Polymerisable surfactant

The second study concerns polymerisation of various monomers, viz. styrene, acrylamide, and methyl methacrylate, in bicontinuous cubic phases [6.11]. These phases are simultaneously continuous in both the hydrophilic component (water) and the hydrophobic component (hydrocarbons), and they also have a crystallographic cubic symmetry. This is a judicious choice. These phases are extremely viscous and rearrange themselves very slowly compared with bicontinuous microemulsions. The latter have low viscosity and continuously reorganise on a microsecond time scale. 

X-ray measurements, together with spin-echo NMR measurements of selfdiffusion coefficients, indicate that the initial structure is at least partially maintained. It should be noted that the initially transparent systems studied generally become opaque during reaction. This would seem to be the result of a phase separation on a microscopic scale. It would be interesting to know over what scale this periodic structure is maintained. 

Polymerisable surfactants constitute another important area of polymerisation in disperse media. Over the past fifteen years, a number of studies have been made of surfactant assemblages possessing a polymerisable group. The aim of these studies is to fix the structure of the initial assemblages in such a way as to obtain stable aggregates with controllable size, rigidity and permeability. These systems could be applied where the non-polymerisable assemblages had proven inadequate as a result of their limited lifetime. The studies concerned two types of self-assembled structures vesicles and micellar systems. 

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The hypothesis formulated to explain the results shown here considers the nanoribbons as an extremely organised (oriented) hybrid organic-inorganic nanocomposite. The size control as well as the isolation of these nanoribbons, which can eventually be done using a polymerisable surfactant, may be feasible for give more information about the composition and the structure of such nanoribbons. 

More recently, Priego-Capote et al. reported on the production of MIP nanoparticles with monoclonal behaviour by miniemulsion polymerisation [63]. In the synthetic method that they employed, they devised to use a polymerisable surfactant that was also able to act as a functional monomer by interacting with the template (Fig. 4). The crosslinker content was optimised at 81% mol/mol (higher or lower contents leading to unstable emulsions). In this way, the authors were able not only to produce rather small particles (80-120 nm in the dry state) but also to locate the imprinted sites on the outer particle surface. The resulting MIP nanobeads were very effective as pseudostationary phases in the analysis of (/ ,S)-propranolol by CEC. 

Aramendia, E., Barandiaran, M.J., Grade, J., Blease, T. and Asua J.M. (2002) Polymerisation of high-solids-content acrylic latexes using a nonionic polymerisable surfactant. /. Polym. Sci. A, 40, 1552-59. 

It is interesting to note, however, that a polymer foam of sufficient durability could be produced even at high surfactant concentrations if, for example, a formulation of polymerising surfactant such as sodium co-acrylamidoundecanate or oleic alcohol is used [134]. This can be realised only in the region of the phase diagram corresponding to the existence of a lamellar liquid-crystalline structure. 

One of the main drawbacks to the commercial development of multiple emulsions is their inherent instability. The intention of this paper is to review studies on the stability and mechanism of breakdown of multiple systems and attempts to minimise such instability, for example, by appropriate choice of surfactant, polymerisable surfactants or gelation of the aqueous or oily phases. 

They are unlikely to be commercially acceptable until problems with their stability in vitro and in vivo are solved. Despite this, there are few reports in the literature, regarding attempts to improve their stability. We have concentrated our efforts on the potential of polymerisable surfactants or other monomers to enhance stability following early attempts to use an oil phase which would solidify at room temperature. Release profiles of methotrexate from water-octadecane-water emulsions are shown in Fig. 8 the photomicrograph insert shows the structure of the emulsion. 

Knowledge of surfactant equilibration and interactions will probably lead to improved formulations of multiple emulsions. Failing this the use of polymerisable surfactants can lead to obvious strengthening of interfacial barriers and allow control of stability and drug release. Nonetheless further detailed work on both w/o/w and o/w/o systems is justified. 

Synergistic templating involves the usage of polymerisable surfactants. The target structure is self-assembled using polymerisable surfactants in solvent (usually water) and then... 

An excess of maleic anhydride (up to 5 % wt.) is generally used. Unreacted ROH, diester, and maleic acid/anhydride are formed as by-products. Note, monoalkylethoxymaleates are of interest as polymerisable surfactants in the emulsion polymerisation [77]. 

Encapsulation of Colloidal Particles. Note also that polymerised vesicles constitute an ideal medium for the formation of small and uniform colloidal particles of metals or oxides. These can be used as catalysts. For example, ultraviolet irradiation of vesicles formed from polymerisable surfactants and containing potassium tetrachloroplatinate (K2PtCl4) results in the formation... 

Many syntheses of polymerisable surfactants have been described in the literature. These cover all possible combinations of the various surfactant classes (non-ionic, anionic, cationic and zwitterionic) and the classic polymerisable groups (vinyl, allyl, diallyl, acrylate, methacrylate, etc.). Once again, the polymerisable group may be located at different points on the molecule, although it is usually near the polar head, or at the end of the hydrophobic tail of the surfactant. It may even be a counterion. 

As a rule, CMC and aggregation number values obtained differ only slightly from those of their non-polymerisable counterparts. For a homologous series of polymerisable surfactants, it can be shown that they obey the classic law ... 

This series of articles focuses on the polymerisation processes used to prepare polymers and resins utilised in the coatings industry. This article concerns latexes and emulsion polymerisation. Surfactants and dispersion stabilisation mechanisms, emulsion polymerisation ingredients and processes, particle nucleation, particle... 

Polymerisable monoquatemary, and structurally related diquatemary anunonium bromide cationic surfactants were synthesised, together with non-polymerisable analogues of each type of surfactant. The surface activity properties of all the surfactants were studied by means of surface tension and electrical conductivity measurements and the results were discussed with reference to the molecular structure of the surfactants and the valency of the salts. Each surfactant was used as the emulsifier for emulsion polymerisation of styrene and of methyl methacrylate and in each case, well defined stable polymer latexes were formed. The results of stability investigations were discussed with reference to the molecular structure of the surfactants. Comparisons were made between the effectiveness of polymerisable and non -polymerisable surfactants and between dicationic and monocationic species. 49 refs. 

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