Preparation And Applicaion Of Pickering Emulsions Stabilized By Laponite Particles Together With Quaternary Ammonium Salts And Carbon Quantum Dots

Recently, emulsions hvave been widely used. For instance, in the paper industry, the emulsions stabilized by Laponite not only increased the content of ASA, the properties and sizing performance of ASA emulsions stabilized by Laponite particles can also be highly enhanced. The appilcatin of solid particles would prevent the hydrolysis of the ASA and the formation of bubbles. However, it needs to adjust the hydrophily of the laponite particles to obtain stabile ASA emulsions stbilzed by Laponite. In this paper, to obtain stable emulsions we selected the Laponite as the stabilizer after it had been modified with short chain quaternary ammonium salts (Tetramethylammonium chloride, TMAC; Tetraethylammonium chloride, TEAC and Tetrabutyl ammonium chloride, TBAC) and carbon quantum dots, ASA and liquid paraffins as the oil to investigated the interactions between the three kinds of short chain quaternary ammonium salt and laponite or ASA; the property, stability and sizing performance of ASA emulsions; the preparation and characterization of carbon quantum and the mechanism of action with Laponite as well as the stability of liquid paraffin emulsions.It was found that, the quaternary ammonium salts moderately neutralized the negative charges of the particles, lowered the apparent viscosity, enhanced the hydrophobicity of the Lpaonite particles througuh ion exchange, favoring adsorption of Laponite particles on the ASA-water interface. TMAC significantly increased the turbidity, decreased the pH value of the Laponite particles and the interfacial tension between ASA water. The introduction of TEAC and TBAC had little effect on the pH value of the aqueous dispersion. When the added amount of TMAC, TEAC and TBAC reached 0.05,0.03 and 0.02 mmol/g based on Laponite, the as-prepared ASA emulsion had small droplet size and uniform droplet size distribution, and exhibited good creaming/coalescence stability. By using TMAC, TEAC and TBAC to modify Laponite particles, the hydrolysis and sizing performance of ASA emulsion were also improved. The sizing degree of the ASA emulsions stabilized by TMAC/TEAC/TBAC-modified-Laponite particles decreased about 8% after being kept for 120 min, was still higher than the ASA emulsions only stabilized with Laponite particles, which decressed about 25%. The ASA emulsions stabilized by TMAC/TEAC/TBAC-modified-Laponite particles would have the best sizing performance when volume fraction of ASA was 35%,35% and 30%, respectively.Herein, the CDs were synthesized by hydrothermal treatment of gelatin and used as both a co-stabilizer of particle stabilized emulsion and a fluorescent probe. The size of the CDs was ranged from 5 nm to 10 nm. The CDs carry litte amount of negative charges, emit green light under UV irradiation and the best excitation/emission length was 365 and 416nm, respectively. When mixed with laponite particles, it would induce aggregation of Laponite particles, significantly increase the turbidity of laponite dispersions. The CDs can regulate the wettability of laponite particles. The CDs itself has a certain surface activity and can reduce the surface tension and the interfacial tension between the quantum dots and liquid paraffin, but not change the interfacial tension between paraffin oil and Laponite aqueous dispersion when interacted with Laponite. The CDs can not play as the stabilizer of the emulsions. While interacted with Lponite, The introduction of CDs thus enhanced the stability of Laponite stabilized emulsions, promoted the formation of emulsions with fine and uniform droplets and the emulsion stability was significantly enhanced. It would promote the formation of W/O/W multiple emulsions when the CDs-to-Laponite mass ratio less than 45wt%. The size of the emulsion decreased with the increase of the carbon quantum dots, and simple O/W emulsion was formed. When the CDs-to-Laponite mass ratio exceeded 60wt%, the emulsions droplets size is small and uniform. The stability of the emulsion decreases with the decrease of the oil-water ratios and the emulsion would have good stability when the oli-water ratio was at the range of 3:1-1:1. Meanwhile, using CDs to co-stabilize emulsions with Laponite allowed the distribution of Laponite particles in emulsions to be traced and the emulsion to be contoured and it would be helpful for studying the stability mechanism of Pickering emulsion.