Bio-based materials for barrier coatings on paper packaging

Eco-Friendly Poly (Butylene Adipate-co-Terephthalate) Coated Bi-Layered Films: An Approach to Enhance Mechanical and Barrier Properties

In this research work, a coated paper was prepared with poly (butylene adipate-co-terephthalate) (PBAT) film to explore its use in eco-friendly food packaging. The paper was coated with PBAT film for packaging using hot pressing, a production method currently employed in the packaging industry. The coated papers were evaluated for their structural, mechanical, thermal, and barrier properties. The structural morphology and chemical analysis of the coated paper confirmed the consistent formation of PBAT bi-layered on paper surfaces. Surface coating with PBAT film increased the water resistance of the paper samples, as demonstrated by tests of barrier characteristics, including the water vapor transmission rate (WVTR), oxygen transmission rate (OTR), and water contact angle (WCA) of water drops. The transmission rate of the clean paper was 2010.40 cc m-2 per 24 h for OTR and 110.24 g m-2 per 24 h for WVTR. If the PBAT-film was coated, the value decreased to 91.79 g m-2 per 24 h and 992.86 cc m-2 per 24 h. The hydrophobic nature of PBAT, confirmed by WCA measurements, contributed to the enhanced water resistance of PBAT-coated paper. This result presents an improved PBAT-coated paper material, eliminating the need for adhesives and allowing for the fabrication of bi-layered packaging.

Recent Progress and Challenges in Paper-Based Microsupercapacitors for Flexible Electronics: A Comprehensive Review

Recent advances in paper-based microsupercapacitors (p-MSCs) have attracted significant attention due to their potential as substrates for flexible electronics. This review summarizes progress in the field of p-MSCs, discussing their challenges and prospects. It covers various aspects, including the fundamental characteristics of paper, the modification of paper with functional materials, and different methods for device fabrication. The review critically analyzes recent advancements, materials, and fabrication techniques for p-MSCs, exploring their potential applications and benefits, such as flexibility, cost-effectiveness, and sustainability. Additionally, this review highlights gaps in current research, guiding future investigations and innovations in the field. It provides an overview of the current state of p-MSCs and offers valuable insights for researchers and professionals in the field. The critical analysis and discussion presented herein offer a roadmap for the future development of p-MSCs and their potential impact on the domain of flexible electronics.

How does plastic compare with alternative materials in the packaging sector? A systematic review of LCA studies

In the recent years, packaging made of conventional plastics has been increasingly replaced by materials believed to be more sustainable. However, perceived sustainability must align with scientific assessments, such as life cycle assessments (LCAs). This review analysed 53 peer-reviewed studies published in the time range 2019-2023, aiming at understanding the state of the art in LCA about the environmental impacts of packaging by focusing on the comparison between plastics and alternative materials. The literature showed that consumer perceptions often differ from LCA findings and revealed that, frequently, conventional plastics are not the least environmentally friendly choice. Bioplastics typically show benefits only in the climate change and the fossil resource depletion impact categories. The heavy weight of glass turns out to affect its environmental performances with respect to the light plastics, with reuse being an essential strategy to lower the burdens. The comparison between plastics and metals is more balanced, leaning more towards plastics for food packaging. Similarly, paper resulted often preferable than plastics. Finally, for the other materials (i.e. wood and textiles), the picture is variable. To be competitive with plastics, the alternative materials require improvements like the optimisation of their production processes, their reuse and enhanced end-of-life options. At the same time, recycled polymers could boost the eco-performance of virgin plastics.

Liquid uptake in porous cellulose sheets studied with UFI-NMR: Penetration, swelling and air displacement

Liquid penetration in porous cellulosic materials is crucial in many technological fields. The complex geometry, small pore size, and often fast timescale of liquid uptake makes the process hard to capture. Effects such as swelling, vapor transport, film flow and water transport within cellulosic material makes transport deviate from well-known relations such as Lucas-Washburn and Darcy's Law. In this work it is demonstrated how Ultra-Fast Imaging NMR can be used to simultaneously monitor the liquid distribution and swelling during capillary uptake of water with a temporal- and spatial resolution of 10 ms and 14.5-18 μm respectively. The measurements show that in a cellulose fiber sheet, within the first 65 ms, liquid first penetrates the whole sheet before swelling takes place for another 30 s. Furthermore, it was observed that the liquid front traps 15 v% of air which is slowly replaced by water during the final stage of liquid uptake. Our method makes it possible to simultaneously quantify the concentration of all three phases (solid, liquid and air) within porous materials during processes exceeding 50 ms (5 times the temporal resolution). We hence believe that the proposed method should also be useful to study liquid penetration, or water diffusion, into other porous cellulosic materials like foams, membranes, nonwovens, textiles and films.

