Synthesis and Application of New Multibranched–Linear–Multibranched Fluorinated Copolymer as Demulsifiers for Naphthenic Compounds Stabilized Emulsion

Abstract

• A series of novel fluorinated copolymer with multibranched–linear–multibranched structure were prepared. • The demulsification process of the copolymers in naphthenic acids and sodium naphthenates stabilized emulsions were evaluated. • The relationship between polymer structure and demulsification performance was discussed. To deal with the demulsification of emulsion stabilized by naphthenic compounds, a series of multibranched–linear–multibranched (MLM) copolymer were designed and synthesized. The hydrophilic core with MLM structure is constructed by anionic ring-opening multibranching polymerization (ROMBP) of glycidol with poly (ethylene glycol). The amphophobic arms are grafted by atom transfer radical polymerization (ATRP) of 2, 2, 2-trifluoroethyl methacrylate (TFEMA). The demulsification performance of the MLM copolymer in n-octane/water emulsion stabilized by naphthenic acids (NAs) and sodium naphthenates (Na-NAs) were evaluated. The influences of copolymer dosage, temperature and Na-NAs/NAs ratio on the demulsification efficiency were investigated in detail. Compared with the blank sample settled for 90 min, the fluorinated MLM copolymer with medium HLB value promoted the demulsification efficiency from 50% to 92%. By analyzing the correlation between the polymer structure and demulsification performance, it can be considered that the PEG segment improved the low solubility of the fluorinated copolymer caused by the solvophobic nature of fluorinated groups. The amphophobic effect of the fluorinated group not only accelerates the diffusion process of polymer molecules from the bulk to the interface, but also reduces the rigidity of the interface film by repelling the original interface active material, and produces effective demulsification.