Dialdehyde cellulose microfibers generated from wood pulp by milling-induced periodate oxidation

An investigation was made into functionalized cellulose microfibers produced from wood chemical pulp with a new method that combines both mechanical and chemical modifications. Dialdehyde cellulose (DAC) microfibers were obtained by reactive milling, i.e. simultaneous cellulose pulp micronization with a wet stirred media mill and oxidation by sodium periodate. Milling significantly enhanced the pulp reactivity towards the periodate oxidation by reducing crystallinity and increasing the specific surface area of cellulose. DAC microfibers with a high aspect ratio and aldehyde content of 0.26 mmol/g were obtained already after the first 15 min of milling. This new way to simultaneously modify cellulose material mechanically and chemically offers an effective route to produce highly functionalized cellulose microfibers within short reaction times and with mild conditions. High temperature and use of metal salt as cellulose activator further enhanced the efficiency of oxidation during milling.