Preparation Of Amphiphilic Alginic Acid Derivatives/Multi-Walled Carbon Nanotubes Dispersion System And Study On The Emulsion Stability

Emulsion is a system composed of two immiscible liquids,one of which is dispersed in the other.Due to the high surface energy at the interface between immiscible phases,emulsions are usually thermodynamically unstable.The polymer forms a three-dimensional network through the entanglement of molecular chains and chemical crosslinking,which has the properties of colloidal particles;nanoparticles have a high surface activity,and both can be used to stabilize emulsions.As a widely available natural biomacromolecule,sodium alginate has good biocompatibility and biodegradability.In this paper,nucleophilic reagent tetrabutylammonium alginate(TBA-Alg)was prepared using alginic acid as raw material.The amphiphilic alginic acid derivative benzyl alginate(Bn-Alg)and aggregation were further obtained by S_N2 bimolecular nucleophilic substitution reaction.Induced luminescent amphiphilic alginic acid derivative alginic acid tetrastyrene ester(AIE-Alg).Fourier infrared spectroscopy(FT-IR),nuclear magnetic resonance hydrogen spectroscopy(1H NMR)and ultraviolet spectroscopy showed that TBA-Alg,Bn-Alg and AIE-Alg were successfully synthesized.Due to the S_N2 reaction,an ester is formed between the carboxyl group on alginic acid and benzyl bromide or[1-4(-bromomethylphenyl)-1,1,2-triphenyl]ethylene,which destroys the original alginic acid molecule Hydrogen bonding leads to a slightly lower thermal stability of Bn-Alg and AIE-Alg compared to the original alginic acid.The results of molecular fluorescence spectroscopy(FL)show that AIE-Alg molecules have higher surface activity compared with protoalginic acid.Dynamic light scattering(DLS)and transmission electron microscopy(TEM)results show that the particle size of Bn-Alg and AIE-Alg micelles presents a multi-distribution trend;the addition of Na+will electrostatically shield the polymer chain ionic groups(COO-)The effect reduces the zeta potential and weakens the electrostatic repulsion.In addition,Acetobacter xylinum cultured with AIE-Alg as a carbon source can be observed under a laser confocal microscope(CLSM).Using the synthetic products Bn-Alg and AIE-Alg as dispersants,the carbon material multi-wall carbon nanotubes(MWCNT)were stably dispersed by ball milling.Use ultraviolet spectroscopy to determine the relative concentration of the dispersion system,obtain the zeta potential of the dispersion system by DLS,and analyze the dispersion stability of the Bn-Alg/MWCNT and AIE-Alg/MWCNT systems by standing observation and Turbiscan Lab Expert stability analyzer.The experimental results show that the concentration of the amphiphilic alginic acid derivative is the most important factor affecting the stability of the dispersion system.Successfully prepared four emulsion systems:(0.1?1.6 g/L)Bn-Alg/MWCNT;Bn-Alg/MWCNT(0.1?4.0 mg/ml);(0.1?2.0 g/L)AIE-Alg;AIE-Alg/MWCNT(0.1?1.5mg/ml)emulsion.Through static observation,Turbiscan Lab Expert stability analyzer to explore the influence of different factors on the stability of the emulsion,and using optical microscope,scanning electron microscope(SEM)and laser confocal scanning microscope(CLSM)to observe the morphology of the emulsion,using rheology The instrument measures the viscosity and viscoelasticity of the emulsion.The results showed that increasing the concentration of amphiphilic alginic acid derivatives and appropriately increasing the content of MWCNT helped to improve the stability of the emulsion,and the resulting emulsions all exhibited gel-like viscoelasticity.