Effect of a supercritical fluid on starch-based polymer processed with ionic liquid

• Starch plasticized with ionic liquid and process with supercritical carbon dioxide.
• Study of the role of ionic liquid in the presence of supercritical carbon dioxide.
• Carbon dioxide parameters lead to change in the crystalline structure of plasticized starch.
• Carbon dioxide acts as a plasticizer and induces a reduction of the glass transition temperature.

Recently, ionic liquids have been proposed as a promising plasticizing agents of starch. In this work, starch was treated with ionic liquid to obtain thermoplastic starch (TPS). The effects of supercritical carbon dioxide (ScCO2) on the processing of starch with 1-butyl-3-methylimidazolium chloride (BMIMCl) were also studied. For this purpose, the effects of different operating parameters such as temperature, pressure and processing time on the structural and thermal properties of TPS were evaluated.The results suggest that carbon dioxide leads to a low change of crystalline structure and this change is primarily influenced by temperature processing. Furthermore, the use of supercritical CO2 with different pressures and temperatures induces a decrease of the glass transition compared to formulations without it. This result can be interpreted as the plasticizing effect of CO2 and the preferred interaction between CO2 and starch plasticized with ionic liquid compared to glycerol–starch samples.

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