Search Results

1 - 10 of 16 items :

  • "emulsion polymerization" x
Clear All

://dx.doi.org/10.1016/j.powtec.2004.07.002 [14] Chern C.S., Principles and applications of emulsion polymerization, John Willey & Sons, 2008. http://dx.doi.org/10.1002/9780470377949 [15] Tanrisever T., Okay O., Sonmezoclu I.C., J. Appl. Polym. Sci., 61 (1996), 485. http://dx.doi.org/10.1002/(SICI)1097-4628(19960718)61:3<485::AID-APP11>3.0.CO;2-0 [16] Madan R.N., Dikshit R.C., Indian J. Chem. Techn., 11 (2004), 74. [17] Cohen S.T., Genzer J., J. Am. Chem. Soc., 133 (2011), 175

Abstract

Poly(methyl methacrylate)-holmium orthovanadate (PMMA-HoVO4) nanocomposites were synthesized using emulsifierfree emulsion polymerization system in two ways. In the first one, the HoVO4 nanoparticle dispersion was added to the emulsion system before or after polymerization start (in situ polymerization). In the other one, nanoparticle dispersion and polymeric latex were mixed together at room temperature (blending). Crystalline HoVO4 nanoparticles (about 60 nm) were synthesized by coprecipitation method. Three different composite latexes were synthesized by varying the potassium persulfate concentration and the time of HoVO4 nanoparticles addition. According to the dynamic light scattering analysis, the size of the polymer beads in the latexes is between 244.8 nm and 502.5 nm and the PDI values are in the range of 0.005 to 0.206. Infrared spectral analysis showed that HoVO4 caused some changes in the structure of the polymer. Luminescence measurements attempted to determine optical properties of the nanocomposites. The results have shown that HoVO4 nanoparticles do not protect their structure due to the reaction with persulfate radicals but that they enter the polymer beads and change the luminescence properties of the polymer forming a new material with different properties.

. & Lansalot, M. (2010). New Ethyl Cellulose/ Acrylic Hybrid Latexes and Coatings via Miniemulsion Polymerization. J. Polym. Sci. Pol. Chem. 48, 2329-2339. DOI: 10.1002/pola.23998. 23. Li, Y., Liao, S., Wu, W., Zhen, D. & Xiao, Z. (2012). Synthesis and characterization of EC/ BA / VAc hybrid latexes via pre-emulsified semi-continuous seed emulsion polymerization. Adv. Mater. Res. 550-553, 183-187. DOI: 10.4028/www. scientific.net/AMR.550-553.183. 24. General Administration of Quality Supervision, Inspection and Quarantine of China (AQSIQ). (2006). Plastics - Determination of

Abstract

Three dimensional cross-linked polymer microgels with temperature responsive N-isopropyl acrylamide (NIPAM) and pH sensitive methacrylic acid (MAA) were successfully synthesized by free radical emulsion polymerization with different amounts of MAA. Silver and gold nanoparticles with the size of 6.5 nm and 3.5 nm (±0.5 nm), respectively were homogeneously reduced inside these materials by chemical reduction method at pH 2.78 and 8.36 for the preparation of hybrid materials. The samples were characterized by FT-IR, DLS and TEM techniques. The catalytic activity of the hybrid materials was investigated for the reduction of 4-nitrophenol (4-NP) using NaBH4 as reducing agent by UV-Vis spectroscopy. The hybrid polymer network synthesized at pH 8.36 showed enhanced catalytic efficiency compared to the catalysts synthesized at pH 2.78. In this study, it has been stated that the catalyst activity strongly depends on the amount of MAA, pH value during synthesis and the type of entrapped metal nanoparticles.

Abstract

The requirements put on coating materials are more and more stringent mainly in the environmental domain, especially as regards VOC emissions. This is why water-based binders as alternatives to solvent-based binders, to provide paints possessing equally good use properties, are intensively sought. The objective of this work was to assess the anticorrosion and chemical properties of paint films based on new self-cross-linking acrylic latexes. The latexes were synthesized via two--step emulsion polymerisation to obtain a core-shell system. Nanostructural ZnO in an amount of 1.5 wt. % was added to the system during the latex binder synthesis. Paints with an enhanced corrosion resistance and chemical resistance of the films were prepared. The binders prepared were pigmented with anticorrosion pigments and their properties were compared to those of commercial water-based dispersions with either identical or different paint film formation mechanisms. The results gave evidence that if a well-selected pigment is used, the binders can be used to obtain anticorrosion coating materials for metallic substrates.

