Pore size, Ultrastyragel

Determination of Pore Size Distributions. The shape and range of a GPC calibration curve are, in part, a reflection of the pore size distribution (PSD) of the column packing material. A consideration of the nature of PSDs for the ULTRASTYRAGEL columns to be used in this work is therefore appropriate. The classical techniques for the measurement of PSDs are mercury porisimetry and capillary condensation. The equipment required to perform these measurements is expensive to own and maintain and the experiments are tedious. In addition, it is not clear that these methods can be effectively applied to swellable gels such as the styrene-divinylbenzene copolymer used in ULTRASTYRAGEL columns. Both of the classical techniques are applied to dry solids, but a significant portion of the pore structure of the gel is collapsed in this state. For this reason, it would be desirable to find a way to determine the PSD from measurements taken on gels in the swollen state in which they are normally used, e.g. a conventional packed GPC column. 

The analyses were performed on a Polymer Lab apparatus, equipped with five ultraStyragel Waters columns (in the order 1000, 500, 10000,100, and 100000 A pore size) attached in series, using a Polymer Lab differential reffactometer. The solvent was THF or CHCI3, the flow rate was 1 mL/min, and 60 microliters of polymeric solution (15 mg/ml) were injected. Normally 50 fractions of 0.2 mL were collected. In the case of sanq)le M30, four different fractionation experiments were performed, and 50 fractions of 0.2 mL, 25 fractions of 0.4 mL, 15 fractions of 0.8 mL, 15 fractions of 1 mL were collected The chromatogram was calibrated using the result of the analysis of MALDI-TOF spectra of selected fractions (see Tables 1 and 2). The average molar masses (Mn and Mw) of the copolymer were measured using the Cahber software distributed by Polymer Lab. The type of calibration selected by us was a narrow standards the calibration function was polynomial of order 1 and the calculation method was area based. ... 

The polymerization of trimethylene carbonate (1,3-dioxan-2-one) with a complexation catalyst was studied by Kriecheldorf et al. " On the basis of GPC measurements employing a universal calibration, weightaverage molecular weights up to approximately 22,000 were found. A combination of four Ultrastyragel columns was used, with nominal pore sizes of 100, 500, 1000, and 10,000 A. The detector was a Waters M410 differential refractometer. The... 

Molecular weights of the polymer were estimated by size-exclusion chromatography (SEC) using Waters Associates 2690 Separations Module equipped with a coliunn heater, ultrastyragel coliunns with pore sizes of 10 -10 A, inline degasser, and a differential refractometer. A flow rate of 1.0 mL/min was used, and the eluent was THE Polystyrene standards pmchased from American Polymer Standards were used for calibration piuqjoses. The 200-MHz H NMR spectra were recorded on a Varian Gemini 200 spectrometer with deuterated chloroform as the solvent. 

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