Phosphate Triester Dynamic Covalent Networks

Majumdar, Soumabrata; Zhang, Huiyi; Soleimani, Mohammad; Benthem, Rolf A. T. M. van; Heuts, Johan P. A.; Sijbesma, RP Rint

doi:10.1021/acsmacrolett.0c00636

Cited by 57 publications

(43 citation statements)

References 45 publications

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“…Our group has recently introduced catalyst-free phosphate triester transesterification as a dynamic covalent chemistry in polymeric networks. 22 Stress relaxation of the network at high temperatures was comparable to that of previously reported carboxylate ester networks but without the need for a catalyst. Subsequent papers have reported flame retardant DCNs based on phosphate esters, 23 including an associative network based on efficient β-hydroxy phosphate exchange, 24 although the chemistry and the mechanism of rearrangement were not studied in detail.…”

Section: Introductionsupporting

confidence: 78%

“…As a result of the neighboring group participation, exchange kinetics, as probed through stress relaxation, are more than 100 times faster than in the phosphate triester network previously published by us, 22 while the activation energy for stress relaxation drops from 104.5 kJ/mol in the associative phosphate network to 68 kJ/mol in the dissociative system. Fast kinetics ensure that after processing the cross-link density is recovered rapidly on cooling.…”

Section: Discussionmentioning

confidence: 66%

“… 34 The temperature dependence of the characteristic relaxation time, obtained from the fit, follows Arrhenius behavior with an activation energy of 68 kJ/mol ( Figure 4 b), significantly lower than in the associative phosphate triester network previously published by us, where the activation energy is 104.5 kJ/mol. 22 The value of the stretch parameter β lies between 0.85 and 0.9 and indicates a similar narrow distribution of relaxation times at all temperatures. Frequency sweep experiments under oscillatory shear were performed at temperatures between 100 °C and 160 °C to probe the effects of bond exchange on viscoelastic properties.…”

Section: Results and Discussionmentioning

confidence: 76%

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Efficient Exchange in a Bioinspired Dynamic Covalent Polymer Network via a Cyclic Phosphate Triester Intermediate

et al. 2021

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Bond exchange via neighboring group-assisted reactions in dynamic covalent networks results in efficient mechanical relaxation. In Nature, the high reactivity of RNA toward nucleophilic substitution is largely attributed to the formation of a cyclic phosphate ester intermediate via neighboring group participation. We took inspiration from RNA to develop a dynamic covalent network based on β-hydroxyl-mediated transesterifications of hydroxyethyl phosphate triesters. A simple one-step synthetic strategy provided a network containing phosphate triesters with a pendant hydroxyethyl group. 31 P solid-state NMR demonstrated that a cyclic phosphate triester is an intermediate in transesterification, leading to dissociative network rearrangement. Significant viscous flow at 60–100 °C makes the material suitable for fast processing via extrusion and compression molding.

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Section: Introductionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 66%

Section: Results and Discussionmentioning

confidence: 76%

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Efficient Exchange in a Bioinspired Dynamic Covalent Polymer Network via a Cyclic Phosphate Triester Intermediate

et al. 2021

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“…[42] Phosphate esters, diesters, and triesters have been shown to be dynamically exchanged through association mechanisms. [24][25][26] Therefore, we assume that the ED samples have vitrimer properties, which can rearrange the topological network through the transesterification reaction and release the stress (Figure 4). Besides the glass transition temperature, vitrimer also has a topological freezing transition temperature (T v , defined as the reversible transition temperature of vitrimer from viscoelastic solid to viscoelastic liquid).…”

Section: Mechanical and Dynamic Properties Of Ed-xmentioning

confidence: 99%

“…[25] Majumdar et al first studied the catalyst-free dynamic covalent network design based on phosphate triester. [26] Phosphate esters are widely found in nature and in our daily lives, such as deoxyribonucleic acid (DNA), ribonucleic acid (RNA), adenosine triphosphate (ATP) and heart therapy drugs, and they can be synthesized in a variety of ways. Compared with carboxylic acid esters, the re-versible transesterification of 𝛽-hydroxy phosphate esters can be induced simply without any catalyst.…”

Section: Introductionmentioning

confidence: 99%

Catalyst‐Free Vitrimer Cross‐Linked by Biomass‐Derived Compounds with Mechanical Robustness, Reprocessability, and Multishape Memory Effects

Huang

Yang

Niu

et al. 2021

Macromol. Rapid Commun.

