Characterization of toluene and 2-methylnaphthalene transport separated by syndiotactic polystyrene having various crystalline forms

Abstract

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 ( ) 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 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. Transport of toluene or 2-methylnaphthalene through nanoporous syndiotactic polystyrene (sPS) film. The δe-sPS was used as a film for transport measurement of toluene or 2-methynaphthalene in hexane. These solutes basically transport in the non-crystalline regions of the polystyrene. The δe-sPS crystal is characterized by the nanopore in the unit cell, which is enough space for toluene to transport, but 2-methylnaphthalene is too large to transport in the pore. This results in low flux of 2-methylnaphthalene in the δe-sPS film.