Preparation And Performance Characterization Of MF Essential Oil Microcapsules

Microcapsules containing oil-based fragrances have been widely used in food,cosmetics,personal-care and household products,textiles and medicine.Various essential oils with only one component which were encapsuled via in situ polymerization of malemine-formaldehyde(MF)as an outer shell were reported.However,there has been nearly no publications in encapsulation of essential oils with multipule components.In addition,MF resin as a typical shell material,has attracted attention from many researchers since its excellent performances and the convenience on its preparation.However,the study on the MF pre-polymer preparation has been seldom mentioned,especially the reaction speed of MF pre-polymer in aqueous phase.At last the reaction mechanism of different protective colloids on the preparation of microcapsules is not very clear.Therefore,in this work,lily flower oil which has various components was encapsulated via in situ polymerization by using MF as the shell material.At the very beginning,MF pre-polymer was prepared by using different methods and then the polymerization rate of MF pre-polymer as a function of temperature,pH,the molar ratios of malemine to formaldehyde were studied;and then the influence of different protective colloids on the preparation of MF microcapsules were investigated.Finally,the influences of the experimental conditions on the preparation of lily flower oil microcapsules were studied.The main conclusions as follow:1)The reaction rate of MF pre-polymer was a function of temperature,pH,and the molar ratios of malemine to formaldehyde.By decreasing the temperature,the raction rate decreases.By decreasing pH,the raction rate increases.In addition,the molar ratio of melamine to formaldehyde is critical to the reaction rate.When the molar ratio of melamine to formaldehyde is 1:3,MF pre-polymer has the fastest reaction rate.2)It has been shown the performance of gelatin,polyvinyl alcohol(PVA)and Poly(acrylamide-co-acrylic)-partial sodium salt(P(AM-co-AA)-pS)on the preparation of MF microcapsules was not very good.Gelatin and PVA molecules impeded the MF pre-polymers move to the suface of essential oil droplets during the preparation process.However,P(AM-co-AA)-Ps was unabled to disperse essential oils well.SMA-520 was the only protective colloid which can both effectively disperse essential oils and promote the migration and solidification of MF prepolymers to the surface of essential oil droplets during the preparation process.3)The preparation of microcapsules was influenced by the protective colloid concentration,O/W ratio,reaction temperature and shell-core ratio.The particle size of microcapsules gradually decreases with the increase of the concentration of SMA-520.As the proportion of O/W ratio decreases,the yield of microcapsules decreases.4)As the reaction temperature or shell-core ratio decreases,increase the reaction time to ensure the microcapsules keep sphere shape in dry state.As the shell-core ratio increases,the release ability of microcapsules decreases.