Jing Shen’s research while affiliated with University of New Brunswick and other places

Green carbon‐based cellulosic pulp foams with excellent renewable and biodegradable properties are promising alternatives to traditional petroleum‐based lightweight materials, for reducing carbon emission and plastic pollution. However, the fabrication of super‐elastic and durable pulp‐based foams for high‐value utilization remains challenging. Herein, a novel composite bio‐foam material is prepared by a simple strategy of wet foaming and ionically cross‐linking. The obtained foam assembled by cellulosic pulp fibers and polylactic acid (PLA) fibers at atmospheric pressure shows an oriented lamellar structure with interconnected macropores and super‐elastic property. The prepared PLA@Pulp‐20 foam shows a high compressive strain of up to 90% with the maximum stress of 150 kPa, while retaining ≈91% of its original height even after 30 000 compressive cycles (far superior to the reported pulp‐based foams with compressive cycles <10). Furthermore, the foam exhibits outstanding recyclability and stability in a wide range of temperature and humidity. Remarkably, the potential application of PLA@Pulp foam as a dielectric layer for capacitive sensors is first demonstrated because of its electrical non‐conductivity, and low dielectric constant (comparable to air). The corresponding device achieves non‐contact touch or contact touch sensing, demonstrating highly attractive performance in sustainable super‐elastic pressure sensing, monitoring, and beyond.

Cellulosic paper has combined characteristics of renewability, biodegradability, flexibility, and recyclability. Based on disassembly-initiated fiber processing, the conversion of regular paper into a multifunctional wet-strength product was explored. In this concept, disassembly generates cellulosic additives for surface engineering. Encouragingly, the use of the aqueous solvent system containing mixed metal salts allows controllable fiber disassembly and formation of room-temperature-stable cellulosic solutions, leading to wet and dry strengthening of paper following cellulose regeneration. In-situ generation of cellulosic film-forming additives led to the increase of dry and wet strengths by more than 8 and 35 times respectively, in the case of a typical grade of quantitative filter paper. The engineered paper shows flame-retardant, antibacterial, and liquid-barrier features. The combination of functional properties can shed light on diversified applications, e.g., replacement of difficult-to-degrade synthetic plastics.

It is still a challenge to realize super clear cellulose-based film materials with different functional combinations. This study presents a novel concept of fabricating flame-retardant, mechanically strong, UV and blue light double-blocking carboxymethylated cellulose-based nanocomposite bioplastics enabled by nano-metal organic framework (MIL-125(Ti)-NH 2). Carboxymethylated cellulose gel with porous structure acts as nanoreactor and carboxyl groups as reactive sites to facilitate the growth and anchorage of nano-MIL-125(Ti)-NH 2. Super clear bioplastics were obtained through hot-pressing. The results show that the neat carboxymethylated cellulose bioplastic possesses high transmittance (94.1% at 600 nm) and low haze (2.0% at 600 nm). The incorporation of nano-MIL-125(Ti)-NH 2 enabled nanocomposite bioplastics to obtain UV and blue light double-shielding capability meanwhile retaining high transmittance (79-92.8%) and low haze (2.6-7.2%). Moreover, the incorporation of nano-MIL-125(Ti)-NH 2 was found to significantly improve the mechanical strength and decrease the flammability of nanocomposite bioplastics. This facile strategy would direct nanocomposite bioplastics toward diversified applications.

Paper-based products are similar to paper wasps’ nests built by biofiber separation and biofiber reassembly, where they add saliva for structural reinforcement and waterproofing. Rice leaves, which contain lignocellulosic components and look like paper sheets, have functional epidermises for directional self-cleaning and defensive barriers. We herein report a bioinspired concept of forming functional nanocomposites from environmentally friendly additives and cellulosic paper. Beeswax–silica hybrids mimic rice leaves’ mineralized biowaxy epidermises. Gelatin, which is chemically similar to protein-containing saliva of paper wasps, acts as a functional additive to facilitate anchorage of hybrids to paper and to consolidate/waterproof the composite structures. Thermal annealing reorganizes as-formed composites and induces the formation of transparent coatings. As expected, the consolidated nanocomposites show self-cleaning superhydrophobicity. The processes of spraying biowax–mineral hybrid dispersion onto gelatin-deposited substrate followed by thermal annealing are integrable into unit operations of paper production as surface sizing or coating. Other features of the strategy would involve antibacterial properties and fruits/vegetables preservation. This simple, bioinspired strategy would direct sustainable paper-based products toward diversified applications: food/drinks containers or packaging materials that can reduce or eliminate liquid wastes, preservation of historic/artistic works, scientific demonstrations relevant to surface engineering and bionics, and children-related safe products, among others.