Gas separation properties of pendent phenyl substituted aromatic polyamides containing sulfone and hexafluoroisopropylidene groups

Effect of substituents on the permeation properties of polyamide membranes

“…This indicated that the dependence between diffusivity and kinetic diameter was not the expected for the case of CO 2 as O 2 has a larger diameter than CO 2 . CO 2 diffusion coefficients generally decrease as polymer polarity increases and, at sufficiently high matrix polymer polarity, it is not uncommon to observe CO 2 diffusion coefficients that are lower than O 2 [11,27]. Thus, the good correlation experimentally found for permeability vs. kinetic diameter should be associated to the high CO 2 solubility coefficient exhibited by the APAs of the class here reported.…”

“…Technical aromatic polyamides have achieved significant importance as high performance materials, thanks to their excellent balance of mechanical and thermal properties [6][7][8]. However, they have not deserved special attention as membrane-forming materials, so that rather few studies have been reported on the permeation properties of aromatic polyamides (APAs), either in scientific journals [9][10][11] or in the patents literature [12][13][14]. On the other hand, commercial APAs are very difficult to process, as they do not melt, and they are insoluble or very poorly soluble in highly polar organic solvents.…”

Structure–gas transport property relationships of hexafluoroisopropylidene based poly(imide-siloxane)s

“…As O 2 (3.46Å) has larger diameter than CO 2 (3.3Å), the dependence of diffusivity on the kinetic diameter was not as expected. CO 2 diffusion coefficient generally decreases as polymer polarity increases and at sufficiently high polymer polarity, it is more common to observe CO 2 diffusion coefficients that are lower than O 2 [39]. In this case, the presence of polar fluorine groups would have caused the reduction in the diffusivity of CO 2 .…”

Synthesis and gas transport properties of rigid block copolyaramides

“…The relationship between the polymer structure and their gas transport properties has been studied systematically for several highly aromatic rigid polymers such as polyesters [9,14,15], polysulfones [16][17][18], polycarbonates [18,19], polyimides [20], polyamides [7,8,10,21], polynorbornene dicarboxyimides [22,23]. It has been established that bulky pendant groups from the main chain increase gas permeability while maintaining selectivity for the gas separation by hindering structural rotations in amorphous rigid polymers.…”