An Orthogonal Dynamic Covalent Polymer Network with Distinctive Topology Transformations for Shape‐ and Molecular Architecture Reconfiguration

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(11)

Опубликована: Янв. 5, 2022

Bond exchange in a typical dynamic covalent polymer network allows access to macroscopic shape reconfigurability, but the architecture is not altered. An alternative possibility that can be designed switch various topological states corresponding different material properties. Achieving both one expand scope, their intrinsically conflicting mechanisms make it challenging. We design undergo two orthogonal transformations, namely transesterification on branched chains and olefin metathesis mainframe. This independent control of molecular architecture. With this design, we illustrate bottlebrush with programmable spatially definable mechanical Our strategy paves way on-demand regulation polymers.

Язык: Английский

---

Fast‐Reprocessing, Postadjustable, Self‐Healing Covalent Adaptable Networks with Schiff Base and Diels–Alder Adduct

Macromolecular Rapid Communications, Год журнала: 2022, Номер 43(13)

Опубликована: Янв. 12, 2022

Covalent adaptable networks (CANs) are a new type of polymers, which possess excellent performance thermosets and reprocessability thermoplastics. Nevertheless, it is still challenge to realize rapid reprocessing postadjusting (adjust properties after preparation). Herein, for the first time, method combining Schiff base Diels-Alder adduct in one network developed achieve postadjusting. Through dissociation at high temperatures, cross-link densities reduced, thereby accelerating rearrangement realizing self-healing. Moreover, reconnecting degree can be easily controlled by annealing; as result, obtained CANs postadjustable. This work provides simple promising approach achieving via synergism an associative dynamic chemistry with dissociative chemistry.

Язык: Английский

---

Vitrimeric Polylactide by Two-step Alcoholysis and Transesterification during Reactive Processing for Enhanced Melt Strength

ACS Applied Materials & Interfaces, Год журнала: 2022, Номер 14(40), С. 45966 - 45977

Опубликована: Сен. 27, 2022

Because of its rather low melt strength, polylactide (PLA) has yet to fulfill promise as advanced biobased and biodegradable foams replace fossil-based polymer foams. In this work, PLA vitrimers were prepared by two-step reactive processing from commercial thermoplastics, glycerol, diphenylmethane diisocyanate (MDI) using Zn(II)-catalyzed addition transesterification chemistry. The reaction glycerol occurs with zinc acetate the catalyst, chain scission will take place due alcoholysis chains free hydroxyl groups glycerol. Long-chain can be obtained then cross-linked MDI. Rheological analysis shows that formed network significantly improve strength promote strain hardening under extensional flow. still maintain ability thermoplastic via extrusion compression. enhanced rearrangement topology facilitate foaming processing. An expansion ratio large 49.2-fold microcellular foam a uniform cell morphology for gel fraction 51.8% through supercritical carbon dioxide technique. This work provides new way scale-up possibility enhance PLA, broadened range applicability brought is truly valuable in terms realization sustainable society.

Язык: Английский

---

Recyclability of Vitrimer Materials: Impact of Catalyst and Processing Conditions

ACS Omega, Год журнала: 2022, Номер 7(33), С. 29125 - 29134

Опубликована: Авг. 9, 2022

With sustainability at the forefront of material research, recyclable polymers, such as vitrimers, have garnered increasing attention since their introduction in 2011. In addition to a traditional glass-transition temperature (Tg), vitrimers second topology freezing (Tv) above which dynamic covalent bonds allow for rapid stress relaxation, self-healing, and shape reprogramming. Herein, we demonstrate memory, reconfigurability properties function experimental conditions, aiming toward recyclability increased useful lifetime material. Of interest, report influence processing makes vulnerable degradation. We decreased crosslink density with thermal cycling compressive stress. Furthermore, that self-healing are enhanced catalyst concentration, while performance memory remains unchanged. Though temperature, clearly enhances recovery must emphasize its trade-off when considering degradation reported here. While hold great promise structural materials, it is vital understand how parameters impact properties, stability, reprocessability before reach true potential.

Язык: Английский

---

Sustainable polyester vitrimer capable of fast self-healing and multiple shape-programming via efficient synthesis and configuration processing

Journal of Materials Chemistry A, Год журнала: 2023, Номер 11(20), С. 10912 - 10926

Опубликована: Янв. 1, 2023

Considering that environmental friendliness and energy conservation are becoming crucial, it is urgent to advance the sustainability of materials in terms their lifecycle, including synthesis, processing, application.

Язык: Английский

---