(571c) Graphene and Graphene Oxide Nanoplatelets As Fillers to Reduce Ageing and Improve Permselectivity of PTMSP Membranes

We have determined the effect of physical dispersion of small amounts (1wt%) of nanoplatelets of graphene and graphene oxide to the gas permeation and ageing behavior of poly(1-trimethylsilyl-1-propyne) (PTMSP). PTMSP has extremely large permeability but is subject to ageing, that causes loss of free volume and permeability with time.[1]

The membranes formed with an optimized protocol based on solvent casting with an organic solvent are stable and mechanically robust, although the repeatability of membrane properties is still not optimal, a main factor to be controlled being the solvent evaporation rate.

To analyze the ageing, that is a thickness-dependent mechanism, we fabricated both thin (1-10 microns) supported over a microporous support, and self-standing thick membranes (50-180 microns).

Although the quantitative extent may vary from one sample to another, it has been found that the addition of Graphene Oxide to PTMSP enhances its gas permeability detectably in all cases, despite the small amount added (1 wt%). On the other hand, the effect of the addition of graphene nanoplatelets depends strongly on the preparation protocol and the final sample behavior cannot be controlled.

The ageing was studied with gas permeability tests over time (up to 9 months) and it was concluded that both graphene and graphene oxide nanoplatelets reduce ageing, for both thin and thick samples. The effect of temperature was studied in the range 30-60°C. In the case of He/CO₂ mixture, the samples show a switchable behaviour (He or CO₂ selective) that can be tuned varying the temperature and the filler.

[1]Olivieri, Ligi, De Angelis, Cucca, Pettinau,  Effect of Graphene and Graphene Oxide Nanoplatelets on the Gas Permselectivity and Aging Behavior of Poly(trimethylsilyl propyne) (PTMSP), «INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH», 2015, 54, 11199 - 11211