scholarly journals Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 396
Author(s):  
Larissa Hammer ◽  
Nathan J. Van Zee ◽  
Renaud Nicolaÿ
Keyword(s):  
Physical Properties ◽  
Dimensional Stability ◽  
Dynamic Networks ◽  
Polymer Networks ◽  
Polymeric Materials ◽  
Self Healing ◽  
Structure Property ◽  
Covalent Bonds ◽  
Design Structure ◽  
Increasing Demand

Covalent adaptable networks (CANs) are polymeric networks containing covalent crosslinks that are dynamic under specific conditions. In addition to possessing the malleability of thermoplastics and the dimensional stability of thermosets, CANs exhibit a unique combination of physical properties, including adaptability, self-healing, shape-memory, stimuli-responsiveness, and enhanced recyclability. The physical properties and the service conditions (such as temperature, pH, and humidity) of CANs are defined by the nature of their constituent dynamic covalent bonds (DCBs). In response to the increasing demand for more sophisticated and adaptable materials, the scientific community has identified dual dynamic networks (DDNs) as a promising new class of polymeric materials. By combining two (or more) distinct crosslinkers in one system, a material with tailored thermal, rheological, and mechanical properties can be designed. One remarkable ability of DDNs is their capacity to combine dimensional stability, bond dynamicity, and multi-responsiveness. This review aims to give an overview of the advances in the emerging field of DDNs with a special emphasis on their design, structure-property relationships, and applications. This review illustrates how DDNs offer many prospects that single (dynamic) networks cannot provide and highlights the challenges associated with their synthesis and characterization.

Shape-memory and self-healing polyurethanes based on cyclic poly(ε-caprolactone)

2016 ◽  
Vol 7 (44) ◽  
pp. 6789-6797 ◽  
Author(s):  
Wei Chen ◽  
Yanyan Zhou ◽  
Ying Li ◽  
Jun Sun ◽  
Xiangqiang Pan ◽  
...  
Keyword(s):  
Shape Memory ◽  
Memory Performance ◽  
Polymeric Materials ◽  
Self Healing ◽  
Structure Property ◽  
Property Relationship ◽  
Structure Property Relationship ◽  
Relationship Of

This work provides an unprecedented example for the exploration of the cyclic topology effects on the shape memory performance of bulk polyurethane materials, providing a novel angle to elucidate the structure–property relationship of polymeric materials.

scholarly journals Design Strategy for Self-Healing Epoxy Coatings

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Dian Yuan ◽  
Vahab Solouki Bonab ◽  
Ammar Patel ◽  
Talha Yilmaz ◽  
Richard A. Gross ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Thermoplastic Polyurethane ◽  
Polymeric Materials ◽  
Secondary Phase ◽  
Diglycidyl Ether ◽  
Self Healing ◽  
Structure Property ◽  
Chain Entanglement ◽  
Epoxy Network

Self-healing strategies including intrinsic and extrinsic self-healing are commonly used for polymeric materials to restore their appearance and properties upon damage. Unlike intrinsic self-healing tactics where recovery is based on reversible chemical or physical bonds, extrinsic self-healing approaches rely on a secondary phase to acquire the self-healing functionality. Understanding the impacts of the secondary phase on both healing performance and matrix properties is important for rational system design. In this work, self-healing coating systems were prepared by blending a bio-based epoxy from diglycidyl ether of diphenolate esters (DGEDP) with thermoplastic polyurethane (TPU) prepolymers. Such systems exhibit polymerization induced phase separation morphology that controls coating mechanical and healing properties. Structure–property analysis indicates that the degree of phase separation is controlled by tuning the TPU prepolymer molecular weight. Increasing the TPU prepolymer molecular weight results in a highly phase separated morphology that is preferable for mechanical performances but undesirable for healing functionality. In this case, diffusion of TPU prepolymers during healing is restricted by the epoxy network rigidity and chain entanglement. Low molecular weight TPU prepolymers tend to phase mix with the epoxy matrix during curing, resulting in the formation of a flexible epoxy network that benefits TPU flow while decreasing Tg and mechanical properties. This work describes a rational strategy to develop self-healing coatings with controlled morphology to extend their functions and tailor their properties for specific applications.

J0470202 Self-healing Polymeric Materials Based on Exchangeable Covalent Bonds

2014 ◽  
Vol 2014 (0) ◽  
pp. _J0470202--_J0470202-
Author(s):  
Hideyuki OTSUKA ◽  
Keiichi IMATO ◽  
Tomoyuki OHISHI ◽  
Atsushi TAKAHARA
Keyword(s):  
Polymeric Materials ◽  
Self Healing ◽  
Covalent Bonds

scholarly journals Low-Temperature-Meltable Elastomers Based on Linear Polydimethylsiloxane Chains Alpha, Omega-Terminated with Mesogenic Groups as Physical Crosslinker: A Passive Smart Material with Potential as Viscoelastic Coupling. Part II—Viscoelastic and Rheological Properties

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2840
Author(s):  
Sabina Horodecka ◽  
Adam Strachota ◽  
Beata Mossety-Leszczak ◽  
Maciej Kisiel ◽  
Beata Strachota ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Smart Materials ◽  
Volume Fraction ◽  
Mechanical Strain ◽  
Polymer Networks ◽  
Building Blocks ◽  
Self Healing ◽  
Structure Property ◽  
Mechanical Coupling

