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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 × 107 (pristine CNC/GLU film) to 12.3 × 104 g µm 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Understanding structure-property relationship between polymer-nanoparticle interface and the distribution of interfacial region and its properties is crucial in establishing the bulk properties of polymer like mechanical stability and conductivity. In this article we try to draw a comparison of the effect of silica nanoparticles modified with three different modifiers on the properties of oxy-polybenzimidazole (OPBI) to understand the role played by the chemical structure of the organic modifying molecule. We highlight how small changes in the structure of the chosen molecule can bring about substantial improvements in polymer nanocomposites owing to the self-assembly of nanofillers. We use aminopropyltriethoxysilane (AMS), N-(3-trimethoxysilylpropyl) diethylenetriamine (LAMS) and ionic liquid modified silica (ILMS) for the surface modification of silica nanoparticles. The extent of interfacial interaction between each of these silica nanoparticles with OPBI matrix was found to be in the order OPBI/AMS < OPBI/LAMS < OPBI/ILMS. The increased interaction from AMS to LAMS to ILMS manifests as stronger adhesion between the polymer and the nanofiller particles that reflects in three important properties i.e storage modulus, acid doping level and proton conductivity of the nanocomposite membranes. Using TEM microscopy we demonstrate the distinct morphological changes induced by the self-assembly of differently modified silica nanoparticles and correlate the morphological features to the observed properties. This systematic study represents a significant step towards predicting desired/undesired nanocomposite properties. [ABSTRACT FROM AUTHOR]

Although microbial fuel cells (MFCs) represent a promising bio-energy technology with a dual advantage (i.e., electricity production and waste-water treatment), their low power densities and high installation costs are major impediments. To address these bottlenecks and replace highly expensive Nafion, which is a proton exchange membrane (PEM), the current study focuses for the first time on membranes made from an easily synthesizable and more economical oxy-polybenzimidazole (OPBI) and its sulfonated analogue (S-OPBI) as alternate PEMs in single-chambered MFCs. The S-OPBI membrane exhibits better properties, with high water uptake, ion exchange capacity (IEC) and proton conductivity and a comparatively smaller degree of swelling compared to Nafion. The membrane morphology is characterized by atomic force microscopy, and the bright and dark regions of the S-OPBI membrane reveals the formation of ionic domains in the matrix, forming continuous water nanochannels when doped with water. These water-filled nanochannels are responsible for faster proton conduction in S-OPBI than in Nafion; therefore, the power output in the MFC with S-OPBI as the PEM is higher than in other MFCs. The open circuit voltage (460 mV), current generation (2.27 mA) and power density profile (110 mW/m 2 ) as a function of time, as well as the polarization curves, exhibits higher current and power density (87.8 mW/m 2 ) with S-OPBI compared to Nafion as the PEM. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is considered to be among the best biopolymer substitutes for the existing petroleum-based polymers in the field of food packaging owing to its renewability, biodegradability, non-toxicity and mechanical properties. However, PLA displays only moderate barrier properties to gases, vapors and organic compounds, which can limit its application as a packaging material. Hence, it becomes essential to understand the mass transport properties of PLA and address the transport challenges. Significant improvements in the barrier properties can be achieved by incorporating two-dimensional clay nanofillers, the planes of which create tortuosity to the diffusing molecules, thereby increasing the effective length of the diffusion path. This article reviews the literature on barrier properties of PLA/clay nanocomposites. The important PLA/clay nanocomposite preparation techniques, such as solution intercalation, melt processing and in situ polymerization, are outlined followed by an extensive account of barrier performance of nanocomposites drawn from the literature. Fundamentals of mass transport phenomena and the factors affecting mass transport are also presented. Furthermore, mathematical models that have been proposed/used to predict the permeability in polymer/clay nanocomposites are reviewed and the extent to which the models are validated in PLA/clay composites is discussed. [ABSTRACT FROM AUTHOR]