scholarly journals Self-Healing in Mobility-Restricted Conditions Maintaining Mechanical Robustness: Furan–Maleimide Diels–Alder Cycloadditions in Polymer Networks for Ambient Applications

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2543 ◽  
Author(s):  
Dorothee Ehrhardt ◽  
Jessica Mangialetto ◽  
Jolien Bertouille ◽  
Kurt Van Durme ◽  
Bruno Van Mele ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Network Formation ◽  
Polymer Networks ◽  
Mechanical Analysis ◽  
Diels Alder ◽  
Self Healing ◽  
Ambient Conditions ◽  
Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Cure Temperature

Two reversible polymer networks, based on Diels–Alder cycloadditions, are selected to discuss the opportunities of mobility-controlled self-healing in ambient conditions for which information is lacking in literature. The main methods for this study are (modulated temperature) differential scanning calorimetry, microcalorimetry, dynamic rheometry, dynamic mechanical analysis, and kinetic simulations. The reversible network 3M-3F630 is chosen to study the conceptual aspects of diffusion-controlled Diels–Alder reactions from 20 to 65 °C. Network formation by gelation is proven and above 30 °C gelled glasses are formed, while cure below 30 °C gives ungelled glasses. The slow progress of Diels–Alder reactions in mobility-restricted conditions is proven by the further increase of the system’s glass transition temperature by 24 °C beyond the cure temperature of 20 °C. These findings are employed in the reversible network 3M-F375PMA, which is UV-polymerized, starting from a Diels–Alder methacrylate pre-polymer. Self-healing of microcracks in diffusion-controlled conditions is demonstrated at 20 °C. De-gelation measurements show the structural integrity of both networks up to at least 150 °C. Moreover, mechanical robustness in 3M-F375PMA is maintained by the poly(methacrylate) chains to at least 120 °C. The self-healing capacity is simulated in an ambient temperature window between −40 and 85 °C, supporting its applicability as self-healing encapsulant in photovoltaics.

scholarly journals The Influence of the Furan and Maleimide Stoichiometry on the Thermoreversible Diels–Alder Network Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2522
Author(s):  
Ali Safaei ◽  
Seppe Terryn ◽  
Bram Vanderborght ◽  
Guy Van Assche ◽  
Joost Brancart
Keyword(s):  
Transition Temperature ◽  
Functional Groups ◽  
Polymer Networks ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Diels Alder ◽  
Stoichiometric Ratio ◽  
Self Healing ◽  
Scanning Calorimetry

In recent work, the thermoreversible Diels–Alder reaction between furan and maleimide functional groups has been studied extensively in the context of self-healing elastomers and thermosets. To elaborate the influence of the stoichiometric ratio between the maleimide and furan reactive groups on the thermomechanical properties and viscoelastic behavior of formed reversible covalent polymer networks, a series of Diels–Alder-based networks with different stoichiometric ratios was synthesized. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and dynamic rheology measurements were performed on the reversible polymer networks, to relate the reversible network structure to the material properties and reactivity. Such knowledge allows the design and optimization of the thermomechanical behavior of the reversible networks for intended applications. Lowering the maleimide-to-furan ratio creates a deficit of maleimide functional groups, resulting in a decrease in the crosslink density of the system, and a consequent decrease in the glass transition temperature, Young’s modulus, and gel transition temperature. The excess of unreacted furan in the system results in faster reaction and healing kinetics and a shift of the reaction equilibrium.

scholarly journals Influence of the Glass Transition Temperature and the Density of Crosslinking Groups on the Reversibility of Diels-Alder Polymer Networks

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1189
Author(s):  
Merlina Thiessen ◽  
Volker Abetz
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Radical Polymerization ◽  
Polymer Networks ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction

The interest in self-healing, recyclable, and adaptable polymers is growing. This work addresses the reversibility of crosslink formation based on Diels-Alder reaction in copolymer networks containing furfuryl and maleimide groups, which represent the “diene” and the “dienophile,” respectively. The copolymers are synthesized by atom transfer radical polymerization (ATRP) and free radical polymerization. The diene bearing copolymers are crosslinked either with a small molecule containing two dienophiles or with a dienophile bearing copolymer. The influence of the crosslinking temperature on the Diels-Alder reaction is analyzed. Furthermore, the influence of the glass transition temperature and the influence of the density of crosslinking groups on the thermo-reversibility of crosslinking are investigated by temperature dependent infrared spectroscopy and differential scanning calorimetry. It is shown that the reversibility of crosslinking is strongly influenced by the glass transition temperature of the system.

