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Topic Review
Metal Complexes of the Porphyrin-Functionalized Polybenzoxazine
Porphyrin is a molecular material with many potential applications. New porphyrin-functionalized benzoxazine (Por-BZ) in high purity and yield was synthesized in this study based on 1H and 13C NMR and FTIR spectroscopic analyses through the reduction of Schiff base formed from tetrakis(4-aminophenyl)porphyrin (TAPP) and salicylaldehyde and the subsequent reaction with CH2O. Thermal properties of the product formed through ring-opening polymerization (ROP) of Por-BZ were measured using DSC, TGA and FTIR spectroscopy. Because of the rigid structure of the porphyrin moiety appended to the benzoxazine unit, the temperature required for ROP (314 °C) was higher than the typical Pa-type benzoxazine monomer (ca. 260 °C); furthermore, poly(Por-BZ) possessed a high thermal decomposition temperature (Td10 = 478 °C) and char yield (66 wt%) after thermal polymerization at 240 °C. An investigation of the thermal and luminescence properties of metal–porphyrin complexes revealed that the insertion of Ni and Zn ions decreased the thermal ROP temperatures of the Por-BZ/Ni and Por-BZ/Zn complexes significantly, to 241 and 231 °C, respectively. The metal ions acted as the effective promoter and catalyst for the thermal polymerization of the Por-BZ monomer, and also improved the thermal stabilities after thermal polymerization. 
  • 788
  • 24 Feb 2022
Topic Review
Membrane-Based Environmental Remediation
During the last century, industrialization has grown very fast and as a result heavy metals have contaminated many water sources. Due to their high toxicity, these pollutants are hazardous for humans, fish, and aquatic flora. Traditional techniques for their removal are adsorption, electro-dialysis, precipitation, and ion exchange, but they all present various drawbacks. Membrane technology represents an exciting alternative to the traditional ones characterized by high efficiency, low energy consumption and waste production, mild operating conditions, and easy scale-up. In this review, the attention has been focused on applying driven-pressure membrane processes for heavy metal removal, highlighting each of the positive and negative aspects. Advantages and disadvantages, and recent progress on the production of nanocomposite membranes and electrospun nanofiber membranes for the adsorption of heavy metal ions have also been reported and critically discussed. Finally, future prospective research activities and the key steps required to make their use effective on an industrial scale have been presented
  • 629
  • 02 Jul 2021
Topic Review
Membrane-Based Direct Air Capture Application
Direct air capture (DAC) is an emerging negative CO2 emission technology that aims to introduce a feasible method for CO2 capture from the atmosphere. Unlike carbon capture from point sources, which deals with flue gas at high CO2 concentrations, carbon capture directly from the atmosphere has proved difficult due to the low CO2 concentration in ambient air. Current DAC technologies mainly consider sorbent-based systems; however, membrane technology can be considered a promising DAC approach since it provides several advantages, e.g., lower energy and operational costs, less environmental footprint, and more potential for small-scale ubiquitous installations. Several recent advancements in validating the feasibility of highly permeable gas separation membrane fabrication and system design show that membrane-based direct air capture (m-DAC) could be a complementary approach to sorbent-based DAC, e.g., as part of a hybrid system design that incorporates other DAC technologies (e.g., solvent or sorbent-based DAC). 
  • 155
  • 05 Feb 2024
Topic Review
Membrane Fabrication Using Recycled Waste
Polymeric membranes are generally manufactured using a variety of monomers/polymers, including polystyrene, polysulfone (PSF), polyether sulfone (PES), polyaniline, polyvinylidene fluoride (PVDF), and others. The industrial manufacturing of these chemical compounds causes significant greenhouse gas emissions. In addition, the application of these monomer/polymer compounds in daily necessities has been posing a massive burden for their post-utilization disposal. The emergence of waste and its recycling potential has attracted attention to its application in membrane fabrication. The utilization of recycled waste for fabricating the membranes can help in reducing the environmental impact by 2× amount (i.e., eliminate the use of polymer for membrane fabrication and its associated environmental impact and mitigating the effect of waste on the environment via its utilization), thus helping in maintaining environmental sustainability.
  • 462
  • 19 Feb 2024
Topic Review
Mechanisms of Temperature-Responsive Polymer Brush Coatings
Modern biomedical technologies predict the application of materials and devices that not only can comply effectively with specific requirements, but also enable remote control of their functions. One of the most prospective materials for these advanced biomedical applications are materials based on temperature-responsive polymer brush coatings (TRPBCs). Despite progress in the development of such interesting materials, there are still some issues that need to be resolved, such as biocompatibility, high efficiency, selectivity of the action, stability, long-term and multiple-use, and the temperature of the transition close to physiological temperatures (appropriate transition temperature). The mechanisms of their temperature-induced reactions are one of the most crucial elements that affect the characteristics of temperature-sensitive grafted brush coatings. The TRPBCs exhibit the response to temperature governed by different mechanisms attributed to intermolecular interactions of the macromolecular chains between themselves and with the environment. The mechanism responsible for the temperature-dependent properties of polymer brushes is strongly dependent on the chemical nature of the macromolecular chains.
  • 506
  • 20 Oct 2022
Topic Review
Mechanism of Self-Healing Hydrogels
Polymeric hydrogels have drawn considerable attention as a biomedical material for their unique mechanical and chemical properties, which are very similar to natural tissues. Among the conventional hydrogel materials, self-healing hydrogels (SHH) are showing their promise in biomedical applications in tissue engineering, wound healing, and drug delivery. Additionally, their responses can be controlled via external stimuli (e.g., pH, temperature, pressure, or radiation). Identifying a suitable combination of viscous and elastic materials, lipophilicity and biocompatibility are crucial challenges in the development of SHH. Furthermore, the trade-off relation between the healing performance and the mechanical toughness also limits their real-time applications. Additionally, short-term and long-term effects of many SHH in the in vivo model are yet to be reported.
  • 1.0K
  • 09 Nov 2022
Topic Review
Mechanical Recycling of Thermoplastics
Plastic materials have gathered attention recently due to their omnipresence in the global economy. The transition towards a circular economy is the only way to prevent the environment from landfilling and incineration.
  • 311
  • 12 Oct 2023
Topic Review
Meat Packaging
The term ‘packaging’ refers to the technological intervention aimed at the protection of food from a variety of factors, which provokes the product detriment. Packaging is considered as one of the most interesting technological aspects and a constantly evolving issue in food production. 
  • 6.5K
  • 21 Jan 2021
Topic Review
Material Reactions, Degradation and Applications of Polyvinylidene Fluoride
Polyvinylidene fluoride (PVDF), the chemical formula is (C2H2F2)n. Its basic building blocks are therefore carbon, hydrogen, and fluorine. These three elements can form several crystalline chain conformations. Conformations are defined by polar and nonpolar phases. Four phases are most commonly found in the literature: α-, β-, γ-, and δ-. 
  • 564
  • 17 Oct 2022
Biography
Mahmoud A. Hussein
M.A. Hussein is a professor of Polymer Chemistry, Polymer Chemistry Lab, Chemistry Department, Faculty of Science, Assiut University (AU), Egypt. He obtained his PhD in Organic Polymer Synthesis from Assiut University, Egypt in 2007. He got a position at Chemistry Department, King Abdulaziz University (KAU), Jeddah, Saudi Arabia from 2010 – till now. He got a postdoctoral position in the Unive
  • 324
  • 13 Mar 2023
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