Polydisperse polystyrene

An illustration of the potential for improved resolution in the determination of size distributions with particles in the small size range is indicated in Figures 12 to ik. These results are for a polydisperse polystyrene (labelled 2D2) which has been doped by the addition (29% by mamber) of the Dow 380 X polystyrene standard. 

A polydisperse polystyrene standard was obtained from Dow Chemical Co. (Midland, Michigan). This material was designated Dow 1683 polystyrene standard and has been well characterized with reported values as follows (18) ... 

Three polydisperse polystyrene samples were used in this study ... 

Materials. GMC and PCLS were synthesized by free radical solution polymerization initiated by benzoyl peroxide as described previously (5,6). Nearly mono and polydisperse polystyrenes were obtained from Pressure Chemical Co. and the National Bureau of Standards respectively. Molecular weight and polydispersity were determined by gel permeation chromatography (GPC) using a Water Model 244 GPC, equipped with a set (102-106 A) of —Styragel columns using THF as the elution solvent. The molecular parameters of the above three polymers are listed in Table I. The copolymer, poly(GMA-co-3-CLS), contained 53.5 mole % 3-CLS and 46.5 mole % GMA, as determined by chlorine elemental analysis. The structure of the copolymer is shown in Figure 1. 

The latexes investigated were the 357 nm Dow monodisperse polystyrene (LS-1010) and two polydisperse polystyrene latexes prepared in our laboratory (2) where the concentration of functional monomer, Cops II (Alcolac-ammonium salt of a short chain vinyl sulfonate), added to the recipe was 10 3 and 10 -M for and C, respectively. 

Ratzsch, M. Kruger, B. Kehlen, H., "Cloud-Point Curves and Coexistence Curves of Several Polydisperse Polystyrenes in Cyclohexane," J. Macromol. Sci., Chem., A27, 683 (1990). 

Experimental evidence has demonstrated that Dean vortices can be effective for enhancement of membrane performance under laminar conditions [18]. As flow conditions approach the transition and turbulent flow regimes, straight membranes have a better mass transfer and higher wall shear rate than in flows with curved membrane channels. The effects of Dean vortices on the performance of membrane filtration have been studied experimentally and theoretically by Belfort and coworkers [19-22]. Mallubhotla and Belfort [21] assessed the filtration of suspensions of polydispersed polystyrene particles (mean diameter 25 pm) and silica particles (mean diameter 20 pm) with and without the presence of Dean flow using an 180° U-bend channel... 

A further important application of CD is the preparation of relatively low polydispersity polystyrenes (compared to radical CD polymerization) using the water-soluble RAFT reagent 3-benzylsulfanyl thiocarbonylsulfanylpropionic acid (TTC) complexed in aqueous Me-P-CD solution (Fig. 28) [65], This method also allows the direct synthesis of amphiphilic block copolymers in aqueous solution without compatibility issues. 

Problem 2.28 A polydisperse polystyrene sample was fractionated into four components of various molecular distributions and Tg of each fraction was measured ... 

Two polystyrene standards (monodisperse) of molecular weight 1.8x10 and 1.6x10 were found to have Tg values of 105.9°C and 104.7°C, respectively. Calculate the Tg of a polydisperse polystyrene made up of four low polydisperse components as shown below ... 

Equations (0 and (m) can be used to calculate the equilibrium constant thru the use of either N or N. For samples with near-monodisperse molecular weight distribution both Eqs. (f) and (m) yield the same value for the equilibrium constant. This situation does not hold though, for polymer systems having polydisperse molecular weight distributions. Thus, the equilibrium constant results presented by Van Beylen and co-workers for polydisperse polystyrenes having the barium... 

Figure Dependence of the cloud point temperature T of a polydisperse polystyrene...

Figure 9-15 shows the Breitenbach-Wolf plots at 25.7°C for three mother solutions of a very polydisperse polystyrene (M = 82 x 10, = 410 x 10, ... 

Fig. 7 compares the experimentally measured (A and C) absorption Cahs,x and (B and D) scattering Csca,x cross-sections between 400 and 700 nm of monodisperse latex spheres 2.02 and 4.5 pm diameter with Lorenz—Mie theory predictions using the complex index of refraction of latex reported by Ma et al. (2003). Flere also, the good agreement between theoretical and experimental results successfully validated the experimental setup and the data analysis. Similar vaHdation has been performed with the same polydisperse polystyrene latex microspheres and randomly oriented and infinitely long glass fibers considered for validating the scattering phase function measurements, as illustrated in Fig. 6 (Berberoglu and Pilon, 2007).

SEC calibration curves for PLgel individual pore size gels, column dimensions 300 x 7.5 mm, eluant tetrahydrofuran, flow rate 1 ml/minute, calibrants narrow polydispersity polystyrene, detector ultraviolet (UV) 254 nm. 

Byrd, H.C.M., Bencherif, S.A., Bauer, B.J., Beers, K.L., Brun, Y., Lin-Gibson, S., and Sari, N. (2005) Examination of the covalent cationization method using narrow polydisperse polystyrene. Macromolecules, 38,1564-1572. 

For all monomers, the obtained molecular weights were in agreement with the targeted molecular weights, as observed from GPC results. The slight discrepancy between the targeted and observed molecular weights of the polymers in Table 1 was expected due to the differences in hydrodynamic volume of these polymers versus narrow polydispersity polystyrene and... 

A number of polydisperse polystyrenes (MW ranges from 56,000 to 358,000) were characterized using a Cig column (A = 262run) and a 35-min 46/54- 66/34 DCM/acetonitrile concave gradient. This method was shown to be less sensitive to concentration (0.5 pg -> 25 pg in 5 pL) and to offer better resolution than the classical size exclusion methodology [751]. 

The protected amino acid, N-(9- uorenyl methoxycarbony 1) cysteine (Fmoc-C) is a building block/mo-del for the attachment of peptide fragments to synthetic materials. Devise a stratgy to synthesize low polydispersity polystyrene with multiple Fmoc units along the backbone. 

Georges, M. K., et al. (1994). Narrow polydispersity polystyrene by a free-radical polymerization process-rate enhancement. Macromolecules, 27(24) 7228-7229. 

Schriemer and Li" used matrix assisted laser desorbtion/ionization (MALDI) mass spectrometry to detect high molecular weight narrow polydisperse polystyrene with molecular weights up to 1.5 x 10 Daltons. The method is rapid and agrees well with results obtained by chemical methods. Retinoic acid was used as the organic matrix for the laser absorption procedure and the samples were analysed as their silver cation adducts. 

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