scholarly journals Dynamic covalent chemistry in polymer networks: a mechanistic perspective

2019 ◽  
Vol 10 (45) ◽  
pp. 6091-6108 ◽  
Author(s):  
Johan M. Winne ◽  
Ludwik Leibler ◽  
Filip E. Du Prez
Keyword(s):  
Physicochemical Properties ◽  
Reaction Mechanisms ◽  
Polymer Networks ◽  
Molecular Network ◽  
Polymer Materials ◽  
Dynamic Covalent Chemistry ◽  
Selection Of

A selection of dynamic chemistries is highlighted, with a focus on the reaction mechanisms of molecular network rearrangements, and on how mechanistic profiles can be related to the mechanical and physicochemical properties of polymer materials.

Light-Driven Integration of Graphitic Carbon Nitride into Polymer Materials

2021 ◽  
Vol 7 (1) ◽  
pp. 9
Author(s):  
Cansu Esen ◽  
Baris Kumru
Keyword(s):  
Visible Light ◽  
Carbon Nitride ◽  
Dye Degradation ◽  
Polymer Networks ◽  
Co2 Reduction ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Visible Range ◽  
Light Illumination ◽  
Present Contribution

As a metal-free polymeric semiconductor with an absorption in the visible range, carbon nitride has numerous advantages for photo-based applications spanning hydrogen evolution, CO2 reduction, ion transport, organic synthesis and organic dye degradation. The combination of g-C3N4 and polymer networks grants mutual benefit for both platforms, as networks are upgraded with photoactivity or formed by photoinitiation, and g-C3N4 is integrated into novel applications. In the present contribution, some of the recently published projects regarding g-C3N4 and polymeric materials will be highlighted. In the first study, organodispersible g-C3N4 were incorporated into a highly commercialized porous resin called poly(styrene-co-divinylbenzene) through suspension photopolymerization, and performances of resulting beads were investigated as recyclable photocatalysts. In the other study, g-C3N4 nanosheets were embedded in porous hydrogel networks, and so-formed hydrogels with photoactivity were transformed either into a ‘hydrophobic hydrogel’ or pore-patched materials via secondary network introduction, where both processes were accomplished via visible light. Since g-C3N4 is an organic semiconductor exhibiting sufficient charge separation under visible light illumination, a novel method for the oxidative photopolymerization of EDOT was successfully accomplished. As a result of the absence of dissolved anions during polymerization, so-formed neutral PEDOT is a highly viscous liquid that can be processed and post-doped easily, and grants facile coating processes.

Impact of dynamic covalent chemistry and precise linker length on crystallization kinetics and morphology in ethylene vitrimers

Soft Matter ◽  
2022 ◽  
Author(s):  
Bhaskar Soman ◽  
Yoo Kyung Go ◽  
Chengtian Shen ◽  
Cecilia Leal ◽  
Christopher M. Evans
Keyword(s):  
Crystal Structure ◽  
Melting Temperature ◽  
Crystallization Kinetics ◽  
Polymer Networks ◽  
Exchange Reactions ◽  
Dynamic Covalent Chemistry ◽  
Linker Length

Vitrimers, dynamic polymer networks with topology conserving exchange reactions, can lead to unusual evolution of the melting temperature and crystal structure of ethylene networks.

scholarly journals Selection of Polymer Materials for Micro Slide Bearings With Respect to Minimization of Resistance to Motion

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 78622-78629 ◽  
Author(s):  
Zbigniew Kusznierewicz ◽  
Marcin Michalowski ◽  
Sergiusz Luczak ◽  
Karol Baginski ◽  
Blazej Kabzinski ◽  
...  
Keyword(s):  
Polymer Materials ◽  
Selection Of

Ability to Control the Glass Transition Temperature of Amorphous Shape-Memory Polyesterurethane Networks by Varying Prepolymers in Molecular Mass as well as in Type and Content of Incorporated Comonomers

2009 ◽  
Vol 1190 ◽  
Author(s):  
Joerg Zotzmann ◽  
Steffen Kelch ◽  
Armin Alteheld ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Glass Transition ◽  
Minimally Invasive Surgery ◽  
Shape Memory ◽  
Molecular Mass ◽  
Amorphous Polymer ◽  
Polymer Networks ◽  
Precise Control ◽  
Low Weight ◽  
Switching Temperature ◽  
Selection Of

AbstractThe need of intelligent implant materials for applications in the area of minimally invasive surgery leads to tremendous attention for polymers which combine degradability and shape-memory capability. Application of heat, and thereby exceeding a certain switching temperature Tsw, causes the device to changes its shape. The precise control of Tsw is particularly challenging. It was investigated in how far Tg, that can be used as Tsw, of amorphous polymer networks from star-shaped polyester macrotetrols crosslinked with a low-weight linker can be controlled systematically by incorporation of different comonomers into poly(rac-lactide) prepolymers. The molecular mass of the prepolymers as well as type and content of the comonomers was varied. The Tg could be adjusted by selection of comonomer type and ratio without affecting the advantageous elastic properties of the polymer networks.

scholarly journals The use of bioceramic root canal sealers for obturation of the root canal system: A review

