Recent years have seen an increased interest toward utilizing biobased and biodegradable materials for barrier packaging applications. Most of the abovementioned materials usually have certain shortcomings that discourage their adoption as a preferred material of choice. Nanocellulose falls into such a category. It has excellent barrier against grease, mineral oils, and oxygen but poor tolerance against water vapor, which makes it unsuitable to be used at high humidity. In addition, nanocellulose suspensions’ high viscosity and yield stress already at low solid content and poor adhesion to substrates create additional challenges for high-speed processing. Polylactic acid (PLA) is another potential candidate that has reasonably high tolerance against water vapor but rather a poor barrier against oxygen. The current work explores the possibility of combining both these materials into thin multilayer coatings onto a paperboard. A custom-built slot-die was used to coat either microfibrillated cellulose or cellulose nanocrystals onto a pigment-coated baseboard in a continuous process. These were subsequently coated with PLA using a pilot-scale extrusion coater. Low-density polyethylene was used as for reference extrusion coating. Cationic starch precoating and corona treatment improved the adhesion at nanocellulose/baseboard and nanocellulose/PLA interfaces, respectively. The water vapor transmission rate for nanocellulose + PLA coatings remained lower than that of the control PLA coating, even at a high relative humidity of 90% (38 °C). The multilayer coating had 98% lower oxygen transmission rate compared to just the PLA-coated baseboard, and the heptane vapor transmission rate reduced by 99% in comparison to the baseboard. The grease barrier for nanocellulose + PLA coatings increased 5-fold compared to nanocellulose alone and 2-fold compared to PLA alone. This approach of processing nanocellulose and PLA into multiple layers utilizing slot-die and extrusion coating in tandem has the potential to produce a barrier packaging paper that is both 100% biobased and biodegradable.

Surface engineering can be used to prevent ice accumulation and adhesion in environments that deal with icing problems. One recent engineering approach, slippery liquid infused porous surfaces (SLIPS), comprises a smooth and slippery lubricating surface, where lubricant is trapped within the pores of a solid material to repel various substances, such as water and ice. However, it remains unclear whether the slippery surfaces retain their icephobic characteristics under the impact of supercooled water droplets or repeated freezing and melting cycles. Here, the icephobic properties of SLIPS are evaluated under multiple droplet freeze–thaw and ice accretion–detachment cycles and compared to hydrophobic and superhydrophobic surfaces. The experiments are designed to mimic real environmental conditions, thus, the icephobicity is investigated in icing wind tunnel, where ice accretion occurs through the impact of supercooled water droplets. The adhesion of ice remained extremely low, <10 kPa, which is four times lower than ice adhesion onto smooth fluoropolymer surfaces, even after repeated ice accretion–detachment cycles. Moreover, cyclic droplet freeze–thaw experiments provide insight into the effects of temperature cycling on SLIPS wettability, showing stable wetting performance. The results suggest liquid infused porous surfaces as a potential solution to icephobicity under challenging and variating environmental conditions.

Slippery, liquid-infused porous surfaces offer a promising route for producing omniphobic and anti-icing surfaces. Typically, these surfaces are made as a coating with expensive and time consuming assembly methods or with fluorinated films and oils. We report on a route for producing liquid-infused surfaces, which utilizes a liquid precursor fed oxygen-hydrogen flame to produce titania nanoparticles deposited directly on a low-density polyethylene film. This porous nanocoating, with thickness of several hundreds of nanometers, is then filled with silicone oil. The produced surfaces are shown to exhibit excellent anti-icing properties, with an ice adhesion strength of ∼12 kPa, which is an order of magnitude improvement when compared to the plain polyethylene film. The surface was also capable of maintaining this property even after cyclic icing testing.

Cellulose nanofiber films (CNFF), were treated via a welding process using ionic liquids (ILs). Acid-base conjugated ILs derived from 1,5-diazabicyclo[4.3.0]non-5-ene [DBN] and 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) were utilized. The removal efficiency of ILs from welded CNFF was assessed using liquid-state nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The mechanical and physical properties of CNFF indicated surface plasticization of CNFF, which improved transparency. Upon 2 treatment, the average CNFF toughness increased by 27 % and the films reached a Young modulus of ~5.8GPa. These first attempts for IL 'welding' show promise to tune bio-based films surfaces, expanding the scope of properties for the production of new bio-based materials in a green chemistry context. The results of this work are highly relevant to the fabrication of CNFFs using ionic liquids and related solvents. nanocomposites, transparent films, layer-by-layer films, paper products, cosmetics, barrier/separation membranes, transparent-flexible electronics, batteries, supercapacitors, catalytic supports, continuous fibers and textiles, food coatings, healthcare, antimicrobial films, biomedical and tissue engineering scaffolds, pH-responsive CNMs, drug delivery, among others 2. The sustainable preparation of cellulose-based nanomaterials is techno-economically challenging since this requires a low energy consumption process without the use, or production of, hazardous chemicals. The benefits are the production of high mechanical performance fibers and films, which 3 have potential applications as textiles, support for particles, and as composite materials for catalytic and electrochemical applications 3. Nanocellulose can form self-standing, thermallystable films and "nano-papers", thus this material has been strongly advocated as potential replacement for traditional packaging materials, primarily based on glass, aluminum, and fossilderived synthetic plastics 4-16 , but in many cases, such applications require an improvement of their physical and mechanical properties, in order to enhance their use 13,17. At this respect, the novel concept of welding has been introduced by Haverlhals 18-21. In this process, the surface of adjacent natural fibers (cotton, silk, and hemp) is plasticized and merged to create a congealed network using ILs such as 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), a well-known cellulose-dissolving ionic liquid (IL). The welding process is intended mainly for cellulosic and protein-based fibers with the purpose to improve mechanical properties, synthesis of composites and functionalization of materials 18,22. The welding procedure has been used for modifying mainly cellulose macrofibers (not hydrolyzed neither treated fibers) to produce electrodes, catalysts, materials with special magnetic and electric features 23,24 , and synthesis of composites with improved mechanical properties 25. The same concept, using N-methylmorpholine-N-oxide (NMMO), was use...

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