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Atomistic packing model and free volume distribution of a polymer with intrinsic microporosity (PIM-1)

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  • Diffusion
  • Free Volume
  • Microporous Materials
  • Simulation And Modeling
  • Solubility
  • Van Der Waals Potential
  • Vibrational Energy (Atomistic Packing Model And Free Vol. Distribution Of Spirobisindane Moiety-Cont
  • Bond Angle
  • Bond Length (Carbon-Carbon
  • Atomistic Packing Model And Free Vol. Distribution Of Spirobisindane Moiety-Contg. Ladder Polymer Wi
  • Bond Angle (Dihedral
  • For Bond Between Spiro Atom And Next Backbone Atom In Polymer
  • Size Distributions (Of Free Vol.
  • Permeation (Of Gases
  • Sorption (Of Nitrogen
  • Polymer Chains (Packing
  • Permeability (Selective
  • Molecular Vibration (Torsional
  • Model Free Vol Distribution Intrinsically Macroporous Polymer
  • Spirobisindane Moiety Ladder Polymer Atomistic Packing Model
  • Physics


Atomistic packing models have been built for PIM-1, a polymer belonging to a recently developed new type of "polymers of intrinsic microporosity" (PIMs). The mol. structure of PIM-1 contains sites of contortion (spiro-centers) within a rigid ladder polymer structure. Nitrogen sorption expts. have shown that the polymer, which traps in the glassy state a large amt. of interconnected free vol., behaves in many respects like a microporous material. The models obtained by force field-based mol. mechanics and mol. dynamic methods allow a prediction of permeation properties of small gasses, the calcn. of N2-sorption isotherms at 77 K, and a detn. of free vol. distributions. The Gusev-Suter transition state theory (TST) was used to calc. gas soly. and diffusion coeffs. for He, H2, Ar, O2, N2, CH4, and Xe. Good agreement with exptl. data (factors 1-4) was found. The calcd. nitrogen adsorption isotherm at 77 K shows properties typical for sorption on microporous materials. The obtained microporous vol. is in good agreement with the resp. exptl. value. The size distribution function of free vol. elements derived from the models agrees well in its range of pore width of 5-15 .ANG. with results obtained from exptl. sorption data and analyzed with the Horvath-Kawazoe method. Dihedral angle distributions in the backbone reveal a certain, unexpected flexibility of plane segments between the spiro-centers which act as connecting links. [on SciFinder (R)]

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