Heterophase Polymerization Of Styrene Research Articles

Synthesis of polymer microspheres of different diameters in the presence of carbofunctional organosilicon surfactants

Based on systematic studies of kinetic regularities of heterophase polymerization of styrene and methyl methacrylate (MMA), and study of physical and chemical properties of polymer suspensions, it was established that stable functional polymer suspensions with narrow particle size distribution with diameters from 0.4 to 1.4 μm are formed, when functional organosilicon surfactants are used as stabilizers at 0.5–1.0 wt% surfactant concentration per monomer mass.

Heterophase Polymerization of Styrene in the Presence of Boltorn Polyester Polyol

This paper presents data on styrene polymerization in emulsions stabilized by biodegradable poorly water-soluble polyester polyol of 2,2-bis(methylol)propionic acid (polyester Boltorn H40). The effect of synthesis conditions on the kinetic laws of polymerization is studied. The results are analyzed in comparison with those previously obtained under similar conditions but in the presence of water-soluble surfactants.

Coatings and surfactants based on oligovinylsiloxanes

Silicate glass and cotton fabric are hydrophobized via treatment of their surface by vinyltriethoxysilane and oligovinylsiloxane. The data of electron microscopy for chemical analysis and the values of contact angles suggest that the hydrophobicity of the surface layer develops via the polymerization of vinyl groups. The arrangement of vinyl groups in neighboring units in oligovinylsiloxane is favorable for formation of a more uniform solid coating with enhanced hydrophobicity. The use of oligovinylsiloxane and its derivatives with amino and carboxyl groups as surfactants in the heterophase polymerization of styrene makes it possible to obtain stable suspensions with a narrow particle size distribution.

Lignin-based polymeric surfactants for emulsion polymerization

A non-ionic surfactant system is synthesized by standard grafting of poly(ethylene oxide) from renewable lignin fragments and used for the emulsion polymerization of styrene. The lignin precursors are formed by hydrogenolysis and utilized as initiator for the oxyanionic polymerization of ethylene oxide leading to amphiphilic polymers, very similar to standard nonionic surfactant synthesis. Subsequently, the formed amphiphilic polymers are employed as stabilizers in the heterophase polymerization of styrene with various initiators. Poly (styrene) latexes with solids contents of up to 21% depending on stabilizer concentration have been obtained. Stabilizer efficiencies and performances were nicely comparable with those of nonylphenol-based, non-ionic industrial performance surfactants.

Heterophase polymerization of styrene in the presence of biodegradable surfactants

Linear and branched copolylactides of various structures are synthesized and characterized. Polystyrene suspensions with various particle diameters are obtained via heterophase polymerization with the use of copolylactides as biodegradable surfactants. The influence of the surfactant structure on the polymer microsphere size and the type of size distribution is studied.

Novel Approach to Synthesis of Monodisperse Polymeric Microspheres: Heterophase Polymerization of Styrene and Methyl Methacrylate in Presence of Water-Insoluble Functional PDMSs

Water-insoluble polydimethylsiloxanes (PDMSs) with functional organic substituents at the silicon atom are promising surface-active substances for the synthesis of monodisperse polymeric microspheres. In this regard a number of PDMS oligomers bearing different functional chain ends (amino, carboxylic and epoxy groups) were synthesized by conventional approaches. Solubility of PDMS in both the monomers (styrene (St) or methyl methacrylate (MMA)) and water as well as their surface-active properties at the water-toluene interface were investigated. Heterophase polymerization of St and MMA was carried out in the presence of functional PMDS and the resulting suspensions of polymeric microspheres were characterized using scanning electron microscopy (SEM). It was shown that the polymeric suspensions obtained have a very narrow particle size distribution and high stability in electrolyte solutions. The mechanism of the interfacial layer formation which explains the observed results is proposed.

Amphiphilically stabilized block copolymer particles via heterophase polymerization in glacial acetic acid

Radical heterophase polymerization of styrene in glacial acetic acid initiated with either 2,2′-azobisisobutyronitrile or poly(ethylene glycol)-azo initiators and in the presence of poly(methyl methacrylate) or poly(ethylene glycol) macromonomers is described for the first time ever. It turned out to be a convenient route to amphiphilically stabilized block copolymer dispersions. These block copolymers, after the polymerization in glacial acetic acid, can be easily transferred to other continuous phases which are selective solvents for one of the different constituent blocks. Electron microscopy results are presented regarding the morphology of the block copolymer particles in glacial acetic acid, water, and in a mixture of tetralin, cis-decalin, and tetrachlormethane. Depending on the particular composition of the block copolymers and the nature of the continuous phase, the changes in the morphology for a given block copolymer can be quite dramatic.

