Topic Review
Electrical Resistance/Conductivity of CFRP
This entry provides a comprehensive basis for readers to grasp recent research progresses on electrical behaviors of Carbon fiber reinforced polymer (CFRP), which plays an important role in many fields, especially in aviation and civil industries. The electrical conductivity of CFRP is critical for its electrical behaviors, such as its lightning strike vulnerability, electromagnetic shielding ability, and potential uses for self-sensing. In addition, the electrical conductivity is related to the mechanical integrity. Therefore, electrical properties can be measured as an indication in the detection of delamination and other defects in CFRP. 
  • 1968
  • 01 Nov 2020
Topic Review
Hyaluronic Acid
Hyaluronic acid, as a natural linear polysaccharide, has attracted researchers’ attention from its initial detection and isolation from tissues in 1934 until the present day. Due to biocompatibility and a high biodegradation of hyaluronic acid, it finds wide application in bioengineering and biomedicine: from biorevitalizing skin cosmetics and endoprostheses of joint fluid to polymeric scaffolds and wound dressings. However, the main properties of aqueous polysaccharide solutions with different molecular weights are different. Moreover, the therapeutic effect of hyaluronic acid-based preparations directly depends on the molecular weight of the biopolymer. The present entry collects the information about hyaluronic acid and its original properties. Particular emphasis is placed on the structural, physical and physico-chemical properties of hyaluronic acid in water solutions, as well as their degradability.
  • 1619
  • 31 Aug 2020
Topic Review
Pyrolysis: Thermochemical decomposition of organic materials in the absence of oxygen. Polymer-derived carbon: Carbon obtained by heat-treatment (pyrolysis followed by carbon-carbon bond formation and rearrangement) of natural or synthetic polymers. In addition to the supplied heat, surrounding gaseous environment, presence of magnetic field and applied pressure influence pyrolysis.
  • 1612
  • 01 Nov 2020
Topic Review
Polyelectrolytes are polymers of oppositely charged ions and their properties differ profoundly than their repeating units. Over recent years, much advancement has been made in the synthesis, characterization, and application of polyelectrolytes and polyelectrolyte complexes (PECs). It has many applications as flocculation agents, dispersant agents, and as super-plasticizers. In this article, the synthesis, types, characteristics, and application of PECs mainly for drug delivery and dynamics study are reviewed.
  • 1518
  • 27 Oct 2020
Topic Review
Coordination Polymers
Coordination polymers are solid-state structures consisting of repeating coordination units extending in one, two or three dimensions. Fields applications of the coordination polymers in general and metal-organic frameworks in particular are briefly discussed.
  • 1477
  • 31 Jul 2020
Topic Review
Aggregation-Induced Emission and Fluorescent Mechanochromism
Mechanochromic fluorescent polymers are defined as materials that are able to detect a mechanical stress through a fluorescence output. This feature has evoked a growing interest in the last decades, thanks to the progress of fluorogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In this contribution, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from dierent types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress.
  • 1412
  • 30 Oct 2020
Topic Review
Microalgae/Cyanobacteria in Biodegradation of Plastics
Cyanobacteria (e.g., Synechocystis sp. PCC 6803, and Synechococcus elongatus PCC 7942), which are photosynthetic prokaryotes and were previously identified as blue-green algae, are currently under close attention for their abilities to capture solar energy and the greenhouse gas carbon dioxide for the production of high-value products. In the last few decades, these microorganisms have been exploited for different purposes (e.g., biofuels, antioxidants, fertilizers, and ‘superfood’ production). Microalgae (e.g., Chlamydomonas reinhardtii, and Phaeodactylum tricornutum) are also suitable for environmental and biotechnological applications based on the exploitation of solar light. In recent years, several studies have been targeting the utilization of microorganisms for plastic bioremediation. Among the different phyla, the employment of wild-type or engineered cyanobacteria may represent an interesting, environmentally friendly, and sustainable option (e.g., mismanaged plastics as source of carbons for their cultivation: the connection between their simultaneous utilization for biofuels or chemicals production and microplastics consumption on the surface of basins).
  • 1380
  • 05 Jan 2021
Topic Review
Citric Acid for Wood Modification
Citric acid (CA) can be found naturally in fruits and vegetables, particularly citrus fruit. CA is widely used in many fields but its usage as a green modifying agent and binder for wood is barely addressed. Esterification is one of the most common chemical reactions applied in wood modification. CA contains three carboxyl groups, making it possible to attain at least two esterification reactions that are required for crosslinking when reacting with the hydroxyl groups of the cell wall polymers. In addition, the reaction could form ester linkages to bring adhesivity and good bonding characteristics, and therefore CA could be used as wood binder too. The environmental impacts and future outlook of CA-treated wood and bonded composite are considered.
  • 1259
  • 31 Jul 2020
Topic Review
Covalent Adaptable Networks
Thermosets are known to be very reliable polymeric materials for high-performance and light-weight applications, due to their retained dimensional stability, chemical inertia and rigidity over a broad range of temperatures. However, once fully cured, they cannot be easily reshaped or reprocessed, thus leaving still unsolved the issues of recycling and the lack of technological flexibility. Vitrimers, introduced by Leibler et al. in 2011, are a valiant step in the direction of bridging the chasm between thermoplastics and thermosets. Owing to their dynamic covalent networks, they can retain mechanical stability and solvent resistance, but can also flow on demand upon heating. More generally, the family of Covalent Adaptable Networks (CANs) is gleaming with astounding potential, thanks to the huge variety of chemistries that may enable bond exchange. Arising from this signature feature, intriguing properties such as self-healing, recyclability and weldability may expand the horizons for thermosets in terms of improved life-span, sustainability and overall enhanced functionality and versatility. In this review, we present a comprehensive overview of the most promising studies featuring CANs and vitrimers specifically, with particular regard for their industrial applications. Investigations into composites and sustainable vitrimers from epoxy-based and elastomeric networks are covered in detail.
  • 1081
  • 26 Oct 2020
Topic Review
Porous Carbon
Porous carbons are an important class of porous materials that have grown rapidly in recent years. They have the advantages of a tunable pore structure, good physical and chemical stability, a variable specific surface, and the possibility of easy functionalization.   
  • 976
  • 29 Dec 2020
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