Objectives.
To create stable artificial polymer suspensions with a positive charge of particles based on polycarbonate and polymethyl methacrylate using cationic surfactants and organosilicon ...surfactants.
Methods
. The size of droplets and polymer suspension particles was determined by photon correlation spectroscopy (dynamic light scattering) using a Zetasizer NanoZS laser particle analyzer (Malvern, UK).
Results
. Domestic cationic surfactants Katamin-AB and Azol-129 were found to be capable of producing stable artificial polycarbonate and polymethyl methacrylate suspensions. Based on the polymer, the optimal surfactant concentration was 6 wt %. The effect of polymer concentration in solution on the stability and particle size of final polymer suspensions was shown. It was determined that the polymer concentration in the solution should not exceed 10%. When obtaining a highly dispersed suspension during dispersion, a higher concentration causes an increase in the viscosity of emulsions. As a result of a synergistic effect formation, we used mixtures of cationic surfactants (Katamin-AB/Azol-138 and Azol-129/Azol-138) to enhance the stability of the final polymer suspensions. The optimal surfactant ratio was 9:1. The total concentration of the mixture is 10 wt %, based on the polymer. Polymer suspensions were stabilized with each of 2:1 mixtures of cationic surfactants Katamin-AB and Azol-129 withan organosilicon surfactant U-851. The total mixture concentration was 9 wt %, based on the polymer.
Conclusions.
New methods of producing artificial polycarbonate and polymethyl methacrylate suspensions in the presence of domestically produced cationic surfactants, as well cationicorganosilicon surfactants mixtures, were proposed. The colloidal-chemical properties of the obtained polymer suspensions were considered. It was found that using a 2:1 mixture of cationic and organosilicon surfactants produces polymer suspensions that are stable during production and storage.
The polymerization of styrene in the presence of an organosilicon comb-shaped surfactant, α,ω‑bis(trimethylsiloxy)-oligodimethylmethyl-(10-carboxydecyl)siloxane, is studied. The reaction yields ...aggregatively stable polystyrene suspensions with a polymer content of up to 50%, a high surface concentration of carboxyl groups, and a particle diameter of up to 2.2 μm. A comparative analysis of the kinetic regularities of polymerization and the properties of polymer suspensions in the presence of the comblike, dimeric, and linear surfactants is carried out.
The behavior of organosilicon surfactants of different structure in model systems—Langmuir films—at the water/air interface is studied. It is shown that, under the compression of Langmuir films, the ...conformational states of surfactants of different structure are different. The obtained data make it possible to explain a high stability of polymer suspensions synthesized in the presence of organosilicon surfactants.
New methods for producing artificial polyetherimide suspensions in the presence of domestic cationic surfactants, their mixtures, and mixtures of cationic and organosilicon surfactants were proposed. ...The effect of the polymer concentration in the initial solution and conditions of emulsion dispersion on the stability and particle size of the final polymer suspensions is shown. The colloidal chemical properties of the obtained polymer suspensions are considered. Conclusions about the influence of the nature and concentration of surfactants on the stability of the obtained suspensions are drawn. When using a mixture of cationic and organosilicon surfactants, polymer suspensions stable during production and storage are formed, which is explained by the formation of structural mechanical and electrostatic stability barriers in the surface layers of the particles.
The effect of the reactant ratio in the reaction of tetramethyldisiloxane with germanium tetrachloride and diethyl ether on the structure and reactivity of the resulting trichlorogermane–diethyl ...ether complexes was studied, and the products were reacted with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane. The hydrogermylation of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane with trimethylgermane in the presence of Karstedtʼs catalyst afforded exclusively the corresponding anti-Markovnikov adducts at one and two double bonds of the substrate.
The elongation of the oligodimethylsiloxane chain in a wide range of values (from 10 to 136 units) and, correspondingly, an increase in the concentration of carboxyl groups (from 2 to 22) in the ...composition of organosilicon surfactants with a comb-like structure significantly affects the surface activity and interfacial layer thickness, which increase from 3.7 to 15.7 mN m
2
mol
−1
and from 2 to 13 nm, respectively. The polymer suspensions obtained in the presence of the studied organosilicon surfactants (polymethyl methacrylate) are characterized by a narrow particle size distribution. The average particle diameter depends slightly on the oligodimethylsiloxane chain length and concentration of carboxyl groups in the surfactant molecules but changes significantly from 0.4 to 1.7 µm with an increase in the monomer concentration in the starting system from 10 to 20 wt.%. The resulting polymer microspheres are characterized by a hydrophilic surface due to a high content of carboxyl groups on the surface.
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.
The effect of the composition and structure of oligodimethylsiloxanes containing carboxy- and amino-functional substituents at the silicon atom on their colloidal-chemical properties was studied. It ...was established that their colloidal-chemical properties are affected not only by the nature and concentration of functional groups, but also by the molecular weight of the organosilicon compound.
The colloidal chemical properties of triple block copolymers of polypropylene oxide and polyethylene oxide (pluronics of various structures) were studied in comparison. All of them are shown to be ...surfactants but differ in interfacial tension, surface activity, surface area occupied in the adsorption layer, and adsorption layer thickness. The kinetic regularities of polymerization of styrene and methyl methacrylate were studied. The particle diameters and their size distribution were determined. Distinctions in the kinetic regularities of polymerization are shown: the shape of the conversion—time curves (for the duration of the initial and stationary stages of polymerization) and the dependences of the diameter on the surfactant concentration and monomer to water volume ratio. In the presence of the water-insoluble pluronics, the mechanism of formation of polymer—monomer particles and interfacial layer on the surface differs from that when using water-soluble surfactants, which makes it possible to distinguish these processes into an independent type of heterophase polymerization.
