Dynamic Ablative Networks: Shapeable Heat-Shielding Materials

ACS Applied Materials & Interfaces, Journal Year: 2023, Volume and Issue: 15(21), P. 25212 - 25223

Published: March 8, 2023

Thermoset materials sacrifice recyclability and reshapeability for increased chemical mechanical robustness because of an immobilized, cross-linked polymeric matrix. The robust material properties thermosets make them well-suited applications such as heat-shielding (HSMs) or ablatives where excellent thermal stability, good strength, high charring ability are paramount. Many these characteristic covalent adaptable networks (CANs), the static connectivity has been replaced with dynamic cross-links. This allows network mobility while retaining cross-link to permit damage repair reshaping that traditionally inaccessible thermoset materials. Herein, we report synthesis hybrid inorganic–organic enaminone vitrimers contain exceptionally weight percent polyhedral oligomeric silsesquioxane (POSS)-derivatives. Polycondensation β-ketoester-containing POSS various diamine cross-linkers led facile tunability, shapeability, predictable glass transition temperatures, residual char mass following degradation. Furthermore, show notable retention their preordained shape decomposition, suggesting future utility in design HSMs complex detailing.

Language: Английский

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Polybenzoxazine-based covalent adaptable networks: A mini-review

Polymer, Journal Year: 2023, Volume and Issue: 287, P. 126426 - 126426

Published: Oct. 25, 2023

Benzoxazines represent a class of thermoset resins known for their exceptional thermal, fire, and mechanical properties. These find wide applications in various industries, including composites electronic components. However, like conventional thermosets, benzoxazines have limitations terms end-of-life options, typically being landfilled or incinerated. To address this concern, researchers been exploring the incorporation dynamic bonds into structure polybenzoxazines to add functionalities such as reprocessability, self-healing, recycling capabilities, develop polybenzoxazine-based covalent adaptable networks (CANs). This mini-review offers an overview recent endeavors focused on introduction within polybenzoxazine structures. It emphasizes synergies between molecular exchanges, transesterification disulfide metathesis, provides comparative summary properties achieved by materials developed context. By leveraging strengths benzoxazine structures, aims foster exploration development innovative approaches that combine unique CANs, enabling more sustainable environmentally friendly materials.

Language: Английский

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Eugenol-based dual-cured materials with multiple dynamic exchangeable bonds

European Polymer Journal, Journal Year: 2024, Volume and Issue: 206, P. 112782 - 112782

Published: Jan. 19, 2024

In the present work, preparation of sustainable thermosets has been approached simultaneously from three different points view: a) use bio-based monomers chemically modified through green methodologies, b) adoption dual curing click-type reactions to implement more efficient manufacturing processes, and c) inclusion interchangeable groups in network, enable reuse recycling material at end its useful life avoid waste generation. The first goal by synthesizing a greener way an acrylate-epoxy derivative eugenol (AEEU) glycerol triacrylate (GTA), both biobased resources. Then, second approach was addressed using cystamine as crosslinker obtain materials dual-curing procedure based on "click" aza-Michael reaction epoxy-amine reaction. Intermediate final could be prepared with tailorable properties controlling molar ratio AEEU GTA. By DSC rheology, we evaluate sequentiality gelation process. Finally, covalent adaptable networks (CANs) contained types dynamic bonds (disulfide, esters, β-aminoesters) their thermomechanical were tested DMA revealing Tgs above room temperature 47 70 °C. Bending tests break performed mechanical reaching values up 90 MPa stress 7 % deformation. Stress relaxation showed that all relax relatively low temperatures (120 °C) less than 21 min. associative dissociative behavior these investigated rheology clear drop modulus high frequencies when used crosslinker. Moreover, reprocessability obtaining homogeneous samples no significant changes chemical thermal highlighting great potential wide range possibilities many fields CANs.

Language: Английский

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Robust and Programmable Liquid Crystal Elastomers through Catalytic Control of Dynamic Aza-Michael Reactions

Macromolecules, Journal Year: 2024, Volume and Issue: 57(2), P. 682 - 690

Published: Jan. 9, 2024

A strategy to efficiently synthesize thermally reprogrammable but mechanically stable liquid crystalline elastomers (LCEs) is reported by investigating the catalytic effects of para-substituted phenols on dynamic aza-Michael reactions. The synthesis LCEs was optimized based a study catalyzed small-molecule reactions, where presence an electron-withdrawing substituent significantly improved reactivity system. catalysts were then screened their exchange adducts. Catalysts with substituents efficient in inducing bonds, thus influencing mesogen alignment and actuation. After programming alignment, catalyst washed away dramatically reduce activity improve creep resistance material while preserving postsynthetic alignment. This approach represents straightforward accessible methodology for obtaining programmable as well actuators from LCEs.

Language: Английский

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Thermomechanical characterisation of reprocessable, siloxane-based, glass-fibre-reinforced vitrimers

Composites Part B Engineering, Journal Year: 2024, Volume and Issue: 276, P. 111354 - 111354

Published: March 1, 2024

Language: Английский

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