Miniemulsion Polymerization of Styrene Initiated by Tween-surfinit

Capek, Ignác

doi:10.1163/138577210x509589

Cited by 4 publications

(2 citation statements)

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“…A vast majority of the studies on dispersion (microemulsion, miniemulsion, and emulsion) polymerization processes focus primarily on thermally initiated polymerization [14][15][16][17][18]. However, there have been several photoinduced polymerizations in microemulsion [19,20], emulsion [21,22], and in micellar media [10][11][12][13][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

On photoinduced miniemulsion polymerization of butyl acrylate with clay

Capek

2012

Designed Monomers and Polymers

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The miniemulsion polymerizations (MiEPs) of butyl acrylate (BA) initiated by UV-light have been studied. The oil-soluble dibenzoyl peroxide was used as a photoinitiator. Furthermore, the effect of sodium montmorillonite on kinetics and BA miniemulsion stabilized by anionic sodium dodecylsulfate (SDS) and anionic cetyltrimethylammonium bromide (CTAB) was studied. The polymerization rate vs. conversion curve of the photoinduced MiEP of BA was described by two and four nonstationary rate intervals. Two rate intervals with one rate maximum was observed with CTAB and four nonstationary rate intervals with two rate maxima appeared with SDS. Variation of the rate of polymerization with conversion was discussed in terms of types of initiating radicals and the gel effect.Keywords: photoinduced miniemulsion polymerization; clays; kinetics; composite nanoparticles Introduction For the past 20 years, there has been increased attention paid to the synthesis of nanocomposites based on either intercalated or exfoliated clay dispersed into various matrix polymers [1][2][3][4][5].There are also some studies on the formation of composite nanoparticles by the dispersion polymerization of monomers with clays as was reviewed by Capek [6]. As an alternative to the procedures described above, the preparation of nanocomposites using UV-curing technology has only recently been reported as summarized below.There are also several studies. Monomer polarity, monomer functionality, and the functional groups on the organoclay surfaces significantly impact both the degree of clay exfoliation and photopolymerization kinetics. The addition of polymerizable organoclays increases photopolymerization rate in sufficiently exfoliated clay systems, whereas the rate decreases with lower degrees of clay exfoliation. With clay exfoliation, the effective surface area is increased, resulting in immobilization of a greater number of the propagating radicals and decreased termination [7].A photoinitiator intercalated into montmorillonite had high photoinitiation efficiency, even only 1/100 (w/w) modified clay could initiate the radical polymerization with the 87% acrylate conversion on UV-light exposure. The d spacing could be enlarged to 13.9 nm after photopolymerization with organoclay loading. This approach provided a novel pathway for using the highly exfoliated clay-polymer composites for designing intercalating agents capable of introducing different functional groups [8,9].The functionalization of the sodium montmorillonite (MMTNa) surface with glycidylpropyl-triethoxysylane allows to obtain a new modified clay mineral which can be dispersed

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Section: Introductionmentioning

confidence: 99%

On photoinduced miniemulsion polymerization of butyl acrylate with clay

Capek

2012

Designed Monomers and Polymers

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“…In contrast, the rate of polymerization increased and the degree of polymerization decreased in the presence of anionic emulsifiers C 8 H 17 SO 3 Na, C 12 H 25 SO 3 Na and C 16 H 25 SO 3 Na [6]. The related data one can find in other papers [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Micellar Aqueous Phase Polymerization of Acrylamide

Capek

Kocsisová

2011

Designed Monomers and Polymers

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The kinetics of aqueous phase radical polymerization of acrylamide initiated by ammonium peroxodisulfate (APS) and 2,2 -azobisizobutyronitrile (AIBN) were studied in the presence of the non-ionic hydrophilic Tween-20 and hydrophobic Tween-85. The polymerization rate vs. conversion curve is described by a curve with two or three rate intervals and the maximal rate is located at medium conversion. This behavior strongly deviates from the kinetic model of the ideal solution polymerization with the steady-state kinetics at low and medium conversions. On the contrary, the present data indicate the kinetics typical for the transparent heterogeneous-micellar or microemulsion polymerization. The associates of polyacrylamide and acrylamide play the role of active particles. Indeed, the light scattering measurements confirmed the presence of polyacrylamide nanoparticles in both polymerization systems with and without emulsifier. The intra-and intermolecular association of polyacrylamide with its monomer is suggested to be the dominant process which induces the formation of particles responsible for the kinetics typical for the micellar or microemulsion polymerization. The experimental data show that the dependence of the maximal rate of polymerization (R p,max ) vs. conversion is the result of polymerization within the nanoscaled polymer aggregates and not by the gel effect. R p,max decreases with increasing emulsifier concentration and the decrease is much more pronounced with hydrophilic emulsifier. Polymerization is faster for the APS-initiated system than for the AIBN-initiated one. The radical polymerization of AAm polymerization with and without emulsifier was discussed in terms of the formation of polymer chain aggregation (nanoparticle) into polymer chains as a main reaction locus.

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