TY - JOUR

T1 - Role of local dynamics in the gas permeability of glassy substituted polyacetylenes. A quasielastic neutron scattering study

AU - Kanaya, Toshiji

AU - Tsukushi, Itaru

AU - Kaji, Keisuke

AU - Sakaguchi, Toshikazu

AU - Kwak, Giseop

AU - Masuda, Toshio

PY - 2002/7/2

Y1 - 2002/7/2

N2 - The local dynamics of 10 substituted polyacetylenes in the glassy state have been investigated using a quasielastic neutron scattering technique in a time range of picoseconds to several tens of picoseconds to see a relationship between the local mobility and the gas permeability of these polymers. Even in the glassy state, these polymers show quasielastic scattering components, suggesting that certain stochastic motions occur in the glassy state. The dynamic scattering laws S(Q,ω) of the quasielastic components were well fitted to the sum of two Lorentzians, i.e., the narrow (slow) and broad (fast) components. It was found that both the relaxation rate Γn and the fraction An of the narrow (slow) component show positive correlations with oxygen permeability coefficient (Po2), suggesting that the local mobility of the matrix polymers plays an important role in gas permeability. We then defined local flux F, which is the product of Γn and An, as a measure of the local mobility to find that F is proportional to the diffusion coefficient of O2 gas (Do2), i.e., F ∝ Do2. To explain and discuss this relation, we have proposed a random gate model, where mobile side groups in the matrix polymer act as a gate for gas diffusion.

AB - The local dynamics of 10 substituted polyacetylenes in the glassy state have been investigated using a quasielastic neutron scattering technique in a time range of picoseconds to several tens of picoseconds to see a relationship between the local mobility and the gas permeability of these polymers. Even in the glassy state, these polymers show quasielastic scattering components, suggesting that certain stochastic motions occur in the glassy state. The dynamic scattering laws S(Q,ω) of the quasielastic components were well fitted to the sum of two Lorentzians, i.e., the narrow (slow) and broad (fast) components. It was found that both the relaxation rate Γn and the fraction An of the narrow (slow) component show positive correlations with oxygen permeability coefficient (Po2), suggesting that the local mobility of the matrix polymers plays an important role in gas permeability. We then defined local flux F, which is the product of Γn and An, as a measure of the local mobility to find that F is proportional to the diffusion coefficient of O2 gas (Do2), i.e., F ∝ Do2. To explain and discuss this relation, we have proposed a random gate model, where mobile side groups in the matrix polymer act as a gate for gas diffusion.

UR - http://www.scopus.com/inward/record.url?scp=0037008093&partnerID=8YFLogxK

U2 - 10.1021/ma0203546

DO - 10.1021/ma0203546

M3 - Article

AN - SCOPUS:0037008093

SN - 0024-9297

VL - 35

SP - 5559

EP - 5564

JO - Macromolecules

JF - Macromolecules

IS - 14

ER -