Ionic Liquids as Designed, Multi-Functional Plasticizers for Biodegradable Polymeric Materials: A Mini-Review

Measures to endorse the adoption of eco-friendly biodegradable plastics as a response to the scale of plastic pollution has created a demand for innovative products from materials from Nature. Ionic liquids (ILs) have the ability to disrupt the hydrogen bonding network of biopolymers, increase the mobility of biopolymer chains, reduce friction, and produce materials with various morphologies and mechanical properties. Due to these qualities, ILs are considered ideal for plasticizing biopolymers, enabling them to meet a wide range of specifications for biopolymeric materials. This mini-review discusses the effect of different IL-plasticizers on the processing, tensile strength, and elasticity of materials made from various biopolymers (e.g., starch, chitosan, alginate, cellulose), and specifically covers IL-plasticized packaging materials and materials for biomedical and electrochemical applications. Furthermore, challenges (cost, scale, and eco-friendliness) and future research directions in IL-based plasticizers for biopolymers are discussed.

Creating anti-viral high-touch surfaces using photocatalytic transparent films

Antimicrobial and self-cleaning surface coatings are promising tools to combat the growing global threat of infectious diseases and related healthcare-associated infections (HAIs). Although many engineered TiO₂-based coating technologies are reporting antibacterial performance, the antiviral performance of these coatings has not been explored. Furthermore, previous studies have underscored the importance of the "transparency" of the coating for surfaces such as the touch screens of medical devices. Hence, in this study, we fabricated a variety of nanoscale TiO₂-based transparent thin films (anatase TiO₂, anatase/rutile mixed phase TiO₂, silver-anatase TiO₂ composite, and carbon nanotube-anatase TiO₂ composite) via dipping and airbrush spray coating technologies and evaluated their antiviral performance (Bacteriophage MS2 as the model) under dark and illuminated conditions. The thin films showed high surface coverage (ranging from 40 to 85%), low surface roughness (maximum average roughness 70 nm), super-hydrophilicity (water contact angle 6-38.4°), and high transparency (70-80% transmittance under visible light). Antiviral performance of the coatings revealed that silver-anatase TiO₂ composite (nAg/nTiO₂) coated samples achieved the highest antiviral efficacy (5-6 log reduction) while the other TiO₂ coated samples showed fair antiviral results (1.5-3.5 log reduction) after 90 min LED irradiation at 365 nm. Those findings indicate that TiO₂-based composite coatings are effective in creating antiviral high-touch surfaces with the potential to control infectious diseases and HAIs.

Solventless Photopolymerizable Paper Coating Formulation for Packaging Applications

Nowadays, packaging applications require the use of advanced materials as well as production methods that have a low environmental impact. In this study, a solvent-free photopolymerizable paper coating was developed using two acrylic monomers (2-ethylhexyl acrylate and isobornyl methacrylate). A copolymer, with a molar ratio of 2-ethylhexyl acrylate/isobornyl methacrylate of 0.64/0.36, was prepared and used as the main component of the coating formulations (50 and 60 wt%). A mixture of the monomers with the same proportion was used as a reactive solvent, yielding formulations with 100% solids. The coated papers showed an increase in the pick-up values from 6.7 to 32 g/m² depending on the formulation used and the number of coating layers (up to two). The coated papers maintained their mechanical properties and presented improved air barrier properties (Gurley's air resistivity of ≈25 s for the higher pick-up values). All the formulations promoted a significant increase in the paper's water contact angle (all higher than 120 °) and a remarkable decrease in their water absorption (Cobb values decrease from 108 to 11 g/m²). The results confirm the potential of these solventless formulations for fabricating hydrophobic papers with potential application in packaging, following a quick, effective, and more sustainable approach.