Efficient room temperature catalytic synthesis of alternating conjugated copolymers via C-S bond activation

Structural defects in conjugated copolymers are severely detrimental to the optoelectronic properties and the performance of the resulting electronic devices fabricated from them. Therefore, the much-desired precision synthesis of conjugated copolymers with highly regular repeat units is important, but presents a significant challenge to synthetic materials chemists. To this end, aryl sulfides are naturally abundant substances and offer unrealized potential in cross-coupling reactions. Here we report an efficient room temperature polycondensation protocol which implements aryl disulfide C-S activation to produce defect-minimized semiconducting conjugated copolymers with broad scope and applicability. Thus, a broad series of arylstannanes and thioethers are employed via the present protocol to afford copolymers with number-average molecular weights (Mns) of 10.0–45.0 kDa. MALDI and NMR analysis of selected copolymers reveals minimal structural defects. Moreover, the polymer trap density here is smaller and the field effect mobility higher than that in the analogous polymer synthesized through thermal-activation Stille coupling.

Bioinspired Self-Shaping Clay Composites for Sustainable Development

Bioinspired self-shaping is an approach used to transform flat materials into unusual three-dimensional (3D) shapes by tailoring the internal architecture of the flat material. Bioinspiration and bioinspired materials have a high potential for fostering sustainable development, yet are often fashioned out of expensive and synthetic materials. In this work, we use bioinspiration to endow clay with self-shaping properties upon drying. The composites created are based on clay and starch, and the internal architecture is built using celery fibers. The viscosity, shrinkage, and bending of the architected composite monolayers are studied for several compositions by measuring penetration depth and using optical characterization methods. Bilayer structures inspired from plants are then processed using a simple hand layup process to achieve bending, twisting, and combinations of those after drying. By layering a mixture of 32 vol% clay, 25.8 vol% starch, and 42.2 vol% water with 40 wt% embedded aligned celery fibers, it is possible to obtain the desired shape change. The work presented here aims at providing a simple method for teaching the concept of bioinspiration, and for creating new materials using only clay and plant-based ingredients. Rejuvenating clay with endowed self-shaping properties could further expand its use. Furthermore, the materials, methods, and principles presented here are affordable, simple, largely applicable, and could be used for sustainable development in the domain of education as well as materials and structures.

Mycelium Composites and their Biodegradability: An Exploration on the Disintegration of Mycelium-Based Materials in Soil

In the search for environmentally friendly materials, mycelium composites have been labelled as high potential bio-based alternatives to fossil-based and synthetic materials in various fields. Mycelium-based materials are praised for their biodegradability, however no scientific research nor standard protocols exist to substantiate this claim. This research therefore aims to develop an appropriate experimental methodology as well as to deliver a novel proof of concept of the material’s biodegradability. The applied methodology was adapted from a soil burial test under predefined laboratory conditions and hands-on preliminary experiments. The mycelium composite samples were placed in a nylon netting and then buried in potting soil with a grain size of 2 mm for different time-intervals ranging between one and sixteen weeks. Results showed that mycelium, which acted as the binder, had the tendency to decompose first. A weight loss of 43% was witnessed for inert samples made of the fungal strain Ganoderma resinaceum and hemp fibres after sixteen weeks. The disintegration rate in this method however depended on various parameters which were related to the material’s composition, its production method and the degradation process which involved the used equipment, materials and environmental properties.

Analysis of the Hybrid of Mudar/Snake Grass Fiber-Reinforced Epoxy with Nano-Silica Filler Composite for Structural Application

Natural fiber composite materials are competent materials that may replace conventional synthetic materials where the strength to weight ratio is essential. In this paper, the mechanical characteristics of composites made up of randomly oriented natural fibers (mudar fiber and snake grass fiber) with nano-silica filler are detailed for the first time. From the various literature surveys, the critical length of mudar and snake grass fiber is chosen as 40 mm and 30 mm, respectively. The test samples were prepared with a fiber content of 10%, 20%, 30%, and 40% with an equal amount of mudar and snake grass fiber. The percentage of nano-filler is maintained as constant as 3% with all the compositions. The composites showed that the highest mechanical properties were found at 30% fiber volume. The maximum tensile strength is 45 MPa, and the flexural strength is 51 MPa. The maximum impact strength is 4.5 J. Sample ID 3 provided the best results compared to other proportions. The fiber/matrix adhesion was investigated using a scanning electron microscope (SEM). These predominant mechanical properties make it easier for the implementation of the prepared composite material in structural and automotive applications.

