Emulsion polymerization

In an effort to develop biomimetic glycosyl transfer catalysts, a polymerization protocol was developed that is applicable to the synthesis of crosslinked microgels via UV-initiated free radical polymerization of miniemulsions at ambient temperature and below. The catalytic activity of the microgels derived from butyl acrylate, EGDMA, and a catalyst-precursor ligand was established using the hydrolysis of 4-methylumbelliferyl β-D-galactopyranoside as a model reaction. The microgel-catalyzed hydrolysis was up to 3 × 10 5-fold accelerated over the background reaction and notably 38-fold faster than the hydrolysis catalyzed by its low molecular weight analog. Dynamic light scattering analysis demonstrated mean hydrodynamic diameters of the particles between 210 and 280 nm and chemical stability of the particles in aqueous solution between pH 1 and 13. A bell-shaped correlation between catalytic proficiency and material rigidity was observed that peaks at 40 mol % of crosslinking content of the microgel.

Copolymers of vinyl acetate and ethylene were prepared by emulsion polymerization using ammonium persulphate and sodium metabisulphite as initiators in presence of cyclohexane. Several copolymer samples were prepared by changing initial pressure of ethylene from 100 to 250 psi. The copolymer composition was determined by 1H-NMR and thermogravimetric analysis in nitrogen atmosphere.

Acrylic-polyurethane hybrid emulsions were prepared by converting amphiphilic acrylic-polyurethane graft copolymers previously synthesized in nonaqueous media by grafting vinyl monomers to partially vinyl-endblocked polyurethanes to aqueous emulsions. These emulsions were ...

Purpose-This paper aims to synthesize new terpolymers by the emulsion polymerization technique composed of acrylamide-based polyurethane monomers (TPM and MPM) with different vinyl acetate copolymer systems, such as vinyl acetate/butyl acrylate (VAc/BA), vinyl acetate/ethylhexyl acrylate (VAc/2-EHA) and vinyl acetate/vinyl ester of versatic acid (VAc/VEOVA 10) systems. The performance of the prepared terpolymers as binders in emulsion coatings and textile industries was investigated and compared with the analogous commercial ones. Design/methodology/approach-New waterborne polyurethane-vinyl ester-vinyl acetate terpolymers with high solid content and nano-scale emulsions have been successfully synthesized in two steps. The polyurethane oligomers were prepared by the prepolymer method as the first step. The second step involved polymerization with different vinyl monomers. The synthesized terpolymers were characterized using FTIR, scanning electron microscope, thermogravimetric analysis, minimum film forming temperature and particle size analyzer methods. Findings-The synthesized emulsion terpolymers have shown small particle sizes averaged of 70 nm and a narrow distribution range, along with good mechanical, thermal and chemical stabilities. The surface coating layers of the terpolymers also have some important in terms of smoothness, clarity and binding ability in water-based coating for up to 4425 scrub cycles at 30 GU. Further, a high potential application textile printing was achieved at high solid content of 47-50%. Originality/value-The effects of different isocyanates and vinyl monomers on the properties of obtained emulsion coatings have been studied. The improvement consequences of the coating evaluation of the waterborne binders for emulsion paints have been described. The properties of polyester/cotton fabric print pigment printing of textiles appear to be most promising enhancements by using the prepared nanocomposites of PUco-vinyl acetate-co-vinyl ester as waterborne binders. So that the prepared emulsions have the potential to replace solvent-based coatings as waterborne binders for both emulsion coating and textile printing applications.

Novel crosslinking method was introduced for
preparation of acrylic thickener microgels based on sodium
acrylate and 2-acrylamido-2-methylpropane sulfonic acid
(AMPS) through inverse emulsion polymerization (IEP).
Usually multifunctional vinyl crosslinkers such as methylene
bisacrylamide are used in preparation of microgels
through IEP. In this paper, a novel crosslinking method was
introduced for microgel preparation through IEP. Diglycidyl
materials were used instead of vinyl crosslinkers for
microgel preparation. The effect of two diglycidyl materials
such as polyethylene glycol diglycidyl ether (PEGDGE)
and ehylene glycol diglycidyl ether (EGDGE) was
investigated as crosslinker in microgel synthesis. Acrylic
microgels prepared through IEP can be used as a thickener
for many industrial applications. The effects of parameters
such as comonomer composition, drying temperature and
crosslinker content on the thickening properties of microgels
were investigated. According to the viscosity measurements,
the microgel containing 12.5 % AMPS possessed the
highest viscosity, while the lower viscosities were found to
be observed for the microgels having the lower and higher
percentages of AMPS. Moreover, the microgel containing
AMPS showed the thickening properties over a wide range
of pH and was nearly pH independent. Increasing drying
temperature and amount of crosslinker led to enhance the
crosslink density. The apparent viscosity was reduced and
the storage modulus was increased in higher crosslink density.
These microgels showed superior thickening properties
in comparison to vinyl-crosslinked microgels, i.e., the thickening efficiency of PEGDGE-crosslinked microgels
was significantly higher (about 500 %) than the conventional
MBA-crosslinked microgels.

