Hierarchical Incorporation of Reduced Graphene Oxide into Anisotropic Cellulose Nanofiber Foams Improves Their Thermal Insulation.

Anisotropic cellulose nanofiber (CNF) foams represent the state-of-the-art in renewable insulation. These foams consist of large (diameter >10 μm) uniaxially aligned macropores with mesoporous pore-walls and aligned CNF. The foams show anisotropic thermal conduction, where heat transports more efficiently in the axial direction (along the aligned CNF and macropores) than in the radial direction (perpendicular to the aligned CNF and macropores).

Anisotropic foams derived from textile-based cellulose nanocrystals and xanthan gum.

The upcycling of discarded garments can help to mitigate the environmental impact of the textile industry. Here, we fabricated hybrid anisotropic foams having cellulose nanocrystals (CNCs), which were isolated from discarded cotton textiles and had varied surface chemistries as structural components, in combination with xanthan gum (XG) as a physical crosslinker of the dispersion used for foam preparation. All CNCs had crystallinity indices above 85 %, zeta potential values below -40 mV at 1 mM NaCl, and true densities ranging from 1.

Thermally Insulating and Moisture-Resilient Foams Based on Upcycled Aramid Nanofibers and Nanocellulose.

Low-density foams and aerogels based on upcycled and bio-based nanofibers and additives are promising alternatives to fossil-based thermal insulation materials. Super-insulating foams are prepared from upcycled acid-treated aramid nanofibers (upANF ) obtained from Kevlar yarn and tempo-oxidized cellulose nanofibers (CNF) from wood. The ice-templated hybrid upANF /CNF-based foams with an upANF content of up to 40 wt% display high thermal stability and a very low thermal conductivity of 18-23 mW m K perpendicular to the aligned nanofibrils over a wide relative humidity (RH) range of 20% to 80%.

Highly magnetic hybrid foams based on aligned tannic acid-coated iron oxide nanoparticles and TEMPO-oxidized cellulose nanofibers.

Lightweight iron oxide nanoparticle (IONP)/TEMPO-oxidized cellulose nanofibril (TOCNF) hybrid foams with an anisotropic structure and a high IONP content were produced using magnetic field-enhanced unidirectional ice-templating. Coating the IONP with tannic acid (TA) improved the processability, the mechanical performance, and the thermal stability of the hybrid foams. Increasing the IONP content (and density) increased the Young's modulus and toughness probed in compression, and hybrid foams with the highest IONP content were relatively flexible and could recover 14% axial compression.

A Stiff, Tough, and Thermally Insulating Air- and Ice-Templated Plant-Based Foam.

By forming and directionally freezing an aqueous foam containing cellulose nanofibrils, methylcellulose, and tannic acid, we produced a stiff and tough anisotropic solid foam with low radial thermal conductivity. Along the ice-templating direction, the foam was as stiff as nanocellulose-clay composites, despite being primarily methylcellulose by mass. The foam was also stiff perpendicular to the direction of ice growth, while maintaining λ < 25 mW m K for a relative humidity (RH) up to 65% and <30 mW m K at 80% RH.

Rheo-SAXS study of shear-induced orientation and relaxation of cellulose nanocrystal and montmorillonite nanoplatelet dispersions.

The development of robust production processes is essential for the introduction of advanced materials based on renewable and Earth-abundant resources. Cellulose nanomaterials have been combined with other highly available nanoparticles, in particular clays, to generate multifunctional films and foams. Here, the structure of dispersions of rod-like cellulose nanocrystals (CNC) and montmorillonite nanoplatelets (MNT) was probed using small-angle X-ray scattering within a rheological cell (Rheo-SAXS).

Unravelling the Hydration Barrier of Lignin Oleate Nanoparticles for Acid- and Base-Catalyzed Functionalization in Dispersion State.

Lignin nanoparticles (LNPs) are promising renewable nanomaterials with applications ranging from biomedicine to water purification. However, the instability of LNPs under acidic and basic conditions severely limits their functionalization for improved performance. Here, we show that controlling the degree of esterification can significantly improve the stability of lignin oleate nanoparticles (OLNPs) in acidic and basic aqueous dispersions.

Assembly of cellulose nanocrystals and clay nanoplatelets studied by time-resolved X-ray scattering.

Time-resolved small-angle X-ray scattering (SAXS) was used to probe the assembly of cellulose nanocrystals (CNC) and montmorillonite (MNT) over a wide concentration range in aqueous levitating droplets. Analysis of the SAXS curves of the one-component and mixed dispersions shows that co-assembly of rod-like CNC and MNT nanoplatelets is dominated by the interactions between the dispersed CNC particles and that MNT promotes gelation and assembly of CNC, which occurred at lower total volume fractions in the CNC:MNT than in the CNC-only dispersions. The CNC dispersions displayed a d ∝ φ-1/2 scaling and a low-q power-law exponent of 2.

Cucurbit[7]uril-Anchored Porphyrin-Based Multifunctional Molecular Platform for Photodynamic Antimicrobial and Cancer Therapy.

Here we report a photoactive supramolecular assembly that is multifunctional and constructed by covalently linking four receptor molecules (cucurbit[7]uril) to a porphyrin derivative with suitable linkers. While this molecular platform serves very efficiently as a light-triggered broad-spectrum antibacterial agent, owing to its negligible dark cytotoxicity and the presence of host molecules (CB7), it can also be utilized as a vehicle to carry drug molecules for a combined chemo and photodynamic cancer therapy.