Probing cellulose-solvent interactions with self-diffusion NMR: Onium hydroxide concentration and co-solvent effects

B Medronho; A Pereira; H Duarte; L Gentile; A M Rosa da Costa; A Romano; U Olsson

doi:10.1016/j.carbpol.2022.120440

Probing cellulose-solvent interactions with self-diffusion NMR: Onium hydroxide concentration and co-solvent effects

Carbohydr Polym. 2023 Mar 1:303:120440. doi: 10.1016/j.carbpol.2022.120440. Epub 2022 Dec 9.

Authors

B Medronho¹, A Pereira², H Duarte³, L Gentile⁴, A M Rosa da Costa⁵, A Romano⁶, U Olsson⁷

Affiliations

¹ MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade do Algarve, Faculdade de Ciências e Tecnologia, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal; FSCN Research Center, Surface and Colloid Engineering, Mid Sweden University, SE-851 70 Sundsvall, Sweden. Electronic address: bfmedronho@ualg.pt.
² MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade do Algarve, Faculdade de Ciências e Tecnologia, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: a36790@ualg.pt.
³ MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade do Algarve, Faculdade de Ciências e Tecnologia, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal.
⁴ Dipartimento di Chimica, Università di Bari "Aldo Moro" & CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), Via Orabona 4, Bari I-70126, Italy. Electronic address: luigi.gentile@uniba.it.
⁵ Algarve Chemistry Research Centre (CIQA), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 8005-139 Faro, Portugal. Electronic address: amcosta@ualg.pt.
⁶ MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade do Algarve, Faculdade de Ciências e Tecnologia, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: aromano@ualg.pt.
⁷ Dipartimento di Chimica, Università di Bari "Aldo Moro" & CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), Via Orabona 4, Bari I-70126, Italy; Physical Chemistry, Chemistry Department and Biochemistry and Structural Biology, Chemistry Department, Lund University, P.O. Box 124, SE-22100 Lund, Sweden. Electronic address: ulf.olsson@fkem1.lu.se.

PMID: 36657835
DOI: 10.1016/j.carbpol.2022.120440

Abstract

The molecular self-diffusion coefficients were accessed, for the first time, in solutions of microcrystalline cellulose, dissolved in 30 wt% and 55 wt% aqueous tetrabutylammonium hydroxide, TBAH (aq), and in mixtures of 40 wt% TBAH (aq) with an organic co-solvent, dimethylsulfoxide (DMSO), through pulsed field gradient stimulated echo NMR measurements. A two-state model was applied to estimate α (i.e., average number of ions that "bind" to each anhydroglucose unit) and P_b (i.e., fraction of "bound" molecules of DMSO, TBAH or H₂O to cellulose) parameters. The α values suggest that TBA⁺ ions can bind to cellulose within 0.5 TBA⁺ to 2.3 TBA⁺/AGU. On the other hand, the P_b parameter increases when raising cellulose concentration for TBA⁺, DMSO and water in all solvent systems. Data suggests that TBAH interacts with the ionized OH groups from cellulose forming a sheath of bulky TBA⁺ counterions which consequently leads to steric hindrance between cellulose chains.

Keywords: Cellulose dissolution; Dimethylsulfoxide; Nuclear magnetic resonance; Self-diffusion; Tetrabutylammonium hydroxide.