Preparation of Cotelomers of Acrylic Acid and n-Hexyl, 2-Ethylhexyl or n-Dodecyl Acrylate and Their Properties as Multi-Alkylated Surfactants

Multi-alkylated surfactants of cotelomers of alkyl acrylate and acrylic acid (xRmA-yAA; x, y and m mean number of alkyl chains, number of hydrophilic functions and alkyl chain length, respectively) were prepared by cotelomerization of n-hexyl acrylate, 2-ethylhexyl acrylate or n-dodecyl acrylate and acrylic acid in the presence of 2-aminoethanethiol hydrochloride and examined for surface activity. Surface tension of aqueous solution of xR6A-yAA, xR8A-yAA and xR12A-yAA was 28-32, 27-30 and 38-45mNm-1, respectively. Critical micelle concentration (cmc) decreased with greater number of alkyl chains and alkyl chain length in xR6A-yAA, xR8A-yAA and xR12A-yAA. 2.9R6A-2.3AA, 2.8R8A2.5AA and 2.7R12A-2.9AA in the presence of 300ppm of Ca2+ exhibited surface tension of 24, 28 and 33 mNm-1, respectively. 2.9R6A-2.3AA, possessing shorter alkyl chains, had high foam stability, while 2.8R8A-2.5AA, having branched alkyl chains, showed poor stability. Interface between aqueous solution of xR6A-yAA, xR8A-yAA and xR12A-yAA and toluene indicated interfacial tension of 11-13, 8-12 and 10-15mNm-1, respectively. Cmcs of cotelomers at the interface were 1/3 to 1/4 that of sodium ndodecanoate, a conventional surfactant. Emulsification of toluene was brought about by shaking with aqueous solution of cotelomers. A highly stable oil-in-water type emulsion was formed on using cotelomers having 2 to 3 alkyl chains.