Wetting, foaming, and emulsification properties of novel methyltriphenylphosphonium carboxylate ionic liquid surfactants

Abstract

Novel methyltriphenylphosphonium carboxylate ionic liquid (IL) surfactants [Ph3PCH3][CH3(CH2)6COO] (MTPP-O), [Ph3PCH3][CH3(CH2)8COO] (MTPP-D), [Ph3PCH3][CH3(CH2)10COO] (MTPP-L), [Ph3PCH3][CH3(CH2)12COO] (MTPP-M), [Ph3PCH3][CH3(CH2)14COO] (MTPP-P), [Ph3PCH3][CH3(CH2)16COO] (MTPP-S) were synthesized via quaternization triphenylphosphine with dimethyl carbonate and anion exchange with different carboxylic acids successively. The structures of these IL surfactants were confirmed by FT-IR and 1H-NMR. Meanwhile, the wetting, foaming, and emulsification properties of these IL surfactants were studied in this paper. The results revealed that methyltriphenylphosphonium carboxylate IL surfactants have lower foaming properties than quaternary ammonium salts with the same anionic units. And, these IL surfactants show better emulsification ability to soybean oil than that of liquid paraffin. Furthermore, contact angle results indicated that these IL surfactants have different wettability for parafilm and the contact angle increases at a higher concentration for MTPP-L, MTPP-M, and MTPP-P.