Molar mass distribution of poly(methyl methacrylate) by sedimentation analysis in a theta solvent

  • A. Jungblut
  • B. Ortlepp
  • D. Panke
Conference paper
Part of the Progress in Colloid & Polymer Science book series (PROGCOLLOID, volume 94)


Molar mass distributions of poly(methyl methacrylate) samples with molar masses in the range between 50 000 and 20 000 000 g·mol−1 and with low polydispersities were measured by sedimentation analysis in the analytical ultracentrifuge (Beckman Model E) with UV optics (λ = 226 nm) using acetonitrile as solvent at the theta temperature (35 °C).

We found good agreement of the weight average molar masses Mw with those determined by light scattering and by size exclusion chromatography (SEC), respectively; however, there are somewhat larger discrepancies in the polydispersities (AUC vs. SEC). In contrast to literature data, we found that with 35°C, we were slightly below the theta temperature, so that the coefficients in the relationship between sedimentation constant and molar mass had to be fitted with the light-scattering results.

Further experiments will aim at an improved signal/noise ratio by employing a very fast analogue/digital converter for the data acquisition.

key words

Analytical ultracentrifuge molar mass distribution poly(methylmethacrylate) sedimentation analysis theta system UV scanner light scattering size exclusion chromatography 


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Copyright information

© Dr. Dietrich Steinkopff Verlag GmbH & Co. KG 1994

Authors and Affiliations

  • A. Jungblut
    • 1
  • B. Ortlepp
    • 1
  • D. Panke
    • 1
  1. 1.Röhm GmbH, Abt. AP2-PCDarmstadtFRG

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