Mucilage of Coccinia grandis as an Efficient Natural Polymer-Based Pharmaceutical Excipient

Natural eco-friendly materials are recently employed in products to replace synthetic materials due to their superior benefits in preserving the environment. The herb Coccinia grandis is widely distributed in continents like Asia and Africa and used traditionally to treat fever, leprosy, asthma, jaundice, and bronchitis. Mucilage of Coccinia grandis was accordingly extracted, isolated by a maceration technique, and precipitated. The mucilage was evaluated for its physicochemical, binding, and disintegrant properties in tablets using paracetamol as a model drug. The crucial physicochemical properties such as flow properties, solubility, swelling index, loss on drying, viscosity, pH, microbial load, cytotoxicity was evaluated and the compatibility was analyzed using sophisticated instrumental methods (TGA, DTA, DSC, and FTIR). The binding properties of the mucilage was used at three different concentrations and compared with starch and PVP as examples of standard binders. The disintegrant properties of mucilage were used at two different concentrations and compared with standard disintegrants MCCP, SSG, and CCS. The tablets were punched and evaluated for their hardness, friability, assay, disintegration time, in vitro dissolution profiles. In vitro cytotoxicity studies of the mucilage were performed in a human embryonic kidney (HEK) cell line. The outcome of the study indicated that the mucilage had good performance compared with starch and PVP. Further, the mucilage acts as a better disintegrant than MCCP, SSG and CCS for paracetamol tablets. Use of a concentration of 3% or less demonstrated the ability of the mucilage to act as a super disintegrating agent and showed faster disintegration and dissolution, which makes it as an attractive, promising disintegrant in formulating solid dosage forms to improve the therapeutic efficacy and patient compliance. Moreover, the in vitro cytotoxicity evaluation results demonstrated that the mucilage is non-cytotoxic to human cells and is safe.

A PROENVIRONMENTAL VALUE CONSTRUCT TO DEAL WITH PLASTIC POLLUTION

Plastics are man-made synthetic materials. They are made mostly from crude oil even though natural gas and coal could also be used for manufacturing plastics. The multiplicity of its uses together with its versatile properties has made it indispensable to modern living. The average life of plastics differs in various industrial sectors. The generation of waste depends on the mean-product lifetime of the product into which plastics have been integrated. And when this waste is not handled properly (recycled or incinerated under controlled environment), the problem of pollution emerges. Plastics in the form of microplastics have been found in food chains as well, threatening human wellbeing. A model to better understand the source - use and afteruse of plastics is the central focus of this article. It looks at the need for building a sustainable model to deal with plastic pollution.

Effect of Polycation Nanostructures on Cell Membrane Permeability and Toxicity

The interaction of nanometric synthetic materials with cell membranes is one of the key factors determining their possible cytotoxicity. This work investigated the interaction of polycation nanostructures with lipid and...

Panoramic insights into semi-artificial photosynthesis: origin, development, and future perspective

Semi-artificial photosynthetic system (SAPS) integrates the strengths of natural and artificial photosynthesis for solar energy conversion. Synthetic materials and biological components both play indispensable roles, where the former can be...

Ubim Fiber (Geonoma baculífera): A Less Known Brazilian Amazon Natural Fiber for Engineering Applications

The production of synthetic materials generally uses non-renewable forms of energy, which are highly polluting. This is driving the search for natural materials that offer properties similar to synthetic ones. In particular, the use of natural lignocellulosic fibers (NLFs) has been investigated since the end of 20th century, and is emerging strongly as an alternative to replace synthetic components and reinforce composite materials for engineering applications. NLFs stand out in general as they are biodegradable, non-polluting, have comparatively less CO2 emission and are more economically viable. Furthermore, they are lighter and cheaper than synthetic fibers, and are a possible replacement as composite reinforcement with similar mechanical properties. In the present work, a less known NLF from the Amazon region, the ubim fiber (Geonoma bacculifera), was for the first time physically characterized by X-ray diffraction (XRD). Fiber density was statistically analyzed by the Weibull method. Using both the geometric method and the Archimedes’ technique, it was found that ubim fiber has one of the lowest densities, 0.70–0.73 g/cm3, for NLFs already reported in the literature. Excluding the porosity, however, the absolute density measured by pycnometry was relatively higher. In addition, the crystallinity index, of 83%, microfibril angle, of 7.42–7.49°, and ubim fiber microstructure of lumen and channel pores were also characterized by scanning electron microscopy. These preliminary results indicate a promising application of ubim fiber as eco-friendly reinforcement of civil construction composite material.

Design and Analysis of a Novel Double-Stator Double-Rotor Motor Drive System for In-Wheel Direct Drive of Electric Vehicles

In-wheel direct drive (IWDD) of electric vehicles (EVs), which simplifies the transmission system and facilitates flexible control of vehicle dynamics, has evolved considerably in the EV sector. This paper proposes a novel double-stator double-rotor motor (DSDRM) with a bidirectional flux modulation effect for in-wheel direct drive of EVs. With the proposed special design, a synthetic-slot structure with synthetic materials containing copper and permanent magnets (PMs) in the slots of the motor is ingeniously employed, and the outer and inner rotors are mechanically connected together as a single rotor, making its mechanical structure less complicated than those of two-rotor machines. The main work of this paper involves the design, analysis, construction, and testing of the proposed machine. The DSDRM with a synthetic-slot structure was demonstrated to be feasible by finite element analysis (FEA), prototype fabrication, and experimental results. In addition, vehicle layout with DSDRM is presented and verified by the vehicle road test experiment. Thus, the DSDRM with the synthetic-slot structure can be used as a hub motor for in-wheel direct drive of EVs.