Microemulsion and emulsion polymerization of butyl acrylate—I. Effect of the initiator type and temperature

Kocsisová

2011

Polym J

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Miniemulsion polymerization of butyl acrylate initiated by 2,2¢-azobisisobutyronitrile in the presence of carbon nanotubes (CNTs) has been investigated. The miniemulsions were stabilized by non-ionic, cationic and anionic emulsifiers. The maximal rate of polymerization (R pmax ) increases with the type of emulsifier in the following order: Triton X-405 (Tr)oTween 60 (Tw)Bdioctyl sodium sulfosuccinate (AOT)oDowfax 2A1 (DW)Bcetylpyridinium bromide (CPB)ocetyl trimethylammonium bromide (CTAB). R pmax increases on addition of CNTs in the runs with Tw and Tr, slightly increases in the runs with CTAB, AOT and DW, and decreases in the run with CPB. Particle evolution is discussed in terms of two 'apparent' limiting cases: zero-one and pseudo-bulk kinetics. In the former case (polymer nanoparticles (PNP) approach), monomer droplets are nucleated by simple entry of radicals and transformed into polymer particles by growth events. Pseudo-bulk kinetics govern the polymerization process by the formation of radicals in the monomer phase (monomer/polymer nanoparticles (MPNP) approach).

Section: Methodsmentioning

confidence: 99%

On the preparation of composite poly(butyl acrylate)/carbon nanotube nanoparticles by miniemulsion polymerization of butyl acrylate

Kocsisová

2011

Polym J

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“…The average particle sizes were determined by the light scattering method. The polymerization technique and the estimation of particle number and particle size distribution were the same as described earlier [9][10][11][12].…”

Section: Recipes and Proceduresmentioning

confidence: 99%

On the Kinetics of Inverse Emulsion Polymerization of Acrylamide

Designed Monomers and Polymers

Fialová

Berek

2008

The inverse emulsion polymerization of acrylamide (AAm) initiated by a water-soluble initiator (ammonium peroxodisulfate, APS) was investigated. The rate of inverse emulsion polymerization increased with both increasing initiator and emulsifier concentrations. The molecular weight of polyacrylamide decreased with increasing the initiator concentration and slightly rose with increasing the emulsifier concentration. With increasing APS concentration the curves are broader. This indicates widening of molecular weight distribution. The decrease in M w with increasing APS concentration results from the increased termination of growing radicals mainly by primary or oligomeric radicals. The number of radicals per particle was inversely proportional to the APS concentration. The increased deactivation of primary and monomeric radicals decreased their desorption rate and re-entry rates as well. The desorption rate of radicals was interpreted using three models: the Nomura model (N model , k des,N ), the Gilbert model (G model , k des,G ) and the Ugelstadt model (T model , k des,T ). The desorption rate constant (k des ) for the different models differs by up to two orders of magnitude. The value of k des increases in the following order: N model < G model < T model . The radical entry rate decreases with rising emulsifier concentration and increases with rising initiator concentration.  Koninklijke Brill NV, Leiden, 2008

“…The measurements of average particle size (a static and dynamic light scattering -LS), the estimation of particle number, and the measurements of light intensity were the same as described earlier [36,37].…”

Section: Polymer and Latex Characterizationmentioning

confidence: 99%

On photoinduced miniemulsion polymerization of butyl acrylate with clay

Designed Monomers and Polymers

2012

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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