The action of ethylamine on cellulose: Part II—Solvent extraction of ethylamine-treated bacterial cellulose: Changes in the hydroxyl-absorption region of the infra-red spectrum

Abstract

Dry bacterial cellulose films were treated with anhydrous ethylamine. The ethylamine was removed by one or more solvents and the films examined in the hydroxyl-stretching region of the infra-red spectrum (a) while still immersed, (b) after pumping-off the immersion liquid, (c) after exposure of the films to air, and (d) after heating the films in boiling water. Some films, kept wet after the ethylamine treatment, were acetylated to a small extent. It was found that the effect of anhydrous ethylamine on bacterial cellulose films was partly preserved even when the ethylamine was washed out. Solvent extraction with pyridine alone preserved this effect in cellulose in the wet state to a larger extent than when chloroform, n-hexane, cyclohexane, dimethyl formamide, water, methanol, or glacial acetic acid was used. There was generally a change, consistent with an increase in the strength of the intra-cellulosic hydrogen bonds on exposing the films to moist air, or heating them in boiling water, but this could be reduced and even reversed by acetylation to a small extent before such exposure to water vapour or hot water. Consequently the ethylamine-treated film washed with pyridine only and acetylated was the most weakly hydrogen-bonded of all the films in the dry state.