Screening of hydrogen bonds in modified cellulose acetates with alkyl chain substitutions

Robin Nilsson; Martina Olsson; Gunnar Westman; Aleksandar Matic; Anette Larsson

doi:10.1016/j.carbpol.2022.119188

Screening of hydrogen bonds in modified cellulose acetates with alkyl chain substitutions

Carbohydr Polym. 2022 Jun 1:285:119188. doi: 10.1016/j.carbpol.2022.119188. Epub 2022 Jan 29.

Authors

Robin Nilsson¹, Martina Olsson², Gunnar Westman³, Aleksandar Matic⁴, Anette Larsson⁵

Affiliations

¹ Applied Chemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; FibRe-Centre for Lignocellulose-based Thermoplastics, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. Electronic address: robnils@chalmers.se.
² Materials Physics, Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. Electronic address: martina.olsson@chalmers.se.
³ FibRe-Centre for Lignocellulose-based Thermoplastics, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden. Electronic address: westman@chalmers.se.
⁴ FibRe-Centre for Lignocellulose-based Thermoplastics, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; Materials Physics, Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. Electronic address: matic@chalmers.se.
⁵ Applied Chemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; FibRe-Centre for Lignocellulose-based Thermoplastics, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. Electronic address: anette.larsson@chalmers.se.

PMID: 35287840
DOI: 10.1016/j.carbpol.2022.119188

Abstract

This study aimed to elucidate how the glass transition temperature and water interactions in cellulose esters are affected by the structures of their side chains. Cellulose acetate, cellulose acetate propionate and cellulose acetate butyrate with three fractions of butyrates, all having the same total degree of substitution, were selected, and hot-melt pressed. The degree of substitution, structural properties, and water interactions were determined. The Hansen solubility parameters were calculated and showed that the dispersive energy dominates the total cohesive energy, followed by hydrogen bonding and polar energy. The glass transition temperature (T_g) decreased, counter-intuitively, with an increased total cohesive energy, which can be explained by the short-range hydrogen bonds being screened by the increased length of the substituents. The solubility and penetration of water in the cellulose esters decreased with increased side chain length, although the hydrogen bonding energies for all the esters were approximately constant.

Keywords: Cellulose acetate; Glass transition temperature; Hansen solubility parameters; Hydrogen bonding; Screening; Water interactions.