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Topic Review
Heterogeneous Catalysts Based on Hypercrosslinked Polystyreneand
Platform chemicals, also known as chemical building blocks, are substances that serve as starting materials for the synthesis of various value-added products, which find a wide range of applications. These chemicals are the key ingredients for many fine and specialty chemicals. Most of the transformations of platform chemicals are catalytic processes, which should meet the requirements of sustainable chemistry: to be not toxic for humans, to be safe for the environment, and to allow multiple reuses of catalytic materials. Hypercrosslinked polymers are already widely applied in industry as excellent (ad)sorbents. Their use for the synthesis of heterogeneous catalysts is a relatively new but dynamically developing area. A new class of heterogeneous catalysts based on nanoparticles of catalytically active metals stabilized in a polymer matrix of hypercrosslinked polystyrene (HPS) are provided, their synthesis, properties, and application to produce several platform chemicals from renewable raw materials. Some transformations of platform chemicals into compounds with high added value are addressed and multiple perspectives are discussed.
  • 189
  • 03 Jan 2024
Topic Review
HCN-Derived Polymers
HCN-derived polymers are a heterogeneous group of complex substances synthesized from pure HCN; from its salts; from its oligomers, specifically its trimer and tetramer, aminomalononitrile (AMN) and diaminomaleonitrile (DAMN), respectively; or from its hydrolysis products, such as formamide, under a wide range of experimental conditions. The characteristics and properties of HCN-derived polymers depend directly on the synthetic conditions used for their production and, by extension, their potential applications. These puzzling systems have been known mainly in the fields of prebiotic chemistry and in studies on the origins of life and astrobiology since the first prebiotic production of adenine by Oró in the early years of the 1960s. However, the first reference regarding their possible role in prebiotic chemistry was mentioned in the 19th century by Pflüger. Currently, HCN-derived polymers are considered keys in the formation of the first and primeval protometabolic and informational systems, and they may be among the most readily formed organic macromolecules in the solar system. In addition, HCN-derived polymers have attracted a growing interest in materials science due to their potential biomedical applications as coatings and adhesives; they have also been proposed as valuable models for multifunctional materials with emergent properties such as semiconductivity, ferroelectricity, catalysis and photocatalysis, and heterogeneous organo-synthesis. However, the real structures and the formation pathways of these fascinating substances have not yet been fully elucidated. Several models based on either computational approaches or spectroscopic and analytical techniques have endeavored to shed light on their complete nature.
  • 1.5K
  • 29 Apr 2021
Topic Review
Graphene-Based Nanocomposites
Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a two-dimensional honeycomb lattice. Carbon atoms are bonded with a covalent sp2bond with a single free electron, which accounts for the conductivity of graphene. Graphene is attracting great interests from the physical, chemical, and biomedical fields as a novel nanomaterial with exceptional physical properties, including extremely high thermal conductivity, excellent electrical conductivity, high surface-to-volume ratio, remarkable mechanical strength, and biocompatibility.
  • 873
  • 27 Jan 2022
Topic Review
Graphene Sensors
Graphene is one of the most promising materials for gas-sensor applications.
  • 549
  • 07 Apr 2021
Topic Review
Glass–fibre–reinforced Polymer
Wind barrier structures are usually installed on railway bridges to reduce wind effects on travelling trains for safety considerations. This however adversely transfers wind loads and causes associated aerodynamic effects to the bridge. An innovative concept of wind barriers using glass fibre reinforced polymer (GFRP) composites is proposed in this work with experimental investigations and numerical modelling. This work provides a solution to mitigate the wind and associated aerodynamic loads. With an appropriate design of bending stiffness, the proposed barriers may deform adaptively in strong wind scenarios and let the wind to pass through their deformed shape and therefore transfer less load to the bridge. Wind-tunnel experiments and numerical studies are conducted on the aerodynamic responses of the train-barrier-bridge system under crosswind with various speeds. The influences of barrier height, air-flow speed and location of the train on the aerodynamic responses of the system were clarified. Both reduced-scale and full-scale finite element models were established for the train-barrier-bridge system and the results were validated with the experimental results to further support the research findings.
  • 573
  • 22 Oct 2020
Topic Review
General Synthesis Methods of Poly (ε-caprolactone)-Based Graft Copolymers
Synthetic biopolymers are attractive alternatives to biobased polymers, especially because they rarely induce an immune response in a living organism. Poly ε-caprolactone (PCL) is a well-known synthetic aliphatic polyester universally used for many applications, including biomedical and environmental ones.  To expand the range of applications for PCL, researchers have investigated the possibility of grafting polymer chains onto the PCL backbone. As the PCL backbone is not functionalized, it must be first functionalized in order to be able to graft reactive groups onto the PCL chain. These reactive groups will then allow the grafting of new reagents and especially new polymer chains. Grafting of polymer chains is mainly carried out by “grafting from” or “grafting onto” methods.
  • 561
  • 29 Nov 2022
Topic Review
General Characteristics of Chitosan
Chitosan is a naturally occurring compound that can be obtained from deacetylated chitin, which is obtained from various sources such as fungi, crustaceans, and insects. Commercially, chitosan is produced from crustaceans. Based on the range of its molecular weight, chitosan can be classified into three different types, namely, high molecular weight chitosan (HMWC, >700 kDa), medium molecular weight chitosan (MMWC, 150–700 kDa), and low molecular weight chitosan (LMWC, less than 150 kDa).
  • 342
  • 14 Jul 2023
Topic Review
Gelatin-Based Hybrid Scaffolds
Gelatin is a biopolymer with interesting properties that have greatly attracted the attention of many biomedical researchers, such as low antigenicity, good biodegradability, and biocompatibility in the physiological environment. The gelatin-based materials offer excellent characteristics of wound dressings. The fast degradation time and highly hydrophilic surface make gelatin inappropriate as a base material for the development of wound dressings.
  • 686
  • 08 Sep 2021
Topic Review
Furane-Based Photoinitiators of Polymerization
Photopolymerization is an active research field enabling to polymerize in greener conditions than that performed with traditional thermal polymerization. A great deal of effort is devoted to developing visible light photoinitiating systems. Indeed, the traditional UV (Ultra Violet) photoinitiating systems are currently the focus of numerous safety concerns so alternatives to UV light are being actively researched. However, visible light photons are less energetic than UV photons so the reactivity of the photoinitiating systems should be improved to address this issue. In this field, furane constitutes an interesting candidate for the design of photocatalysts of polymerization due to its low cost and its easy chemical modification.
  • 403
  • 09 Mar 2023
Topic Review
Fundamental Concepts of Hydrogels
Hydrogels are three-dimensional crosslinked porous networks and can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical and hybrid bonding. The bonding is formed via different routes such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties such as mechanical strength, flexibility, biocompatibility, biodegradability, swellability, and stimuli sensitivity. Furthermore, owing to the smart and aqueous medium, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability, hydrogels can be potentially used in biomedical, electrochemical, sensors, contact lens, and soft robotic applications.
  • 2.1K
  • 03 Dec 2020
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