Preparation And Application Of Starch-based Particle Stabilized Pickering High Internal Phase Emulsions

In this paper,the stability and regulation of Pickering high internal phase emulsions(Pickering HIPEs)were realized by using functional starch-based nanoparticles as stabilizer,and the application of Pickering emulsion in the field of controlled release and interfacial biocatalysis were explored.In addition,the design and application of recyclable Pickering emulsion polymerization,multi-functional opening materials and dual-phase gel materials were further studied through the multi-phase Pickering emulsion polymerization technology.The specific contents are as follows:1.starch was modified by butyl glycidyl ether(BGE),and starch nanoparticles with particle size of about 120 nm were successfully prepared by solvent replacement method.The introduction of functional 2-hydroxy-3-butoxy propyl group not only improved the hydrophobicity of starch,but also endowed starch particles with temperature responsiveness.The size of starch nanoparticles increased with the increase of temperature.Subsequently,different concentrations(0.5-4.0 wt%)of temperaturesensitive starch nanoparticles were used as efficient stabilizers to prepare O/W Pickering HIPEs,and then the obtained Pickering HIPE was used as a nutrient container for the encapsulation and controlled release of nutrients(β-carotene).In vitro release experiments showed that,the release of this system could be controlled by adjusting the temperature.It was found that Pickering HIPEs had ultra-high stability and did not demulsify after one month.Moreover,increasing the concentration of nanoparticles was beneficial to the formation of stable and rigid Pickering HIPEs.2.A switchable Pickering HIPEs with transition between emulsification and demulsification triggered by temperature as controllable scaffolds to proceed efficient biocatalysis.The thermo-responsive Pickering HIPEs were stabilized by Candida Antarctica lipase B(CALB)immobilized starch particles modified with BGE and glycidyl trimethyl ammonium chloride(GTAC).Thanks to the enzyme being immobilized to the thermo-responsive emulsifier particles,and the ultrahigh specific surface area provided by the Pickering HIPEs,the separation and reuse process were simplifed and the catalytic efficiency was improved simultaneously.In addition,the switching temperature could be precisely well-tuned by adjusting the substitution degree of modified starches to meet the temperature required by various enzymes.3.A thermoresponsive starch particles(HBPS)were synthesized by a simple chemical modification with BGE,and used as an effective stabilizer for Pickering emulsion formation.The state of the resulting emulsions could be switched by adjusting the temperature,with emulsification at low temperatures(lower than lower critical solution temperature(LCST)of HBPS)and demulsification at high temperatures(higher than the LCST of HBPS).Based on this temperature-switchable emulsion system,a straightforward recyclable Pickering emulsion polymerization was designed and used for the fabrication of polymer spheres.The distinct superwettability(superlipophilicity and underoil superhydrophobicity),porosity,and small pore size of polymer spheres achieved resulted in excellent performance in separating oil-in-water and water-in-oil emulsions with separation efficiencies over 99.9%.4.A macroporous polymers with controllable opening and closing reversible configuration were obtained by using Pickering HIPEs as templets.The pore size of macroporous polymers could be adjusted by temperature,and the pore throat could be turn on or off through controlling temperature switch as well(like lungs breathing).In addition,the "switching temperature" could be adjusted to the desired temperature range by adding comonomers,such as acrylamide.The reversible structure and hydrophilic-hydrophobic changes of the macroporous polymers were used to realize the controlled capture and release of bovine albumin(BSA).5.A facile method for preparing organohydrogels with micron-scale interpenetrating network by using Pickering emulsion as template through an in situ one-pot simultaneous synthesis in which monomers were added both to the emulsion’s external phase and internal phase.The obtained gels possessed excellent enchancing mechanical and anti-swelling properties benefitting from micron-scale interpenetrating networks combining two intrinsically incompatible components.In addition,the effects of synthetic conditions on its structure and mechanical properties were investigated in detail.