A method for preparing reprocessable epoxy thermoset is presented. The process is composed of synthesis of a bisphenol monomer bridged by an imine bond, glycidylation of the bisphenol, and cross-linking with a hardener to form thermoset. The resulting epoxy thermoset possesses comparable properties to conventional high-performance thermosets made from bisphenol A. However, when treated by a stimulus like acid, temperature, and/or water, the described thermoset exhibits reprocessability. Degradation and recycling involve hydrolysis and re-formation of imine bonds; reshaping and repairing of the thermoset are realized through imine exchange reactions. All the described processes require no metal catalyst, press heating, or additional monomer, which significantly widens thermoset reprocessing.

Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate). The Cit-GNRs are indefinitely stable at low ionic strength, and are conducive to further ligand exchange without loss of dispersion stability. The reliability of the surface exchange process supports the systematic analysis of ligand structure on the hydrodynamic size of GNRs, as described in a companion paper.

Three modification methods, which either improved molecular weight, orientation or the number of functional groups, were employed to increase the cross-linking density of biobased epoxy networks based on 2methoxy-4-propylphenol (dihydroeugenol, DHE). The modifications were realized through o-demethylation and phenol−formaldehyde reactions. Structures of DHE-based monomers and cured networks were characterized by NMR and FTIR spectroscopy. Cross-linking densities of cured networks were calculated using rubber elasticity theory from dynamic mechanical analysis (DMA). Networks with higher cross-link density were found to exhibit greater mechanical and thermal performance as measured by DMA and thermogravimetric analysis. GEDHEO-NOVO, an epoxy monomer featuring all three modification processes, exhibited significant improvements in cross-linking density (0.39 to 9.77 mol/dm 3 ), α-relaxation temperature (T α , 40 to 139 °C) and statistic heat-resistant index temperature (T s , 125 to 153 °C) compared to the unmodified DHEO-based networks.

Lithium is widely used in contemporary energy applications, but its isolation from natural reserves is plagued by time-consuming and costly processes. While polymer membranes could, in principle, circumvent these challenges by efficiently extracting lithium from aqueous solutions, they usually exhibit poor ion-specific selectivity. Toward this end, we have incorporated host–guest interactions into a tunable polynorbornene network by copolymerizing 1) 12-crown-4 ligands to impart ion selectivity, 2) poly(ethylene oxide) side chains to control water content, and 3) a crosslinker to form robust solids at room temperature. Single salt transport measurements indicate these materials exhibit unprecedented reverse permeability selectivity (∼2.3) for LiCl over NaCl—the highest documented to date for a dense, water-swollen polymer. As demonstrated by molecular dynamics simulations, this behavior originates from the ability of 12-crown-4 to bind Na+ ions more strongly than Li+ in an aqueous environment, which reduces Na+ mobility (relative to Li+) and offsets the increase in Na+ solubility due to binding with crown ethers. Under mixed salt conditions, 12-crown-4 functionalized membranes showed identical solubility selectivity relative to single salt conditions; however, the permeability and diffusivity selectivity of LiCl over NaCl decreased, presumably due to flux coupling. These results reveal insights for designing advanced membranes with solute-specific selectivity by utilizing host–guest interactions.

Biobased epoxy nanocomposites were synthesized based on 2-methoxy-4-propylphenol (dihydroeugenol, DHE), a molecule that has been obtained from the lignin component of biomass. To increase the content of hydroxyl groups, DHE was o-demethylated using aqueous HBr to yield propylcatechol (DHEO), which was subsequently glycidylated to epoxy monomer. Optimal conditions in terms of yield and epoxy equivalent weight were found to be 60 °C with equal NaOH/phenolic hydroxyl molar ratio. The structural evolution from DHE to cured epoxy was followed by (1)H NMR and Fourier transform infrared spectroscopy. The nano-montmorillonite modified DHEO epoxy exhibited improved storage modulus and thermal stability as determined from dynamic mechanical analysis and thermogravimetric analysis. This study widens the synthesis routes of biobased epoxy thermosets from lignin-based molecules.