Micellar solution-polymerized polymers

Hydrophobically associating polymers consist primarily of water-soluble monomer units with a small number of water-insoluble monomer units. Synthesis of high-molecular-weight random copolymers of acrylamide and alkylacrylamides required a novel aqueous surfactant micellar solution polymerization (2-4) because of the mutual immiscibility of the water-soluble and hydrophobic monomers. The use of surfactant micelles enabled solubilization of the hydrophobic monomer (alkylacrylamide [R]) into the aqueous phase containing the water-soluble monomer (acrylamide [AM]). The resulting RAM polymer after isolation provided homogeneous aqueous solutions. 

When the appropriate precautions are taken the method appears particularly suited for measuring very low tensions 10 mN m sometimes even as low as 10 mN m ). Such ultralow tensions are for example encountered in micro-emulsion systems and in just phase-separated polymeric or micellar solutions. For phase-separated colloid-polymer systems de Hoog and Lekkerkerker ) even reported values down to a few pN m , reproducibly being obtained after implementing a number of methodical improvements. (Alternatives for low tensions are the sessile and pending (micro-) drop but these do not usually go below 10 mN m ) Commercial apparatus are nowadays available. A variant proposed by Than et al. J employs a thin rod in the axis of the cylinder, to reduce spin-up time and suppress drift. Another variant, proposed by Kokov, analyses the centrifugal field required to squeeze liquid out of an orifice" ). 

A thymidine-containing polyphenol was synthesized by SBP-catalyzed oxidative polymerization of thymidine 5 -/>hydroxyphenylacetate.44 Amphiphilic esters of tyrosine were polymerized in a micellar solution to give the polymer showing surface activity at the air—water interface.45 Polymerization monitoring using a quartz crystal microbalance was reported. 

Particles of the enzymatically synthesized phenolic polymers were also formed by reverse micellar polymerization. A thiol-containing polymer was synthesized by peroxidase-catalyzed copolymerization of p-hydroxythiophenol and p-ethylphenol in reverse micelles [70], CdS nanoparticles were attached to the copolymer to give polymer-CdS nanocomposites. The reverse micellar system was also effective for the enzymatic synthesis of poly(2-naphthol) consisting of qui-nonoid structure [71], which showed a fluorescence characteristic of the naphthol chromophore. Amphiphilic higher alkyl ester derivatives were enzymatically polymerized in a micellar solution to give surface-active polymers at the air-water interface [72, 73]. 

Surfactant-polymer interactions in an aqueous solution have been studied by many researchers [132], and the adsorption and surface-induced self-assembly of the surfactant at the solid-aqueous interface have been recently studied [133]. On the other hand, these subjects have been rarely studied for oil solutions. The surfactant-polymer interaction in oil and the surface-induced self-assembly of surfactants at the oil-solid interface are important for further research studies to enhance the polymerization at the interface of the liquid/solid in reversed micellar solutions. 

A polynucleoside with lumatiu-al polymeric backbone was synthesized by SBP-catalyzed oxidative polymerization of thymidine 5 -p-hydroxyphenylacetate (268). Chemoenzymatic synthesis of a new class of poly(amino acid), poly(tyrosine) containing no peptide bonds, was achieved by peroxidase-catalyzed oxidative polymerization of tyrosine ethyl esters, followed by alkaline hydrolysis (269). The am-phiphile higher alkyl ester derivatives were also polymerized in micellar solution to give the polymer showing surface activity at the air-water interface (270). The polymerization was monitored by the quartz crystal microbalance (271). 

In another report, Collard and Stoakes described the self-assemblage of potassium 3-(3-alkylpyrrol-l-yl)pro-pane sulfonate monomers and their subsequent electrochemical polymerization to form lamella conjugated polymers [31]. These authors use the fact that potassium 3-(3-alkylpyrrol-l-yl)propane sulfonates possess amphiphilic character and form micellar solutions above critical concentrations. A series of polymers possessing varying alkyl chain length were prepared by first forming A/-tosyl-3-alkanoylpyrroles... 

Peggion et al. [76], however, concluded that the strong deviations from the micellar theory cannot be ascribed to the solution polymerization which competes with the micellar polymerization and suggest the following reaction mechanism The radicals produced by decomposition of the initiator react with the monomer dissolved in water. The polymer radicals separate from the... 

Alternatives to LB techniques for the preparation of multilayer thin films are also available. Control of the microscopic ordering can be achieved through structured self-assembly methods. Lamellar conjugated polymer structures have been prepared [105] using in situ electrochemical polymerization of heteroarene-contain-ing surfactants from micellar solutions. This method avoids the highly controlled conditions necessary for monolayer film formation. 

The polymer polymerized by the micellar technique (surfactant polymer) contained 0.25 mole% APS, while the solution polymerized (solution polymer, DMF/H2O 57 43 volume fraction) polymer contained 0.35mole%. Steady-state emission spectra of the two polymers, shown in Fig. 2.13, indicated that at constant polymer concentration, Ie/Im was higher for the surfactant polymer even though it contained less of the pyrene-sulfonamide label. This was indicative of a higher local label concentration in the surfactant polymer and thus a blocky copolymer microstructure. 

Many micellar catalytic applications using low molecular weight amphiphiles have already been discussed in reviews and books and will not be the subject of this chapter [1]. We will rather focus on the use of different polymeric amphiphiles, that form micelles or micellar analogous structures and will summarize recent advances and new trends of using such systems for the catalytic synthesis of low molecular weight compounds and polymers, particularly in aqueous solution. The polymeric amphiphiles discussed herein are block copolymers, star-like polymers with a hyperbranched core, and polysoaps (Fig. 6.3). 

Phase separation controlled by diffusion exchange often results in a skin which is composed of a micellar assembly of nodules, as will be discussed below. When extremely hydrophobic polymers (e.g., modifled-PPO) are cast from dioxane into water (pg = p = p ) a dense polymer layer is formed at the solution s interface that somewhat resembles the type of layer formed by Interfacial polymerization. There is almost no inward contraction of the interfacial skin, and the coagulation process is controlled by diffusion through the dense, interfacial thin film. These result in an anisotropic membrane with a very fine "coral" structure (Figures 9 and 10). 

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