scholarly journals Electrically-Responsive Reversible Polyketone/MWCNT Network through Diels-Alder Chemistry

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1076 ◽  
Author(s):  
Rodrigo Araya-Hermosilla ◽  
Andrea Pucci ◽  
Patrizio Raffa ◽  
Dian Santosa ◽  
Paolo Pescarmona ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Polymer Networks ◽  
Conductive Polymer ◽  
Mechanical Analysis ◽  
Diels Alder ◽  
Resistive Heating ◽  
Compression Moulding ◽  
Electrically Conductive ◽  
The Matrix ◽  
Tan Δ

This study examines the preparation of electrically conductive polymer networks based on furan-functionalised polyketone (PK-Fu) doped with multi-walled carbon nanotubes (MWCNTs) and reversibly crosslinked with bis-maleimide (B-Ma) via Diels-Alder (DA) cycloaddition. Notably, the incorporation of 5 wt.% of MWCNTs results in an increased modulus of the material, and makes it thermally and electrically conductive. Analysis by X-ray photoelectron spectroscopy indicates that MWCNTs, due to their diene/dienophile character, covalently interact with the matrix via DA reaction, leading to effective interfacial adhesion between the components. Raman spectroscopy points to a more effective graphitic ordering of MWCNTs after reaction with PK-Fu and B-Ma. After crosslinking the obtained composite via the DA reaction, the softening point (tan(δ) in dynamic mechanical analysis measurements) increases up to 155 °C, as compared to the value of 130 °C for the PK-Fu crosslinked with B-Ma and that of 140 °C for the PK-Fu/B-Ma/MWCNT nanocomposite before resistive heating (responsible for crosslinking). After grinding the composite, compression moulding (150 °C/40 bar) activates the retro-DA process that disrupts the network, allowing it to be reshaped as a thermoplastic. A subsequent process of annealing via resistive heating demonstrates the possibility of reconnecting the decoupled DA linkages, thus providing the PK networks with the same thermal, mechanical, and electrical properties as the crosslinked pristine systems.

Preparation and properties of self-healing polyether amines based on Diels–Alder reversible covalent bonds

2018 ◽  
Vol 31 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Xiaofei Wang ◽  
Kaifeng Zhao ◽  
Xiaowen Huang ◽  
Xiaoyue Ma ◽  
Yanyan Wei
Keyword(s):  
Glycidyl Ether ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Diels Alder ◽  
Proton Nuclear Magnetic Resonance ◽  
Self Healing ◽  
Covalent Bonds ◽  
Reversible Covalent ◽  
Automotive Coating

Over time, automotive coating is bound to be damaged; therefore, it is necessary to give the coating a self-healing ability to make its performance even better. First, furfuryl glycidyl ether (FGE) was synthesized by epichlorohydrin and furfuryl alcohol. Then, furanyl-terminated resin FGE-T5000 was synthesized by polyether amine T5000 and FGE. Finally, 4,4′-diphenylmethane bismaleimide (BDM) was added to FGE-T5000 as a cross-linking agent to form a resin named FGE-T5000-BDM which has Diels–Alder (DA) bonds. The products were characterized by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, differential scanning calorimeter, dynamic mechanical analysis, thermogravimetric analysis, optical microscope, tensile tests, and other tests. The results showed that FGE-T5000-BDM demonstrated thermally reversible self-healing property from 50°C to 150°C, and that the best temperature of the DA reaction was 80°C. The gel content of FGE-T5000-BDM was 98%. Also, the glass transition temperature and the initial temperature of the Retro-DA (r-DA) reaction were −58°C and 88°C, respectively. Moreover, the self-healing efficiency of FGE-T5000-BDM was up to 88% after staying at 80°C for 12 h. The innovation shown in this article was that the reversible covalent bonds (DA) were combined with the polyether amines, which produced the characteristics of self-healing. Its unique self-healing properties are useful in some areas, such as automobile coatings and other materials.

scholarly journals Properties and structure of high temperature resistant cyanate ester/polyethersulfone blends using solvent-free toughening approach

2020 ◽  
Author(s):  
Lyaysan Amirova ◽  
Fabian Schadt ◽  
Markus Grob ◽  
Christian Brauner ◽  
Thomas Ricard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Network Formation ◽  
Mechanical Analysis ◽  
Solvent Free ◽  
Cyanate Ester ◽  
Low Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
The Difference

