Kinetics of emulsifier-free emulsion polymerization of methyl methacrylate

Abstract

SYNOPSISThe influences of polymerization temperature, initiator and monomer concentrations, ionic strength of the aqueous phase, as well as ethylene glycol dimethacrylate (EGDM) comonomer, on the kinetics of the emulsifier-free emulsion polymerization of methyl methacrylate (MMA) and on the properties of the resulting poly(methy1 methacrylate) (PMMA) lattices were studied. The polymerizations were carried out using potassium persulfate (KPS) as the initiator. Monodisperse PMMA lattices with particle diameters varying between 0.14-0.37 pm and polymer molecular weights of the order 0.4 X lo6 to 1.2 X lo6 g/ mol were prepared. The initial rate of polymerization increases with increasing temperature, KPS-MMA mole ratio, EGDM content, or with decreasing ionic strength of the aqueous phase. It was shown that the bead size can be limited by reducing the monomer concentration or by using the cross-linking agent EGDM. The ionic strength of the aqueous phase has a dominant effect on final particle diameter and polymer molecular weight. The uniformity of the latex particles increases as the temperature increases or as the initiator concentration decreases. The experimental results can be reasonably interpreted by the homogeneous nucleation mechanism of the emulsifier-free emulsion polymerization of MMA. 0 1996 John Wiley & Sons, Inc.

Poly (acrylonitrile-co-methyl methacrylate) nanoparticles: I. Preparation and characterization

“…He found the same trend where the average particle size increased with increasing (K 2 S 2 O 8 ) concentration. Similar trend has been observed by Tanrisever et al (1996) during their study of Kinetics of emulsifier-free emulsion polymerization of methyl methacrylate. They attributed the obtained results to increase in the ionic strength of the aqueous phase which strongly affected the particle size.…”

Optical properties of CCA films prepared with poly[styrene-co-sodium 1-allyloxy-2-hydroxypropane sulphonate] particles

“…That is, the increased ion strength of the aqueous phase led to increased instability of the particles. 12,16,19,26 Thus, particle size increased with the COPS-I content by the agglomeration of particles because of the increased instability. Refractive indices of the poly[ST-co-(COPS-I)] polymers, calculated by the Bragg's equation were found to increase with COPS-I concentration from 1·58 to 1·66, along with the reflectivity as shown in Table 2, might be because of the formation of core-shell shaped The maximum reflection wavelength (λmax) for the poly[ST-co-(COPS-I)] colloidal photonic crystals increased with the COPS-I concentration from 591·7 to 991·5 nm by the effect of particle diameter and the refractive index and showed the respective iridescent structural colours as shown in Fig.…”

“…Surfactant-free emulsion polymerisation of styrene (ST) with water-soluble functional monomers is known to be a good method for the preparation of highly uniform and highly charged particles. [16][17][18][19][20] Usually, these are synthesised by copolymerisation of ST with ionic monomers. 4,[11][12][13][21][22][23][24][25][26] Sodium 1-allyloxy-2-hydroxypropane sulphonate (COPS-I) 10 is one of the good candidates for this purpose, systematically for the synthesis of highly charged, monodisperse latices and their photonic crystals.…”

Preparation of magnetic latexes functionalized with chloromethyl groups via emulsifier-free miniemulsion polymerization

“…In such systems the water-soluble initiator like potassium persulfate (KPS) polymerizes the slightly water-soluble monomers, such as styrene, in aqueous phase to form oligomeric radicals with sulfate end groups, which are surface active and form micelles in an emulsion polymerization [18,19].…”