This work is an attempt to study the effect of different latex types containing various auxiliary mono-mers and emulsifiers on their pigmentation and their corresponding behavior on scrub resistance. The auxiliary monomers investigated were acrylic acid (AA), metha-crylic acid (MAA), and itaconic acid and the emulsifiers contained sodium lauryl sulfate (SLS) and sodium dode-cylbenzene sulfonate (SDBS). It was shown that a semi-batch polymerization technique which led to smaller particles and sharper size distributions is preferable. The best wet scrub results were obtained by using MAA and SLS. It was also shown that the proper selection of an auxiliary monomer generally depended on the range of incorporated pigment volume concentration (PVC). At high PVCs, AA gave better performances compared with MMA. The reverse effect was shown to occur at low PVCs. V

A series of core–shell polymeric particles with poly(n-butyl acrylate-co-methacrylic acid-co-ethylene glycol dimethylacrylate) as core and poly(styrene-co-methyl methacrylate) as shell were prepared by seeded emulsion polymerization. The role of ethylene glycol dimethylacrylate (EGDMA) is to crosslink the core so as to avoid any probability of gel formation and to bind both the core and the shell phase together. The spherical morphology of the core–shell structure was achieved at 60:40 core to shell ratio. The core–shell morphology was confirmed by SEM and TEM analyses. GPC analysis of the particles reveals that the polymer shows a bimodal mode. The first peak has M w = 382700 and M n = 245200 with polydispersity index of 1.6, and the second peak has M w = 21200 and M n = 14800 with polydispersity index of 1.4. These core–shell latexes were applied as a pigment/binder in emulsion paint and the paint properties like gloss, rock hardness, washability, opacity, etc. were compared with the standard. The results show that these core–shell latexes can provide similar hiding power with 17% reduction of TiO2 in the paint formulation.

A method is developed to enable emulsion polymerization to be performed under RAFT control to give living character without the problems that often affect such systems: formation of an oily layer, loss of colloidal stability, or loss of molecular weight control. Trithiocarbonate RAFT ...

Poly(vinyl acetate-co-butyl acrylate) latexes having oligomeric N-methylol acrylamide were prepared by semi-continuous emulsion polymerization. The effects of new protective colloid and comonomer ratios on the physicochemical and colloidal properties of latexes were investigated. The changes in homopolymer and copolymer latexes were determined by measuring viscosity, particle size, molecular weight (MW), molecular weight distribution (MWD), and surface tension. \( \bar{M}_{n} \) values of copolymer latexes were found to be lower than the MWs of the poly(vinyl acetate) and poly(butyl acrylate) homopolymers. In general, \( \bar{M}_{n} \) and \( \bar{M}_{\text{w}} \) values of copolymer latexes changed irregularly with increasing BuA ratio in the copolymer composition.

ABSTRACT:

Surfactants plays a vital role in various cosmetic formulation. To formulate compounds sparingly soluble in water, Cosmetic science acceptable co-solvents or surfactants are typically employed to increase solubility. Polymeric micelles made by surfactants have a whole set of unique characteristics, which make them a very promising carrier system for a wide range of cosmeceutical products. The low solubility in biological materials displayed by about 50% of the cosmeceuticals still remains the main limitation in skin, hair, and nail and transdermal administration. Among the existing strategies to overcome these drawbacks, inclusion of hydrophobic actives into polymeric micelles which composed of surfactants are one of the most attractive alternatives. This article reviews about the surfactants, their basics explaining the mechanism to form micelles and its applications related to various site of action.

One of the most important aspects of particle formation in emulsion polymerization systems with monomer emulsion feed is of secondary nucleation. It is one such aspect that is not well understood and has fascinated the research community. Understanding secondary particle formation is vital for production of synthetic latexes. On one hand, secondary particles might ruin surface-coating properties of latexes while on the other hand, secondary nucleation contributes to PSD (particle size distribution) broadening and its advantage can be taken to produce high solids content latexes by introducing a new crop of small particles that increases the solids content but prevents the resulting high viscosity. Despite all the extensive work on seeded emulsion polymerization, the available literature on secondary particle formation is scarce. The aim of the present work was to explore the research done on secondary nucleation as it occurs inside the seeded emulsion polymerization systems. The particle nucleation mechanism and the prediction of conditions leading to secondary nucleation for seeded batch emulsion polymerization has been analyzed by a few researchers (Hansen and Ugelstad (1978-1979), [1,2], Morrison and Gilbert, (1995) [3]). This review paper investigates the work of those scientists & researchers to the present-day advances in the field. Some of these models also predict the effect of different variables on particle evolution and the situations in which secondary nucleation can be safely ignored. However, one consideration to be kept in mind is that all such explanations are often based on a large number of unknown parameters and lack physical transparency.