The Effect of Cellulose Nanocrystal Reassembly on Latex-Based Pressure-Sensitive Adhesive Performance.

Different cellulose nanocrystal (CNC) forms (dried vs never-dried) can lead to different degrees of CNC reassembly, the formation of nanofibril-like structures, in nanocomposite latex-based pressure-sensitive adhesive (PSA) formulations. CNC reassembly is also affected by CNC sonication and loading as well as the protocol used for CNC addition to the polymerization. In this study, carboxylated CNCs (cCNCs) were incorporated into a seeded, semibatch, 2-ethylhexyl acrylate/methyl methacrylate/styrene emulsion polymerization and cast as pressure-sensitive adhesive (PSA) films. The addition of CNCs led to a simultaneous increase in tack strength, peel strength, and shear adhesion, avoiding the typical trade-off between the adhesive and cohesive strength. Increased CNC reassembly resulted from the use of dried, redispersed, and sonicated cCNCs, along with increased cCNC loading and addition of the cCNCs at the seed stage of the polymerization. The increased degree of CNC reassembly was shown to significantly increase the shear adhesion by enhancing the elastic modulus of the PSA films.

The alkali degradation of LDPE-based radiation-grafted anion-exchange membranes studied using different ex situ methods.

Radiation-grafted anion-exchange membranes (RG-AEM) in alkaline membrane fuel cells (AEMFC) exhibit promising performances (low in situ resistances, high power outputs and reasonably high alkali stabilities). Much research is focused on developing AEMs with enhanced chemical stabilities in the OH--forms at temperatures >60 °C. This study contributes towards this effort by providing a comparison of three different ex situ methods of screening alkali stabilities (where different laboratories conducted experiments on exactly the same batches of RG-AEM). Vinylbenzyl chloride monomer was radiation-grafted onto 25 µm thick low-density polyethylene (LDPE) precursor film in a single batch. This batch of grafted membrane was then split into three sub-batches, which were converted into RG-AEMs via amination with either: trimethylamine (TMA), N-methylpyrrolidine (MPY), or N-methylpiperidine (MPIP). Samples of each RG-AEM (l-AEM-TMA, l-AEM-MPY, and l-AEM-MPIP) were then distributed between the three collaborating institutes for evaluation using each institutes' test protocols. Out of the three head-group chemistries, the l-AEM-TMA generally exhibits the best balance of conductivity and ex situ alkali degradation, especially in lower humidity environments. The l-AEM-TMA also exhibited interestingly high Cl- ion conductivities (ca. 100 mS cm-1) when heated to 80 °C in a relative humidity RH = 95% atmosphere, a measurement frequently overlooked in favour of determining conductivities of RG-AEMs submerged in water (conductivities of submerged RG-AEMs can be suppressed due to excessive water contents and swelling).

Data of thermally active lignin-linkages and shape memory of lignin-rubber composites.

This data article presents the utilization of thermally dynamic covalent bonds of lignin linkages such as ß-O-4', Cα-O of ß-5' phenylcoumaran, and ß-ß resinol to modify the thermomechanical properties of high loading lignin-nitrile rubber composites. These thermally active lignin linkages can be triggered at 180 °C to generate free-radicals for crosslinking reactions. The evolution of crosslinking density was measured in-situ using dynamic mechanical analysis and rheological characterization. The shape programmability and shape recovery of these composites were determined by both ex-situ and in-situ methods. The thermally modified composites exhibited excellent shape memory properties. The data in this article are related to our recent research article entitled "Responsive lignin for shape memory applications" (Nguyen et al., 2018).

A path for lignin valorization via additive manufacturing of high-performance sustainable composites with enhanced 3D printability.

We report the manufacture of printable, sustainable polymer systems to address global challenges associated with high-volume utilization of lignin, an industrial waste from biomass feedstock. By analyzing a common three-dimensional printing process-fused-deposition modeling-and correlating the printing-process features to properties of materials such as acrylonitrile-butadiene-styrene (ABS) and nylon, we devised a first-of-its-kind, high-performance class of printable renewable composites containing 40 to 60 weight % (wt %) lignin. An ABS analog made by integrating lignin into nitrile-butadiene rubber needs the presence of a styrenic polymer to avoid filament buckling during printing. However, lignin-modified nylon composites containing 40 to 60 wt % sinapyl alcohol-rich, melt-stable lignin exhibit enhanced stiffness and tensile strength at room temperature, while-unexpectedly-demonstrating a reduced viscosity in the melt. Further, incorporation of 4 to 16 wt % discontinuous carbon fibers enhances mechanical stiffness and printing speed, as the thermal conductivity of the carbon fibers facilitates heat transfer and thinning of the melt. We found that the presence of lignin and carbon fibers retards nylon crystallization, leading to low-melting imperfect crystals that allow good printability at lower temperatures without lignin degradation.

A Solvent-Free Synthesis of Lignin-Derived Renewable Carbon with Tunable Porosity for Supercapacitor Electrodes.

Synthesis of multiphase materials from lignin, a biorefinery coproduct, offers limited success owing to the inherent difficulty in controlling dispersion of these renewable hyperbranched macromolecules in the product or its intermediates. Effective use of the chemically reactive functionalities in lignin, however, enables tuning morphologies of the materials. Here, we bind lignin oligomers with a rubbery macromolecule followed by thermal crosslinking to form a carbon precursor with phase contrasted morphology at submicron scale. The solvent-free mixing is conducted in a high-shear melt mixer. With this, the carbon precursor is further modified with potassium hydroxide for a single-step carbonization to yield activated carbon with tunable pore structure. A typical precursor with 90 % lignin yields porous carbon with 2120 m2 g-1 surface area and supercapacitor with 215 F g-1 capacitance. The results show a simple route towards manufacturing carbon-based energy-storage materials, eliminating the need for conventional template synthesis.

Sulfonated Polymerized Ionic Liquid Block Copolymers.

The successful synthesis of a new diblock copolymer, referred to as sulfonated polymerized ionic liquid (PIL) block copolymer, poly(SS-Li-b-AEBIm-TFSI), is reported, which contains both sulfonated blocks (sulfonated styrene: SS) and PIL blocks (1-[(2-acryloyloxy)ethyl]-3-butylimidazolium: AEBIm) with both mobile cations (lithium: Li(+) ) and mobile anions (bis(trifluoromethylsulfonyl)imide: TFSI(-) ). Synthesis consists of polymerization via reversible addition-fragmentation chain transfer, followed by post-functionalization reactions to covalently attach the imidazolium cations and sulfonic acid anions to their respective blocks, followed by ion exchange metathesis resulting in mobile Li(+) cations and mobile TFSI(-) anions. Solid-state films containing 1 m Li-TFSI salt dissolved in ionic liquid result in an ion conductivity of >1.5 mS cm(-1) at 70 °C, where small-angle X-ray scattering data indicate a weakly ordered microphase-separated morphology. These results demonstrate a new ion-conducting block copolymer containing both mobile cations and mobile anions.