Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective and efficient transport mechanism of CO$_2$ in subnano-porous
  crystalline membrane of syndiotactic polystyrene   The gas permeation behavior in the single crystal of syndiotactic polystyrene
(s-PS) S-I form was investigated in detail, in comparison to that in the s-PS
$\varepsilon$ form. The S-I form exhibits high CO$_2$/N$_2$ and CO$_2$/CH$_4$
separation factors while preserving its high CO$_2$ permeability; a trade-off
between selectivity and permeability was broken through.The mechanism of the
effective and efficient transport of CO$_2$ in the S-I form was examined in
relation to the cavity structure in the crystal. Because the CO$_2$ molecule is
only fitted to the cavities in the S-I form, the solubility of CO$_2$ becomes
high. In addition, tri-atomic molecules can more effectively diffuse in the S-I
form compared with di-atomic molecules, as proved by the "long-gas" model. A
novel design criterion for the CO$_2$ separation membranes is proposed based on
the aspect of momentum transfer from polymer matrix to the penetrant.

34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin