Surfactant mechanism

Abele, S., Gauthier, C., Graillat, C. and Guyot, A. (2000) Films from styrene-butyl acrylate lattices using maleic or succinic surfactants mechanical properties, water rebound and grafting of the surfactants. Polymer, 41, 1147-55. 

Faizon, M., A. Nielsch, and M.D. Burke (1986). Denaturation of cytochrome P-450 by indo-methacin and other non-steroidal anti-inflammatory drugs Evidence for a surfactant mechanism and a selective effect of a p-chlorophenyl moiety. Biochem. Pharmacol. 35, 4019—4024. 

Slack and T. Horbett, unpublished observations). These latter observations support the generalized mixed surfactant mechanism as an explanation of the Vroman effect. 

Previously published J. Venzmer, S. P. Wilkowski, "Trisiloxane Surfactants — Mechanisms of Spreading and Wetting , Pesticide Formulations and Application Systems, 18, ASTM STP 1347, (Eds J. D. Nalewaja, G. R. Goss, R. S. Tann), American Society for Testing and Materials, 1998. 

PLLA/PDLLA blends with different concentration of surfactant, mechanical properties of PLLA/PDLLA/2% surfactant blends, mechanical properties of PLLA/PCL blends and mechanical properties of PLLA/PCL/2% surfactant blends are shown in Table 4.8 - 4.16, respectively. 

Venzer, J. and Wilkowski, S. P., Trisiloxane surfactants - mechanism of spreading and wetting, in Pesticide Formulations and Applications Systems, Vol. 18, ASTM Special Technical Publication, STP 1347, American Society for Testing and Materials, West Conshohocken, PA, 1998, pp. 140-151. 

Hemandez-Barajas J, Hunkeler DJ. Inverse-emulsion polymerization of acrylamide using block copolymeric surfactants mechanism, kinetics and modelhng. Polymer 1997 38 437 7. 

Uses Surfactant mechanical and chemical stabilizer for latex Properties Liq. 55% act. 

Surfactant-coated surfaces may also rearrange on contact with a liquid as shown by Israelachvili and co-workers [77]. This mechanism helps to explain hysteresis occurring on otherwise smooth and homogeneous surfaces. 

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

In addition to lowering the interfacial tension between a soil and water, a surfactant can play an equally important role by partitioning into the oily phase carrying water with it [232]. This reverse solubilization process aids hydrody-namically controlled removal mechanisms. The partitioning of surface-active agents between oil and water has been the subject of fundamental studies by Grieser and co-workers [197, 233]. 

An important aspect of the stabilization of emulsions by adsorbed films is that of the role played by the film in resisting the coalescence of two droplets of inner phase. Such coalescence involves a local mechanical compression at the point of encounter that would be resisted (much as in the approach of two boundary lubricated surfaces discussed in Section XII-7B) and then, if coalescence is to occur, the discharge from the surface region of some of the surfactant material. 

FT-EPR spectra of the ZnTPPS/DQ system in a solution of cetyltriinethylaininonium chloride (CTAC), a cationic surfactant, are shown in figme BE 16.21. As in the TX100 solution, both donor and acceptor are associated with the micelles in the CTAC solution. The spectra of DQ at delays after the laser flash of less than 5 ps clearly show polarization from the SCRP mechanism. While SCRPs were too short-lived to be observed in TXlOO solution, they clearly have a long lifetime in this case. Van Willigen and co-workers... 

A considerable number of experimental extensions have been developed in recent years. Luckliam et al [5] and Dan [ ] review examples of dynamic measurements in the SFA. Studying the visco-elastic response of surfactant films [ ] or adsorbed polymers [7, 9] promises to yield new insights into molecular mechanisms of frictional energy loss in boundary-lubricated systems [28, 70]. 

Block copolymers are closer to blends of homopolymers in properties, but without the latter s tendency to undergo phase separation. As a matter of fact, diblock copolymers can be used as surfactants to bind immiscible homopolymer blends together and thus improve their mechanical properties. Block copolymers are generally prepared by sequential addition of monomers to living polymers, rather than by depending on the improbable rjr2 > 1 criterion in monomers. 

Quick-breaking foams consist of a miscible solvent system such ethanol (qv) [64-17-5] and water, and a surfactant that is soluble in one of the solvents but not in both. These foams are advantageous for topical appHcation of pharmaceuticals because, once the foam hits the affected area, the foam coUapses, deUvering the product to the wound without further injury from mechanical dispersion. This method is especially usehil for treatment of bums. Some personal products such as nail poHsh remover and after-shave lotion have also been formulated as quick-breaking foams. 

Cake Dewatering. Dewatering (qv), identified as a separate entity in filtration, is used to reduce the moisture content of filter cakes either by mechanical compression or by air displacement under vacuum pressure or drainage in a gravitational or centrifugal system. Dewatering of cakes is enhanced by addition of dewatering aids to the suspensions in the form of surfactants that reduce surface tension. 

Urea.—Forma.IdehydeResins. Cellular urea—formaldehyde resins can be prepared in the following manner an aqueous solution containing surfactant and catalyst is made into a low density, fine-celled foam by dispersing air into it mechanically. A second aqueous solution consisting of partially cured urea—formaldehyde resin is then mixed into the foam by mechanical agitation. The catalyst in the initial foam causes the dispersed resin to cure in the cellular state. The resultant hardened foam is dried at elevated temperatures. Densities as low as 8 kg/m can be obtained by this method (117). 

The Vanderbilt process involves the mechanical frothing of air into a plastisol containing proprietary surfactants by means of an Oakes foamer or a Hobart-type batch whip. The resulting stable froth is spread or molded in its final form, then gelled and fused under controlled heat. The fused product is open-ceUed with fine cell size and density as low as 160 kg/m (10 lbs/fT). 

---