The need for renewable alternatives to traditional petroleum-derived plastics has driven recent interest in biobased composite materials that are sourced from carbon-neutral feedstocks. Lignin, an abundant plant-derived feedstock, has been a candidate for renewable materials; however, it is often difficult to blend with other biopolymers. In order to improve the miscibility of lignin with other bioplastics, we developed a catalytic and solvent free method for synthesis of a lignin–PLA copolymer. Graft polymerization of lactide onto lignin catalyzed by triazabicyclodecene (TBD) resulted in a lignin-g-poly(lactic acid) copolymer; chain length of the PLA is controlled by varying of the lignin/lactide ratio and preacetylation treatment. End-group analysis reveals high grafting efficiency and preferential grafting on lignin aliphatic hydroxyls over phenolic hydroxyls. The lignin-g-PLA copolymers display a glass transition temperature range from 45 to 85 °C and multiphase melting behavior. The lignin-g-PLA copolymers are used as dispersion modifiers in PLA-based materials to enhance UV absorption and reduce brittleness without a sacrifice in the modulus of elasticity.

Benzotriazoles (BTs) are xenobiotic contaminants widely distributed in aquatic environments and of emerging concern due to their polarity, recalcitrance, and common use. During some water reclamation activities, such as stormwater bioretention or crop irrigation with recycled water, BTs come in contact with vegetation, presenting a potential exposure route to consumers. We discovered that BT in hydroponic systems was rapidly (approximately 1-log per day) assimilated by Arabidopsis plants and metabolized to novel BT metabolites structurally resembling tryptophan and auxin plant hormones; <1% remained as parent compound. Using LC-QTOF-MS untargeted metabolomics, we identified two major types of BT transformation products: glycosylation and incorporation into the tryptophan biosynthetic pathway. BT amino acid metabolites are structurally analogous to tryptophan and the storage forms of auxin plant hormones. Critical intermediates were synthesized (authenticated by (1)H/(13)C NMR) for product verification. In a multiple-exposure temporal mass balance, three major metabolites accounted for >60% of BT. Glycosylated BT was excreted by the plants into the hydroponic medium, a phenomenon not observed previously. The observed amino acid metabolites are likely formed when tryptophan biosynthetic enzymes substitute synthetic BT for native indolic molecules, generating potential phytohormone mimics. These results suggest that BT metabolism by plants could mask the presence of BT contamination in the environment. Furthermore, BT-derived metabolites are structurally related to plant auxin hormones and should be evaluated for undesirable biological effects.

Wood products are extensively used to make furniture items and construction materials; however, the majority contain formaldehyde-based adhesives that raise serious health concerns.

Quaternary ammonium cationic polymers, such as poly(diallyldimethylammonium chloride) (polyDADMAC) are widely used for coagulating and removing negatively charged particles and dissolved organic matter (DOM) from drinking water. Their use, however, has been linked to the formation of carcinogenic N-nitrosamines as byproducts during chloramine-based drinking water disinfection. In this study, a novel quaternary phosphonium cationic polymer, poly(diallyldiethylphosphonium chloride) (polyDADEPC), was synthesized such that the quaternary nitrogen atom of polyDADMAC was substituted with a phosphorus atom. Formation potential tests revealed that even under strong nitrosation conditions, polyDADEPC and related lower-order P-based compounds formed oxygenated and not nitrosated products. Bench-scale jar tests using three different source waters further demonstrated that polyDADEPC achieved coagulation performance comparable to commercial polyDADMACs for particle and DOM removals within the typical dose range used for drinking water treatment. This work highlights the potential use of a phosphonium coagulant polymer, polyDADEPC, as a viable alternative to polyDADMAC to avoid nitrosated byproduct formation during chloramination.

Quaternary ammonium cationic polymers, such as poly(diallyldimethylammonium chloride) (polyDADMAC) and epichlorohydrin-dimethylamine (Epi-DMA), are commonly used by water utilities to enhance removal of particles and dissolved organic matter (DOM) from raw waters. Unfortunately, chloramination of waters treated with quaternary ammonium polymers leads to the formation of carcinogenic N-nitrosodimethylamine (NDMA). In this study, two approaches were developed to modify polyDADMAC and Epi-DMA to inhibit N-nitrosamine formation. The first approach involved treatment of polymers with methyl iodide (MeI), an alkylating agent, to convert polymer-bound tertiary amine groups to less chloramine-reactive quaternary ammonium groups. The second approach involved synthesis of polymers bearing less chloramine-reactive quaternary ammonium groups with dipropylamino (DPA) substituents. Treatment with MeI reduced NDMA formation from polymers by ∼75%, while synthesis of DPA-based polymers eliminated NDMA formation and formed N-nitrosodipropylamine, which is 10-fold less carcinogenic than NDMA, at 20-fold lower yields. Bench-scale jar tests demonstrated that both MeI-treated and DPA-based polymers achieved similar removal of particles and DOM as the original polyDADMAC and Epi-DMA at both low and high doses, but formed significantly less N-nitrosamines. This work demonstrates two approaches for modifying quaternary ammonium cationic polymers, which may enable water utilities to meet potential future regulations on N-nitrosamines while maintaining polymer usage to meet existing regulations.