On the formation and stability of cellulose-based emulsions in alkaline systems: Effect of the solvent quality

Carolina Costa; Bruno Medronho; Alexandra Filipe; Anabela Romano; Björn Lindman; Håkan Edlund; Magnus Norgren

doi:10.1016/j.carbpol.2022.119257

On the formation and stability of cellulose-based emulsions in alkaline systems: Effect of the solvent quality

Carbohydr Polym. 2022 Jun 15:286:119257. doi: 10.1016/j.carbpol.2022.119257. Epub 2022 Feb 15.

Authors

Carolina Costa¹, Bruno Medronho², Alexandra Filipe³, Anabela Romano³, Björn Lindman⁴, Håkan Edlund⁵, Magnus Norgren⁵

Affiliations

¹ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: carolina.costa@miun.se.
² FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden; MED - Mediterranean Institute for Agriculture, Environment and Development, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal.
³ MED - Mediterranean Institute for Agriculture, Environment and Development, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal.
⁴ Physical Chemistry, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden; Coimbra Chemistry Center (CQC), Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
⁵ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden.

PMID: 35337494
DOI: 10.1016/j.carbpol.2022.119257

Abstract

With amphiphilic properties, cellulose molecules are expected to adsorb at the O/W interface and be capable of stabilizing emulsions. The effect of solvent quality on the formation and stability of cellulose-based O/W emulsions was evaluated in different alkaline systems: NaOH, NaOH-urea and tetrabutylammonium hydroxide (TBAH). The optimal solvency conditions for cellulose adsorption at the O/W interface were found for the alkaline solvent with an intermediate polarity (NaOH-urea), which is in line with the favorable conditions for adsorption of an amphiphilic polymer. A very good solvency (in TBAH) and the interfacial activity of the cation lead to lack of stability because of low cellulose adsorption. However, to achieve long-term stability and prevent oil separation in NaOH-urea systems, further reduction in cellulose's solvency was needed, which was achieved by a change in the pH of the emulsions, inducing the regeneration of cellulose at the surface of the oil droplets (in-situ regeneration).

Keywords: Amphiphilicity; Dissolution; NaOH; O/W emulsions; Regenerated cellulose; TBAH; Urea.