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Free Volume Expansion of Poly[1-(trimethylsilyl)-1-propyne] Treated in Supercritical Carbon Dioxide As Revealed by Positron Annihilation Lifetime Spectroscopy

In English

Författare

  • Stan Claes
  • Pieter Vandezande
  • Steven Mullens
  • Marlies K. Van Bael
  • Frans Maurer

Summary, in English

The free volume changes of poly[1-(trimethyl-silyl)-1-propyne] (PTMSP) treated in supercritical CO2 (scCO(2)) were investigated with positron annihilation lifetime spectroscopy (PALS). CO2 is known to plasticize and increase the free volume size of a broad range of polymers. In this work dense PTMSP films were treated with scCO(2) under different pressures and temperatures, resulting in the enlargement of the characteristic channel-like holes (R-3) and the larger free volume cages (R-4) up to 39% and 19%, respectively. The free volume enlargement was found to have a relaxation time of similar to 30 years. At higher temperatures (110-150 degrees C), the o-Ps intensities and gel permeation chromatography (GPC) data revealed chemical changes of the scCO(2)-treated polymer due to the onset of PTMSP's degradation. However, at lower temperatures (40-70 degrees C), significant free volume cavity size increases to 25% for R-3 and 9% for R-4 were also observed.

Publiceringsår

2011

Språk

Engelska

Sidor

2766-2772

Publikation/Tidskrift/Serie

Macromolecules

Volym

44

Issue

8

Dokumenttyp

Artikel i tidskrift

Förlag

The American Chemical Society (ACS)

Ämne

  • Chemical Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0024-9297