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Bilayer actuators, traditionally consisting of two laminated materials, are the most common types of soft or hybrid actuators. Herein, a nanomaterial‐based organic–inorganic humidity‐sensitive bilayer actuator composed of TEMPO‐oxidized cellulose nanofibrils (TCNF‐Na+) and reduced graphene oxide (rGO) sheets is presented. The hybrid actuator displays a large humidity‐driven locomotion with an atypical fast unbending. Cationic exchange of the anionically charged TCNF‐Na+ and control of the layer thickness is used to tune and dictate the locomotion and actuator's response to humidity variations. Assembly of a self‐oscillating electrical circuit, that includes a conductive rGO layer, displays autonomous on‐and‐off lighting in response to actuation‐driven alternating electrical heating. [ABSTRACT FROM AUTHOR]

Anisotropic cellulose nanocrystal (CNC) foams with densities between 25 and 130 kg m−3 (CNC25 –CNC130) were prepared by directional ice-templating of aqueous dispersions. Estimates of the solid and gas conduction contributions to the thermal conductivity of the foams using a parallel resistor model showed that the relatively small increase of the radial thermal conductivity with increasing foam density can be attributed to interfacial phonon scattering. The foam wall nanoporosity and, to a lesser extent, the orientation of the CNC particles and alignment of the columnar macropores, also influence the insulation performance of the foams. The insight on the importance of phonon scattering for the thermal insulation properties of nanocellulose foams provides useful guidelines for tailoring nanofibrillar foams for super-insulating applications. [ABSTRACT FROM AUTHOR]

Weak interfacial binding of lignin within synthetic polymer composites results in unsatisfactory mechanical properties that limit their application prospects. In the present work, polystyrene (PS) and poly(butyl methacrylate) (PBMA) nanocomposites containing lignin nanoparticles (LNPs) are produced by simple melting of polymeric latex dispersions obtained from free radical polymerization of oil-in-water Pickering emulsions stabilized by hybrid LNPs coated with chitosan and glucose oxidase. Owing to the formation of viscous polymer melts, the hybrid LNPs ended up uniformly dispersed within the polymeric matrices, which gave the polymeric nanocomposites markedly improved tensile strength without sacrificing their elasticity in comparison to pure PS and PBMA. Consequently, the composites reinforced with 15 wt% of the hybrid particles showed improvement in toughness by a factor of 3.5 and 15 compared to those of the corresponding pristine PS and PBMA. In addition, the presence of the hybrid particles conferred the nanocomposites with commendable UV-blocking and antioxidant properties which are relevant for protective packaging and coating applications. Overall, our results show a new and green route with excellent material economy (overall mass yield up to 91%) to obtain strong and transparent polymeric nanocomposites reinforced with up to 30 wt% of LNPs, which is expected to attract renewed interest in lignin–polymer composites for a broad range of applications. [ABSTRACT FROM AUTHOR]

We report the fabrication of anisotropic lightweight composite foams based on commercial colloidal silica particles and TEMPO-oxidized cellulose nanofibrils (TOCNF). The unidirectional ice-templating of silica-TOCNF dispersions resulted in anisotropic foams with columnar porous structures in which the inorganic and organic components were homogeneously distributed. The facile addition of silica particles yielded a significant enhancement in mechanical strength, compared to TOCNF-only foams, and a 3.5-fold increase in toughness at a density of 20 kg m−3. The shape of the silica particles had a large effect on the mechanical properties; anisotropic silica particles were found to strengthen the foams more efficiently than spherical particles. The water uptake of the foams and the axial thermal conductivity in humid air were reduced by the addition of silica. The composite foams were super-insulating at dry conditions at room temperature, with a radial thermal conductivity value as low as 24 mW m−1 K−1, and remained lower than 35 mW m−1 K−1 up to 80% relative humidity. The combination of high strength, low thermal conductivity and manageable moisture sensitivity suggests that silica-TOCNF composite foams could be an attractive alternative to the oil-based thermal insulating materials. [ABSTRACT FROM AUTHOR]

Highly porous and hyper‐cross‐linked polymers (HCPs) have a range of applications and are typically synthesized in an unsustainable manner. Herein, HCPs were synthesized from abundant biobased or biorelated compounds in sulfolane with iron(III) chloride as Lewis acid catalyst. As reactants, quercetin, tannic acid, phenol, 1,4‐dimethoxybenzene, glucose, and a commercial bark extract were used. The HCPs had high CO2 uptake (up to 3.94 mmol g−1 at 0 °C and 1 bar), total pore volumes (up to 1.86 cm3 g−1), and specific surface areas (up to 1440 m2 g−1). 1H NMR, 13C NMR, and IR spectroscopy, wide‐angle X‐ray scattering, elemental analysis, and SEM revealed, for example, that the HCPs consisted of amorphous and cross‐linked aromatic and phenolic structures with significant contents of aliphatics, oxygen, and sulfur. Greener HCPs: A wide range of biomass‐based aromatic compounds are used as precursors for highly porous hyper‐cross‐linked polymers (HCPs) in a sustainable synthesis system. The HCPs have large pore volumes and high CO2 uptakes, which are useful in sustainability‐related applications. [ABSTRACT FROM AUTHOR]

In this work Imidazolium Nanoparticle Networks (INNs) with chloride counter-ions were used to complex copper dichloride. This complexation reaction leads to the formation of a green material. The properties of the copper INN material were compared to: first, copper imidazolium complexes, without the presence of silica nanoparticles, which are not thermochromic; second, chloride-containing INN material. The copper INN material showed irreversible thermochromic behaviour, with a clear colour change from green to yellow at 180 °C, which is due to a configuration change of the copper complex from planar to tetragonal. This structural change was studied using DSC and in situ SAXS measurements during heat treatment. The thermochromic material is stable under air up to 250 °C. This preliminary study opens the door of optical sensors for INN materials. [ABSTRACT FROM AUTHOR]