Thiol-norbornene reactions to improve natural rubber dispersion in cellulose nanofiber coatings

Kendra Fein; Douglas W Bousfield; William M Gramlich

doi:10.1016/j.carbpol.2020.117001

Thiol-norbornene reactions to improve natural rubber dispersion in cellulose nanofiber coatings

Carbohydr Polym. 2020 Dec 15:250:117001. doi: 10.1016/j.carbpol.2020.117001. Epub 2020 Aug 29.

Authors

Kendra Fein¹, Douglas W Bousfield¹, William M Gramlich²

Affiliations

¹ Paper Surface Science Program, University of Maine, Orono, ME 04469, United States; Department of Chemical and Biomedical Engineering, University of Maine, Orono, ME 04469, United States.
² Paper Surface Science Program, University of Maine, Orono, ME 04469, United States; Department of Chemistry, University of Maine, Orono, ME 04469, United States. Electronic address: william.gramlich@maine.edu.

PMID: 33049906
DOI: 10.1016/j.carbpol.2020.117001

Abstract

Cellulose nanofibrils (CNF) coatings are excellent grease barriers for biodegradable packaging. However, barrier properties are moisture sensitive, so hydrophobic components such as latexes or polymers are needed to impart moisture resistance, but incompatibility leads to poor dispersion. In this work, CNF modified with norbornenes was reacted with natural rubber (NR) latex in water to improve dispersion, coating formation, and coating moisture resistance by creating hybrid particles. Mixtures and reacted samples were coated through filtration onto paper. The hybrid particles improved NR retention and drainage rate as compared to the CNF/latex mixture. Hybrid particle coatings showed more uniform NR dispersion as compared to the mixtures, which formed NR and CNF layers. NR addition to coatings increased the water contact angle, reduced water absorption, and decreased the water vapor transmission rate. All coatings passed a 12-kit grease test before folding and the mixtures formed a crack-resistant CNF layer on the surface.

Keywords: Cellulose nanofibrils; Coatings; Compatibilization; Natural rubber; Thiol-ene reactions; Water-based chemistry.