A Simple Relationship Relating Linear Viscoelastic Properties and Chemical Structure in a Model Diels–Alder Polymer Network

Sheridan, Richard J.; Bowman, Christopher N.

doi:10.1021/ma301329u

Cited by 74 publications

(88 citation statements)

References 38 publications

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“…To understand the reversibility in molecular structure, in situ FTIR of the cured epoxy was examined in thermal cyclic tests. The evolution of the maleimide band (696 cm −1 ) intensity reflects the DA/rDA reactions progress . Figure (b) shows the band intensity of 696 cm −1 in the first heating and cooling cycles between 20°C and 120°C.…”

Section: Resultsmentioning

confidence: 99%

“…The evolution of the maleimide band (696 cm 21 ) intensity reflects the DA/rDA reactions progress. 35,36 Figure FIGURE ARTICLE 4(b) shows the band intensity of 696 cm 21 in the first heating and cooling cycles between 20 C and 120 C. The rise in band intensity during heating process indicates the generation of maleimide moiety, demonstrating the occurrence of rDA reaction. The rDA reaction started from about 70 C and proceeded steadily from 90 C to 120 C. The intensity kept constant for prolonged time at 120 C, indicating the rDA reaction equilibrium.…”

Section: Thermo-reversibility Of Reversibly Cross-linked Epoxy Polymermentioning

confidence: 96%

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Facile fabrication of fast recyclable and multiple self‐healing epoxy materials through diels‐alder adduct cross‐linker

Xiao

Liu

Dong

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

139

103

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A reversibly cross‐linked epoxy resin with efficient reprocessing and intrinsic self‐healing was prepared from a diamine Diels‐Alder (DA) adduct cross‐linker and a commercial epoxy oligomer. The newly synthesized diamine cross‐linker, comprising a DA adduct of furan and maleimide moieties, can cure epoxy monomer/oligomer with thermal reversibility. The reversible transition between cross‐linked state and linear architecture endows the cured epoxy with rapid recyclability and repeated healability. The reversibly cross‐linked epoxy fundamentally behaves as typical thermosets at ambient conditions yet can be fast reprocessed at elevated temperature like thermoplastics. As a potential reversible adhesive, the epoxy polymer with adhesive strength values about 3 MPa showed full recovery after repeated fracture‐thermal healing processes. The methodology explored in this contribution provides new insights in modification of conventional engineering plastics as functional materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2094–2103

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Section: Resultsmentioning

confidence: 99%

Section: Thermo-reversibility Of Reversibly Cross-linked Epoxy Polymermentioning

confidence: 96%

Facile fabrication of fast recyclable and multiple self‐healing epoxy materials through diels‐alder adduct cross‐linker

Xiao

Liu

Dong

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

139

103

View full text Add to dashboard Cite

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“…[ 32 ] Briefl y, SRF(3.0) was synthesized via Michael addition of fi rst furfuryl mercaptan then octanethiol to SR295 to achieve an average furan functionality of three. To a round bottom fl ask charged with 50 mL of THF, 5 g (0.055 mol of acrylate) SR295 and 0.094 g (1 w/w%) TEA was dissolved following the addition of 4.44 g (0.039 mol) of furfuryl mercaptan at ambient temperature.…”

