Cosurfactant effects on the microemulsion polymerization of styrene

The polymerization of styrene in o/w microemulsions stabilized with dodecyltrimethylammonium bromide (DTAB) with or without cosurfactant (n-butanol, n-hexanol or n-octanol) is examined here. The addition of a cosurfactant enhances the one-phase region in the order: n-butanol > n-hexanol > n-octanol. The kinetics of polymerization slows down in the presence of the alcohol. With the alcohol, the molar masses increase, but no particular trend was noticed on particle size of the lattices. However, by changing the surfactant counter-ion to chloride, alcohol effects on the kinetics almost vanish. Possible explanations to these results are given here. To cite this article: J.E. Puig et al., C. R. Chimie 6 (2003).     

Effect of the surfactant concentration on the kinetics of oil in water microemulsion polymerization: a case study with butyl acrylate

A comprehensive investigation of aqueous microemulsion polymerization of butyl acrylate at high surfactant concentrations by means of reaction calorimetry and dynamic light scattering revealed unexpected results with regard to polymerization kinetics and colloidal properties of the final latexes. Particularly, with increasing surfactant concentrations, a decrease in the overall rate of polymerization accompanied by an increasing incubation time of the polymerization and increasing average particle sizes in the final latexes has been observed. Based on reviewing former results on microemulsions and microemulsion polymerizations published in the open literature and the presentation of new experimental results an attempt is made to explain the experimental results consistently with a particle nucleation mechanism based on the classical nucleation theory. To cite this article: K. Tauer et al., C. R. Chimie 6 (2003).     

On the optimal surfmer addition profile in emulsion polymerisation

In this work, the optimal surfmer feeding profile for stabilizing a high-solid-content acrylic latex with a non-ionic alkenyl functional ^TMMaxemul 5011 was calculated. For this purpose, the model developed by de la Cal and Asua (J. Polym. Sci., Part A: Polym. Chem. 39 (2001) 585) was used. It was observed that, in spite of the low reactivity of the surfmer, it was possible to increase substantially the surfmer conversion using an optimal surfmer addition policy. To cite this article: E. Aramendia et al., C. R. Chimie 6 (2003).     

Hybrid copolymer latexes cross-linked with methacryloxy propyl trimethoxy silane. Film formation and mechanical properties

We describe in this work the copolymerization reaction of 3-trimethoxysilyl propyl methacrylate (MPS) with styrene (Styr.) and n-butyl acrylate (BuA) monomers through emulsion polymerization. The so-produced hybrid copolymer (P(BuA-co-MPS)) and terpolymer (P(Styr-co-BuA-co-MPS)) latexes were cast into films that displayed a good optical transparency. The copolymers microstructure in the films was characterized by FTIR, ¹³C and ²⁹Si solid state NMR spectroscopies, and was found to be highly dependent on parameters such as the monomer feed composition, the suspension pH and the silane addition profile. The films obtained from the hybrid latexes showed improved dynamic mechanical properties indicating that a reinforcing organo-mineral network had formed in the composite materials. The dynamic modulus of the hybrids increased with increasing silane contents while, concurrently, the tan δ peak shifted to higher temperatures, broadened and decreased in intensity. To cite this article: S. Vitry et al., C. R. Chimie 6 (2003).     

A unique transurf in styrene emulsion polymerization

The surface-active, chain transfer agent (‘transurf’) sodium ω-mercapto-decane sulfonate, SMDSo, was synthesized, purified, and its interfacial properties determined. The compound acted normally in styrene emulsion polymerization to produce extremely stable colloids containing only sulfonate ionic surface functional groups. It was then used to control the surface charge density of a model polystyrene colloid by means of seeded emulsion polymerization. Surface charge could thus be increased 16-fold over that of the seed particles, and was due solely to sulfonate groups introduced by the SMDSo. Unlike most conventional emulsion polymerizations, this technique allows one to control surface chemistry independently of particle size. To cite this article: C.C. Fifield, R.M. Fitch, C. R. Chimie 6 (2003).     

Maleic diamide polymerizable surfactants. Applications in emulsion polymerization

A series of new polymerizable non-ionic and ionic surfactants (surfmers) with amides groups on both sides of the C=C double bonds have been prepared upon reaction of maleic isoimide carrying a long alkyl chain (or a benzyl group) with a hydrophilic amine derivative. Their critical micellar concentration (CMC) was measured with a surface tensiometer. They have been engaged in batch emulsion polymerization of styrene, and semi-batch seeded copolymerization of styrene and butyl acrylate, giving stable latexes during the polymerization process, and upon extraction with ethanol, showing a high rate of incorporation at the particle surface. However these surfmers do not confer good steric stabilization properties, which may be expected from the use of non-ionic surfactants. To cite this article: I. Klimenkovs et al., C. R. Chimie 6 (2003).     

Emulsion and dispersion polymerization of styrene in the presence of PEO macromonomers with p-vinylphenylalkyl end groups

Poly(ethylene oxide) (PEO) macromonomers with α-p-vinylphenylalkyl (propyl, pentyl, and hexyl) and ω-hydroxy end groups were applied to emulsion and dispersion polymerization of styrene as reactive emulsifiers and dispersants in water and in methanol-water mixture (9:1 v/v), respectively. Nearly monodisperse microspheres of submicron to micron size were obtained. Particle size in the emulsion system was one or half order of magnitude smaller than that in the dispersion system, while in both systems the size decreased approximately according to minus one half power of the macromonomer concentration in weight. The particle size was substantially independent on the PEO chain length and also on the spacer alkyl chain length of the α-polymerizing end group. The total weight of the PEO chains incorporated by copolymerization into the particle surfaces (shells), relative to that of styrene polymerized into the particle cores, appears to be a key factor for controlling the particle size. To cite this article: K. Landfester et al., C. R. Chimie 6 (2003).     

Poly(N-ethylmethacrylamide) thermally-sensitive microgel latexes: effect of the nature of the crosslinker on the polymerization kinetics and physicochemical properties

Thermally-sensitive crosslinked submicronic particles were prepared by an emulsion/precipitation process of N-ethylmethacrylamide (NEMAM), using potassium persulphate as initiator and four different crosslinkers; ethylene glycol dimethacrylate (EGDMA), 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA) and tetraethylene glycol dimethacrylate (TEGDMA). At first, polymerization kinetics was studied by NMR, revealing the negligible effect of the crosslinker nature. On the contrary, the water-soluble polymer amounts, the final hydrodynamic particle size, the swelling ability, the electrokinetic properties were found to be dependent upon the nature of crosslinker. The final latexes were found to be narrowly size distributed irrespective of the crosslinker agent’s chemical nature. In this study, the water solubility of the cross-linker was reported to be an important criterion, but other factors, such as diffusion and reactivity, have to be taken into consideration. To cite this article: P. Hazot et al., C. R. Chimie 6 (2003).