Surfactant-acrylamide polymers

Surfactant-acrylamide Polymers. Copolymers of acrylamide and alkylarylpoly(ethoxy)-acrylate were prepared using standard free radical solution polymerization techniques. The alkylarylpoly(ethoxy)-acrylate monomers referred to as Surf" monomers were water dispersible and thus additional surfactants were not needed to effect random copolymerization. These so called "PAM-SURF" polymers were prepared with a variety of Surf monomers containing different amounts of ethylene oxide and different alkylaryl functionality. 

By performing in situ the polymerization of acrylamide in water/AOT/toluene microemulsions, clear and stable inverse latexes of water-swollen polyacrylamide particles stabilized by AOT and dispersed in toluene have been found [192-194], It was shown that the final dispersions consist of two species of particles in equilibrium, surfactant-coated polymer particles (size about 400 A) with narrow size distribution and small AOT micelles (size about 30 A). 

Effect of Dispersed Phase Concentration. In any application of these microemulsion systems to polyn rization processes, it would be desirable to maximize polymer yield. This can be accomplished by maximizing the acrylamide ratio at constant surfactant loading or, of course, the acrylamide ratio (as well as the water ratio) to the surfactant can be fixed and the total amount of surfactant in the system increased. Therefore, the effect of total dispersed phase concentration on the phase behavior was investigated. The dispersed phase concentration was defined as a volume fraction equalling the total volume of surfactants + acrylamide -l- water divided by the total volume. 

Typical polymeric pseudostationary phases include micelle polymers, polymeric surfactants, water-soluble anionic siloxanes and dendrimers [223-231]. Micelle polymers [e.g. poly(sodium 10-undecylenate), poly (sodium 10-undecenylsulfate), poly(sodium undeconylvalinate), etc.] are synthesized from polymerizable surfactant monomers at a concentration above their critical micelle concentration. These polymers have similar structures to micelles without the dynamic nature of the micelle structure. Polymeric surfactants are polymers with surfactant properties [e.g. acrylate copolymers, such as 2-acrylamide-2-methyl-l-propanesulfonic acid and alkyl methacrylamide, alkyl methacrylate or alkyl acrylate, poly (ally lamine)-supported phases, poly(ethyleneimine), etc]. Water-soluble anionic siloxane polymers are copolymers of alkylmethylsiloxane... 

Howley C, Marangoni DG, Kwak JCT. 1997. Association and phase behavior of hydrophobically modified photoresponsive poly(acrylamide)s in the presence of ionic surfactant. Coll Polym Sci 275(8) 760 768. 

Until recently, the manufacture of high molecular weight acrylamide polymers or copolymers was accomplished by one of two methods. The polymers could be produced as water-in-oil emulsions (or "latex" polymers), consisting of a hydrocarbon-based solvent for the continuous phase and various surfactants to provide emulsion stability. Polymers prepared in this fashion are generally 20% to... 

The first type is a standard polysoap derived from a polymerizable surfactant leading to poly(sodium 11-acryloyloxyundecane-l-sulfonate) PSl whereas the second polysoap is an alternating copolymer of maleic acid anhydride and acrylamide leading to a polymer with carboxylic acid groups and hydrophobic n-alkylamide groups PS2 (see Fig. 6.9). The organometaUic catalyst was not covalently bound to the polysoaps in the catalytic experiments. 

Water-in-oil concentrated emulsions have also been utilised in the preparation of polymer latexes, from hydrophilic, water-soluble monomers. Kim and Ruckenstein [178] reported the preparation of polyacrylamide particles from a HIPE of aqueous acrylamide solution in a non-polar organic solvent, such as decane, stabilised by sorbitan monooleate (Span 80). The stability of the emulsion decreased when the weight fraction of acrylamide in the aqueous phase exceeded 0.2, since acrylamide is more hydrophobic than water. Another point of note is that the molecular weights obtained were lower compared to solution polymerisation of acrylamide. This was probably due to a degree of termination by chain transfer from the tertiary hydroxyl groups on the surfactant head group. 

Shea and colleagues [109-111] added an exciting contribution to this field They created molecular imprints for the peptide melittin, the main component of bee venom, in polymer nanoparticles, resulting in artificial antibody mimics that can be used for the in vivo capture and neutralization of melittin. Melittin is a peptide comprising 26 amino acids which is toxic because of its cytolytic activity. Shea and colleagues strategy was to synthesize cross-linked, acrylamide-based MIP nanoparticles by a process based on precipitation polymerization using a small amount of surfactant. To maximize the specificity and the affinity for melittin, a number of hydrophilic monomers were screened for complementarity with the template. The imprinted nanoparticles were able to bind selectively the peptide with an apparent dissociation constant of Ax>app > 1 nM [109]. 

An example of the first approach is the integration of hydrogels into nanostructured silica films by addition of a suitable monomer (e.g., methyl methacrylate, /V-isopropyl acrylamide, etc.) and an initiator for radical polymerization to a solution containing a structure-directing surfactant and a prehydrolyzed silica precursor. During self-assembly, the monomers partition within the hydrophobic core of the surfactant mesophase postsynthesis polymerization (for instance, by UV treatment) followed by solvent washing to remove the surfactant template yields a polymer-silica nanohybrid. 

Greenshields, J.N. (2000) Surfactants in inverse (water-in-oil) emulsion polymers of acrylamide. In D.R. Karsa (ed.), Surface Active Behavior of Performance Surfactants, Annual Surfactants Review vol. 3. Sheffield Academic, CRC Press, Boca Raton, FL. 

Hernandez-Barajas J, Hunkeler DJ (1997) Inverse-emulsion copolymerization of acrylamide and quaternary ammonium cationic monomers with block copolymeric surfactants copolymer composition control using batch and semi-batch techniques. Polymer 38(2) 449—458... 

Single-step preparations of composite polymers have been examined in previous sections. The volume fraction of the continuous phase was, however, relatively small in those cases. In contrast, the present method allows us to prepare composites with larger volume fractions of the continuous phase. Composites with large volume fractions of the continuous phase can also be obtained in a single-step by polymerizing an emulsion or a microemulsion [24]. An emulsion of a hydrophobic (hydrophilic) monomer in another hydrophilic (hydrophobic) monomer can be extremely stable (even thermodynamically stable, and then it is called a microemulsion) if a sufficiently large amount of surfactant is introduced into the system. For an emulsion to be thermodynamically stable, a cosurfactant is in most cases needed besides the surfactant. The latter method was used to prepare composites by employing acrylamide... 

Hjerten and co-workers prepared substrate-specific polyacrylamide gels by carrying out cross-linking polymerisation in the presence of proteins [47]. Polymerisation of acrylamide and 7V,A -methylenebisacrylamide was carried out in the presence of cytochrome C and haemoglobin as the templates. After removal of the templates using surfactants and acetic acid, substrate selectivities of the polymer gels were tested by chromatography. The imprinted polymers reportedly showed preferential affinities for their templates. 

As well as the more common oil in water suspension methods, it is also possible to make stable water in oil suspensions by choosing alternative surfactants with much lower hydrophilic/lipophilic balance values, combined with solvents such as hydrocarbons as the dispersing phase. These can be used to make beaded polymers from water-soluble monomers such as acrylamide. Although little work has been done to date with imprinting in aqueous conditions (using hydrophobic interactions... 

Hair sprays contain ethanol as a solvent with resin polymers composed of vinyl acetate, acrylamide, and methyl vinyl ether. Hair conditioners contain cationic surfactants, perfumes, and alcohols. 

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