The stability of polymers against environmental factors, chemicals, microorganisms, and hydrolysis has challenged society with the accumulation of plastic waste and its management worldwide. Large ...amounts of plastic litter accumulate in the environment and disintegrate into microplastics (small pieces less than 5 mm in size), a topic of real concern especially for products and applications where the plastics are used for a short time before becoming waste, and where they are difficult to recover after use and remain in the environment. Whether biodegradable polymers can be one of the solutions to the problem of plastic waste is a question very often raised in this context. Although the use of biodegradable polymers appears to be highly promising based on recent and past studies, several aspects need to be considered further regarding environmental sustainability, acceptability, and degradability in the complex natural environment. Intensive efforts need to be invested in developing new environmentally biodegradable polymers and smart mechanisms of degradation after use in the environment. The present viewpoint article discusses the present scenario of the environmental acceptability of biodegradable polymers and the opportunities and challenges they offer regarding solving the problem of microplastics and their impact on the environment.
The opportunities and challenges of the environmental acceptability of biodegradable polymers from the point of view of solving the problem of microplastics (MPs) is discussed. Properly tested and precisely classified biodegradable polymers with complete biodegradation in a definite time matching to the application might be an opportunity for stepping toward an MP‐reduced environment.
This article highlights the progress in the field of radical ring-opening polymerization (RROP) of cyclic ketene acetals for the synthesis of functionalised polyesters, (bio)degradable vinyl ...polymers, and speciality designed degradable polymers. The method of radical ring-opening polymerization offers the advantage in either making special functional polyesters which are not possible by conventional methods or for making polyesters for special applications where low volume shrinkage is of utmost importance. Furthermore, the beauty of radical ring-opening polymerization is in making a new class of degradable materials called poly(vinyl-
co
-ester)s. Having ester linkages distributed onto the vinyl polymer backbone is emphasised, no other method can combine vinyl polymer backbone with ester units in a random way. The method has opened new opportunities of using the known biomaterials for degradable applications. Other possibilities and challenges in using this method are making specialised degradable materials like ionomers and polymeric-inorganic hybrid materials, which are also discussed in detail.
This article highlights the progress in the field of radical ring-opening polymerization (RROP) of cyclic ketene acetals for the synthesis of functionalised polyesters, (bio)degradable vinyl polymers, and speciality designed degradable polymers.
Low‐density macroporous sponges with densities less than 100 mg cm−3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation ...of the sponges with property combinations that lead to novel applications. Bottom‐up and top‐down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed.
Less is more: Low‐density macroporous sponges made of carbon or polymer materials offer an opportunity for advanced chemistry and materials science. The light weight, sustainability, breathability, special wetting characteristics, high mass transfer, mechanical stability, and large pore volumes of these materials suggest they may be “perfect” sponges. This Review critically addresses the status of the field along with opportunities and future directions.
Electrospinning Wendorff, Joachim H; Agarwal, Seema; Greiner, Andreas
2012, 2012-02-08, 2012-02-01, c2012
eBook
Electrospinning is from the academic as well as technical perspective presently the most versatile technique for the preparation of continuous nanofi bers obtained from numerous materials including ...polymers, metals, and ceramics. Shapes and properties of fi bers can be tailored according to the demand of numerous applications including filtration, membranes, textiles, catalysis, reinforcement, or biomedicals. This book summarizes the state-of-the art in electrospinning with detailed coverage of the various techniques, material systems and their resulting fi ber structures and properties, theoretical aspects and applications. Throughout the book, the current status of knowledge is introduced with a critical view on accomplishments and novel perspectives. An experimental section gives hands-on guidance to beginners and experts alike.
About a decade ago electrospinning was primarily concerned with the preparation of nanofibers from synthetic polymers and to a lower degree from natural polymers targeting predominantly technical ...applications areas such as textiles and filters as well as medical areas such as tissue engineering and drug delivery. Since then strong progress has been made not only in the understanding and theoretical modeling of the complex processes governing electrospinning and in the strict control of fiber formation by material and operating parameters but also in the design of a broad range of technical spinning devices. These achievements have in turn allowed for an extension of electrospinning towards fiber formation based not only on polymers – of synthetic, biological nature – but also on metals, metal oxides, ceramics, organic/organic, organic/inorganic as well as inorganic/inorganic composite systems. Here not only preparation schemes were investigated but properties and functions of the nanofibers were analyzed and potential applications were evaluated. As far as technical applications are concerned nanofibers composed of such materials can today be designed in a highly controlled way to display specific structural features. They include phase morphology and surface topology as well as unique functions including in particular magnetic, optical, electronic, sensoric, catalytic functions specific for one-dimensional architectures. Significant developments have also been achieved towards the exploitation of such functional nanofibers in applications involving among others fuel cells, lithium ion batteries, solar cell, electronic sensors as well as photocatalysts. One major target is currently the incorporation of such functional nanofibers in micrometer-sized electronic devices or even the construction of such devices purely from nanofibers.