Abstract

Studies in recent years have consistently shown that polymeric drug nanocarriers can be used in drug release and drug delivery systems to treat eye disorders. To achieve effective control over drug delivery, it is of crucial importance what kind of polymer and which method for drug inclusion in the nanoscale carrier we choose and what conditions are needed for the performance of this process.

OBJECTIVE: The aim of this study was to produce poly(vinyl acetate) nanoparticles with indomethacin incorporated in them, assess the effect of time for dialysis of the residual monomer and initiator on the degree of incorporation of indomethacin in the nanoparticles and on the kinetics of its release, to include them in ophtalmic formulations.

MATERIALS AND METHODS: Poly(vinyl acetate) nanoparticles with indomethacin were obtained by emulsion radical polymerization of vinyl acetate in the presence of indomethacin (in situ inclusion) and the absence of emulsifier. To release the residual monomer and initiator (ammonium persulfate) the obtained latexes were dialysed for 6, 9, 18 and 23 hours and then the nanoparticles were freeze-dried. Structural analysis was performed by transmission electronic microscopy, infrared spectroscopy, differential thermal analysis and thermogravimetry. Release of indomethacin was observed using ultraviolet spectroscopy.

RESULTS: We proved the delayed release of indomethacin from the poly(vinyl acetate) nanocarrier and the lack of chemical interaction between the polymer and indomethacin. After 9-hour dialysis the initiator and the residual vinyl acetate were removed from the nanoparticles, while the entrapped indomethacin kept therapeutic concentrations.

CONCLUSIONS: Dialysis for more than 6 and no more than 9 hours is recommended to remove the residual monomer and initiator when preparing indomethacin nanoparticles by in situ radical emulsion polymerization of vinyl acetate, for inclusion in liquid ocular formulations.

. Textile Research Journal, 87(17), 2127-2132. [12] Chern, C. S., Lin, S. Y., Chen, L. J., Wu, S. C. (1997). Emulsion polymerization of styrene stabilized by mixed anionic and nonionic surfactants. Polymer, 38(8), 1977-1984. [13] Meng, Y., Tang, B., Xiu, J., Zheng X., Ma W. (2015). Simple fabrication of colloidal crystal structural color films with good mechanical stability and high hydrophobicity. Dyes & Pigments, 123, 420-426. [14] Xi, L. I, Liu, Y., Jiawen, L. I., Wen-hao H. (2010). Influence of the optical multi-film thickness on the saturation of the structural color

synthesis of polystyrene-silica nanocomposite particles by soap-free emulsion polymerization using cationic initial or in company with colloidal silica sol solution. Nanosci Nanotechnol, 2009, 9(12):7229-35.

References S. R. Croy and G. S. Kwon, Polymeric micelles for drug delivery, Curr. Pharm. Des.   12 (2006) 4669-4684; DOI: 10.2174/138161206779026245. J. L. Mura and G. Riess, Polymeric surfactants in latex technology: polystyrene-poly(ethylene oxide) block copolymers as stabilizers in emulsion polymerization, Polym. Adv. Technol.   6 (1995) 497-508; DOI: 10.1002/pat.1995.220060711. R. Nagarajan, Solubilization in aqueous solutions of amphiphiles, Curr. Opin. Colloid Interf. Sci.   1 (1996) 391-401; DOI: 10.1016/s1359-0294(96)80139-7. S. Kim, J. Y. Kim, K. M

[bis(ethyl glycinat-N-yl)phosphazene]−poly(ethylene oxide) block copolymers. Biomacromolecules 2002 , 3 , 1364–1369. 11. Garnier, S.; Laschewsky, A. Synthesis of new amphiphilic diblock copolymers and their self-assembly in aqueous solution. Macromolecules 2005 , 38 , 7580–7592. 12. Gaillard, N.; Guyot, A.; Claverie, J. Block copolymers of acrylic acid and butyl acrylate prepared by reversible addition–fragmentation chain transfer polymerization: Synthesis, characterization, and use in emulsion polymerization. J. Polym. Sci. A Polym. Chem. 2003 , 41 , 684-698. 13. Nikova