Surfactant affected

Lin, S. Y. 1987. Pluronic surfactants affecting diazepam solubility, compatibility, and absorption from i.v. admixture solutions Parenteral Sci. Technol. 41 83-87. 

Surfactants are a group of chemicals that touch our everyday lives in countless ways. They are present in our food, our drinks, the products that we use to clean ourselves, cars that we drive and clothes that we wear. Surfactants affect us all and enable us to clean, prepare and process countless articles around us. The quality of our lives and our health is related to the availability and safe use of surfactants. 

When specifying an anionic surfactant for an application, it is important to understand how the composition of the raw material (especially that of the hydrophobe) influences the performance of the surfactant and the properties of the formulated product. In looking at the properties of each surfactant type, the basic chemistry will be considered together with sources of hydrophobe and the manufacturing process used to functionalise them. How the composition of the surfactant affects its performance and physical properties will be examined together with how these properties lead to the applications of the surfactant. 

On one hand it is investigated how the addition of cationic surfactants affects the pattern collapse of 193 nm photoresist lines. On the other hand, the adsorption of the surfactant on model photoresist surfaces is explored by a variety of surface chemical methods. Of special interest is how the surfactant changes the surface properties of the photoresist as surface potential and wettability. For an optimum modelling of the properties of real photoresist structures, both unexposed photoresists and photoresists that have been UV exposed, baked and developed are studied. 

Goal of the present study was to investigate how solutions of cationic surfactants affect the pattern collapse in the photolithographic sub-100 nm structuring. On one hand, the solutions were applied directly in the photolithographic process to investigate their ability to reduce the pattern collapse. On the other hand, the adsorption of the surfactant on flat model photoresist layers was studied using a variety of physicochemical characterization methods and its influence on the capillary forces was determined. 

Naturally occurring micellar systems, such as phospholipids and bile salts (e.g. cholic and desoxycholic acids, as well as surfactants affect the rates of numerous chemical reactions in vivo and in vitro (Hanahan, 1960 Kavanau, 1965 Knaak et al., 1966a, b Elworthy et al., 1968 Marriott, 1969). The effects of micellization on enzymatic reactions and other biochemical processes have been discussed by Elworthy et al. (1968), Jencks (1969), and Mysels (1969). 

The above cited information showed unanimously that, in a mixed-surfactant system of emulsion polymerization, the composition of the mixed surfactant affects the rate of polymerization. Since by Harkins-Smith-Ewart theory, rate of polymerization is proportional to the total number of particles in the system, composition of mixed surfactants seems to affect the efficiency of nucleation. 

Because HIC is based on surface-tension phenomena, changing those characteristics by the addition of surfactants affects retention. In a study of the effects of surfactants on retention of proteins by HIC, the addition of CHAPS 3-[(3-cholamidopropyl) di-methylammonio]-l-propane sulfonate to the mobile phase resulted in shortened retention, improvement of peak shape, and a change in peak order for enolase and bovine pancreatic trypsin inhibitor [8]. The effects were dependent on the concentration of the surfactant. Surfactants can usually be washed easily from hydrophobic interaction columns because the bonded phases are neither highly hydrophobic nor ionic. 

Beyond single component metal catalysts, the nanofabricated model catalysts can be used to study alloy catalysts, with compositions controlled by co-evaporation from two or more PVD sources. Alternatively, arrays of alternating particles or areas of two different materials can be made to study lateral communication between two types of catalysts at the nanoscale. For example, sequential reactions consisting of a first step on one type of catalyst and a second step on another catalyst particle could be studied systematically. The role of reactants and reaction intermediates as surfactants, affecting particle shape and morphology [163], will be possible to study in detail by in situ TEM studies in reactive environments. 

The change in charge with pH of amphoteric surfactants affects their properties, such as wetting, detergency, and foaming. Atthe i.e.p., the properties of amphoterics resemble those of nonionics very closely, but below and above the i.e.p. the properties shift towards those of cationic and anionic surfactants, respectively. Zwitterionic surfactants have excellent dermatological properties, and also exhibit low eye irritation consequently, they are frequently used in shampoos and other personal care products (e.g., cosmetics). 

Addition of a block copolymer, A-B, to immiscible blend of homopolymers A and B reduces the interfacial tension coefficient similarly as addition of a surfactant affects emulsions. Thus, the idea of the critical micelle concentration, CMC, and the limiting value of the interfacial tension coefficient, can be applied to polymer... 

The presence of EO groups in the oxyethylated sodium alkyl sulphate molecule (CnEOmS04Na), similarly to other ionic surfactants, affects significantly the adsorption behaviour at the water/air interface [76]. The experimental data for n, = 8, 10 and 12, and m = 1,2, 3 obtained in [69, 76] are presented in Fig. 3.49. For comparison the isotherms for sodium alkyl sulphates with the same hydrocarbon chain length are shown. One can see that the... 

When we have small water pools in a continuous oil phase an emulsion is produced that can be stabilized by the introduction of surfactants such as cetyl trimethyl ammonium bromide. The microemulsions thus produced can serve as nanoreactors for the synthesis of nanorods. The ratio of water to surfactant affects the size of the nanoreactor and this in turn can influence the size and shape of nanorods. Nanorods of oxides, metals, and semiconductors have been synthesized examples include Ce02, BaTiOa, BaCr04, Ag, and CdSe (25). 

It was earlier shown that a layer of epoxy polymer on a metal siuface does not change the polymer condition [422, 423]. Treatment of the basalt surface with surfactant affects the glass-transition temperature of the polymer. As seen from Fig. 9.1, for a low-energy siuface (basalt, treated with surfactant) the polymer glass-transition temperature does not depend on variation of the thickness of the pol5rmer layer. 

The application properties of many latexes are strongly affected by the chemistry of the surface of the polymer particles. Relatively small amounts (1-2 wt% based on monomers) of acidic monomers (e.g., acrylic acid, AA) are frequently used in the manufacture of latexes. Because this monomer is water-soluble, upon polymerization, most of the AA-rich polymer chains are located at the surface of the polymer particles. The presence of AA at the surface of the polymer particles is beneficial for both the stability of the latex [11] and the application properties (e.g., both the shear strength of the adhesives [ 12] and the pick strength of coated paper [9] increase with the AA content). In addition, the type and amount of surfactant affects application properties such as colloidal stability and water sensitivity of the film [13]. 

The presence of both polymers and surfactants affects phase behavior as well. For instance, the presence of SDS increases the cloud point temperature of PEO. The negatively charged micelles produce an electrical repulsion between polymer chains that impedes their aggregation to form a polymer-rich phase. (SDS... 

In many cases, surfactant is applied to the fiber for rewetting, lubricity, antistatic, or other purposes, while in other cases the surfactant affects the processing solution in some way, such as stabilization of an emulsion or dispersion. Surfactant residues are present in fiber, yam, or fabric from applications in upstream operations. Oils and waxes on natmal fibers, fiber finishes on synthetic fibers, winding emulsion on yam, coning oil, yam finish, knitting oil, and warp size are examples of surfactant-containing residues found on textile substrates [10]. In addition to uses in which the surfactant is applied to the substrate, many textile processes use water-insoluble textile processing assistants that are applied from aqueous emulsions. Essentially all chemical specialties contain surfactants to improve solubility and dispersability and to suspend water-insoluble materials... 

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