To study surface adsorption of cationic surfactants on a hydrophilic polymer latex, ζ-potential of styrene/2-hydroxyethyl methacrylate [P (St/HEMA)] copolymer latex was measured in aqueous solutions of alkyl pyridinium bromides (abbr. APB, CnH2n+1NC5H5Br; n=12 : DPB, n=14 : TPB and n=16 : HPB). Hydrophobic polystyrene (PS) latex was used as the reference sample. The amount of surfactant adsorbed per unit area of the latex was calculated from the ζ-potential value. With increasing concentration of surfactant, the sign of the ζ-potential of the latex changed from negative to positive and the amount of surfactant adsorbed increased. The surfactant adsorption increased with the hydrocarbon chain length of APB in the order HPB > TPB > DPB. These results can be explained by electrostatic bonds and the van der Waals force between the latex and surfactant. The amount of surfactant adsorbed on the P (St/HEMA) latex was less than that on the PS latex. The free energy of adsorption ΔG for a surfactant on a latex was calculated from parameters such as the slope of the ζ-log Cs (Cs : the concentration of surfactant) curve. The negative value of ΔG increased with chain length of the surfactant. Also this value on the P (St/HEMA) latex was less than that on the PS latex. The large positive value of the entropy of adsorption ΔG indicates the importance of entropic interactions and the formation of hydrophobic bonds as driving forces for adsorption of the surfactant on the latex surface. The ΔG for P (St/HEMA) latex had a smaller positive value than that for PS latex. It is concluded that the adsorbability of surfactant on P (St/HEMA) latex is lower than that on the PS latex, since hydrophilic poly-HEMA layer is present on the surface of the P (St/HEMA) latex.
New type polycarboxylates containing either ether linkages or ether and hydroxyl groups were prepared by the reaction of methyl α-D-glucopyranoside with ethyl diazoacetate (acetate-type) or diethyl diazomalonate (malonate-type), or by the air oxidation of ethoxylated methyl α-D-glucopyranoside with 5% platinum catalyst on carbon (acetate-type). Their building performance in detergents, sequestration capacity for Ca (II), dispersion capacity for MnO2 and biodegradabilities were determined and compared in these respects with sodium tripolyphosphate (STPP), disodium 3-oxapentanedioate (ODA) and trisodium citrate (CA). O-carboxymethylated methyl α-D-glucopyranoside was found to have better detergency building performance than that of ODA, but was slightly inferior to that of STPP. Malonate-type ether polycarboxylate showed building performance far superior to that of the corresponding acetate type ether polycarboxylates. Of the acetate-type builders tested in this report, tribasic acid was the most effective. These polycarboxylates derived from methyl α-D-glucopyranoside were found to be biodegradable under aerobic conditions. Binary mixtures of zeolite with these polycarboxylates showed synergistic properties in detergency powers.
Many studies have been carried out on the mechanism of the adsorption of anionic and cationic surfactants on textiles. The case of cationic and anionic surfactants used in combination has also been reported. In such a case, the cationic surfactant is treated as a dispersion and when used with excess anionic surfactant solution, it is not adsorbed on textiles. In the present research, it was found that if a cationic surfactant is used as a corpuscle (fine solid, over 10 μm) in the presence of excess anionics, adsorption on to various textiles becomes possible. For an understanding of this phenomenon, the work of adhesion (Wa) between an anionic/cationic surfactant complex and the surface of a textile was calculated, measuring the contact angle of 2 liquids with the complex by Wu's equation. Wa and the amount of adsorbed cationic surfactant on textiles were found to show a very close correlation. Thus, in an excess anionic surfactant solution, an anionic/cationic surfactant complex is apparently formed on the surface of a corpuscle of a cationic surfactant, and the work of adhession between this complex and each textile is related to the adsorption (or deposition) of a cationic surfactant on textiles.
The relationship between the surface tension change with time and the foam volume was investigated for a system containing anionic AOS, LAS and/or nonionic alkyl or s-alkyl poly (oxyethylene) ether with alkyl chains of the same length. Dynamic and equilibrium surface tension was measured by the vibrating jet and Wilhelmy's plate methods, respectively. The anionics showed similar foam volume and surface tension change with time. In regard to the nonionics, on increase in the number of moles of ethylene oxide per molecule was found to make the equilibrium surface tension higher and foam volume smaller. As for dynamic surface tension change, some difference was noted between the alkyl and s-alkyl poly (oxyethylene) ethers. That is, the dynamic surface tension of the s-alkyl poly (oxyethylene) ethers decreased with an increase in the number of moles of ethylene oxide per molecule (abbrev. “EOp”), but that of the alkyl poly (oxyethylene) ethers remained constant regardless of EOp. In AOS/nonionics mixed systems, a s-alkyl poly (oxyethylene) ethers having a high EOp gave lower dynamic surface tension and smaller foam volume.
To determine if solid wax esters are hydrolyzed by enzymes (lipase or esterase) they were dissolved in organic solvents followed by incubation with aqueous solutions of commercial enzymes at 45°C, 500 rpm. Among the commercial preparations of several microbial enzymes tested, lipases from Candida cylindracea and Rhizopus chinensis were found to act on vegetable wax esters such as rice bran wax, candelilla wax and esparto wax. The carnauba wax ester hardly underwent any hydrolysis by any lipase. There was virtually no reaction of the lipases with the above wax esters in aqueous reaction systems. The time courses of hydrolysis of the wax esters was noted to vary according to the particular lipase used. The amount of each lipase required to bring about the same extent of hydrolysis on the same wax ester differed significantly. These findings may be accounted for primarily on the basis of the substrate specificity of each lipase for the carbon chain length of alcohols and fatty acids which are constituents of the vegetable wax esters. The data of the present study demonstrate the enzymatical hydrolysis of solid wax esters. This is at variance with the generally held notion that solid waxes are not attacked by enzymes.
3-Methyl-4-octanolide (1), (Whisky lactone or Quercus lactone), was synthesized from crotonic acid and pentanal. The reaction of pentanal (3) with crotonic acid (4) provided 3-methyl-4-oxooctanoic acid (5) in a 66% yield, which was reduced by NaBH4 to give whisky lactone (1) in a 88% yield. Similarly, trans-3-methyl-4-nonanolide (2), one of the component of cognac, was prepared from crotonic acid and hexanal.