2021 ◽  
Vol 2 (1) ◽  
pp. 14-25
Author(s):  
Musliana Mustaffa
Keyword(s):  
Physicochemical Properties ◽  
Root Canal ◽  
Scientific Evidence ◽  
Filling Material ◽  
Flow Properties ◽  
Filling Materials ◽  
System A ◽  
Root Canal System ◽  
Root Canal Sealers ◽  
Selection Of

The use of bioceramic root canal sealers in endodontics is a promising approach because of the advantages such as improved flow properties, biocompatible and could promote the formation of hard tissue. Due to the recent technology and limited scientific evidence, the effectiveness of bioceramic root canal sealers remains unclear. This article focuses on the physicochemical properties, biocompatibility, biomineralisation, retreatability, 3D obturation and current practice of using bioceramic root canal sealers. The relevant articles for this review were searched manually from Google Scholar and PubMed using keywords ‘bioceramic root filling material AND endodontics’, ‘bioceramic root canal sealers AND endodontics’, ‘cytotoxicity AND bioceramic root canal sealers’, ‘bioceramic root canal sealers AND physicochemical properties’, ‘biomineralisation AND bioceramic root canal sealers’ and ‘retreatment efficacy AND bioceramic root filling materials’. Since the clinical data concerning the obturation with bioceramic root canal sealers is lacking, the selection of materials should be made based on the available scientific evidence, individual cases, material availability and operator’s preference.

scholarly journals The use of polymer materials for medical applications

2020 ◽  
pp. 5-13
Author(s):  
D. M. Los' ◽  
V. M. Shapovalov ◽  
S. V. Zotov
Keyword(s):  
Cardiac Surgery ◽  
Medical Devices ◽  
Metabolic Pathways ◽  
Living Organism ◽  
Polymer Materials ◽  
Medical Applications ◽  
Allergic Reactions ◽  
Important Criterion ◽  
Practical Medicine ◽  
Selection Of

The article analyzes the use of polymer materials for solving problems of theoretical and practical medicine. The effectiveness of the use of polymers in reconstructive cardiac surgery, radiation therapy, etc. has been shown. The basic requirements set for polymers and composites for medical devices have been identified. The most important criterion for the selection of polymers is the safety of their use in clinical practice and their ability to biodegrade when they enter a living organism along the usual metabolic pathways in the absence of inflammatory and allergic reactions of surrounding tissues during longterm followup care.

scholarly journals Selection of structural elements of cross-linked polymers used in construction

Vestnik MGSU ◽  
2021 ◽  
pp. 347-359
Author(s):  
Andrey A. Askadskii ◽  
Sergey V. Matseevich ◽  
Tat’yana A. Matseevich
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Computer Program ◽  
Water Permeability ◽  
Polymer Network ◽  
Polymer Networks ◽  
Physical Characteristics ◽  
Network Polymers ◽  
Optical Coefficient ◽  
Selection Of

Introduction. For the first time, a model and a principle for constructing an appropriate computer program for the selection of polymer networks with a given interval of a number of physical characteristics are proposed. These characteristics include density, the temperature of the onset of intense thermal degradation, thermal conductivity, water permeability, and the stress-optical coefficient. As an example, 16 smallest base fragments are given, which, when attached to each other, allow the selection of structural fragments of repeating fragments of polymers of the following classes: polyolefins, vinyl polymers, polystyrene, polyamides, polyethers and polyesters, polycarbonates, polyetherketones, polyimides, polysulfides, polysulfones, silicone polymers, polyurethanes, cellulose derivatives, methacrylic polymers, etc. The purpose of the study is to develop a model for writing a computer program that allows the selection of structural fragments of network polymers possessing specified intervals of physical characteristics. For polymers used in the construction industry, the most important are the glass transition temperature, the stress-optical coefficient, density, water permeability, and thermal conductivity. Materials and methods. A repeating fragment of the network is selected from the smallest basic fragments, which are connected to each other using a control matrix of interactions. The matrix contains labels that allow you to control the interaction of carbon with three carbon atoms, with a carbon atom and two nitrogen atoms, with two carbon atoms and one oxygen atom, with two carbon atoms and one nitrogen atom, with four carbon atoms. There are also labels that control the interaction of carbon atoms included in the aromatic cycles with two carbon atoms and one oxygen atom, with four carbon atoms, with four nitrogen atoms, with two carbon atoms and one sulfur atom, and three oxygen atoms. This makes it possible to select a huge amount of cross-linked polymer. Results. As an example, the possible chemical structure of 14 cross-linked nodes of the polymer network is presented and the corresponding calculations are carried out, showing the adequacy of the model and the principle of constructing a computer program. The structures of the five cross-linked nodes of polymer network were used and the following physical characteristics of the resulting networks were calculated: density, the temperature of the onset of intense thermal degradation, water permeability, thermal conductivity, and the stress-optical coefficient. All these characteristics are important for the manufacture of building materials. Conclusions. The results of the work allow us to write a real computer program for the selection of repeating fragments of polymer networks that have a given interval of a number of important physical characteristics of network polymers. Among these characteristics are not only those listed above, but also other characteristics, such as glass transition temperature, Hildebrand solubility parameter, surface energy, heat capacity, intermolecular interaction energy, permittivity, etc.

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