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 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 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 Influence of Material Properties on the Damage-Reporting and Self-Healing Performance of a Mechanically Active Dynamic Network Polymer in Coating Applications

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2468
Author(s):  
Da Hae Son ◽  
Gi Young Kim ◽  
Ji-Eun Jeong ◽  
Sang-Ho Lee ◽  
Young Il Park ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Material Properties ◽  
Substrate Surface ◽  
Polymer Network ◽  
Polymer Networks ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Self Healing

We conducted a detailed investigation of the influence of the material properties of dynamic polymer network coatings on their self-healing and damage-reporting performance. A series of reversible polyacrylate urethane networks containing the damage-reporting diarylbibenzofuranone unit were synthesized, and their material properties (e.g., indentation modulus, hardness modulus, and glass-transition temperature) were measured conducting nanoindentation and differential scanning calorimetry experiments. The damage-reporting and self-healing performances of the dynamic polymer network coatings exhibited opposite tendencies with respect to the material properties of the polymer network coatings. Soft polymer network coatings with low glass-transition temperature (~10 °C) and indentation hardness (20 MPa) exhibited better self-healing performance (almost 100%) but two times worse damage-reporting properties than hard polymer network coatings with high glass-transition temperature (35~50 °C) and indentation hardness (150~200 MPa). These features of the dynamic polymer network coatings are unique; they are not observed in elastomers, films, and hydrogels, whereby the polymer networks are bound to the substrate surface. Evidence indicates that controlling the polymer’s physical properties is a key factor in designing high-performance self-healing and damage-reporting polymer coatings based on mechanophores.

scholarly journals Thermal analysis: basic concept of differential scanning calorimetry and thermogravimetry for beginners

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nurul Fatahah Asyqin Zainal ◽  
Jean Marc Saiter ◽  
Suhaila Idayu Abdul Halim ◽  
Romain Lucas ◽  
Chin Han Chan
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Commercial Application ◽  
Scanning Calorimetry ◽  
Teaching Activities ◽  
Sample Decomposition ◽  
Calibration Baseline

AbstractWe present an overview for the basic fundamental of thermal analysis, which is applicable for educational purposes, especially for lecturers at the universities, who may refer to the articles as the references to “teach” or to “lecture” to final year project students or young researchers who are working on their postgraduate projects. Description of basic instrumentation [i.e. differential scanning calorimetry (DSC) and thermogravimetry (TGA)] covers from what we should know about the instrument, calibration, baseline and samples’ signal. We also provide the step-by-step guides for the estimation of the glass transition temperature after DSC as well as examples and exercises are included, which are applicable for teaching activities. Glass transition temperature is an important property for commercial application of a polymeric material, e.g. packaging, automotive, etc. TGA is also highlighted where the analysis gives important thermal degradation information of a material to avoid sample decomposition during the DSC measurement. The step-by-step guides of the estimation of the activation energy after TGA based on Hoffman’s Arrhenius-like relationship are also provided.

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

Self-Healing Hydrophobic POSS-functionalized Fluorinated Copolymer via RAFT Polymerization and dynamic Diels-Alder Reaction

2021 ◽  
Author(s):  
Siva Ponnupandian ◽  
Prantik Mondal ◽  
Thomas Becker ◽  
Richard Hoogenboom ◽  
Andrew B Lowe ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Raft Polymerization ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Diels Alder Reaction ◽  
Reversible Addition

This investigation reports the preparation of a tailor-made copolymer of furfuryl methacrylate (FMA) and trifluoroethyl methacrylate (TFEMA) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The furfuryl groups of the copolymer...

New Chain Extenders for Self-Healing Polymers

2021 ◽  
Vol 899 ◽  
pp. 628-637
Author(s):  
Daria V. Zakharova ◽  
Zalina A. Lok’yaeva ◽  
Alexander A. Pavlov ◽  
Alexander V. Polezhaev
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Hydroxyl Groups ◽  
Structural Fragment ◽  
Self Healing ◽  
Diels Alder Reaction ◽  
Small Series ◽  
Chain Extenders ◽  
Reversible Covalent ◽  
Thermochemical Parameters

We present here a small series of compounds designed to modify the polymer chain of various polyurethanes in order to introduce a structural fragment with the ability of thermally-triggered reversible covalent interactions. Bismaleimides (2a-2e) were synthesized from commercially available aromatic and aliphatic symmetric diamines (1a-1e) and were further introduced into the Diels-Alder reaction with furfuryl alcohol as dienophiles. The Diels-Alder adducts (3a-3e) were obtained as a mixture of endo- and exo-isomer. The presence of symmetrical hydroxyl groups in the structure of the obtained compounds makes them suitable as chain extenders of low molecular weight diisocyanate prepolymers. The presence of a thermally reversible Diels-Alder reaction adduct in the structure of potential chain-extenders opens a possibility to create unique materials with self-healing properties. All compounds obtained were characterized by 1H, 13C NMR, ESI-HRMS, and IR spectroscopy. The thermochemical parameters of the reverse Diels-Alder reaction were established using DSC analysis.

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