Solution properties hydrophobically modified

Thuresson, K., B. Nystroem, G. Wang, and B. Lindman (1995). Effect of surfactant on structural and theimo-dynamic properties of aqueous solutions of hydrophobically modified ethyl (hydroxyethyl) cellulose. Langmuir 11(10) 3730-3736. 

After the cleaning process, other techniques are used to prepare the surface of the substrate for coating. Some techniques include drying, surface etching, and chemical surface preparation. Examples of chemical surface preparation include the formation of an oxide layer or the monolayer assembly of an adhesion promoter on the surface. These processes modify the surface of the substrates so as to facilitate the subsequent deposition process. In surface preparation, frequently, the hydrophilic/hydrophobic character of the surface is controlled to match the coating solution properties. For example, Van Driessche et al.19 reported on improving the wettability of Ni-4at%W tapes... 

In a dilute solution, when the polymer is in a coil state (Fig. 6a), the diffusion of hydrophobic particles into the coil is normally faster than the chemical reaction [53]. In this case, the local concentration of particles H inside the coil is practically the same as in the bulk. Therefore, we expect that at the initial stage, the reaction will lead to a random copolymer some of the P monomeric units will attach to H reagent and thereby they will acquire amphiphilic (A) properties P + H —A (Fig. 6b). As long as the number of modified A units is not too large, the chain remains in a swollen coillike conformation (Fig. 6b). However, when this number becomes sufficiently large, the hydrophobically modified polymer segments would tend to form... 

In simple terms, in aqueous media, micelles result in hydrophobic domains within the solution whereby the surfactant may solubilise or emulsify particular solutes. Hence, surfactants will modify solution properties both within the bulk of the solution and at interfaces. 

SURFACE ACTIVITY. The surface tension results for aqueous solutions of Polymer JR and Oxiatrlsof t are given In Figure 1. The hydrophobe modified polymers clearly show more surface activity than the unmodified polymer. The surface activity of the modified polymers as measured hy the surface tension criterion Is only moderate compared to conventional surfactants which exhibit ultimate surface tension values In the range of 20-40 mN/m. The effect of the molecular changes resulting In this moderate surface activity can, however, be considerable on other properties of the polymer, as will- be shown In subsequent sections. 

Wang TK, Iliopoulos I, Audebert R. Aqueous solution behavior of hydrophobically modified poly(acrylic acid). In Shalaby SW, McCormick C, Butler GB, eds. Water-Soluble Polymers Synthesis, Solution Properties, and Applications. ACS Symposium Series 467, 1991 218-231. 

Modification of poly(2-vinylpyridine) with a long-chain K-dodecyl bromide was the first published example of a polysoap in the literature [192]. (The term polysoap arises from the fact that the resulting modified polyelectrolyte displays similar properties to that of an ordinary soap [192,193].) Dependent on the aqueous solution conditions and the nature of the hydrophobe, modified polyelectrolytes can associate either intramolecularly or intermolecularly [194], and this has created interest from a technological perspective potential applications include use as associative thickeners and rheology modifiers [195]. 

The data on the chain-growth polymerization of hydrophobe-modified monomers are insufficient to provide a quantitative analysis of the influence of hydrophobe sequence lengths and placement in copolymers on solution properties. The concentration of the hydrophobe-modified monomer in the... 

Synthesis and Solution Properties of Hydrophobically Modified (Hydroxyethyl)cellulose... 

Hydrophobically modified water-soluble polymers (HMWSPs) exhibit enhanced solution viscosity and unique rheological properties. These properties can be explained in terms of intermolecular associations via hydrophobes. This chapter describes the synthesis and solution properties of HMWSPs, Particularly discussed are the solution properties of hydrophobically modified hydroxyethytjcellulose (HMHEC) in aqueous and surfactant systems, HMHECs interact with surfactants and thus modify solution viscosities. The structure and the concentration of the surfactant dictate the solution behavior of HMHEC. The unique solution properties of HMHEC can be exploited to meet industrial demands for specific formulations or applications. 

A few years ago, Landoll (2-4) reported that grafting a small amount of long-chain alkyl hydrophobes onto a nonionic water-soluble polymer leads to associative thickening behavior (i.e., enhanced viscosity, surface activity, and unusual rheological properties). This chapter deals with the general methods of preparation and solution properties of hydrophobically modified nonionic WSPs. Particularly described are the solution properties of hydrophobically modified (hydroxyethyl)cellulose (HMHEC) in aqueous and surfactant systems. 

This chapter is concerned with just one of this class of thickeners, namely a hydrophobically modified (hydroxyethyl)cellulose (HMHEC), Hercules WSP D-47. Gelman and Barth (i) reported on the viscosity of such HMHECs. This sample contained up to four hexadecyl chains grafted to the cellulose backbone. The preparative route was that described by Landoll (2). The dilute solution properties were characterized by capillary viscom-etry, whereas the more concentrated solutions were characterized by continuous-shear viscometry, forced oscillation measurements, and shear-wave propagation. In addition, the adsorption onto polymer latex particles was investigated. 

Domain associations in hydrophobically modified copolymers and associations of macroions in aqueous solution can lead to remarkable solution properties in properly tailored systems. An example of each type and selected observations of experimental findings were presented herein. The challenge now for the scientific community is to thoroughly understand the balance of structural forces responsible for macroscopic behavior so that systems may be properly tailored for specific commercial application. 

Hydrophobically modified, ethoxylated urethanes (HEURs) are the thickeners of choice in exterior coatings and in corrosion-resistant, high-gloss industrial latex finishes. This chapter presents an overview of our research efforts and discusses approaches to the synthesis of HEUR polymers with different molecular architectures, geometrical influences on solution properties, and viable mechanisms by which this class of associative thickener effects desirable coatings rheology and applied film properties. 

PRI Principi, T., Goh, C.C.E., Liu, R.C.W., and Wimiik, F.M., Solution properties of hydrophobically modified copolymers of A-isopropylaciylamide and A/-glycineacryl-amide A study by microcalorimetiy and fluorescence spectroscopy. Macromolecules, 33, 2958, 2000. 

The ease of incorporating funchonal groups to modify the pSi surface for mass spectrometric application has allowed for the development of a convenient and simple method for enriching the concentration of analytes. This technique, termed DIOS solid-liquid extraction (SLE), uses the property of differential adsorption selectively to capture analytes from a solution containing contaminants that impede MS analysis. Hydrophobically modified DIOS surfaces could be readily used selectively to remove interferences prior to analysis. DIOS S LE simply involves the deposition of a droplet containing analytes onto the chemically modified DIOS surface then, after approximately 3 s, the sample is aspirated with the same pipette. This short-term deposition allows for any molecule with a propensity to be adsorbed onto the surface to attach itself, while any potential hydrophilic contaminants such as salts and buffers will remain in solution, leaving the surface free from such contaminants. The van der Waals interaction between the analyte and surface leads to a selective extraction of the small molecules, while the hydrophilic contaminants such as salts are removed with the droplet. The DIOS analysis of peptides and small molecules from complex matrices is greatly enhanced by differential adsorption [47]. 

Wang, T. K., Iliopoulos, I., Audebert, R., Aqueous-Solution Behavior of Hydrophobically Modified Poly(acrylic Acid), in Water-Soluble Polymers Synthesis, Solution Properties and Applications, Shalaby, S.W., McCormick, C. L., Butler, G. B., Eds., ACS Symposium Series No. 467, American Chemical Society, Washington, DC, 1991, pp. 218-231. 

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