No abstract

The synthesis of a new series of polymers of intrinsic microporosity (PIM) containing vinyl groups and its performance as gas separation membranes are reported. The incorporation of the vinyl group on the spirobisindane backbone was based on the postmodification of the methylated spirobisindane polymers. Generally, the prepared polymers display good solubility and easy processability to form robust films. Characterization of the new polymers was performed by 1H and 13C nuclear magnetic resonance spectroscopy, gel permeation chromatography, infrared spectroscopy, thermal gravimetric analysis, and density measurements. The gas permeability of the CO2, N2, O2, and CH4 was measured, and selectivities for the CO2/N2 and CO2/CH4 gas pairs were calculated for the prepared polymers and compared to the values obtained from PIM-1. The two vinyl groups per repeating units enabled the modified homopolymers to engage in π-orbital overlap and conjugation with the π-orbitals of the aromatic backbone, thus leading to a reduction in CO2 permeability but surpassing the Robeson’s upper bound with CO2/N2 selectivity. The attractive CO2/N2 gas separation characteristics of the newly synthesized vinylated PIMs might be useful for postcombustion application in the capture of CO2 from power plant flue gases. The chemical versatility of the vinyl groups has been tested in two successful addition reactions (bromination and thiol–ene click).

The poly(ethylene glycol)-based benzoxazine polymers were synthesized via a polycondensation reaction between Bisphenol-A, paraformaldehyde, and poly(ether diamine)/(Jeffamine®). The structures of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR), indicating the presence of a cyclic benzoxazine ring. The polymer solutions were casted on the glass plate and cross-linked via thermal treatment to produce tough and flexible films without using any external additives. Thermal properties and the crosslinking behaviour of these polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Single gas (H2, O2, N2, CO2, and CH4) transport properties of the crosslinked polymeric membranes were measured by the time-lag method. The crosslinked PEG-based polybenzoxazine membranes show improved selectivities for CO2/N2 and CO2/CH4 gas pairs. The good separation selectivities of these PEG-based polybenzoxazine materials suggest their utility as efficient thin film composite membranes for gas and liquid membrane separation technology.

In this work, the synthesis of novel polymers of intrinsic microporosity (PIMs) with different degrees of bromine substitution by a free-radical substitution reaction was performed. The synthesized polymers were thoroughly characterized and their bromination degree was verified via nuclear magnetic resonance. The brominated PIMs were investigated by infrared spectroscopy, X-ray diffraction, and density measurements and correlated with their gas transport properties. It was found that with an increase in the bromination degree, the synthesized PIMs exhibited a significant increase in polymer chain packing density which led to reduced fractional free volume and consequent decrease in gas diffusion and permeability coefficients. The change in permeability coefficients caused an improvement in the CO 2 /N 2 , CO 2 /CH 4 , and O 2 /N 2 ideal permeability selectivities.

No abstract