Synthesis And Demulsification Performance Of Linea Multi-block Fluorosilicone Polymers

Straight-run diesel oil contains a certain amount of naphthenic acid which affecting the quality of diesel seriously.And diesel often occur serious emulsification phenomenon in the process of alkaline washing.Thus,it is important to design an efficient and low-volume diesel demulsifier.In the first part of this paper,four fluorosilicone polymers with different lengths of fluorine segments were synthesized.Allylpolyethyleneglycol(PEG-allyl)was obtained via nucleophilic substitution reaction of Polyethylene glycol(PEG)and allyl Bromide,followed by hydrosilylation reaction of Allylpolyethyleneglycol with dimethyl monochloro-silicate(HSi(CH3)2Cl),the initiator(PEG-Si-Cl)was obtained.Finally,four kinds of fluorine-containing fluorosilicone polymers PEG-Si-TFEMA1-4 were prepared by ATRP method,using trifluoroethyl methacrylate(TFEMA)as monomer and adjusting the reaction temperature.The products were characterized by 1H NMR,13 C NMR,19 F NMR,FT-IR as well as GPC.The results showed that fluorosilicone polymers with clear chemical structure were successfully synthesized in our work.In the second part of this paper,the phase-separation performance of four fluorosilicone polymers was evaluated in diesel oil/water system,and the phase-separation mechanism for the fluorosilicone polymers was investigated with interfacial tension and interfacial viscoelasticity measurements.The results showed that the oil-water separation time decreased at first and then increased with the DP(degree of polymerization)of fluoride group.Especially,the diesel oil/water emulsion was separated by the polymer with fluoride DP =16 within 23 s at the concentration of 200mg/L.Moreover,the phase-separation performance of the kind of polymer was mainly prompted by decreasingthe elastic properties of the interfacial film,and the interfacial tension was not main factor to influence the phase-separation behavior.In the third part of this paper,the demulsification performance of four kinds of fluorosilicone polymers were studied in coal tar/water system.And the mechanism of demulsification were analyzed by interfacial tension and droplet fold experiment.The results showed that fluorosilicone polymers had little impact on the interfacial tension of the coal tar/water system.The main reason for the demulsification was that the fluorosilicone polymers,the fluoride group has a “hydrophobic and oleophobic” properties,which can produce rejection on film-forming substances of the emulsion droplet interface membrance,prompted a mass exchange between the inner and outer phase droplets phenomenon.It causes the droplets coalescence and eventually leads to demulsification.