Bio-Polyethylene and Polyethylene Biocomposites: An Alternative toward a Sustainable Future.

Polyethylene (PE), a highly prevalent non-biodegradable polymer in the field of plastics, presents a waste management issue. To alleviate this issue, bio-based PE (bio-PE), derived from renewable resources like corn and sugarcane, offers an environmentally friendly alternative. This review discusses various production methods of bio-PE, including fermentation, gasification, and catalytic conversion of biomass. Interestingly, the bio-PE production volumes and market are expanding due to the growing environmental concerns and regulatory pressures. Additionally, the production of PE and bio-PE biocomposites using agricultural waste as filler materials, highlights the growing demand for sustainable alternatives to conventional plastics. According to previous studies, addition of ≈50% defibrillated corn and abaca fibers into bio-PE matrix and a compatibilizer, results in the highest Young's modulus of 4.61 and 5.81 GPa, respectively. These biocomposites have potential applications in automotive, building construction, and furniture industries. Moreover, the advancement made in abiotic and biotic degradation of PE and PE biocomposites is elucidated to address their environmental impacts. Finally, the paper concludes with insights into the opportunities, challenges, and future perspectives in the sustainable production and utilization of PE and bio-PE biocomposites. In summary, production of PE and bio-PE biocomposites can contribute to a cleaner and sustainable future.

Bio-Polypropylene and Polypropylene-based Biocomposites: Solutions for a Sustainable Future.

Polypropylene (PP) is among the most widely used commodity plastics in our everyday life due to its low cost, lightweight, easy processability, and exceptional chemical, thermo-mechanical characteristics. The growing awareness on energy and environmental crisis has driven global efforts for creating a circular economy via developing sustainable and eco-friendly alternatives to traditional plastics produced from fossil fuels for a variety of end-use applications. This review paper presents a brief outline of the emerging bio-based PP derived from renewable natural resources, covering its production routes, market analysis and potential utilizations. This contribution also provides a comprehensive review of the PP-based biocomposites produced with diverse green fillers generated from agro-industrial wastes, with particular emphasis on the structural modification, processing techniques, mechanical properties, and practical applications. Furthermore, given that the majority of PP products are currently destined for landfills, research progress on enhancing the degradation of PP and its biocomposites is also presented in light of the environmental concerns. Finally, a brief conclusion with discussions on challenges and future perspectives are provided.

Face Masks in the New COVID-19 Normal: Materials, Testing, and Perspectives.

The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health. Routes of transmission differ, but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse, while being amenable to prevention by the humble face mask. Different types of masks give different levels of protection to the user. The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them, driving individuals to self-produce masks from household items. At the same time, research has been accelerated towards improving the quality and performance of face masks, e.g., by introducing properties such as antimicrobial activity and superhydrophobicity. This review will cover mask-wearing from the public health perspective, the technical details of commercial and home-made masks, and recent advances in mask engineering, disinfection, and materials and discuss the sustainability of mask-wearing and mask production into the future.

pH-Responsive Poly(dimethylsiloxane) Copolymer Decorated Magnetic Nanoparticles for Remotely Controlled Oil-in-Water Nanoemulsion Separation.

A smart and recyclable oil absorber based on pH-responsive block copolymer modified magnetic nanoparticles is constructed for effective separation of oil-in-water emulsions. Superparamagnetic iron(III) oxide (Fe3 O4 ) nanoparticles are designed as the core materials for providing the separation force, and surface modification with poly(4-vinylpyridine-b-dimethyl siloxane-b-4-vinylpyridine) (P4VP-PDMS-P4VP) block copolymer is performed to supply switchable oil wettability. The mean hydrodynamic radius of the nanoparticles increases from 43.8 ± 3.6 to 75.2 ± 5.3 nm when the neutral pH is reduced to 3, due to the protonation and subsequent swelling of P4VP segments at lower pH. The nanoparticles show excellent separation performance and can absorb octadecene up to 78.2 times of their own weight, simply by switching the pH of the oil-in-water emulsion treated with the nanoparticles and using a magnetic field. The different dipole of P4VP-PDMS-P4VP and protonated P4VP-PDMS-P4VP, as confirmed by density functional theory calculations, is responsible for the different oil miscibility and wettability of the nanoparticles.

Biodegradable polyester shape memory polymers: Recent advances in design, material properties and applications.

Shape memory polymers (SMPs) is a class of well-studied smart materials with a variety of applications. In recent years, biodegradable polyester SMPs have received increasing attention from the research community both as academic interest and for their potential usefulness in biomedicine and soft robotics. In this contribution, the most recent progress in the area of biodegradable polyester-based SMPs is summarized with regards to their structural designs, thermomechanical properties, shape memory performance and some emerging characteristics, followed by a discussion on the specific applications of these SMPs in biomedicine and soft robotics. The prospective research direction for the future development of polyester SMPs as advanced functional materials is also discussed.

Towards the development of polycaprolactone based amphiphilic block copolymers: molecular design, self-assembly and biomedical applications.

Polycaprolactone (PCL) and its copolymers are a type of hydrophobic aliphatic polyester based on hydroxyalkanoic acids. They possess exceptional qualities: biocompatibility; FDA approval for clinical use; biodegradability by enzyme and hydrolysis under physiological conditions and low immunogenicity. These critical properties have facilitated their value as sutures, drug delivery vehicles and tissue engineering scaffolds in pharmaceutical and biomedical applications. However, the hydrophobicity of PCL and its copolymers remains a concern for further biological and biomedical applications. One promising approach is to design and synthesize well-controlled PCL-based amphiphilic block copolymers. This review summarizes recent advances in the synthesis and self-assembly of PCL-containing amphiphilic block copolymers and their bio-related applications including drug delivery and tissue engineering.