The electrospinning technique provides non-wovens to the order of few nanometers with large surface areas, ease of functionalisation for various purposes and superior mechanical properties. Also, the ...possibility of large scale productions combined with the simplicity of the process makes this technique very attractive for many different applications. Biomedical field is one of the important application areas among others utilising the technique of electrospinning like filtration and protective material, electrical and optical applications, sensors, nanofiber reinforced composites etc. Electrospinning assembly can be modified in different ways for combining materials properties with different morphological structures for these applications. The importance of electrospinning, in general, for biomedical applications like tissue engineering drug release, wound dressing, enzyme immobilization etc. is highlighted in this feature article. The focus is also on the types of materials that have been electrospun and the modifications that have been carried out in conventional electrospinning apparatus keeping in view the specific needs for various biomedical applications.
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Historically, it has been difficult to propagate cells in vitro that are derived directly from human tumors or healthy tissue. However, in vitro preclinical models are essential tools for both the ...study of basic cancer biology and the promotion of translational research, including drug discovery and drug target identification. This protocol describes conditional reprogramming (CR), which involves coculture of irradiated mouse fibroblast feeder cells with normal and tumor human epithelial cells in the presence of a Rho kinase inhibitor (Y-27632). CR cells can be used for various applications, including regenerative medicine, drug sensitivity testing, gene expression profiling and xenograft studies. The method requires a pathologist to differentiate healthy tissue from tumor tissue, and basic tissue culture skills. The protocol can be used with cells derived from both fresh and cryopreserved tissue samples. As approximately 1 million cells can be generated in 7 d, the technique is directly applicable to diagnostic and predictive medicine. Moreover, the epithelial cells can be propagated indefinitely in vitro, yet retain the capacity to become fully differentiated when placed into conditions that mimic their natural environment.
Electrospinning is an extremely promising method for the preparation of tissue engineering (TE) scaffolds. This technique provides nonwovens resembling in their fibrillar structures those of the ...extracellular matrix (ECM), and offering large surface areas, ease of functionalization for various purposes, and controllable mechanical properties. The recent developments toward large‐scale productions combined with the simplicity of the process render this technique very attractive. Progress concerning the use of electrospinning for TE applications has advanced impressively. Different groups have tackled the problem of electrospinning for TE applications from different angles. Nowadays, electrospinning of the majority of biodegradable and biocompatible polymers, either synthetic or natural, for TE applications is straightforward. Different issues, such as cell penetration, incorporation of growth and differentiating factors, toxicity of solvents used, productivity, functional gradient, etc. are main points of current considerations. The progress in the use of electrospinning for TE applications is highlighted in this article with focus on major problems encountered and on various solutions available until now.
Progress concerning the use of electrospinning for TE applications has advanced impressively. Different issues such as cell penetration, incorporation of growth and differentiating factors, toxicity of solvents used, productivity, functional gradient, etc. are main points of current considerations, and are discussed here in addition to progress in this field.
The stability of polymers with CC and stable Cheteroatom backbones against chemicals, hydrolysis, temperature, light, and microbes has challenged society with the problem of accumulation of plastic ...waste and its management worldwide. Given careless disposal of plastic waste, large amounts of plastic litter accumulate in the environment and disintegrate into microplastics. One of the questions frequently raised in the recent times is if so‐called biodegradable polymers can substitute conventional polymers for several applications and help to tackle this challenge. The answer is not so simple as biodegradability is a certified property occurring only under certain environmental conditions and therefore requires systematic study. As a first step, this study focusses on comparative degradation studies of six polymers (five taken from the so‐called biodegradable polyesters, including poly(lactic‐co‐glycolic acid) (PLGA), polycaprolactone (PCL), polylactic acid (PLA), poly(3‐hydroxybutyrate) (PHB), Ecoflex, and one well‐known non‐degradable polymer poly(ethylene terephthalate) (PET) in artificial seawater and freshwater under controlled conditions for 1 year. Only amorphous PLGA shows 100% degradation as determined by weight loss, change in molar mass with time, NMR, electron microscopy, and high‐performance liquid chromatography. This is a step forward in understanding the degradability of polyesters required for the design of environmentally friendly novel polymers for future use.
A comparative study regarding degradability of so‐called biodegradable polymers in the seawater and freshwater under controlled conditions shows only poly(lactic‐co‐glycolic acid) as a degradable polymer. It degrades 100% in ≈270 d, whereas polycaprolactone, polylactic acid, and Ecoflex do not indicate any change. Bacterial polyester poly(3‐hydroxybutyrate) shows ≈8% degradation by surface erosion in 1 year.
The separator is an important component for energy storage devices. At present, the membranes for supercapacitors are rare, especially the ones that work with an alkaline electrolyte. Herein, a type ...of flexible and highly porous polymer hybrid nanofiber membrane was prepared via a facile electrospinning process and served as a separator for supercapacitor’s work with strong alkaline electrolyte. As obtained, polypoly(2,5-benzophenone)bibenzopyrrolone/polyimide (PBPY/PI) membrane showed good thermal stability, high mechanical strength, large electrolyte uptake (452%), and fast ion conductivity (0.68 mS/cm). Moreover, PBPY/PI membrane exhibited excellent alkali resistance. The supercapacitor assembled with PBPY/PI membrane showed much better performance than those assembled with a commercial polypropylene membrane and electrospun polyimide nanofiber membrane and was found without capacitance loss after charge/discharge at 30 A/g for 10,000 cycles at 80 °C. The PBPY/PI membrane is a good candidate with temperature resistance and alkali resistance for high-performance supercapacitors.
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