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Updated: Aug 7, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Molecular simulation and experimental study of substituted polyacetylenes: fractional free volume, cavity size
Xiao-Yan Wang1, Roy D Raharjo, Hyuck J Lee
1Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
Abstract:
Glassy, disubstituted acetylene-based polymers exhibit extremely high gas permeabilities and high vapor/gas selectivities, which is quite unusual for conventional glassy polymers such as polysulfone. Diffusion coefficients of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) and poly[diphenylacetylene] (PDPA) were obtained using both molecular simulation and experimental techniques. PTMSDPA, a disubstituted glassy acetylene-based polymer, exhibits higher diffusivity than its desilylated analogue, PDPA. Simulation results are in good agreement with experimental data. Cavity size (free volume) distributions of both polymers are also obtained using an energetic-based algorithm (in't Veld et al., J. Phys. Chem. B 2000, 104, 12028) developed recently. Larger cavities in PTMSDPA contribute to its higher diffusivity, and higher permeability.
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