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Photonic films based on cellulose nanocrystals (CNCs) are sustainable candidates for sensors, structurally colored radiative cooling, and iridescent coatings. Such CNC-based films possess a helicoidal nanoarchitecture, which gives selective reflection with the polarization of the incident light. However, due to the hygroscopic nature of CNCs, the structural colored material changes and may be irreversibly damaged at high relative humidity. Thus, moisture protection is essential in such settings. In this work, hygroscopic CNC-based films are protected with a bioinspired synthetic plant cuticle; a strategy already adopted by real plants. The protective cuticle layers altered the reflected colors to some extent, but more importantly, they significantly reduced the water vapor permeance by more than two orders of magnitude, from 2.1 x 10(7) (pristine CNC/GLU film) to 12.3 x 10(4) g mu m m(-2) day(-1) atm(-1) (protected CNC/GLU film). This expands significantly the time window of operation for CNC/GLU films at high relative humidity., Funding Agencies|Olle Byggmaestare [194-0679]; Knut and Alice Wallenberg Foundation (WWSC); Linkoeping University; Wallenberg Wood Science Center; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [2009 00971]

Biocomposites being environmentally-friendly alternative to synthetic composites are gaining increasing demand for various applications. Hence, biocomposite development should be integrated within a circular economy (CE) model to ensure a sustainable production that is simultaneously innocuous towards the environment. This review presents an overview of the state-of-the-art technologies for the adoption of the CE concept in biocomposite development. The study outlined the properties, environmental and economic impacts of biocomposites. A critical review of the life-cycle assessment of biocomposite for evaluating greenhouse gas emissions and carbon footprints was conducted. In addition, the opportunities and challenges pertaining to the implementation of CE have been discussed in detail. Recycling and utilisation of bio-based constituents were identified as the critical factors in embracing CE. Therefore, the development of innovative recycling technologies and an enhanced use of novel biocomposite constituents could lead to a reduction in material waste and environmental footprints. This article is one of the first studies to review the circularity of biocomposites in detail that will stimulate further research in enhancing the sustainability of these polymeric materials., QC 20220321

The global coronavirus disease 2019 (COVID-19) pandemic has rapidly increased the demand for facemasks as a measure to reduce the rapid spread of the pathogen. Throughout the pandemic, some countries such as Italy had a monthly demand of ca. 90 million facemasks. Domestic mask manufacturers are capable of manufacturing 8 million masks each week, although the demand was 40 million per week during March 2020. This dramatic increase has contributed to a spike in the generation of facemask waste. Facemasks are often manufactured with synthetic materials that are non-biodegradable, and their increased usage and improper disposal are raising environmental concerns. Consequently, there is a strong interest for developing biodegradable facemasks made with for example, renewable nanofibres. A range of natural polymer-based nanofibres has been studied for their potential to be used in air filter applications. This review article examines potential natural polymer-based nanofibres along with their filtration and antimicrobial capabilities for developing biodegradable facemask that will promote a cleaner production., QC 20220112

The plant cuticle is a hydrophobic barrier membrane found mainly on leaf surfaces and fruit skin. This work presents the structural and barrier properties of cuticle-inspired poly(hydroxyhexadecanoate) (PHHA), an omega-hydroxy fatty acid-derived biopolyester. PHHA was copolymerized and cross-linked with glycerol by melt polycondensation, and films were fabricated by compression molding. The study showed the effect of the addition of a trifunctional comonomer on the thermal, mechanical, and barrier properties. The neat PHHA, owing to its higher crystallinity, demonstrated the best water vapor barrier properties, but formed brittle films. The glycerol-copolymerized films, on the other hand, were flexible and displayed a good balance between barrier and mechanical properties. The water vapor transmission rate was overall similar to that of PLA, and limonene (a hydrophobic food component) uptake and diffusivity were lower than that of low-density polyethylene, the commonly used polymer for packaging. In addition, the polyester had UV-blocking properties. The way the films were made yielded a rough surface, mimicking the outer rough wax layer in plant cuticles with high water repellence. Hence, these cutin-inspired polyesters are promising for, e.g., water barrier (packaging/device) applications, provided means of efficient/sustainable production/isolation of the monomer is developed., QC 20210928

Microbial treatment of biodegradable wastes not only ensures neutralization of harmful substances such as volatile organic compounds but also enables valorization and bio-circularity within the society. Single cell protein (SCP) is a value-added product that can be obtained from biodegradable waste materials such as food waste via microbial fermentation. In this article, SCP derived from potato starch waste was demonstrated as a viable alternative to existing plant/animal proteins used in the production of films, for example, packaging applications. Flexible glycerol-plasticized SCP films were prepared through compression molding, and tensile tests revealed strength and stiffness similar to other plasticized protein films. The oxygen barrier properties were significantly better compared to the common polyethylene packaging material, but as with other highly polar materials, the SCP material must be shielded from moisture if used in, for example, food packaging. The biodegradation test revealed a similar degradation pattern as observed for a household compostable bag. The results showed that SCP-based bioplastic films can be considered as potential alternative to the existing plant/animal protein films and certain synthetic polymers. An important advantage with these protein materials is that they do not cause problems similar to microplastics., QC 20210629