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Vitrimerization of thermoset polymers plays an important role in addressing resource recovery and reuse. Vitrimer elastomers with good mechanical properties often require well-designed crosslinking agents or fillers, but this increases processing complexity or reduces vitrimer dynamic properties. In this report, a simple green strategy to build a strong vitrimer elastomer is designed. Commercially available epoxidized natural rubber (ENR) is cross-linked with biomass-derived D-Fructose 1,6-bisphosphoric acid to get a vitrimer elastomer cross-linked by 𝜷-hydroxy phosphate ester bonds and has abundant hydrogen bonds. Hydrogen bonds can preferentially break and dissipate energy under external forces, which makes the sample robust. The topological network can be reformed at high temperatures through the dynamic exchange of 𝜷-hydroxy phosphate ester bonds, which gives the material malleability and recyclability. In addition, through the strategy of combining reprocessing and welding, multiple shape memory effects can be achieved in one postprocessing step. Considering that a variety of commercially available epoxy polymers are easily available, it is believed that this strategy can be a simple and versatile way to enable commercial epoxy polymers to achieve green crosslinking through biomass crosslink agents, which results in robust and recyclable vitrimers based on 𝜷-hydroxy phosphate bonds.

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Ultrastrong and Thermo‐Remoldable Lignin‐Based Polyurethane Foam Insulation with Active‐Passive Fire Resistance

Sun,

Guo,

et al. 2024

Adv Funct Materials

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Foam thermal insulators are indispensable for prevailing energy‐saving engineering, however their widespread use brings intractability such as unsustainability, “white pollution”, and fire hazards. The emergence of bio‐based foams is highly appreciated, but the fabrication approaches are economically unattractive and/or the product properties are inferior, making their large‐scale implementation unviable. Herein, a versatile, thermally remoldable phosphate‐containing polyurethane composite foam (LPU‐G) is constructed from natural lignin and expanded graphite flakes via an atmospheric pressure and scalable one‐pot strategy. The optimal LPU‐G exhibits exceptional mechanical strength, capable of supporting over 6000 times its weight without significant deformation. Moreover, the LPU‐G demonstrates the desired multifunctionality in handling extreme circumstances, including humidity‐tolerant thermal insulation, superb water vapor barrier, and withstanding ≈1200 °C flame without ignition. Based on the “expansion‐conductivity” micro‐mechanism, LPU‐G is the first foam material to be constructed as a sensitive fire alarm system with an ultra‐long alarm time (>1800 s). Surprisingly, LPU‐G can be rapidly upcycled into recyclable bulk composites for a second life through simple thermo‐molding processes rooted in the multi‐dynamic behavior of the phosphate, carbamate, and hydrogen bonds. The easy‐to‐scale LPU‐G represents a new generation of thermal insulators that address concerns regarding unsustainability, high cost, fire risk, and inferior mechanical properties.

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Phosphate Triester Dynamic Covalent Networks

Abstract: This work was funded by the Dutch Research Council (NWO), Project No. 731.016.202. We are grateful to Annelore Aerts for her help in mechanical testing of the samples. We thank Dr. Ruth Cardinaels for fruitful discussions.

Cited by 57 publications

References 45 publications

Efficient Exchange in a Bioinspired Dynamic Covalent Polymer Network via a Cyclic Phosphate Triester Intermediate

Efficient Exchange in a Bioinspired Dynamic Covalent Polymer Network via a Cyclic Phosphate Triester Intermediate

Catalyst‐Free Vitrimer Cross‐Linked by Biomass‐Derived Compounds with Mechanical Robustness, Reprocessability, and Multishape Memory Effects

Ultrastrong and Thermo‐Remoldable Lignin‐Based Polyurethane Foam Insulation with Active‐Passive Fire Resistance

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