Polystyrene sulphonate Molecular weight

Field flow fractionation has been used to fractionate and determine the molecular weight of sodium polystyrene sulphonate" and polystyrene sulphonate (molecular weight range 6.6 x 10 to 6.9 x 10 ). 

The system was calibrated using polystyrene sulphonates (PSS) (Polysciences, NJ, USA). 1 gL standards were prepared (35, 18, 8, 4.6 kDa). Blue Dextran, a high molecular weight polysaccharide (approx. 2 000 kDa) and an acetone solution (1%) were used to determine the column s void volume and total permeation volumes, respectively. The PSS s were detected at 224 nm (see Figure 4.7), the acetone at 280 nm and the Blue Dextran at 260 nm. All samples were detected well inside the 15 min/sample run time. 

Several papers are concerned with motions of polymers containing backbone sulphur atoms. - > In poly(phenyl thiirane), it is found that backbone correlation times are an order of magnitude shorter than in polystyrene. An unusual feature > of relaxation in poly(alkene sulphones) is that C Ti s are independent of molecular weight whereas dielectric relaxation times are not. This has been rationalized in terms of specific conformational transitions which re-orient C—H bonds but not the sulphone dipole. 

Field flow techniques have been reviewed in a number of articles [148-150]. Sedimentation field flow fractionation has found use in the separation of PVC [151, 152], polystyrene [151-153], poly(methyl methacrylate) [153, 154], poly (vinyl toluene) [155] and poly(glycidyl methacrylate) latexes [156] to produce particle-size distributions and particle densities. It has also been applied in polymer-aggregation studies [157], pigment [157] quality control and in the separation of silica particles [158] and its performance has been compared with that of ultracentrifugation [159]. Thermal field flow fractionation has been used successfully in the characterisation of ultra-high-molecular-weight polystyrenes [160, 161], poly(methyl methacrylate), polyisoprene, polysulphane, polycarbonate, nitrocellulose, polybutadiene and polyolefins [162]. In the difficult area of water-soluble polymers, poly(ethylene glycol), poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(styrene sulphonate) have been analysed [163, 164]. In addition, compositional separations have been achieved for polystyrene-poly(methyl methacrylate) mixes [165] and comparisons between TFFF and SEC have been made [166]. 

The speculations were supported by experimental results using sodium salts of polystyrene sulphonic acid or polyacrylic acid. Figure 7 shows that the electrophoretic mobility is independent of molecular weight and as high as the mobility of a monomer [21]. The radius of a monomer calculated from the mobility using the Stokes law is about 3.0 A which is reasonable compared with the molecular radius of the monomer. Table I shows that the electrophoretic mobility of polyion is independent of ionic species of counter-ion [22]. 

Fig. 8. Specific conductance of sodium polystyrene sulphonate solutions in the presence of NaCl [29]. Number average molecular weight 2.0 x 10, 25 °C, 1 kHz. The extrapolation of the specific conductance to infinite high frequency was carried out for the solutions in the absence of added salt, assuming the linearity between specific conductance and reciprocal square root of frequency, but the error was within 0.4 %. NaCl concentrations are 0, 0.005, 0.01, 0.02, 0.05 and 0.1 N from bottom to top. Both solid and broken lines are drawn in parallel, respectively.

Fig. 1. Examples of the sedimentation coefficient vs. polymer concentration plots. (Reproduced from Reference [2].) Samples, sodium polystyrene sulphonate (Na-PSS). Molecular weight open...

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