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Biodegradability is a key feature for the application of polymeric devices in medicine. This study reports an experimental and theoretical study of the degradation of poly(thioether-ester) (PTEe) nanoparticles in aqueous media. The α,ω-diene diester derived from vegetable oil, 1,3-propylene diundeca-10-polenoate (Pd10e), was used as monomer in the solvent-free synthesis of Pd10e-based nanoparticles (A-PTEe nanoparticles) via thiol-ene miniemulsion polymerization. The theoretical partition coefficients of A-PTEe and a PTEe based on dianhydro-d-glucityl diundec-10-enoate (DGU) (B-PTEe nanoparticles) were calculated using density functional theory (DFT), in order to compare their degradation behavior. The results showed that A-PTEe is more hydrophilic than B-PTEe, thus indicating the possible faster degradation of the former. The experimental degradation studies showed that, in fact, A-PTEe nanoparticles are faster degraded than B-PTEe, presenting substantial molecular weight decrease, which confirms the theoretical results. The effects of degradation could be observed in the chemical composition and thermal properties of the polymer. Considering its applicability potential as a biomaterial due to its fast degradation behavior, the cytotoxicity of A-PTEe nanoparticles and its degradation products were evaluated. In vitro assays confirmed the biocompatibility of A-PTEe nanoparticles and its degradation products when exposed on fibroblasts and red blood cells. These results suggest A-PTEe nanoparticles can be promising candidates as biobased nanocarriers for biomedical applications. [ABSTRACT FROM AUTHOR]

A post-modification process based in the swelling of polymeric nanoparticles with a low boiling point alkane ( n -pentane) to decrease the viscosity of the polymer phase and promote a controlled coalescence succeeded to change particle morphology and size of preformed polymer latexes. The swelling procedure was performed at 120 °C followed by pressure release at temperatures lower than the T g of the pure polymer and higher than the boiling point of n -pentane to promote the complete recovery of the alkane. Polystyrene latexes with different particle sizes and molar masses were prepared by emulsion and miniemulsion polymerizations. The post-modification of the latexes was evaluated at different n -pentane contents and temperature of pressure release. Results showed that the emulsion polymerization latexes with smaller particle size (≈60 nm) underwent controlled coalescence resulting in stable latexes of spherical particles with diameter in the range of 600–1000 nm, while latexes with larger particles (above 200 nm) showed little sign of coalescence under the same swelling and pressure release conditions. The presence of a medium molar mass alkane (hexadecane) in the polymeric particles obtained by miniemulsion polymerization resulted in nanocapsules morphology probably due to polymer–alkane phase segregation during the swelling procedure. [ABSTRACT FROM AUTHOR]

The impact resistance of polymeric materials can be modified by the addition of polymer particles with core shell structure, in which the core consists of a rubber phase and the shell of a glassy phase. In this work, the synthesis of core-shell particles (polybutadiene-rich phase / polystyrene rich phase) by emulsion polymerization and their use as impact modifiers in crystal polystyrene, PS, was investigated. Reactions were followed by gravimetry and dynamic light scattering analysis and core-shell morphology was determined by transmission electron microscopy. This latex, after dried, was incorporated into a PS matrix in a single screw extruder. The impact resistance increased with the incorporation of the core-shell particles and with the number of passes through the extruder. [ABSTRACT FROM AUTHOR]

