Phase Segregation and Gas Separation Properties of Thermally Treated Copoly(ether-imide) from an Aromatic Dianhydride, an Aromatic Diamine, and Various Aliphatic Diamines

Abstract

Copoly(ether-imide)s formed by the reaction of an aromatic dianhydride (BPDA), an aromatic diamine (ODA), and various aliphatic diamines (PEO-2000, PPO-2000, RT-1000, pTHF-1700 have been obtained. These copolymers underwent phase segregation processes, as confirmed by small-angle X-ray scattering (SAXS), when they were thermally treated. Gas permeabilities of these materials depended on the phase separation. Thus, a linear relationship between gas permeability and increasing percentage and size of the domains of the segregated phase has been obtained. The differences in the degree of segregation have been examined for the different aliphatic diamines used in the synthesis of the copolymers. The effect of polarity, length, and structure of the chain were examined in terms of permeability for the gases O 2 , N 2 , CO 2 , and CH 4 . It has been shown that long aliphatic chains with adequate polarity and the ability to interact with and enhance the condensation of a certain gas give better materials. Improved selectivities, approaching the Robeson limit, were seen as a consequence of the thermal treatment. Also, an interesting reverse selectivity has been observed for the mixture CH 4 /N 2 , probably due to a combined effect of a specific interaction and an increase in solubility of CH 4 in the soft segregated portions of the copolymer.

Advances in the design of co-poly(ether-imide) membranes for CO2 separations. Influence of aromatic rigidity on crystallinity, phase segregation and gas transport

“…After this process, the polymer films resulted to be insoluble in dimethyl acetamide (DMAc), NMP, Hexane, Toluene, tetrahydrofuran (THF ) and dichloromethane. Under the commented protocol, the films were almost completely imidized according to their FTIR spectra (within the detection limits of the FTIR technique) at 160 ºC as it was shown in previous studies [21]. For the synthesized copolymers, few differences were observed.…”

Influence of the PEO length in gas separation properties of segregating aromatic–aliphatic copoly(ether-imide)s

“…The mass loss in this third step for the different copolyimides is close to the percentage of polyether blocks in the feed (see Table 1), proving that it is related to the degradation of this part of the copolymer, as already found previously in other similar copolymers (Marcos-Fernández et al, 2010;Tena et al, 2012b;Tena et al, 2012c). From Figure 3, it is clear that the polyether extended copolymers cPI-PEO900+HDI and cPI-PEO2000+HDI start to degrade at lower temperatures (circa 250 ºC) than the other copolymers (circa 350 ºC).…”

“…As for other described copoly(ether imide)s (Marcos-Fernández et al, 2010;Tena et al, 2012b;Tena et al, 2012c), it was possible to observe the IR bands centered around 1774, 1713, 1372…”

“…This was attributed mainly to the high solubility-selectivity due to strong interactions between the oxyethylene group and CO 2 (Tena et al, 2012b;Tena et al, 2012c).…”

Polymeric films based on blends of 6FDA–6FpDA polyimide plus several copolyfluorenes for CO2 separation

“…Measurements were carried out at 3 bar and 30 ºC. The equations used and the mode of operation of the equipment, as well as an outline of it, has been described previously 31,32 .…”