AbstractA high temperature resistant novolac cyanate ester was blended with polyethersulfone (PES) with different molecular weights using the solvent-free approach. The phase separation, curing behavior and thermal properties were studied using hot stage microscopy, differential scanning calorimetry and dynamic mechanical analysis. Results showed the difference in the morphology for blends with different molecular weight PES explained by possible network formation. The influence of PES content on the glass transition temperature and mechanical properties was investigated. The most significant toughening effect (increase of 132% in fracture toughness) was achieved on a functionalized low molecular weight PES (20 parts per hundred of resin, phr). Rheology investigation allowed to estimate the optimal content of PES (15 phr) for further prepreg manufacturing.

scholarly journals Crosslinking Kinetics of Methylcellulose Aqueous Solution and Its Potential as a Scaffold for Tissue Engineering

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1772 ◽  
Author(s):  
Beata Niemczyk-Soczynska ◽  
Arkadiusz Gradys ◽  
Dorota Kolbuk ◽  
Anna Krzton-Maziopa ◽  
Pawel Sajkiewicz
Keyword(s):  
Aqueous Solution ◽  
Tissue Engineering ◽  
Hydrophobic Interactions ◽  
Research Work ◽  
Mechanical Analysis ◽  
Biological Properties ◽  
Ambient Conditions ◽  
Scanning Calorimetry ◽  
Engineering Applications ◽  
Methoxy Groups

Thermosensitive, physically crosslinked injectable hydrogels are in the area of interests of various scientific fields. One of the representatives of this materials group is an aqueous solution of methylcellulose. At ambient conditions, methylcellulose (MC) is a sol while on heating up to 37 °C, MC undergoes physical crosslinking and transforms into a gel. Injectability at room temperature, and crosslinkability during subsequent heating to physiological temperature raises hopes, especially for tissue engineering applications. This research work aimed at studying crosslinking kinetics, thermal, viscoelastic, and biological properties of MC aqueous solution in a broad range of MC concentrations. It was evidenced by Differential Scanning Calorimetry (DSC) that crosslinking of MC is a reversible two-stage process, manifested by the appearance of two endothermic effects, related to the destruction of water cages around methoxy groups, followed by crosslinking via the formation of hydrophobic interactions between methoxy groups in the polymeric chains. The DSC results also allowed the determination of MC crosslinking kinetics. Complementary measurements of MC crosslinking kinetics performed by dynamic mechanical analysis (DMA) provided information on the final storage modulus, which was important from the perspective of tissue engineering applications. Cytotoxicity tests were performed using mouse fibroblasts and showed that MC at low concentration did not cause cytotoxicity. All these efforts allowed to assess MC hydrogel relevance for tissue engineering applications.

Catalyst-Free Room-Temperature Self-Healing Polymer Networks Based on Dynamic Covalent Quinone Methide-Secondary Amine Chemistry

2021 ◽  
Author(s):  
Yuanxing Zhang ◽  
Ying Wu ◽  
Jiayi Li ◽  
Ke Zhang
Keyword(s):  
Secondary Amine ◽  
Michael Addition ◽  
Room Temperature ◽  
Polymer Networks ◽  
Quinone Methide ◽  
Self Healing ◽  
Ambient Conditions ◽  
Catalyst Free ◽  
External Stimuli

An aza-Michael addition between 2,6-di-t-butyl-7-phenyl-p-quinone methide and secondary amine was demonstrated to hold the dynamic covalent reaction property under ambient conditions requiring no external stimuli. Based on this dynamic covalent...

scholarly journals Thermally Self-Healing Graphene-Nanoplate/Polyurethane Nanocomposites via Diels–Alder Reaction through a One-Shot Process

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 434 ◽  
Author(s):  
Cho-Rong Oh ◽  
Sang-Hyub Lee ◽  
Jun-Hong Park ◽  
Dai-Soo Lee
Keyword(s):  
Molecular Design ◽  
Alder Reaction ◽  
Chain Extender ◽  
Diels Alder ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction ◽  
A Chain ◽  
The Fourier Transform

