One-step hyper-cross-linking of porous styrenic polymers using dichloroalkane cross-linkers to maintain hydrophobicity

Publication date: 5 May 2017
Source:Polymer, Volume 116
Author(s): Mohsen Ghafari, John D. Atkinson
Styrenic polymers (XAD2 and XAD4) were hyper-cross-linked using dichloroalkane (-methane, -ethane, -butane, and -hexane) cross-linkers in the presence of a Friedel-Crafts catalyst (FeCl3). Hyper-cross-linking with dichloromethane generated the largest micropore volume increase; surface area and micropore volume decreased with increasing cross-linker length. Longer dichloroalkane cross-linkers also generated more hydrophobic polymers with less bulk oxygen content. Despite this variability, at 90% relative humidity, polymers directly hyper-cross-linked with dichloroalkanes consistently adsorb >80% less water than polymers hyper-cross-linked via chloromethylation. Results demonstrate an opportunity to add micropores needed for adsorption applications without sacrificing the polymer's unique, and often advantageous, hydrophobicity. Given that industrial adsorbate streams often contain moisture, this work is important because it provides a method that allows polymers to remain hydrophobic after hyper-cross-linking, making them competitive for industrial use.

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