Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. By applying specific pretreatments and manufacturing methods, lignin can be converted into a variety of value-added carbon materials. However, the physical and chemical heterogeneities of lignin complicate its use as a feedstock. Herein lignin manufacturing process, the effects of pretreatments and manufacturing methods on the properties of product lignin, and structure-property relationships in various applications of lignin-derived carbon materials, such as carbon fibers, carbon mats, activated carbons, carbon films, and templated carbon, are discussed.

Fiber adsorbents synthesizedviaATRP.

Dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to study the effect of chain-end hydrogen bonding on the dynamics of hydroxyl-terminated poly­dimethyl­siloxane. We demonstrate that hydrogen bonding has a strong influence on both segmental and slower dynamics in the systems with low molecular weights. In particular, the decrease in the chain length leads to an increase of the glass transition temperature, viscosity, and fragility index, at variance with the usual behavior of nonassociating polymers. The supramolecular association of hydroxyl-terminated chains leads to the emergence in dielectric and mechanical relaxation spectra of the so-called Debye process traditionally observed in monohydroxy alcohols. Our analysis suggests that the hydroxyl-terminated PDMS oligomers may associate in brush-like or chain-like structures, depending on the size of their covalent chains. The effective length of the linear-associated chains was estimated from the rheological measurements.

Seawater contains a large amount of uranium (∼4.5 billion tons) which can serve as a nearly limitless supply for an energy source. However, to make the recovery of uranium from seawater economically feasible, lower manufacturing and deployment costs are desirable, and good solid adsorbents must have high uranium uptake, reusability, and high selectivity toward uranium. In this study, atom-transfer radical polymerization (ATRP), without the high-cost radiation-induced graft polymerization, was used for grafting acrylonitrile and tert-butyl acrylate from a new class of trunk fibers, forming adsorbents in a readily deployable form. The new class of trunk fibers was prepared by the chlorination of polypropylene (PP) round fiber, hollow-gear PP fiber, and hollow-gear polyethylene fiber. During ATRP, degrees of grafting (d.g.) varied according to the structure of active chlorine sites on trunk fibers and ATRP conditions, and the d.g. as high as 2570% was obtained. Resulting adsorbent fibers were evaluated in U-spiked simulated seawater, and the maximum adsorption capacity of 146.6 g U/kg, much higher than that of a standard adsorbent Japan Atomic Energy Agency fiber (75.1 g/kg), was obtained. This new type of trunk fiber can be used for grafting a variety of uranium-interacting ligands, including designed ligands that are highly selective toward uranium.