Tailoring nanospace

Document Type

Article

Publication Date

4-4-2005

Abstract

Low free volume liquid crystalline barrier polymers are compared and contrasted with ultrahigh free volume membrane polymers. The free volume cavities and hence the transport properties of the liquid crystalline polymers, based on p-hydroxybenzoic acid, isophthalic acid and hydroquinone in the ratio 40:30:30 mol% (HIQ-40), are tuned by thermal treatment. The mean size of the free volume cavities, or the average dimension of nanospace, in these polymers can be varied from 0.46 to 0.53 nm resulting in a systematic change in permeability dependent on penetrant size. In ultrahigh free volume poly(1-trimethylsilyl-1-propyne) PTMSP, the mean size of the large free volume cavities is varied from 1.40 to 1.44 nm via the addition of silica nanoparticles in order to alter the chain packing. This increase in the free volume cavity size results in a systematic increase in permeability. Remarkably, at the mean cavity size of 1.42 nm in PTMSP there is a crossover in transport mechanism from solution-diffusion to Knudsen transport, resulting in H2/CH 4 selectivity going from <1 to >1. © 2005 Elsevier B.V. All rights reserved.

Identifier

16344366715 (Scopus)

Publication Title

Journal of Molecular Structure

External Full Text Location

https://doi.org/10.1016/j.molstruc.2004.05.041

ISSN

00222860

First Page

173

Last Page

178

Issue

1-3

Volume

739

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