Section: Methodsmentioning

confidence: 99%

Scaffolded Thermally Remendable Hybrid Polymer Networks

Lyon

Baranek

Bowman

2016

Adv Funct Materials

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Step‐growth Diels–Alder (DA) networks using furan and maleimide groups are particularly useful in forming thermally remendable crosslinked polymers, due to the dramatic shift in equilibrium over a relatively low temperature range as compared with other diene‐dienophile pairs. However, the efficient healing observed in these materials at high temperature is directly tied to their ability to depolymerize and flow, and thermal treatment often results in deformation of the original shape. To overcome this limitation, a hybrid network material is developed, which consists of orthogonal Diels–Alder and polyurethane networks. Both step‐growth networks form simultaneously at elevated temperature without the presence of a catalyst. At high temperatures, the Diels–Alder network depolymerizes and flows into fractures through capillary action, while the polyurethane serves as a scaffold to maintain the overall shape of the sample. The DA network then repolymerizes at lower temperatures, creating a crosslinked, scar‐like “patch” throughout the crack. This healing process is repeatable without concern of monomer depletion. During heating through the glass transition, a shape memory “assist” is observed, which reverses some of the localized damage by bringing broken edges closer together. Samples are repeatedly damaged and then healed through temperature cycling, as evidenced through tensile fracture tests and electrochemical conductivity tests.

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“…The direct relationship between the bond kinetics and the relaxation behavior is achieved by applying the Semenov-Rubinstein (SR) model for the dynamics of an associating polymer to a DA-crosslinked network. 33 By contemplating clusters within the network that are made up of dynamic connectivity, a scaling model is developed that ultimately relates the longest relaxation time to the bond lifetime and kinetics. The network connectivity must be taken into account, and is adequately done so by using Miller-Macosko formalism.…”

Section: Stress Relaxationmentioning

confidence: 99%

Covalent adaptable networks: smart, reconfigurable and responsive network systems

2013

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Covalently crosslinked materials, classically referred to as thermosets, represent a broad class of elastic materials that readily retain their shape and molecular architecture through covalent bonds that are ubiquitous throughout the network structure. These materials, in particular in their swollen gel state, have been widely used as stimuli responsive materials with their ability to change volume in response to changes in temperature, pH, or other solvent conditions and have also been used in shape memory applications. However, the existence of a permanent, unalterable shape and structure dictated by the covalently crosslinked structure has dramatically limited their abilities in this and many other areas.These materials are not generally reconfigurable, recyclable, reprocessable, and have limited ability to alter permanently their stress state, topography, topology, or structure. Recently, a new paradigm has been explored in crosslinked polymers -that of covalent adaptable networks (CANs) in which covalently crosslinked networks are formed such that triggerable, reversible chemical structures persist throughout the network. These reversible covalent bonds can be triggered through molecular triggers, light or other incident radiation, or temperature changes. Upon application of this stimulus, rather than causing a temporary shape change, the CAN structure responds by permanently adjusting its structure through either reversible addition/condensation or through reversible bond exchange mechanisms, either of which allow the material to essentially reequilibrate to its new state and condition. Here, we provide a tutorial review on these materials and their responsiveness to applied stimuli. In particular, we review the broad classification of these materials, the nature of the chemical bonds that enable the adaptable structure, how the properties of these materials depend on the reversible structure, and how the application of a stimulus causes these materials to alter their shape, topography, and properties. Key learning pointsCritical differences between thermosets, thermoplastics, and covalent adaptable networks. Bond-breaking, bond-forming versus bond-forming, bond-breaking network strand rearrangement sequence. Behavior and mechanical properties derived from reversible addition/condensation and exchange crosslinking. Design and synthesis of covalent networks with reversible structures. Triggers enabling activation of covalent adaptable network.

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A Simple Relationship Relating Linear Viscoelastic Properties and Chemical Structure in a Model Diels–Alder Polymer Network

Abstract: Miller & Macosko crosslink density The crosslink density υ of a classical, Bethe-lattice, An+An-1+…+A1+B2 step-growth polymer network can be calculated according to the equation υ = i − 2 2 X i

Cited by 74 publications

References 38 publications

Facile fabrication of fast recyclable and multiple self‐healing epoxy materials through diels‐alder adduct cross‐linker

Facile fabrication of fast recyclable and multiple self‐healing epoxy materials through diels‐alder adduct cross‐linker

Scaffolded Thermally Remendable Hybrid Polymer Networks

Covalent adaptable networks: smart, reconfigurable and responsive network systems

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