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Topic Review
Plasticized Polyvinyl Chloride
Plasticized polyvinyl chloride (p-PVC)—widely present in modern and contemporary art collections as objects, clothing and footwear, furniture and upholstery, and housewares and toys—is known to deteriorate very rapidly in museum collections. The tendency of colorless p-PVC-based objects to yellowing-browning in combination with stickiness and cracking are the main issues of this important plastic material, which require the attention of conservation scientists in cooperation with conservators, engineers, curators, and art historians.
  • 1.8K
  • 19 Dec 2023
Topic Review
Constituents of a Free Radical UV Curing System
The essential constituents of a UV curing system are a resin, which is an oligomer whose backbone confers the properties to the final polymer; a monomer, which acts as a cross-linking agent and adjusts the viscosity of the mixture to an acceptable level for application; and a photoinitiator, which is responsible for the light absorbance and governs the curing depth and rate.
  • 1.8K
  • 21 Jul 2022
Topic Review
Corroles and Hexaphyrins
Recent developments in the synthesis of corroles and hexaphyrins are reviewed, highlighting their potential application in photodynamic therapy.
  • 1.8K
  • 24 Aug 2020
Topic Review
Alginate-Based Biomaterials
Alginates are naturally occurring polysaccharides extracted from brown marine algae and bacteria. Being biocompatible, biodegradable, non-toxic and easy to gel, alginates can be processed into various forms, such as hydrogels, microspheres, fibers and sponges, and have been widely applied in biomedical field.
  • 1.8K
  • 31 May 2021
Topic Review
Functional Polymer Materials for Energy Applications
This entry provides insight into the recent energy applications of polymers.
  • 1.8K
  • 15 Dec 2021
Topic Review
Synthesis of Hydrogels
Hydrogels are polymeric materials with a characteristic hydrophilic structure that enables the storage of large amounts of water and biological fluids in their three-dimensional (3D) network. For hydrogel synthesis, the incorporation of a cross-linking agent is important to achieve a better structuring due to its ability to form new polymeric chains within the structure through a large variety of reactions between different polymeric molecules or fibrous proteins.
  • 1.8K
  • 16 Aug 2022
Topic Review
Vitamin E
Vitamin E is a common compound used for tocopherols and tocotrienols (α, β, γ, δ); it is the component of many natural products of both plant and animal origin. 
  • 1.8K
  • 12 Jul 2021
Topic Review
Applications of Flexible Strain Sensors
Based on the ingenious design and distinguished performance of the reported flexible strain sensors, there are a great deal of applications that have been demonstrated for various occasions. The in vitro detections for human health and implantable in vivo devices for biomedical engineering, as well as human-machine interface and soft robotics applications are reviewed. 
  • 1.8K
  • 11 May 2021
Topic Review
Substrate
In chemistry, a substrate is typically the chemical species being observed in a chemical reaction, which reacts with a reagent to generate a product. It can also refer to a surface on which other chemical reactions are performed, or play a supporting role in a variety of spectroscopic and microscopic techniques. In synthetic and organic chemistry, the substrate is the chemical of interest that is being modified. In biochemistry, an enzyme substrate is the material upon which an enzyme acts. When referring to Le Chatelier's principle, the substrate is the reagent whose concentration is changed. The term substrate is highly context-dependent.
  • 1.8K
  • 06 Oct 2022
Topic Review
Eugenol-based O/W Emulsion by Low-energy Emulsification
Emulsions are systems formed by two immiscible liquids, one of which is dispersed in the other as droplets with a relative stability. These have multiple applications, among them, in the formulation of pharmaceutical and cosmetic products. Its preparation requires generating a large interfacial area, which is usually attained by using the physicochemical formulation know-how on surfactant-oil-water (SOW) systems. Among the applications in the pharmaceutical industry, topical creams, and emulsions for intravenous and for oral administration can be found.  Eugenol can be extracted from cloves (Syzygium aromaticum) by various methods, including steam distillation, hydrodistillation and Soxhlet extraction. Furthermore, emulsions based on eugenol can be obtained for a variety of applications, including as topical and oral anesthetic. Nanoemulsions can be formulated with a mixture of non-ionic surfactants Span 20/Tween 80 at an HLB of 11 to 13 and a total surfactant concentration of 4%, using the dilution phase transition method (so-called spontaneous emulsification) to attain stable O/W eugenol-based emulsions. Paraffin oil/eugenol ratio of 4/1 can be used to reach a final emulsion internal oil phase content of 10% with 4% surfactant and 86% aqueous phase. Different polymers are used as viscosifiers, including carboxymethylcellulose. Under these conditions, eugenol-based emulsions with an average droplet size of less than 2 μm can be attained, with topical and oral anesthetic characteristics.
  • 1.8K
  • 03 Apr 2022
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