UC Davis

Diffusion of toluene and 2-methylnaphthalene, in hexane solutions, through amorphous, δe and β films of syndiotactic polystyrene (sPS) is investigated. The diffusivity for the transport of toluene (amorphous>δe -sPS>β-sPS) is inversely proportional to the crystallinity. Flux in the non-crystalline region (N̄ amsol) for the amorphous and δe -sPS films are similar, and greater than for the β-sPS film, because crystallization is promoted in the amorphous film during transport measurements. Nanopores in crystalline δe -sPS act as tunnels for the transport of toluene, whereas there are no such structures for β-sPS; and thus, the toluene flux is slower. The transport of 2-methynaphthalene is much slower in comparison to toluene, which can be attributed to molecular size. The diffusivity in the amorphous film is slightly larger than that for the δe -sPS, whereas no diffusion is observed in the β-sPS film because of the presence of deformed noncrystalline chains resulting from the high crystallinity. The N̄amsol for the amorphous film is larger than that for the δe -sPS film, because the pores in the δe -sPS are of insufficient size for the transport of 2-methynaphthalene. Copyright © 2013 The Society of Polymer Science, Japan.