Rheological and viscoelastic properties of physically crosslinked low-temperature elastomers were studied. The supramolecularly assembling copolymers consist of linear polydimethylsiloxane (PDMS) elastic chains terminated on both ends with mesogenic building blocks (LC) of azobenzene type. They are generally and also structurally highly different from the well-studied LC polymer networks or LC elastomers: The LC units make up only a small volume fraction in our materials and act as fairly efficient physical crosslinkers with thermotropic properties. The aggregation (nano-phase separation) of the relatively rare, small and spatially separated terminal LC units generates temperature-switched viscoelasticity in the molten copolymers. Their rheological behavior was found to be controlled by an interplay of nano-phase separation of the LC units (growth and splitting of their aggregates) and of the thermotropic transitions in these aggregates (which change their stiffness). As a consequence, multiple gel points (up to three) are observed in temperature scans of the copolymers. The physical crosslinks also can be reversibly disconnected by large mechanical strain in the ‘warm’ rubbery state, as well as in melt (thixotropy). The kinetics of crosslink formation was found to be fast if induced by temperature and extremely fast in case of internal self-healing after strain damage. Thixotropic loop tests hence display only very small hysteresis in the LC-melt-state, although the melts show very distinct shear thinning. Our study evaluates structure-property relationships in three homologous systems with elastic PDMS segments of different length (8.6, 16.3 and 64.4 repeat units). The studied copolymers might be of interest as passive smart materials, especially as temperature-controlled elastic/viscoelastic mechanical coupling.

Recycling and self-healing of dynamic covalent polymer networks with a precisely tuneable crosslinking degree

2019 ◽  
Vol 10 (6) ◽  
pp. 672-678 ◽  
Author(s):  
Qi An ◽  
Isabelle D. Wessely ◽  
Yannick Matt ◽  
Zahid Hassan ◽  
Stefan Bräse ◽  
...  
Keyword(s):  
Polymer Networks ◽  
Self Healing ◽  
Crosslinking Degree ◽  
Covalent Bonds ◽  
External Stimuli

Dynamic covalent polymer networks combine intrinsic reversibility with the robustness of covalent bonds, creating chemically stable materials that are responsive to external stimuli.

scholarly journals Functional Materials Based on Cyclometalated Platinum(II) β-Diketonate Complexes: A Review of Structure–Property Relationships and Applications

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4236
Author(s):  
Ashanul Haque ◽  
Hani El Moll ◽  
Khalaf M. Alenezi ◽  
Muhammad S. Khan ◽  
Wai-Yeung Wong
Keyword(s):  
Photophysical Properties ◽  
Functional Materials ◽  
Polymeric Materials ◽  
Organometallic Complexes ◽  
Structure Property ◽  
Covalent Bonds ◽  
Ancillary Ligands ◽  
Structure Property Relationships ◽  
Materials Research ◽  
Recent Developments

Square planar organoplatinum(II) complexes have garnered immense interest in the area of materials research. The combination of the Pt(II) fragment with mono-, bi- tri- and tetradentate organic ligands gives rise to a large variety of complexes with intriguing properties, especially cyclometalated Pt(II) complexes in which ligands are connected through covalent bonds demonstrate higher stability, excellent photoluminescence properties, and diverse applications. The properties and applications of the Pt(II)-based materials can be smartly fine-tuned via a judicious selection of the cyclometalating as well as ancillary ligands. In this review, attempts have been made to provide a brief review of the recent developments of neutral Pt(II) organometallic complexes bearing bidentate cyclometalating ligands and β-diketonate ancillary ligands, i.e., (C^N)Pt(O^O) and (C^C)Pt(O^O) derivatives. Both small (monomeric, dimeric) and large (polymeric) materials have been considered. We critically assessed the role of functionalities (ligands) on photophysical properties and their impact on applications.

Imine Based Self-Healing Hydrogel Triggered by Periodate

2020 ◽  
Author(s):  
Alexis Wolfel ◽  
Cecilia Inés Alvarez Igarzabal ◽  
Marcelo Ricardo Romero
Keyword(s):  
Functional Groups ◽  
Time Window ◽  
Crosslinking Reaction ◽  
Self Healing ◽  
Swelling Properties ◽  
Covalent Bonds ◽  
Smart Systems ◽  
Primary Amino ◽  
Vicinal Diols ◽  
Aldehyde Groups

<p>Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by <i>N,N'</i>-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from <a>2-aminoethyl methacrylate </a>hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p>

APEX 417

Alloy Digest ◽  
1958 ◽  
Vol 7 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Dimensional Stability ◽  
High Strength ◽  
Heat Treating ◽  
Casting Alloy ◽  
Excellent Corrosion Resistance ◽  
Magnesium Casting ◽  
Strength And Ductility

Abstract APEX 417 is an aluminum-magnesium casting alloy having high strength and ductility, excellent corrosion resistance and good dimensional stability. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-61. Producer or source: Apex Smelting Company.

COMPAX

Alloy Digest ◽  
1988 ◽  
Vol 37 (3) ◽  
Keyword(s):  
Wear Resistance ◽  
Compressive Strength ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tool Steel ◽  
Dimensional Stability ◽  
Heat Treating ◽  
High Toughness ◽  
Steel Corporation

Abstract COMPAX is a chromium-molybdenum shock-resistant tool steel characterized by high toughness, good wear resistance, good through hardening and good dimensional stability during hardening. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength. It also includes information on heat treating, machining, joining, and surface treatment. Filing Code: TS-488. Producer or source: Uddeholm Steel Corporation.

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