Free Volume Expansion of Poly[1-(trimethylsilyl)-1-propyne] Treated in Supercritical Carbon Dioxide As Revealed by Positron Annihilation Lifetime Spectroscopy
Author
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.
Department/s
Publishing year
2011
Language
English
Pages
2766-2772
Publication/Series
Macromolecules
Volume
44
Issue
8
Document type
Journal article
Publisher
The American Chemical Society (ACS)
Topic
- Chemical Sciences
Status
Published
ISBN/ISSN/Other
- ISSN: 0024-9297