Polymer latex organic

Recently, a miniaturized thermal apparatus, [t-ThFFF, was developed and applied to characterize the molar mass distribution of synthetic polymers in organic solvent as well to determine the particle size distribution of nanoparticles (PSs latex) in aqueous carrier. This 4-ThFFF proved to performed well in both macromolecule and particle analysis [48]. 

Albert Einstein derived a simple equation for the viscosity of a solution of spherical particles, and from this result it is obvious that if we could make the polymer in small colloidal-sized balls, then the solution would be much less viscous. Also, if we could use surfactants to stabilize (e.g. by charging) the polymer particles in water, then there would be no need for organic solvents. Both these conditions are neatly obtained in the emulsion polymerization process, which is schematically explained in Figure 5.3. A polymer latex is produced by this process and can contain up to 50% polymer in the form of 0.1-0.5 im size spherical particles in water. A typical starting composition is ... 

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. 

Several approaches towards the synthesis of hierarchical meso- and macro-porous materials have been described. For instance, a mixture that comprised a block co-polymer and polymer latex spheres was utilized to obtain large pore silicas with a bimodal pore size distribution [84]. Rather than pre-organizing latex spheres into an ordered structure they were instead mixed with block-copolymer precursor sols and the resulting structures were disordered. A similar approach that utilized a latex colloidal crystal template was used to assemble a macroporous crystal with amesoporous silica framework [67]. 

The concentrated emulsion polymerization was also applied to an aqueous solution of acrylamide dispersed in decane. Compared to the conventional inverse emulsion polymerization [20], a much smaller amount of organic solvent is employed to produce polymer latexes. 

Polymer latexes possess a low viscosity by comparison to a solution of the polymer in an organic solvent. During the polymerization process, this enables high yields per reactor volume. The latex products can be handled readily, e.g. they can be pumped. Also, many applications require a restricted viscosity. Polymer... 

The application potential of polypeptide copolymers has also not been exhausted. Most studies deal with ordinary micelles for the controlled delivery of drugs or genes. Not much attention has, for whatever reason, been paid to other colloidal systems like for instance emulsions, polymer latexes, and inorganic-organic biohybrid nanoparticles. 

A variety of organic colloids including emulsions and polymer latexes have been dispersed in carbon dioxide in the presence of surfactants (3,13). In most cases, owing to the lower interfacial tension of the former as explained shortly it is easier to form organic-in-C02 emulsions than water-in-C02, emulsions. Sterically stabilized colloids are stable above the critical flocculation density (CFD) and precipitate below this density. In some cases the CFD occurs at the upper critical solution density of the steric stabilizer, that is, the density at which the stabilizer phase separates from CO2, as has been shown by theory (14,15) and experiment (16). So-called ambidextrous surfactants have been designed to allow polymer latexes produced in CO2 to be transferred to an aqueous solution to form a dispersion (17,18). 

Surfactants have been designed to lower y in C02-based systems. The first generation of research involving surfactants in SCFs addressed water-in-oil (W/O) microemulsions and polymer latexes in ethane and propane, as reviewed elsewhere. (43-45). This work provided a foundation for studies in CO2, which has weaker van der Waals forces (a/v) than ethane. Surfactants with both C02-philic and C02-phobic segments have been used to form microemulsions, emulsions, and organic polymer latexes in CO2. 

PCA may be utilized to produce stable PMMA polymer latexes in CO2 by spraying the polymer solution in the presence of a steric stabilizer, introduced in either the organic or the CO2 phase. One of the most successful stabilizers is poly(l,l-dihydroperfiuorooctyl acrylate) or copolymers con-... 

A polymer latex in CO2 with an organic-C02 interface may be transferred into water to form an aqueous latex with an organic-water interface. This... 

This method has been used to prepare nanoemulsions of such polymers as cellulose esters and epoxy resins, similar to latexes produced by emulsion polymerization. The nanoemulsions are prepared by direct emulsification of solutions of the polymers in organic solvents, followed by removal of the organic solvent by steam distillation under reduced pressure. The nanoemulsions produced in this fashion had stabilities > 1 year. 

When aerosol droplets of organic monomers are exposed to the vapor containing polymerization initiator, the uniform particles of polymer latexes, such as polystyrene and polydivinylbenzene, are obtained [6]. 

There is one more method of adding resistance to moisture and anticorrosive properties to carton by the introduction of Cl into the polymer latex coating. The film-forming water or organic solvent-based components are used to form a durable inhibited polymer coating on the paper glued directly on the inner side of the carton. 

Detachable or removable paint coats are applied from compositions on the base of polymers in organic solvents or aqueous latexes. 

Latex-modified mortar and concrete are made by using a composite binder of inorganic cements and organic polymer latexes, and have a network structure which consists of cement gels and microfilms of polymers. Consequently, the properties of the latex-modified mortar and concrete are markedly improved over conventional cement mortar and concrete. The properties of the fresh and hardened mortar and concrete are affected by a multiplicity of factors such as polymer type, polymer-cement ratio, water-cement ratio, air content, and curing conditions. 

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