Thermally self-healing graphene-nanoplate/polyurethane (GNP/PU) nanocomposites were prepared via a bulk in-situ Diels–Alder (DA) reaction. Graphene-nanoplate (GNP) was used as a reinforcement and crosslinking platform by a DA reaction with a furfuryl-based chain extender of polyurethane (PU). Results showed that a DA reaction occurred in GNP during the PU forming cure process. This procedure is simple and solvent free because of the absence of any independent surface modification process. Through the calculation of the interfacial tensions, the conditions of the bulk in-situ DA reaction were determined to ensure that GNP and the furfuryl group can react with each other at the interface during the curing process without a solvent. The prepared composites were characterized in terms of thermal, mechanical, and thermally self-healing properties via the DA reaction. In the PU capable of a DA reaction (DPU), characteristic peaks of DA and retro DA reactions were observed in the Fourier transform infrared (FT-IR) spectroscopy and endothermic peaks of retro DA reactions appeared in differential scanning calorimetry (DSC) thermograms. The DPU showed significantly enhanced physical properties and chemical resistance. The thermally self-healing capability was confirmed at 110 °C via the retro DA reactions. It is inferred that thermally self-healable crosslinked GNP/PU nanocomposites via DA reactions could be prepared in a simple bulk process through the molecular design of a chain extender for the in-situ reaction at the interface.

scholarly journals Control of Gelation and Properties of Reversible Diels–Alder Networks: Design of a Self-Healing Network

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 930 ◽  
Author(s):  
Beata Strachota ◽  
Adama Morand ◽  
Jiří Dybal ◽  
Libor Matějka
Keyword(s):  
Network Formation ◽  
Branching Processes ◽  
Dynamic Networks ◽  
Dynamic Network ◽  
Diels Alder ◽  
Structure Theory ◽  
Gel Point ◽  
Self Healing ◽  
Dynamic Network Formation ◽  
Thermoreversible Networks

Reversible Diels–Alder (DA) type networks were prepared from furan and maleimide monomers of different structure and functionality. The factors controlling the dynamic network formation and their properties were discussed. Evolution of structure during both dynamic nonequilibrium and isothermal equilibrium network formation/breaking was followed by monitoring the modulus and conversion of the monomer. The gelation, postgel growth, and properties of the thermoreversible networks from tetrafunctional furan (F4) and different bismaleimides (M2) were controlled by the structure of the maleimide monomer. The substitution of maleimides with alkyl (hexamethylene bismaleimide), aromatic (diphenyl bismaleimide), and polyether substituents affects differently the kinetics and thermodynamics of the thermoreversible DA reaction, and thereby the formation of dynamic networks. The gel-point temperature was tuned in the range Tgel = 97–122 °C in the networks of the same functionality (F4-M2) with different maleimide structure. Theory of branching processes was used to predict the structure development during formation of the dynamic networks and the reasonable agreement with the experiment was achieved. The experimentally inaccessible information on the sol fraction in the reversible network was received by applying the theory. Based on the acquired results, the proper structure of a self-healing network was designed.

scholarly journals Environmental interactions to composite elements of all-GFRP Kolding Footbridge

2018 ◽  
Vol 174 ◽  
pp. 04006
Author(s):  
Beata Stankiewicz
Keyword(s):  
Structural Integrity ◽  
Materials Science ◽  
Mechanical Analysis ◽  
Material System ◽  
Load Spectrum ◽  
Scanning Calorimetry ◽  
Time Dynamic ◽  
Gfrp Composite ◽  
Composite Bridge ◽  
Flexural Tests

Structural integrity of a composite material embraces contributions from: materials science and engineering, processing science, design and fabrication technology. It combines a number of interacting factors: the criticality of the application, the accessibility for and ability to inspect vital parts and components, the intended use including load spectrum and time, the consequences of impact, fatigue, temperature and hostile environment, the nature of inherent flaws, the constituent properties of the material system utilized, and it takes into account human factors. Glass fibre-reinforced polymer GFRP pultruded profiles have great potential in the construction industry, presenting certain advantages when compared with traditional materials, including the potentially improved durability under fluctuating levels of environmental factors. The contribution presents analysis of GFRP composite, acquired from cablestayed Fiberline Bridge exploited for 20 years in the fjord area of Kolding, Denmark. The differential scanning calorimetry (DSC) experiments were performed in the GFRP composite bridge material, in order to determine the mass variation and the energy changes suffered by the materials, as a function of temperature and time. Dynamic mechanical analysis (DMA) was allowed to detect thermal effects based on changes in the modulus or damping behavior. Tensile and flexural tests let to observe the decomposition process and had taken information of basic stress parameters of GFRP material used in Kolding Footbridge. Aforementioned analyses of durability are necessary to examine and monitoring for environmentally aged composites bridge elements.

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