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Topic Review
The Assembly of PPTA Nanofibers and the Applications
Poly (p-phenylene terephthalamide) (PPTA) is one kind of lyotropic liquid crystal polymer. Kevlar fibers made from PPTA is widely used in many fields due to the superior mechanical properties resulted from highly oriented macromolecular structure. However, the “infusible and insoluble” characteristic of PPTA gives rise to its poor processability, which limits its scope of application. The strong interactions and orientation characteristic of aromatic amide segments make PPTA attractive in the field of self-assembly. The chemical derivations have proved an effective way to modify the molecular structure of PPTA to improve its solubility and amphiphilicity, which resulted in different liquid crystal behaviors or supramolecular aggregates, but the modification of PPTA is usually complex and difficult. Alternatively, higher order all-PPTA structures have also been realized through the controllable hierarchical self-assembly of PPTA from the polymerization process to the formation of macroscopic products. It briefly introduces the self-assembly methods of PPTA based materials in recent years, and focuses on the polymerization-induced PPTA nanofibers which can be further fabricated into different macroscopic architectures when other self-assembly methods are combined. This monomer-started hierarchical self-assembly strategy evokes the feasible processing of PPTA, and enriches the diversity of product, which is expected to be expanded to other liquid crystal polymers.
  • 696
  • 20 Jul 2022
Topic Review
Polyurea for Blast and Impact Protection
Polyurea has attracted extensive attention from researchers and engineers in the field of blast and impact protection due to its excellent quasi-static mechanical properties and dynamic mechanical properties. Its mechanical properties and energy absorption capacity have been tuned by means of formulation optimization, molecular dynamics (MD) simulation and the addition of reinforcing materials. Owing to the special molecular structure of polyurea, the mechanism of polyurea protection against blasts and impacts is the simultaneous effect of multiple properties. For different substrates and structures, polyurea needs to provide different performance characteristics, including adhesion, hardness, breaking elongation, etc., depending on the characteristics of the load to which it is subjected. 
  • 695
  • 11 Jul 2022
Topic Review
Single-Component Cationic Photoinitiators
With the advantages offered by cationic photopolymerization (CP) such as broad wavelength activation, tolerance to oxygen, low shrinkage and the possibility of “dark cure”, it has attracted extensive attention in photoresist, deep curing and other fields in recent years. The applied photoinitiating systems (PIS) play a crucial role as they can affect the speed and type of the polymerization and properties of the materials formed. Much effort has been invested into developing cationic photoinitiating systems (CPISs) that can be activated at long wavelengths and overcome technical problems and challenges faced. 
  • 695
  • 24 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.
  • 685
  • 08 Sep 2021
Topic Review
Antimicrobial Polymeric Structures
Certain natural and synthetic polymers are versatile materials that have already proved themselves to be highly suitable for the development of the next-generation of antimicrobial systems that can efficiently prevent and kill microbes in various environments.
  • 683
  • 28 May 2021
Topic Review
Chromophoric Dendrimer-Based Materials
Dendrimers (from the Greek dendros → tree; meros → part) are macromolecules with well-defined three-dimensional and tree-like structures. Remarkably, this hyperbranched architecture is one of the most ubiquitous, prolific, and recognizable natural patterns observed in nature. 
  • 682
  • 16 Jan 2022
Topic Review
Waste Plastics’ Liquefaction into Fuel Fraction
Polymers and plastics are crucial materials in many sectors of our economy, due to their numerous advantages. They also have some disadvantages, among the most important are problems with the recycling and disposal of used plastics. The recovery of waste plastics is increasing every year, but over 27% of plastics are landfilled. The rest is recycled, where, unfortunately, incineration is still the most common management method. From an economic perspective, waste management methods that lead to added-value products are most preferred—as in the case of material and chemical recycling. Since chemical recycling can be used for difficult wastes (poorly selected, contaminated), it seems to be the most effective way of managing these materials. Moreover, as a result this of kind of recycling, it is possible to obtain commercially valuable products, such as fractions for fuel composition and monomers for the reproduction of polymers. 
  • 671
  • 06 Dec 2022
Topic Review
Thermodynamic Aspects Governing Shape Memory Elastomers
Shape memory elastomers have revolutionised the world since their introduction in the 20th century. The ability to tailor chemical structures to produce a family of materials in wide-ranging forms with versatile properties has propelled them to be ubiquitous.
  • 668
  • 02 Sep 2022
Topic Review
Conducting Silicone-Based Polymers
Conducting polymers (CPs) are unique due to their ease of synthesis, environmental stability, and simple doping/dedoping chemistry. Electrically conductive silicone polymers are the current state-of-the-art for, e.g., optoelectronic materials. 
  • 667
  • 23 Apr 2021
Topic Review
Hybrid Materials Based on Polyhydroxyalkanoates
Polyhydroxyalkanoates (PHAs) constitute a family of biopolyesters that are synthesized and accumulate within the cellular structure of prokaryotic cells by bacteria, and they act as carbon and energy reserve materials under conditions of limited nutrient, such as nitrogen, oxygen, phosphorous or magnesium. As naturally derived materials, PHAs have been used for multiple cell and tissue engineering applications; however, their widespread biomedical applications are limited due to their lack of toughness, elasticity, hydrophilicity and bioactivity. To overcome this challenge combination of PHA with different polymers and inorganic materials are used to form hybrid composites with improved structural and functional properties.
  • 659
  • 07 Jun 2021
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