The correlation between solvent treatment and the microstructure of PAN-b-PEG copolymer membranes

Abstract

Block copolymer membranes consisting of thiophene-permselective components for use in gasoline desulfurization were prepared by the copolymerization of polyethylene glycol (PEG) with acrylonitrile by water-phase precipitation copolymerization. In this study, a solvent annealing treatment was applied to evaluate the microdomain orientation and the affinity between polyacrylonitrile-block-polyethylene glycol (PAN-b-PEG) copolymers and solvents. Using atomic force microscopy, appreciable microphase separation was observed in the PAN-b-PEG membranes. The affinity of the PEG segments and solvents was reflected by the different sizes of the PEG domains. The sizes of the PEG domains grew gradually with solvent annealing treatments of heptane, toluene and thiophene for all of the copolymers. Using phase separation by different solvent annealing treatments, PAN-b-PEG could be used as a highly selective material for thiophene. This method can also be applied as an important alternative to provide a semi-quantitative method for determining the adsorption properties of pervaporation membranes, which cannot be evaluated by sorption experiments.

Study on the influence of reaction time on the structure and properties of the PVDF membrane modified through the method of atom transfer radical polymerization

“…Figure shows clearly that compared to the pristine PVDF membrane whose water contact angle was changed from 95° to 87° in 600 s, the water contact angle of PVDF‐g‐PNIPAAm membrane descended obviously. When the reaction time was 36 h, the water contact angle decreased to 50° after 600 s. It was indicated that the hydrophilicity of the grafted membrane was improved, and with the reaction time increased [], the hydrophilicity of the modified membrane improved gradually. It corresponded to the results of XPS, and the reaction time of 36 h was in favor of surface‐initiated ATRP.…”

Applications of Biomimetic and Bioinspired Membranes

“…In addition to the PDMS, PEG can also act as an appropriate membrane material for pervaporation desulfurization of gasoline in accordance with the methodology outlined in the solubility parameter theory. Kong et al [74,78] created PEG-b-PAN membranes based on dispersed PEG micro domains and bulk PAN phases. In this case, an increase in the total flux and a decrease in sulfur enrichment factor were attained by either lowering PEG molecular weight or by increasing PEG mass content value that caused greater proportion of PEG micro domains.…”