Electrostatically crosslinked cellulose nanocrystal and polyelectrolyte complex sponges with pH responsiveness

Mor Boas; Patrick Martin; Gleb Vasilyev; Jong-Gun Lee; Rita Vilensky; Chengzhang Xu; Andreas Greiner; Eyal Zussman

doi:10.1016/j.carbpol.2021.118131

Electrostatically crosslinked cellulose nanocrystal and polyelectrolyte complex sponges with pH responsiveness

Carbohydr Polym. 2021 Aug 15:266:118131. doi: 10.1016/j.carbpol.2021.118131. Epub 2021 Apr 28.

Authors

Mor Boas¹, Patrick Martin¹, Gleb Vasilyev¹, Jong-Gun Lee¹, Rita Vilensky¹, Chengzhang Xu², Andreas Greiner², Eyal Zussman³

Affiliations

¹ NanoEngineering Group, Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
² Bavarian Polymer Institute, Macromolecular Chemistry, University of Bayreuth, Bayreuth 95440, Germany.
³ NanoEngineering Group, Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel. Electronic address: meeyal@technion.ac.il.

PMID: 34044947
DOI: 10.1016/j.carbpol.2021.118131

Abstract

This work focuses on the development of a responsive sponge made of an anionic cellulose nanocrystal (CNC) skeleton that is electrostatically crosslinked by a pH-responsive poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) polyelectrolyte complex (PEC). The results prove the formation of a global percolated network comprised of disordered CNC rods crosslinked by PEC clusters. The bulk density of the freeze-dried CNC-PEC sponges increases from 35 to 93 mg/cm³ with PEC concentration, while the compression modulus of dry specimens increases from 7 up to 62 kPa. At the lowest PEC concentration of 1 wt%, at pH 2.0, the compression modulus decreases to 0.9 kPa, whereas at pH 5.5, it increases to 42 kPa. The intensive complexation between sponge constituents is also reflected in a reduced ability to bind charged dyes at neutral pH values. Decreasing the pH results in an increased adsorption efficiency for anionic dyes, while raising the pH improves the cationic dye adsorption.

Keywords: Aerogel; Cellulose nanocrystal; Freeze-drying; Polyelectrolyte complex; Sponge.