One-pot synthesis of thermoplastic mixed paramylon esters using trifluoroacetic anhydride

• Thermoplastic mixed paramylon esters were prepared using one-pot synthesis.
• Trifluoroacetic anhydride was used as a promoter and solvent.
• The degree of substitution, a key factor for thermoplasticity, was controllable.
• One-pot synthesis produces thermally stable thermoplastics.

Mixed paramylon esters prepared from paramylon (a storage polysaccharide of Euglena), acetic acid, and a long-chain fatty acid by one-pot synthesis using trifluoroacetic anhydride as a promoter and solvent were shown to have thermoplasticity. Size exclusion chromatography indicated that the mixed paramylon esters had a weight average molecular weight of approximately 4.9 − 6.7 × 105. Thermal analysis showed that these esters were stable in terms of the glass transition temperature (>90 °C) and 5% weight loss temperature (>320 °C). The degree of substitution of the long alkyl chain group, a dominant factor determining thermoplasticity, was controlled by tuning the feed molar ratio of acetic acid and long-chain fatty acid to paramylon. These results implied that the one-pot synthesis is useful for preparing structurally-well defined thermoplastic mixed paramylon esters with high molecular weight.