Per-and poly fluorinated alkyl substances (PFASs), notably perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid, contaminate many ground and surface water resources and are environmentally persistent. Furthermore, there are many other PFASs in use that are persistent and contaminate fresh water resources. A polymer consisting of β-cyclodextrin (β-CD) cross-linked with decafluorobiphenyl (DFB-CDP) has shown promise for sequestering PFOA at environmentally relevant concentrations, though its efficacy to remove other PFASs from water has not yet been explored. Additionally, although the DFB-CDP was designed to sequester PFASs on the basis of favorable fluorous interactions, the rationale for its relatively high affinity for PFOA compared to other previously synthesized β-CD polymers remains unknown. In this study, we explored cross-linker chemistry as a potential determinant of PFAS affinity for β-CD polymers. We synthesized three DFB-CDP derivatives with varying degrees of phenolation in the cross-linker (to evaluate effects of polymer surface charge) along with two β-CD polymers cross-linked by two other chemically distinct strategies, epichlorohydrin and 2isocyanatoethyl methacrylate. We measured the equilibrium removal of ten PFASs from water by each of the five polymers at environmentally relevant concentrations. We found that β-CD polymers cross-linked by perfluorinated aromatics with low degrees of phenolation are more favorable for PFAS adsorption. These findings provide insight into the mechanism of PFAS adsorption by β-CD-based polymers and will inspire modular designs of β-CD-based adsorbents to target other PFASs and micropollutants.

Herein, we present the direct modification of glucose, an abundant and inexpensive sugar molecule, to produce new sustainable and functional polymers.

The thermal activation of cellulose by initial glycosidic bond cleavage determines the overall rate of conversion to organic products for energy applications. Here, the kinetics of ether scission by transglycosylation of β-1,4-glycosidic bonds was measured using the “pulse-heated analysis of solid reactions” (PHASR) method from 400 to 500 °C. Levoglucosan (LGA) formation from cellulose was temporally resolved over the full extent of conversion, which was interpreted via a coupled reactant–product evolution model to determine an apparent barrier of LGA formation of 27.9 kcal mol–1. In parallel, LGA formation from the glucose monomer of cellobiosan was measured at temperatures between 380 and 430 °C by isotopically labeling the 13C1 carbon; an apparent activation energy of LGA formation was measured as 26.9 ± 1.9 kcal mol–1. The unusually low activation barrier for LGA formation at lower temperature is in agreement with previous PHASR studies for cellulose breakdown and is indicative of catalytic rather than thermal C–O bond activation. A catalytic mechanism was proposed wherein vicinal hydroxyl groups from neighboring cellulose sheets promote transglycosidic C–O bond activation. First-principle density functional theory (DFT) calculations showed that these vicinal hydroxyl groups cooperatively act to create an environment that (a) stabilizes charged transition states and (b) aids in proton transfer, thus leading to reduced activation barriers for transglycosylation. Models incorporating intrasheet H bonding of cellulose were also used to establish their influence on kinetics. The calculated apparent barrier (29.5 kcal mol–1) agreed well with the experimental apparent activation energy (26.9 ± 1.9 kcal mol–1) and establishes the dominant mode for cellulose activation and subsequent levoglucosan formation at lower temperatures (<467 °C) as site-specific, vicinal hydroxyl-catalyzed transglycosylation.

Isosorbide is a rigid, sugar-derived building block that has shown promise in high-performance materials, albeit with a lack of available controlled polymerization methods. To this end, we provide mechanistic insights into the cationic and quasi-zwitterionic ring-opening polymerization (ROP) of an annulated isosorbide derivative (1,4:2,5:3,6-trianhydro-d-mannitol, 5). Ring-opening selectivity of this tricyclic ether was achieved, and the polymerization is selectively directed toward different macromolecular architectures, allowing for formation of either linear or cyclic polymers. Notably, straightforward recycling of unreacted monomer can be accomplished via sublimation. This work provides the first platform for tailored polymer architectures from isosorbide via ROP.