Polystyrene dispersions

Figure 14 Particle size distribution of a ten-component mixture of narrow polystyrene dispersions. Left intensity measured as function of t with a turbidity detector. Right integral and differential particle size distribution. Reproduced from Machtle [84] by permission of The Royal Society of Chemistry. 

From a plot of log W versus log c determine the CCC value and T0 [by means of Eq. (53)]. Use the approximation for T0 given in Problem 6 to estimate for this colloid. Use the values of the CCC and T0 determined in Eqs. (5) and (6) to estimate the effective Hamaker constant Ain for polystyrene dispersed in water. Describe how A might be estimated using a more realistic model than that used in the derivation of Eqs. (5) and (6). 

I. Polystyrene (Dispersed Phase)-Polyacrylamide (Continuous Phase) Composite (Table 6), and... 

Determination of Solubility of Monomers in Dispersions of Polymer. W e applied a method given by Smith for polystyrene dispersions (32). Known volumes of polymer dispersion and monomer were shaken together for 15 minutes in a graduated centrifuge glass tube, and then centrifuged. The excess monomer creams and can be determined by its volume. This method is not very accurate, but gives reproducible results sufficient for our studies (Table I). 

The particles in the polystyrene dispersions had an average diameter of about 1150 A. The particles in the PMMA dispersions showed an average diameter of about 500 A. 

Equation (21.8) was tested for polystyrene dispersions, as illustrated in Figure 21.3. 

Figure 21.3 Variation of sedimentation rate with volume fraction for polystyrene dispersions.

This kind of NAD, resulting from the reaction of crude or pure MDI with high molecular weight polyether triols, is very efficient in stabilising copoly (ACN - styrene) dispersions or even polystyrene dispersions in polyether polyols. 

The smaller values of the equilibrium swelling of hypercrosslinked hydro-phobic networks in water, as compared to organic solvents, arise from the disadvantageousness of replacing the strong interactions between water molecules in bulk liquid by extremely weak water-polystyrene dispersive interactions, if water would be placed into the numerous nano-sized compartments within the polystyrene network. Still, according to Fig. 7.8, even water does solvate the hypercrosslinked polystyrene network to a certain extent, causing an up to twofold expansion of the latter compared to its dry state. Naturally the internal strains of the dry network partially relax on this expansion. 

The sorption of hydrocarbons proved to be a strongly exothermic process. This is not surprising because both the adsorption (pentane-polystyrene dispersion interactions) and the relaxation of strong inner stresses of the network result in heat generation. The temperature increase of the packing affects the sorption process in two different ways. First, it results in a considerable acceleration of the sorption process due to the facilitated diffusion of the sorbate molecules into the bead interior (the effective diffusion coefficient increases by 1 order of magnitude with the temperature... 

Polystyrene Dispersions. On account of their glass transition temperature T of ca. lOO C, polystyrene dispersions do not form films at room temperature. These rigid polymers can only be applied with means of heat drying (e.g., to stiffen fabrics and nonwovens). Film formation is not required in agents used to protect floor coverings and paper coatings (plastic pigments) in this case polystyrene is therefore applied in the form of a dispersion at room temperature. 

TS-1 alumina binder and polystyrene dispersion MFI Tetraisopropyl orthotitanate TEOS TPAOH Calcined TS-1 is mixed with aluminum oxide, formic acid, polystyrene, and water 175 °C, 92 h Muller, 2002 (27)... 

Kobayashi, M. Yoshioka, T Imai, M. Iton, Y. Structural ordering on physical gelation of syndiotactic polystyrene dispersed in chloroform studied by time-resolved measurements of small angle neutron scattering (SANS) and infrared spectroscopy. Mactvmolecules, 1995,28(22), 7376-7385. 

An alternative approach to fabricate a superhydrophobic surface on a device is to utilize the nanoimprint technique to create nanostructures on the chip surfaces, which are coated with a thin film of hydrophobic materials. The fabrication scheme for a superhydrophobic surface using nanoimprint is illustrated in Fig. 2. To conduct nanoimprint lithography, the first step is to fabricate the stamp for nanoimprint. Previously [24-26], we demonstrated a simple technique to fabricate nanoimprint stamp by nanosphere lithography. In this process, a monodispersed polystyrene dispersion with 400 nm diameter beads (Bangs Laboratories, Inc., Fishers, IN) was... 

Fig. 20. Appearance of polystyrene dispersions stabilized with poly(vinyl alcohol) prepared with different initiators. C initiator soluble in the continuous phase, potassium peroxodisulfate D initiator soluble in the disperse phase, dibenzoyl peroxide I initiator located mainly at the interface, PEGA200.

The stable free radical polymerization technique is characterized by the growing polymer chains that are reversibly capped by a stable free radical [e.g., 2,2-tetramethyl-l-piperidynyloxy nitroxide (TEMPO)]. For example, stable polystyrene dispersions were prepared by the stable free radical polymerization of styrene conducted in miniemulsion polymerization at 135 C [62]. Sodium dodecylbenzene sulfonate, hexadecane, and potassium persulfate/ TEMPO were used as the surfactant, costabihzer, and initiator system, respectively. Prodpran et al. [63] studied the styrene miniemulsion polymerization stabilized by Dowfax 8390 and hexadecane and initiated by benzoyl peroxide at 125 °C. A molar ratio of TEMPO to benzoyl peroxide equal to 3 to 1 resulted in polystyrene with the lowest polydispersity index (1.3) of polymer molecular weight distribution. 

Many types of metal oxide nanoparticles can be successfully electrospun examples include magnesium, aluminum, silicon, titanium, iron, zinc, and mixed metal oxide nanoparticles. Silica nanoparticles electrospun with polystyrene dispersions are extensively utilized in the production of superhydrophobic meshes (Fig. 16.9a) [23, 24]. Nanoporous silica nanoflbers with ultrahigh surface area have been fabricated... 

Polystyrene dispersions have a glass transition temperature of 105 C. They are used in paper coating to improve gloss, in liquid soaps to provide opacity and in medical diagnosis as carrier for active ingredients. 

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