Truxene-Based Porous Triazole-Linked Polymers for Dye Removal through Synergetic Adsorption and Photodegradation

Abstract

Two high surface area porous polymers (TxTri and PhTxTri) consisting of semiconducting truxene units connected through triazole nodes have been synthesized via Cu(I)-catalyzed azide-alkyne click polymerization, and their ability to remove different organic dyes (Nile blue, Rhodamine B, and Methyl orange) from aqueous solutions has been investigated. The presence of triazole moieties in the polymer walls, capable of binding guest molecules through different intermolecular interactions (such as dipole-dipole interactions, hydrogen bonding, and π-π interactions), is expected to benefit dye capture. We have found that these materials show a high adsorption capacity toward cationic dyes (reaching values as high as 1562 mg g-1 for Nile blue). This preference is probably due to the high electron density of the polymeric networks, which will favor electrostatic interactions with electron-deficient dyes. Interestingly, owing to the semiconducting nature of the truxene units, these polymers also act as photocatalysts in the oxidative degradation of the dyes, allowing for easy recovery and reuse of the polymers without the need for additional cleaning steps to remove trapped dyes. This interesting adsorption/photodegradation synergy represents a huge advantage compared to common dye adsorbents and makes them promising candidates for water remediation.