Synthesis and properties of dehydroabietyl glycidyl ether grafted hydroxypropyl chitosan

A nonionic surfactant based on chitosan and rosin, i.e. dehydroabietyl glycidyl ether grafted hydroxypropyl chitosan (DAGE-g-HPCS), was synthesized for the first time through reaction between hydroxypropyl chitosan (HPCS) and dehydroabietyl glycidyl ether (DAGE). The surface activities of DAGE-g-HPCS in aqueous solution were investigated via determination of surface tension, and its emulsifying ability was evaluated according to the stability time of emulsion composed of benzene-water with DAGE-g-HPCS as emulsifier; the foam stability was evaluated using the oscillation method. Through modulating the molecular weight of HPCS and the grafting degree (DG) of DAGE-g-HPCS, the emulsion stability and foam stability were surprisingly controllable. Compared to HPCS and specific emulsifier, the stability time of emulsion composed of benzene-water with DAGE-g-HPCS showed a remarkable performance with DG of 16.5% as the emulsifier was 7320 s, and the foam retention of DAGE-g-HPCS with 2.0 g·L-1 was 91.5%. Simultaneously, the critical micelle concentration (CMC) of DAGE-g-HPCS decreased with increased DG, while the emulsifying ability and foam stability exhibited opposite trend. The CMC, emulsifying ability, and foam stability of DAGE-g-HPCS increased with decreased HPCS molecular weight. These results demonstrated that the DAGE-g-HPCS was an excellent surfactant that should be considered as a promising substitute for petrochemical nonionic surfactant.