Novel cationic and amphiphilic pullulan derivatives I: Synthesis and characterization

Abstract

Cationic amphiphilic modified pullulan’s were obtained in two steps: firstly the synthesis of diethylaminoethylpullulan (DEAE-Pullulan) with DS 0 = 0.80 in water (all degrees of substitution (DS) are calculated in anhydroglucose units (AGU)) followed by the incorporation of different alkyl chains (C 10, C 12 and C 16) using Hoffmann alkylation reaction. Three alkylated derivatives (Y-Cx-DEAE-Pullulan) were produced with a degree of substitution of alkyl chains (Y = 100 DS Cx) of 40 in the case of C10 and C12 and 20 in the case of C16. The three samples contained two functional types: an amine function (DS N), dependent on pH and a quaternary ammonium function (DS N+) linked to a hydrophobic alkyl chain (DS Cx). Chemical characterizations were carried out by conductimetric measurements, elemental analysis and 1H NMR. The amphiphilic and associative properties have been confirmed by flow field flow fractionation (F4) coupled on-line with multi-angle laser light scattering (MALLS). The intermolecular associations were observed for DEAE-Pullulan and Y-Cx-DEAE-Pullulan in 0.1 M LiNO 3.