Humidity-Driven Transparent Holographic Free-Standing Polyelectrolyte Films

Konstantin G. Nikolaev, Sviatlana A. Ulasevich, Olga Luneva, Olga Yu Orlova, Daria Vasileva, Semen Vasilev, Alexander S. Novikov, Ekaterina V. Skorb

Research output: Contribution to journalReview articlepeer-review

Abstract

In the present work, transparent holographic poly(diallyldimethylammonium chloride) (PDADMAC)/heparin and PDADMAC/poly(styrenesulfonate) (PSS) films were synthesized via polyelectrolyte coacervates. PDADMAC/heparin films were obtained without temperature treatment. Thin holographic free-standing films with a 1 μm grating period and uniform surface of a polyelectrolyte complex were readily and quickly made by pressing polyelectrolyte coacervate, the hydrated viscoelastic fluid-like form of polyelectrolyte complex precursor, between a flat surface and holographic mask. Heparin replaces PSS in film composition to prepare the sheer film. Thus, the PDADMAC/heparin holographic film demonstrates transparency and reversible response for humidity under diffraction detection. In addition to diffraction humidity signal measurements, the cobalt(II) chloride was impregnated in polyelectrolyte coacervate to make an additional colorimetric signal response. In this case, the free-standing film serves both as the substrate for the hygroscopic salt and as a diffraction humidity sensor. The PDADMAC/heparin/Co(II) chloride film demonstrates a linear humidity range from 50 to 90%. Additionally, due to hydrated inorganic salt ion size, cobalt chloride prevents film porosity, which initiates under film swelling. Based on the results and calculations obtained, the study proposes the mechanism of water incorporation, including the reptation model and polyelectrolyte complex behavior. Results of density functional theory calculations prove that binding of cobalt aqua complexes [Co(H2O)6]2+ with the dimeric associates heparin/PDADMAC via noncovalent interactions (hydrogen bonds) additionally is much more energetically favorable compared with the alternative association of heparin/PDADMAC with water molecules.

Original languageEnglish
Pages (from-to)105-112
Number of pages8
JournalACS Applied Polymer Materials
Volume2
Issue number2
DOIs
Publication statusPublished - 14 Feb 2020

Keywords

  • holographic film
  • humidity sensor
  • hygroscope
  • polyelectrolytes
  • swelling

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