaporation-induced complexation approach creates a new pathway to prepare PEC films in one simple step while allowing the possibility of recycling.

Original languageEnglish
Pages (from-to)21844-21853
Number of pages10
JournalACS Applied Materials and Interfaces
Volume13
Issue number18
DOIs
Publication statusPublished - 12 May 2021

Keywords

  • UT-Hybrid-D
  • gas barrier
  • phase diagrams
  • polyelectrolyte complexation
  • waterborne coatings
  • food packaging

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