Green Williamson enhancement of the hydrophobic properties of cellulose fibers: thermodynamic study and application to elaborate rosemary essential oil (REO) biodegradable plastic coacervates

Abstract

In this paper, the dispersion encapsulation was investigated as new process to elaborate the principal active (PA) loaded biodegradable plastic coacervates, which designs a model of vector system and drug delivery matrix. The Rosemary Essential Oil (REO) (~ 54%w) was wrapped, as PA-model, in Benzyl cellulose acrylate (BCac, DSBnz ~ 1.4 and DSAcr ~ 0.4) coacervates that elaborated in the dispersing aqueous phase as new cellulose derivative. The advantage of this modification is to ensure the transition from hydrophilic to hydrophobic character of the cellulosic shell during the encapsulation process, which leads to encapsulation in one step. Indeed, during the reaction, the dispersive forces, generated by the grafting reaction, disturb the hydrophilic character of the water-soluble cellulose acrylate (Cac0.4). Then, the hydrophobic behavior, acquired by the grafted benzylic entities, increases the BCac-affinity to the organic compounds (oily dispersed phase). Therefore, the migration of the resulting polymer chains to the EO-rich (discontinuous) micellar dispersed phase, to form a biphasic micellar membrane, is strongly suggested. Experimental investigations, such as the relationship between the degree of substitution (DS) and the demixing behavior of the polymer solutions, are in good agreement with the theoretical interpretations basing on the Flory–Huggins thermodynamic theory. The results showed a high DS effect on the physicochemical properties, especially the molar Gibbs free energy of mixing.