Ενζυμική επεξεργασία βιοπολυμερών: ακυλίωση κυτταρίνης με εστεράσες σε μη συμβατικά συστήματα

• Main Authors: Gremos, Stavros, Γκρέμος, Σταύρος
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: National Technical University of Athens (NTUA) 2012
• Subjects: Βιοκατάλυση; Ένζυμα; Μη συμβατικά συστήματα; Εστέρες κυτταρίνης; Θερμοπλαστικά; Ιοντικά υγρά; Υπερκρίσιμα ρευστά; Biocatalysis; Enzymes; Non conventional media; Cellulose esters; Thermoplastics; Ionic liquids; Supercritical fluids; Επιστήμες Μηχανικού και Τεχνολογία; Επιστήμη Χημικού Μηχανικού; Άλλες Επιστήμες Μηχανικού και Τεχνολογίες; Engineering and Technology; Chemical Engineering; Other Engineering and Technologies; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10442/hedi/33309; https://doi.org/10.12681/eadd/33309

The present study focuses on the enzymatic acylation of cellulose. Aliphatic esters of cellulose have recently raised the interest on the field of biopolymers, because of their thermoplastic properties. Due to the extended intra- and intermolecular hydrogen bonding between the cellulose chains, this biopolymer has a high crystalline structure. As a result it is completely insoluble in water or in common solvents leading to difficulties in chemical manipulation. In this work there have been developed two different processes in order to open the strict structure of cellulose and make its hydroxyl groups as permeable as possible. In the first methodology, cellulose (Avicel and fibrous) was putted into specific ionic liquids ([bmim]Cl, [emim]OAc), in order to facilitate the unwrap of the structure of the polysaccharide molecule and make it accessible to the enzyme. Thus, after this pretreatment the enzymatic esterification reaction was tested using various media (organic solvents, ionic liquids, solvent free systems). There were used three different acyl donors: vinyl propionate, vinyl laurate and vinyl stearate. The biocatalysts used were the following hydrolases: lyophilized lipase B Candida αntarctica, lyophilized lipase Candida cylindracea, lyophilized lipase Aspergillus niger, lyophilized lipase Rhizomucor miehei, immobilized lipase B Candida antarctica, lyophilized esterase from hog liver, immobilized esterase from hog liver and immobilized cutinase Fusarium solani pisi. From the reaction systems tested, only the solvent free were able to produce the cellulose esters. The enzymes capable of catalyzing the acylation of cellulose were found to be the lyophilized and immobilized esterases from hog liver and the immobilized cutinase from Fusarium solani pisi, while the lipases used did not show any catalytic activity. In order to investigate those reactions further, a number of parameters that affect the reaction course were also studied. Cellulose esters of propionate, laurate and stearate were synthesized with a ...