This review describes several methods for activating cellulose so that it dissolves in N,Ndimethylacetamide/ lithium chloride and can then be analyzed by size exclusion chromatography (SEC) and light scattering for the determination of molar mass and molar mass distribution (MMD). This contribution lists the effects of these methods and approaches on the molar mass distribution of cellulose. Cellulose I and cellulose II behave differently and are considered separately. The activation procedures are grouped according to mechanical, chemical, and biological mechanisms. The mechanical processes include milling, freeze drying, steam explosion, and ultrasonic treatment, while chemical mechanisms are heating, irradiation, alkaline pretreatment, and derivatization strategies are discussed. Treatments with ethylene diamine and ionic liquids are also summarized from chemical aspects. Enzymes represent the biological strategy for treating solubility problems involving cellulose. These activation mechanisms are reviewed with regard to their efficiency, effect on MMD, and possible side reactions.
Keywords: Accessibility, activation, derivatization, dissolution, enzyme, ethylene diamine, freeze-drying, heating, hornification, hydrogen bond, irradiation, milling, sodium borohydrate, sodium hydroxide, solvent exchange, steam explosion, swelling, ultrasonication.