Eric LEROY1, Frédérica FEUZING1,2, Jean-Pierre MBAKIDI2, Bruno PONTOIRE3, Delphine QUÉVEAU1, Guillaume ROELENS1, Denis LOURDIN3, Sandrine BOUQUILLON2
1Université de Nantes, Oniris, CNRS, GEPEA, UMR 6144, Saint Nazaire, France
2Institut de Chimie Moléculaire de Reims, CNRS UMR 7312, Université de Reims Champagne-Ardenne, Reims, France
3Biopolymers Interactions Assemblies Research Unit 1268 (BIA), INRAE, Nantes, France
Paramylon is a linear b-1,3-glucan produced by the microalgae Euglena Gracilis. Due to its native crystalline structure, involving hexagonally packed triple helices, paramylon is neither water soluble nor thermoplastic. While this latter property is generally obtained by chemical modification of paramylon, the present work demonstrates that using ionic liquids as plasticizers may be an alternative: A mixture of water with cholinium glycinate (40:60) allowed the thermomechanical processing of paramylon below 100°C by extrusion and hot-press into transparent films. The thermoplastic paramylon obtained consists of an amorphous matrix, self-reinforced by oriented triple helices packed as nanofibers. This results in a storage modulus ranging from 300 to 450 MPa at 25°C, depending on the plasticizer content, and in a tensile strain at break of 27%. For storage times larger than 1 month, a recrystallization of paramylon is observed, with an unidentified crystalline structure different from the native one.