Single crystals of cellulose IV_II: Influence of the cellulose molecular weight

Abstract

Abstract The influence of the degree of polymerization (DP) of cellulose was evaluated in the preparation of micron‐sized cellulose IV II lamellar crystals in order to ascertain whether a regular chain‐folded morphology could develop during their growth. For this purpose, sharp fractions of cellulose acetate were collected by preparative gel permeation chromatography. Aliquots of these fractions were deacetylated and crystallized in dilute solutions containing water, methylamine, and DMSO, and held at 150°C under pressure. Well‐developed cellulose IV II lamellar crystals were obtained with fractions of DP 22–24 whereas higher‐DP material gave polycrystalline aggregates. This behavior indicates that large lamellar crystals of cellulose IV II can be obtained only with unfolded short cellulose chains. The occurrence of chain‐folded crystals with high–DP cellulose samples cannot be demonstrated.