In this work, the encapsulation of magnetic nickel nanoparticles in polyacrylamide particles was performed via inverse miniemulsion polymerization. The dispersion of nickel nanoparticles was characterized in polar solvents including water, ethanol, and dimethyl sulfoxide using different stabilizers. The best results were obtained when the nonionic stabilizer poly(ethylene glycol) octadecyl ether (Brij 76) was used to stabilize the nickel nanoparticles in dimethyl sulfoxide. In addition, the block copolymer poly(ethylene- co-butylene)- b-poly(ethylene oxide) was used as a surfactant to create inverse miniemulsions while minimizing the coalescence of the miniemulsion droplets. Different types of salts such as zinc, nickel, and sodium nitrates were tested as lipophobes to retard Ostwald ripening. Transmission electron microscopy images of polyacrylamide/nickel particles synthesized with zinc and nickel salts as lipophobes indicate that nickel nanoparticles are embedded in the polyacrylamide matrix. Magnetization curves show that the saturation magnetization of polyacrylamide/nickel particles is only slightly below that of the pure nickel nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The aim of this work is to study the use of an ionic liquid (IL) as surfactant in emulsion polymerization reactions and to evaluate its effect when these reactions are heated under microwave irradiation. The IL 1- n-dodecyl-3-methylimidazolium chloride was chosen to replace the surfactant dodecyltrimethylammonium bromide (DTAB) in methyl methacrylate emulsion polymerizations. The conversion evolutions and the final average diameter of polymeric particles were quite similar for reactions using the surfactant DTAB or the IL, showing that the IL acted efficiently as surfactant in emulsion polymerizations. Comparing the polymerization reactions performed under microwave irradiation and conventional heating, reaction rate enhancements were obtained for both DTAB and IL. Using a pulsed scheme, under high-power microwave irradiation, slightly higher reaction rates and molecular weights were obtained in reactions using IL, in comparison with surfactant DTAB, indicating the existence of some specific effects linked to IL-microwaves interaction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012 [ABSTRACT FROM AUTHOR]

Reaction calorimetry is a very useful tool to monitor exothermic polymerization reactions as it is based on the estimation of the heat generated by the reaction. The objective of this work is to analyze the performance of an unscented Kalman filter (UKF) for online monitoring of batch vinyl acetate emulsion polymerization reactions. Reactions are performed in isoperibolic and isothermal conditions. The UKF is compared to an extended Kalman filter that has a very poor performance. The results show that the UKF is able to provide good estimates for the conversion, for the reactor and jacket temperatures, for the overall heat transfer coefficient between the reaction medium and the jacket, and for the heat loss from the jacket to the surroundings. [ABSTRACT FROM AUTHOR]

The ionic liquid 1‐n‐butyl‐3‐methylimidazolium heptachlorodiferrate (BMI.Fe2Cl7) is efficiently used as catalyst in the cationic emulsion polymerization of styrene. The effect of different reaction temperatures, surfactant, and ionic liquid concentrations on polymer properties as molecular weight distribution and particle size is evaluated. High weight average molecular weights, above 1000 kDa, are achieved at 70% of conversion in 100 nm polystyrene particles formed mainly by micellar nucleation. Particle sizes and molecular weights increase with the decrease of the amount of surfactant. Even at low concentrations, BMI.Fe2Cl7/styrene molar ratio equal to 1/1000, the ionic liquid proves to be efficient for the emulsion polymerization of styrene, and lower ionic liquid concentrations lead to the formation of longer polymer chains. [ABSTRACT FROM AUTHOR]

Abstract: Emulsion and suspension polymerizations are important industrial processes for polymer production. The end-user properties of polymers depend strongly on how the polymerization reactions proceed in time (i.e. a batch or semicontinuous, rate of reagents feeding, etc.). In other words, these reactions are process dependent, which makes the successful process control a key point to ensure high-quality products. In several process control strategies the on-line monitoring of reaction performance is required. Due to the multiphase nature of the emulsion and suspension processes, there is a lack of sensors to perform successful on-line monitoring. Near infrared and Raman spectroscopies have been pointed out as useful approaches for monitoring emulsion and suspension polymerizations and several applications have been described. In such instance, the chemometric approach on relating near infrared and Raman spectra to polymer properties is widely used and has proven to be useful. Nevertheless, the multiphase nature of emulsion and suspension polymerizations also represents a challenge for the chemometric approach based on multivariate calibration models and demands the development of new methods. In this work, a set novel results is presented from the monitoring of 15 batch emulsion reactions that show the chemometric challenge to be faced on development of new methods for successful monitoring of processes taken under dispersed medium. In order to discuss these results, several chemometric approaches were revised. It is shown that Raman and NIR spectroscopic techniques are suitable for on-line monitoring of monomer concentration and polymer content during the polymerizations, as well as medium heterogeneity properties, i.e. average particle size. It is also shown that Hotteling and Q statistics, widely used in chemometrics, might fail in monitoring these reactions, while an approach based on principal curves is able to overcome such restriction. [Copyright &y& Elsevier]

