Increased hydrophilicity of lignin-derivable vs. bisphenol-based polysulfones for potential water filtration applications†

The functionality inherent in lignin-derivable aromatics (e.g., polar methoxy groups) can provide a potential opportunity to improve the hydrophilicity of polysulfones (PSfs) without the need for the additional processing steps and harsh reagents/conditions that are typically used in conventional PSf modifications. As determined herein, lignin-derivable PSfs without any post-polymerization modification exhibited higher hydrophilicity than comparable petroleum-based PSfs (commercial/laboratory-synthesized) and also demonstrated similar hydrophilicity to functionalized BPA-PSfs reported in the literature. Importantly, the lignin-derivable PSfs displayed improved thermal properties relative to functionalized BPA-PSfs in the literature, and the thermal properties of these bio-derivable PSfs were close to those of common non-functionalized PSfs. In particular, the glass transition temperature (T_g) and degradation temperature of 5% weight loss (T_d5%) of lignin-derivable PSfs (T_g ∼165–170 °C, T_d5% ∼400–425 °C) were significantly higher than those of typical functionalized BPA-PSfs in the literature (T_g ∼110–160 °C, T_d5% ∼240–260 °C) and close to those of unmodified, commercial/laboratory-synthesized BPA-/bisphenol F-PSfs (T_g ∼180–185 °C, T_d5% ∼420–510 °C).