Analysis of celluloses, plant holocelluloses, and wood pulps by size-exclusion chromatography/multi-angle laser-light scattering

Size-exclusion chromatography with multi-angle laser-light scattering and refractive index detection (SEC/ MALLS/RI) provides the number- and weight-average molar masses, molar mass distributions, conformations, and linear/branched structures of polymers. In the case of pure celluloses including highly crystalline tunicate and alga celluloses, and hemicellulose-rich plant holocelluloses, soaking in ethylene diamine (EDA) and subsequent solvent exchange to N,N-dimethylacetamide (DMAc) though methanol is effective for complete dissolution in similar to 8% (w/w) LiCl/DMAc. SEC/MALLS/RI analysis can, therefore, be applied to pure celluloses, chemical wood pulps, and plant holocelluloses after dissolution in similar to 8% (w/w) LiC1/DMAc, dilution to 1% (w/v) LiCl/DMAc and membrane filtration. All pure celluloses and the high-molar-mass cellulose fractions of hardwood and grass holocelluloses have linear and random-coil conformations and various average molar masses and molar mass distributions depending on the cellulose and holocellulose resources. In contrast, Japanese cedar (i.e., softwood) holocellulose and softwood bleached kraft pulp have alkali-stable cellulose/glucomannan branched structures in the high-molar-mass fractions.

Automated summary

Size-exclusion chromatography with multi-angle laser-light scattering and refractive index detection (SEC/MALLS/RI) provides detailed information on the number- and weight-average molar masses, molar mass distributions, conformations, and linear/branched structures of polymers. By dissolving in a solvent system similar to 8% (w/w) LiC1/DMAc, analysis can be conducted on pure celluloses, chemical wood pulps, and plant holocelluloses. The results vary depending on the cellulose and holocellulose resources, with linear and random-coil conformations observed in pure celluloses and high-molar-mass cellulose fractions. Softwood holocellulose and bleached kraft pulp, on the other hand, exhibit alkali-stable cellulose/glucomannan branched structures in the high-molar-mass fractions.