Trip-PIM

Fig. 5 Molecular repeat unit structures for vruious linear, soluble PIMs (PIM-1, PIM-7) and insoluble PIM networks (HATN-PIM, CTC-PIM, Trip-PIM, Porph-PIM) [79]...

Figure 5.7 Nitrogen adsorption (solid lines with symbols) and desorption (dashed lines) isotherms at 77 K for (a) PIM-7 (+), PIM-l(x), CTC-PIM ( ) and (b) HATN-PIM (A), Porph-PIM ( ), Trip-PIM ( ). = ...

A special kind of PIM network has been demonstrated to adsorb around 1.5-1.7 wt% H2 at 77.3 K and 1 bar, and up to 2.71 wt% at 10 bar. Hydrogen uptake for these materials is observed to be 1.4% by mass adsorbed at 1 bar and 1.7% at 10 bar for the cyclotricatechylene-PIM (CTC-PIM). The tripty-cene-based polymer (Trip-PIM) shows a better result of 1.6% by mass at 1 bar and 2.7% at 10 bar. Porphyrin-PIM (Porph-PIM) and PIM-7 have also been reported to absorb significant amounts of Ha- Table 10.1 represents the hydrogen uptake for all of these PIMs at 77 K. Trip- R)-PIMs with shorter all l chains at moderate pressure show excellent H2 adsorption for Trip-(Me)-PIMs, the adsorption of 3.4% by mass at 18 bar is comparable to different types of microporous compounds with similar BET surface areas (Table 10.1). 

Figure 5.6 Representation of two ideal fragments of the network of Trip(Et)-PIM,...

Both PIMl-COl-40 and PIM demonstrate high N2 uptake at extremely low pressure with hysteresis, which may be an indication of the microporous nature. Trip(R)-PIMs exert surface areas in the range of 618 m (when R = octyl) to 1760 m g (when R = methyl). Flexible, linear side chains occupy larger volume than branched ones. That is why higher surface area is observed with branched alkyl-derived PIMs than their linear chain derivatives. Polyimide-linked PIMs have BET surface areas in the range of 471-683 m g ... 

Fig ure 9.2 Representation of two ideal fragments of the network of Trip(Et)-PIM, showing how the shape of each macromolecule, as dictated by the architecture of the triptycene (Trip) units, prevents close intermolecular interactions between the planar struts . The loose network that arises from the ideal layered structure may account for the tendency of the materials to swell in organic solvents or during nitrogen adsorption, as indicated by the arrows, especially when bridgehead alkyl chains block interpenetration of the nitrile groups. 

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