The Preparation And Application Of Pickering Emulsion Stabilized By Polydopamine Nanoparticles

Pickering emulsions are a class of kinetically relatively stable disperse system consisting of two immiscible liquids stabilized by solid particles,which attracted much interest in the field of colloid science.In contrast to conventional surfactant stabilized traditional emulsions,Pickering emulsions have many advantages,such as low toxicity,less emulsifier consumption,and adjustable droplet size.Therefore,Pickering emulsions are widely applied in a broad range including emulsion polymerization,materials synthesis and drugs controllable release,etc.Over the past two decades,diverse kinds of Pickering emulsions stabilized by different types of particulate emulsifiers have been exploited.In this paper,preparation and application of polydopamine?PDA?nanoparticles stabilized Pickering emulsions were conducted.The main content included the following two parts:?1?Templated fabrication of colloidosomes by Pickering emulsion stabilized by PDA/CTAB complex.Firstly,PDA nanoparticles were synthesized by the self-polymerization of dopamine monomers under an alkaline condition using oxygen as the oxidant.By means of the electrostatic interaction,positive-charged CTAB could be readily adsorbed on the surfaces of PDA nanoparticles,forming PDA/CTAB complexes.Using PDA/CTAB complex as emulsifiers,toluene-in-water Pickering emulsion was prepared.PDA/CTAB-stabilized toluene-in-water Pickering emulsion was then applied as template for the formation of colloidasomes,where toluene oil contained reactive monomers of isophorone diisocyanate?IPDI?and trimethylolpropane tris?3-mercaptopropionate??TMMP?.By means of thiol-isocyanate click reaction occurred on oil-water interface,colloidosomes were readily formed.And Pickering emulsion that was stabilized by PDA nanoparticles alone was used as a control.The experimental results indicated that the utilization of PDA nanoparticles was inefficient,and the distribution of PDA nanoparticles on the surfaces of droplets was heterogeneous and ill-defined colloidosomes were achieved when PDA alone stabilized Pickering emulsion was used as a template.On the contrary,more PDA nanoparticles were transferred from water to oil-water interface and the nearly homogeneous distribution of emulsifiers on the surfaces of droplets for PDA/CTAB stabilized Pickering emulsion.Well-defined colloidosomes with adjustable thickness of shell were readily achieved templated by PDA/CTAB stabilized Pickering emulsion.And PDA nanoparticles were covalently attached on the cross-linked polythiourethanes.Using this method,the hydrophobic drugs,such as10-hydroxycamptothecin was facilely encapsulated in the interior of the formed colloidosomes.?2?N,O co-doped porous carbons:templated preparation and its application in capacitor.N,O co-doped porous carbons were prepared templated by n-decane-in-water Pickering emulsion.To this end,PEO-b-PS/PDA nanoparticles co-stabilized n-decane-in-water Pickering emulsion was prepared.Resorcinol,urea and formaldehyde were then added into the continuous water phase of the generated Pickering emulsion,followed by the adjustment of pH to⁹,resorcinol-urea-formaldehyde?RUF?resin microcapsules were achieved via the co-condensation reaction occurring at the oil-water interface and in the water phase.After the removal of the internal n-decane oil phase,RUF microcapsules were carbonized,leading to N,O co-doped porous carbon.The resulting N,O co-doped porous carbon was further applied for the formation of the supercapacitor,and the capacitance performances were investigated.The experimental results showed that the porous carbon derived from PEO-b-PS micelles stabilized Pickering emulsion exhibited a low specific surface area(281 m²g^-1)and the low total pore volume(0.178cm³ g^-1),and the fabricated supercapacitor exhibited poor capacitance performance.The specific capacitance was 153 F g^-11 at the current density of 0.5 A g^-1.However,the specific surface area and total pore volume of porous carbon materials originated from PEO-b-PS/PDA nanoparticles co-stabilized Pickering emulsion were 432 m² g^-1and 0.799 cm³ g^-1,respectively.The specific capacitance of the fabricated supercapacitor was 206 F.g^-1at the current density of 0.5 A g^-1.After the further activation with KOH,the specific surface area and total pore volume of the activated carbon were 2248 m² g^-11 and 1.147 cm³ g^-1,respectively.The specific capacitance of the fabricated supercapacitor with the activated carbon material was 340 F g^-1at the current density of 0.5 A g^-1.