New Green Williamson Hydrophobization of Cellulose: Thermodynamic Study and Application as New Process to Elaborate the Drug Delivery System Coacervates

Abstract

<title>Abstract</title> In this paper, the “<italic>Dispersive Coacervation (D-Coac)</italic>” was investigated as new process to elaborate new Rosemary Essential Oil (REO) dispersion-loaded biodegradable plastic coacervates. The active principle (REO) is coated using D-Coac as a model process for designing vector systems and drug delivery matrix. The REO (~ 54%w) was wrapped in Benzyl cellulose acrylate (BCac, DS_Bnz~1.4 and _DSAcr~0.4) coacervates, which is prepared in the dispersing aqueous phase. During the reaction, the dispersive forces "generated by the grafting reaction" disturb the hydrophilic character of the water-soluble cellulose acrylate (Cac0.4). At this stage, 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 is strongly suggested. As a result, the BCac0.4 chains form "Pickering" type membranes at the biphasic micellar interface, and therefore encapsulating the AP. Experimental investigations, such as the relationship between the degree of substitution (DS) and the demixing behavior of the polymer solutions, were in good agreement with the theoretical interpretations that based on <italic>the Flory-Huggins thermodynamic theory</italic>. In addition, the results showed a high DS effect on the physicochemical properties, especially the <italic>molar Gibbs free energy</italic> of mixing.