Polysaccharides with a structure controlled by chemo-enzymatic or enzymatic synthesis using various C-sources are considered valuable renewable resources. α-1,3-Glucan is engineered by conversion of sucrose with a glycosyl transferase enzymes. In the frame of our work about the chemical modification of polysaccharides, different reactions of this interesting glucan were studied. Results about the esterification will be discussed. α-1,3-glucan could be successfully acetylated under homogeneous conditions in DMA/LiCl yielding product with degree of substitution (DSAc) of up to 2.61. The α-1,3-glucan acetates possess a DS-dependent solubility and show the interesting effect of upper critical solution temperature (UCST). Because swelling is observed at low temperature followed by dissolution upon heating and gelation upon cooling, the novel α-1,3-glucan esters might be useful as novel organogelators. Moreover, they are worth studying as bio-based absorbents for, e.g., oil spills. Long chain glucan esters were prepared by a new method using molten imidazole and Ionic Liquids as solvent in comparison to converisons in N,N-dimethylacetamide/LiCl. The reactions yield highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. The melting temperature of the long chain fatty acid esters of α-1,3-glucan could be adjusted by type of ester moiety and by amount of ester functions (DS) introduced.

Engineered PolySaccharides: α-1,3-Glucan esters showing UCST in organic solvents and thermoplastic properties

2019 Spring National Meeting

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