Influence of surface treatment of SiO2 and stirring rate on fragrant oil release behavior of poly(ε-caprolactone) microcapsules

In this work, the fragrant oil release behavior of poly(c-caprolactone) (PCL) microcapsules containing SiO2 was investigated. The SiO2 was chemically treated in 10, 20, and 30 wt% hydrochloric acid and sodium hydroxide. The acid and base values were determined. by Boehm's titration technique and N-2/77 K adsorption isotherm characteristics, the specific surface area and total pore volume were studied by BET. The PCL microcapsules containing SiO2 and fragrant oil were prepared by oil-in-water (o/w) emulsion solvent eyaporation method. The shape and surface of PCL microcapsules were observed using image analyzer and scanning electron microscope (SEM). The fragrant oil release behavior of PCL microcapsules was characterized using UV/vis. spectra. The average diameters of PCL microcapsules were decreased from 35 to 21 pm with increasing stirring rate. It was found that in the case of acidic treatment the fragrant oil adsorption capacity and release rate were increased due to the increase of specific surface area and acid value. In the case of basic treatment, the fragrant oil adsorption capacity and release rate were decreased due to the decrease of specific surface area and the increase of acid-base interactions between SiO2-NaOH and fragrant oil with increasing base value Of SiO2.