Diversified Applications of Chemically Modified 1,2-Polybutadiene

Commercially available 1,2-PB was transformed into a well-defined reactive intermediate by quantitative bromination. The brominated polymer was used as a polyfunctional macroinitiator for the cationic ring-opening polymerization of 2-ethyl-2-oxazoline to yield a water-soluble brush polymer. Nucleophilic substitution of bromide by 1-methyl imidazole resulted in the formation of polyelectrolyte copolymers consisting of mixed units of imidazolium, bromo, and double bond. These copolymers, which were soluble in water without forming aggregates, were used as stabilizers in the heterophase polymerization of styrene and were also studied for their ionic conducting properties.

Synthesis and characterization of thermosensitive core–shell polymeric nanoparticles

Thermosensitive core–shell nanoparticles were synthesized by semicontinuous heterophase polymerization of styrene, followed by a seeded polymerization for forming a shell of poly(N-isopropyl acrylamide) (PNIPAM). Nanoparticles characterization by scanning transmission electronic microscopy showed core–shell morphology with average particle diameters around 40 nm. An inverse dependence of the particle size with temperature in the range 20–55 °C was identified by quasielastic light scattering measurements. As was expected for core–shell particles with PNIPAM as the shell, a volume phase transition near 32 °C was detected. In spite of thermosensitive properties of core–shell nanoparticles synthesized here, the volume percentage loss values were not so high, probably due to their relatively low content of PNIPAM.

Heterophase polymerization of styrene in the presence of organosilicon compounds of various natures

The heterophase polymerization of styrene has been carried out in the presence of surfactants—organosilicon compounds with different solubilities in aqueous and styrene phases and surface activities at the interface. It has been demonstrated that the stability of polymer suspensions prepared with water-insoluble organosilicon compounds is much higher than that in the presence of organosilicon surfactants soluble in organic and aqueous phases. In the former case, suspensions with narrower particle-size distributions are produced. The stability of polymer microspheres prepared at various monomer-to-water volume ratios has been tested. An increase in the monomer concentration above 25 vol % leads to the loss of system stability.

Polymerization of styrene in the presence of monoesters of aromatic dicarboxylic acids as surfactants

The colloidal properties of monoesters of aromatic dicarboxylic acids and the heterophase polymerization of styrene in their presence have been studied. It has been shown that particles are formed from micro-droplets of the monomer. A high stability of polymer suspensions during the synthesis has been found to be provided by a strong interfacial adsorption layer formed on the surface of particles from the polymer being synthesized and a surfactant.

Linear and Star-Shaped Polystyrene-block-poly(sodium glutamate)s as Emulsifiers in the Heterophase Polymerization of Styrene

Linear and hetero multiarm polystyrene-block-poly(sodium dl-glutamate) copolymers were used as emulsifiers in the radical emulsion polymerization of styrene in order to investigate the impact of the stabilizer topology on the main latex properties, namely average particle size, polydispersity, electrolyte stability, and electrophoretic mobility of particles, in dependence of the electrolyte concentration and pH. Compared to the linear analogues (dH = 100−220 nm, PDI < 1.04), the star-shaped stabilizers yield smaller latexes particles (dH = 70−130 nm) with broad or even bimodal distributions (PDI > 1.13), which indicates a higher stabilizing efficiency and the ability to stabilize a second generation of particles. The topology of the stabilizer affects as well the critical coagulation concentration of the latex, which is 1.0 M NaCl for linear and 0.2 M for branched copolymers. The observed stability of the latexes against electrolytes and the mobility of particles support an electrosteric stabilization of the particles.

Kinetics of Aqueous Heterophase Polymerization of Styrene with Polyurethane Emulsifier

This paper describes the synthesis of an amphiphilic polyester polyurethane and its use as a stabilizer for the aqueous heterophase polymerization of styrene. The polymerization process was investigated using dilatometry and reaction calorimetry methods. The polyurethane proved to be an efficient stabilizer in the heterophase polymerization of styrene.

The synthesis of polymer suspension with narrow particle size distribution for immunochemical investigations

Heterophase polymerization of styrene in the presence of di-p-tolyl-o-carbalkoxyphenylcarbinol (DTC) soluble in monomer and insoluble in water, as stabilizer, was investigated. The factors affecting polymer particle diameter, their size distribution and stability were investigated. It was suggested that polymer particles are formed from monomer droplets. The polystyrene suspension with narrow particle size distribution synthesized in the presence of DTC, was used for immunochemical research.

Styrene heterophase radical polymerization in the presence of water-soluble polyvinylamides

Heterophase polymerization of styrene in the presence of poly-N-vinylamides of different structures as stabilizers was investigated. Optimal conditions for preparing of stable polystyrene suspensions with narrow size distribution and the factors affecting the diameter and size distributions of polymer particles were established.