Preparation And Application Of High Oil-carrying Organic Hollow Mesoporous Silica Pickering Emulsion

The microplastics added in personal care products have posed threat to the safety of the environment and human health.So,it is urgent to find an environmentally friendly substitute for microplastics in personal care products.Polymer-inorganic materials,which combine the advantages of easy processing,wide sources and good flexibility of organic components,as well as the mechanical and controllable morphology of their inorganic counterparts,overcome the poor high temperature resistance of polymers,low mechanical strength,poor encapsulation and low sealing of inorganic materials.Therefore,they have broad development space and application prospects.Studies have shown that hollow mesoporous silica nanoparticles are particularly valuable because of their large internal space and pore structure,which can provide high loading capacity and slow-release properties for guest molecules.However,the guest molecules are encapsulated by the hollow mesoporous silica material mainly by the impregnation method,and the traditional impregnation method requires higher hydrophilic and hydrophobic properties of the encapsulated guest molecules.In order to increase the adsorption performance of the hollow mesoporous silica to the essential oil,the hollow mesoporous silica need to be hydrophobic modified.The effects of the addition amount of organosilane deposited on the shell,the addition amount of cetyltrimethylammonium chloride（CTAC）and the etching time influence on organic hollow mesoporous silica were discussed by using pre-modification method and selective etching method,and then n-octyltrimethoxysilane（OTMS）was used as organic hydrophobic agent to prepare organic hollow mesoporous silica materials.At the same time,using the hollow mesoporous silica as the nano-carrier,the effects of the amount of silicon source deposited on the shell,the addition of ammonium hydroxide solution,the proportion of OTMS and the addition of CTAC on the WCA of organic hollow mesoporous silica and its loading capacity to SEO were investigated.A novel hollow mesoporous silica with high loading capacity and good adsorption was designed to load sandalwood essential oil in the form of nano-particle cavity and Pickering emulsion.The morphology of the obtained material was characterized by SEM and TEM.It was found that the materials were spherical hollow mesoporous structure with a particle size of about 222 nm and an inner diameter of about 175 nm.BET and SAXRD were used to analyze the organic hollow mesoporous silica.According to the Barret-Joyner-Halenda（BJH）method,the surface area and pore volume of the mesopores were 86.48 m² g^-1 and 0.188 cm³ g^-1,respectively.The mesoporous pore size was about 3.3 nm.The water contact angle was 90.4°.The elemental analysis of organic hollow mesoporous silica using EDS and XPS proved that OTMS and TEOS were successfully hydrolyzed and condensed to form silicon shell.The results of CLSM and FTIR showed that sandalwood essential oil（SEO）was not only absorbed into the internal space of the organic hollow mesoporous silica,but also formed Pickering emulsion with the organic hollow mesoporous silica.The loading capacity of SEO was as high as 40%,which can be stable for up to 21 hours.TG showed that SEO was encapsulated by organic hollow mesoporous silica,which can not only reduce the volatility of SEO,but also improve the thermal stability of SEO.The obtained organic hollow mesoporous silica Pickering emulsion in the best stable state was applied to the skin layer by spraying method to obtain a long-lasting fragrance skin layer,which can achieve a continuous release effect of 90 days.