This work describes evidences of correlation between polymer particle size and Raman scattering and shows that it is possible to use Raman scattering to monitor the evolution of average particle size during emulsion polymerization reactions. The main focus is the estimation of the average polymer particle diameter from spectra collected in a short acquisition time and consequently low signal-to-noise ratio. Finally, a multivariate linear model, (Partial Least Square-PLS), is fitted from the reaction data and a good linearity between spectra and average polymer particle diameter is found. It is shown that despite varying monomer and polymer concentrations it is possible to monitor average particle sizes during emulsion polymerization reactions using Raman spectroscopy. [Copyright &y& Elsevier]

Herein, we present the synthesis and characterization of poly(thioether-ester) nanoparticles via thiol-ene miniemulsion polymerization using a biobased α,ω-diene diester monomer, namely dianhydro- d -glucityl diundec-10-enoate (DGU), synthesized from 10-undecenoic acid (derived from castor oil) and isosorbide (derived from starch). DGU was copolymerized with 1,4-butanedithiol by thiol-ene miniemulsion polymerization resulting in waterborne poly(thioether-ester) particles with diameter around 200 nm. Polymers with number average molecular weight up to 11 kDa were obtained via miniemulsion polymerization. DSC and XRD analyses indicated a semi-crystalline polymer with a degree of crystallinity of at least 20% and T m around 68 °C. In addition, Coumarin 6 was encapsulated in the polymer particles with efficiency up to 98%. Nanoparticles presented biocompatibility in murine fibroblast (L929) and uterine colon cancer (HeLa) cells. The substantial cellular uptake of poly(thioether-ester) nanoparticles by HeLa cells suggests a potential use in uterine colon cancer treatment. [ABSTRACT FROM AUTHOR]

Superparamagnetic materials encapsulated in a polymeric matrix are interesting for several applications, including biomedical, separation, and biotechnology and enzyme immobilization. In this work, superparamagnetic poly(urea-urethane), PUU, nanoparticles were obtained by interfacial miniemulsion polymerization. Magnetite nanoparticles presenting superparamagnetic behavior were obtained by co-precipitation method and after the synthesis the magnetic nanoparticles, MNPs, were coated with oleic acid, OA, to provide a hydrophobic surface. The synthesis of PUU nanoparticles was performed using 1,6-hexanediol as polyol and IPDI as diisocyanate. The MNPs-OA were incorporated in-situ during the interfacial miniemulsion polymerization. PUU with MNPs-OA were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, electromagnetic vibrating sample magnetometry, VSM, and transmission electron microscopy. Results show a high encapsulation efficiency and VSM analysis showed that PUU with MNPs-OA still presented superparamagnetic behavior after the encapsulation step. [ABSTRACT FROM AUTHOR]

Abstract: The effect of using a redox initiation system (hydrogen peroxide and ascorbic acid), on the morphology of the nanoparticles formed in methyl methacrylate miniemulsion polymerization reactions with lecithin as surfactant and using high amounts of miglyol 812 or castor oil as costabilizer is compared to the use of a conventional organic phase initiator (2,2′-azo-bis-isobutironitrile). It was observed that with miglyol 812 as co-stabilizer the preferential formation of the nanocapsule morphology was achieved with both evaluated initiation systems when initiator concentrations were chosen in such a way that monomer conversions of 90% were only attained after 30 min of reaction. [Copyright &y& Elsevier]