Cationic emulsion polymerisation

Poly(vinyl chloride) is commercially available in the form of aqueous colloidal dispersions (latices). They are the uncoagulated products of emulsion polymerisation process and are used to coat or impregnate textiles and paper. The individual particles are somewhat less than 1 p,m in diameter. The latex may be coagulated by concentrated acids, polyvalent cations and by dehydration with water-miscible liquids. 

A multistep emulsion polymerisation technique was used to produce cationic latex particles with surface amino groups. Seed particles of polystyrene were copolymerised with aminoethyl methacrylate hydrochloride or vinyl... 

No.6, March 1999, p.1359-66 REACTIVE SURFACTANTS IN HETEROPHASE POLYMERISATION. XXTV. EMULSION POLYMERISATION OF STYRENE WITH MALEATE- AND SUCCINATE-CONTAINING CATIONIC SURFACTANTS Montoya-Goni A Sherrington D C Schoonbrood H A S AsuaJM... 

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. 

Cationic latex particles with surface amino groups were prepared by a multi-step batch emulsion polymerisation. Monodisperse cationic latex particles to be used as the seed were synthesised first. Then the amino-functionalised monomer, aminoethylmethacrylate hydrochloride, was used to synthesise the final functionalised latex particles. Three different azo initiators were used 2,2 -azobisisobutyramidine dihydrochloride, 2,2 -azobisdimethyleneisobutyramidine dihydrochloride, and 2,2 -azobisisobutyronitrile. Hexadecyltrimethylammonium bromide was used as the emulsifier. The latices were characterised by photon correlation spectroscopy to study the mean particle diameters, transmission electron microscopy to deteimine the particle size distributions, and hence the number- and weight-average diameters and the polydispersity index. The conversion was determined gravimetrically, the surface density of the amino groups was detemiined by conductimetric titrations, and the... 

Azad A R M, J Ugelstad R M Fitch and F K Hansen. Emulsification and Emulsion Polymerisation of Styrene using Mixtures of Cationic Surfactant and Long Chain Fatty Alcohols or Alkanes as emulsifiers in I PiIrma and J L Cardon eds, ACS S3miposlum Series. Emulsion Polymerisation, (1976), 1-23. 

Cationic surfactants are not often used in emulsion polymerisation of acrylic polymers for surface coating applications. 

Cauvin S, Ganachaud F, Moreau M, et al. (2005) High molar mass polymers by cationic polymerisation in emulsion and miniemulsion. Chem Commun 21 2713-2715... 

The polymerisation and the properties of the latexes depended sensitively on the emulsifier and on the charge of the initiator. There was no visible correlation between the properties of the final latexes and the properties of the emulsifiers such as surface activity, solubilisation capacity, or the ability to stabilise the initial monomer emulsion. When a cationic (2,2 -dimethyl-2,2 -azo-N-benzylpropionamidine hydrochloride, VA-552 from Wako Chemicals) initiator was employed, all emulsifiers lead to stable monodisperse latexes, except for polysoaps with low hydrophobe content. The polymerisable, as well as the polymeric emulsifiers, yielded latex solutions with very high surface tensions, different from the use of the standard surfactant. In contrast, the use of an anionic initiator (potassium persulphate) can pose difficulties. The... 

This was shown to good effect in an experiment [22] carried out to prepare a series of cationic acrylamide copolymers (60/40 weight ratio) as inverse emulsion polymers using identical polymerisation conditions, in which only the concentration of cross-linking monomer was varied. Subsequent determination of intrinsic viscosity values for this set of polymers showed the results in Table 3.1. 

The particle size of the monomer is reduced to colloidal dimensions by more vigorous stirring and use of synthetic surfactants (anionic, cationic or non-ionic) in place of protective colloids used in sus )ension polymerisation. Usually water soluble catalysts such as persulphate or hydrogen peroxide are u.sed. Thermal dissipation and viscosity problems are absent. Both the rate of polymerisation and the molecular weight of the product formed arc very high. The product, which is in the fonn of fine particles dispersed in water (called latex), can used directly as adhesive or an emulsion paint, or it can be isolated by coagulating with an electrolyte. The technique is employed for the industrial production of PVC,... 

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