N-Sulfonyl Urethanes to Design Polyurethane Networks with Temperature-Controlled Dynamicity

Macromolecules, Journal Year: 2023, Volume and Issue: 56(5), P. 1934 - 1944

Published: Feb. 22, 2023

(Re)processing of cross-linked polyurethanes (PUs) is often energy intensive and inefficient since dissociation urethane linkages at elevated temperatures generates highly reactive isocyanate moieties that can react with a wide range nucleophiles. In this study, we first show small molecule study the introduction N-sulfonyl bonds leads to dynamic covalent exchange reactions under much milder conditions compared regular groups. Then, these exchangeable motifs have been introduced, in relatively amounts (5, 10, 20%), PU matrix an attempt facilitate plastic flow lower temperatures. Rheological analysis elastomeric dissociative networks revealed interesting double relaxation behavior, even for between 150 100 °C, which could be described by Maxwell model two elements, related activated less bonds. Finally, (re)processability sulfonyl urethanes containing PUs was demonstrated through multiple cutting hot pressing cycles corresponding materials showed good retention thermal properties.

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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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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Aza-Michael Chemistry for PDMS-Based Covalent Adaptable Elastomers: Design and Dual Role of the Silica Filler

Macromolecules, Journal Year: 2024, Volume and Issue: 57(10), P. 4817 - 4825

Published: May 7, 2024

In this study, polydimethylsiloxane (PDMS)-based covalent adaptable networks have been prepared in a one-pot, catalyst-free way which dynamic β-amino esters (BAEs) are introduced via aza-Michael addition between available acrylate/amine-terminated PDMS-compounds. The straightforward introduction of those BAE-groups such high-value elastomers provides the ability to relax applied stress at elevated temperatures and hence capability reshaping by compression molding least 5 times without significant changes properties. Moreover, mechanical properties tunable varying cross-linker and/or filler content. Interestingly, utilization silica fillers not only enhances network formation but also accelerates exchange reactions, resulting twice faster relaxation while maintaining creep resistance service temperatures.

Language: Английский

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Dynamic Chemistry Toolbox for Advanced Sustainable Materials

Advanced Science, Journal Year: 2024, Volume and Issue: 11(14)

Published: Feb. 6, 2024

Abstract Developing dynamic chemistry for polymeric materials offers chemical solutions to solve key problems associated with current plastics. Mechanical performance and function are equally important in material design because the former determines application scope latter enables recycling hence sustainability. However, it is a long‐term challenge balance subtle trade‐off between mechanical robustness properties single material. The rise of chemistry, including supramolecular covalent provides many opportunities versatile molecular tools designing constitutionally that can adapt, repair, recycle. Facing growing social need developing advanced sustainable without compromising properties, recent progress showing how toolbox be explored enable high‐performance by engineering strategies discussed here. state art milestones summarized discussed, followed an outlook toward future challenges present this field.

Language: Английский

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