Polymer-bound dodecyl groups

The intermolecular association of polymer-bound dodecyl groups is evidenced by an effect of a surfactant molecule added to polymer solutions. Hgure 7 compares relaxation time distributions for the copolymers with, X)d = 2.5 and 10 mol % at a 10.0 g/L polymer concentration in the presence of varying concentrations of n-dodecyl hexaoxyethylene glycol monc tiier (C12E6). In the cai of the copolymer with j >od =... 

Hydrophobic functional-molecules can be incorporated into the higher-order unimer micelles either via chemical bonding of the functional molecules to amphiphilic polymers or by physically solubilizing tiie mol ules into the unimer micelle. For example, when an AMPS-DodMAm copolymer and a hydrophobic small-molecule are dissolved together in ethanol, and the ethanol solution is poured into excess water, then the hydrophobic molecules can be entrapped in a hydrophobic microdomain during the process of the hydrophobic self-association of polymer-bound dodecyl groups. However, it is practically difficult to precisely control the number of the sm l... 

Surfactant concentration (varied after polymerization) greatly affects the viscosity of associating polymer systems. Iliopoulos et al. studied the interactions between sodium dodecyl sulfate (SDS) and hydrophobically modified polyfsodium acrylate) with 1 or 3 mole percent of octadecyl side groups [85]. A viscosity maximum occurred at a surfactant concentration close to or lower than the critical micelle concentration (CMC). Viscosity increases of up to 5 orders of magnitude were observed. Glass et al. observed similar behavior with hydrophobically modified HEC polymers. [100] The low-shear viscosity of hydrophobically modified HEC showed a maximum at the CMC of sodium oleate. HEUR thickeners showed the same type of behavior with both anionic (SDS) and nonionic surfactants. At the critical micelle concentration, the micelles can effectively cross-link the associating polymer if more than one hydrophobe from different polymer chains is incorporated into a micelle. Above the CMC, the number of micelles per polymer-bound hydrophobe increases, and the micelles can no longer effectively cross-link the polymer. As a result, viscosity diminishes. 

Another approach to producing latexes with chemically bound surface-active groups is to use a reactive surfactant—a surfactant with a polymerizable double bond, such as sodium dodecyl allyl sulfosuccinate [Wang et al., 2001a,b,c]. Copolymerization of the reactive surfactant with the monomer of interest binds the surface active groups into the polymer chains. 

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