Dissolution and modification of cellulose using high-pressure carbon dioxide switchable solution

•Phase diagram on cellulose dissolution in CO2 switchable solution is proposed.•High-pressure CO2 switchable solution was also used for the cellulose modification.•Transparent cellulose film was fabricated from the modification in the switchable solution.

High-pressure carbon dioxide switchable solution with 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and ethylene glycol (EG) was applied for a dissolution and modification of cellulose derived from a cassava pulp waste. The switchable solution of DBU and EG were formed by adding carbon dioxide under a pressure range of 0.1-10.0 MPa and a temperature range of 298 and 333 K. The cellulose was dissolved into the CO2 switchable system at a pressure of 0.1 and 5.8 MPa and a temperature of 313 K. The precipitates of bicarbonate salt of reaction between DBU and carbon dioxide were observed in the switchable solution at the higher pressures and lower temperatures. The cellulose was also modified in the switchable solution with the ionized DBU, EG and carbon dioxide as analyzed by Fourier transform infrared spectroscopy. The modified cellulose was then utilized for the fabrication of the transparent film.

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