Topology Matters: Conformation and Microscopic Dynamics of Ring Polymers

Macromolecules, Journal Year: 2023, Volume and Issue: 56(18), P. 7203 - 7229

Published: Sept. 2, 2023

Ring polymers have fascinated theorists, simulators, and experimentalists as they are the simplest polymer without ends, giving rise to important topology related properties. We present state of art recent synthetic efforts investigations into structure dynamics dense nonconcatenated ring systems. Analyzing existing knowledge, we identify challenges for future research: In realm synthesis creation well-defined high molecular weight rings based on different monomers highly desirable. field conformations, existence double folded structures that at basis many theoretical approaches was severely challenged further scrutiny is needed. Similarly, issue size dependent transition mass fractal structures, or effect local stiffness conformation open questions. The role ring–ring threading in terminal needs be elucidated. particular, novel proposed topological glass very melts awaits experimental verification. Experimentally, ring-linear blends seldomly investigated: only a small number studies miscibility such available. Microscopic experiments nearly entirely missing. Finally, always backed by corresponding simulations, crucial task would find out how connect each other which should performed.

Language: Английский

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Enabling Closed‐Loop Circularity of “Non‐Polymerizable” α, β‐Conjugated Lactone Towards High‐Performance Polyester with the Assistance of Cyclopentadiene

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(22)

Published: March 16, 2024

Abstract Chemical recycling of polymers to monomers presents a promising solution the escalating crisis associated with plastic waste. Despite considerable progress made in this field, primary efforts have been focused on redesigning new produce readily recyclable polymers. In contrast, limited research into potential seemingly “non‐polymerizable” has conducted. Herein, we propose paradigm that leverages “chaperone”‐assisted strategy establish closed‐loop circularity for α, β‐conjugated lactone, 5,6‐dihydro‐2H‐pyran‐2‐one (DPO). The resulting PDPO, structural analogue poly(δ‐valerolactone) (PVL), exhibits enhanced thermal properties melting point ( T m ) 114 °C and decomposition temperature d,5% 305 °C. Notably, owing similarity between DPO δ‐VL, copolymerization generates semi‐crystalline P(DPO‐ co ‐VL)s irrespective incorporation ratio. Intriguingly, inherent C=C bonds enable their convenient post‐functionalization via Michael‐addition reaction. Lastly, PDPO was demonstrated be chemically ring‐closing metathesis (RCM), representing significant step towards pursuit enabling lactones without altering ultimate polymer structure.

Language: Английский

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Air and Thermally Stable Cyclic (Alkyl)(amino)carbene Ruthenium Complexes for Efficient Ring Expansion Metathesis Polymerization

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 8, 2025

Ring expansion metathesis polymerization (REMP) has emerged as a potent strategy for obtaining cyclic polymers over the past two decades. The scope of monomers, however, remains limited due to poor functional group tolerance and stability catalyst, necessitating rational catalyst design address this constraint. Here, we present ruthenium complexes featuring tethered (alkyl)(amino)carbene ligands REMP, aiming deepen our understanding structure–property relationship in newly designed catalysts. Notably, these catalysts exhibit remarkable thermal even air, confirmed through monitoring air-exposed solution at 80 °C. In addition, initiation rate was effectively modulated by tuning steric hindrance N-aryl substituent, adjusting chain lengths, or introducing Blechert-type ligand. Based on systematic studies catalysts, successfully demonstrate challenging REMP allene (2,8-dimethylnona-4,5-diene) first time, well methyl-5-norbornene-2-carboxylate, resulting polymers. We also note that exceptional enables under air. This study provides valuable insights into introduces novel, user-friendly platform synthesis

Language: Английский

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Click chemistry in polymer science

Chem, Journal Year: 2023, Volume and Issue: 9(9), P. 2416 - 2424

Published: Sept. 1, 2023

Language: Английский

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Kinetics of heterogeneous polymerization of glycidol with B(C6F5)3 in toluene in the absence and presence of water

Materials Today Chemistry, Journal Year: 2024, Volume and Issue: 37, P. 101993 - 101993

Published: March 7, 2024

The synthesis of polyglycidol (or polyglycerol) using tris-(pentafluorophenyl)borane [B(C6F5)3] as a catalyst produces branched structure with cyclic core by mechanism zwitterionic ring expansion polymerization. solvent choice is limited since the polymerization does not occur in good solvents for (e.g. DMF, DMSO). In poor but glycidol toluene), heterogeneous manner. polymer precipitates during reaction forming two phases, solution and precipitated phase. presence water competitive initiation consisting formation hydronium ions between B(C6F5)3 molecules, followed protonation (Gly) epoxide responsible analogous linear-core structures. present study we evaluated kinetic parameters initial stage Gly absence situ 1H NMR monitoring toluene-d8 results indicated first order kinetics respect to B(C6F5)3, zero water, similar rate constants initiated H3O+ activation energies water. decrease intensity 19F signal relative value that goes phase just after started due change solubility formed oligomeric active chains carry catalyst. precipitate, continued chain fusion events take place increasing molecular weight producing product identical mass distribution produced under dry solvent-free conditions. Density functional theory calculations supported data obtaining energy barriers thermodynamic enthalpies H3O+.

Language: Английский

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Programming mechanical properties through encoded network topologies

Journal of Polymer Science, Journal Year: 2024, Volume and Issue: 62(16), P. 3663 - 3680

Published: Jan. 12, 2024

Abstract Polymer networks remain an essential class of soft materials. Despite their use in everyday materials, connecting the molecular structure network to its macroscopic properties remains active area research. Much current research is enabled by advances modern polymer chemistry providing unprecedented level control over macromolecular structure. At same time, renewed interest self‐healing, dynamic, and/or adaptable materials continues drive substantial design. As part a special issue focused on performed Science and Engineering Department at University Massachusetts, Amherst, this review highlights connections between observed mechanical as investigated Tew group.

Language: Английский

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Computational Analysis of the Lewis Acid-Catalyzed Zwitterionic Ring-Expansion Polymerization (ZREP) of Monosubstituted Ethylene Oxide

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 6, 2025

This study investigates the reaction mechanism of zwitterionic ring expansion polymerization (ZREP) monosubstituted ethylene oxide using boron-based Lewis acids as catalysts to produce cyclic polyethers. The research analyzes various parameters, such nature substituents (electron-withdrawing, EWG or electron-donating, EDG), type catalyst, and solvent, understand their influence on reaction's kinetics, thermodynamics, regioselectivity. Key findings include that EDGs lower kinetic barrier rate-determining step favor at substituted carbon, while EWGs increase this barrier, making less favorable. also shows all tested efficiently activate epoxide monomer with similar barriers for step, regioselectivity trends align substituent's electronic effects. Steric effects were found dominate competition between addition cyclization termination, most promoting cyclization. Additionally, solvent had minimal impact mechanism. computational provides valuable insights into synthesis polymers advances development ZREP oxide.

Language: Английский

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Side-Chain Architecture-Dependent Thermoresponsive Behaviors of Graft Polymers with Poly(N-isopropylacrylamide) Pendants

Macromolecules, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 30, 2025

The variations of side-chain architecture can significantly affect the thermoresponsive behaviors graft polymers. This study is aimed at designing linear polymers with or cyclic pendants (LGPLs/LGPCs) to elucidate distinct thermostability polymer solutions. Three pairs poly(N-isopropylacrylamide) (PNIPAM)-bearing a weight-average number (Ng) up 16 are synthesized by combination ring-first method, fractionation, and topology transformation. chain thermosensitivity aqueous solutions, in which thermo-induced maximal transmittance, light scattering intensity, fluorescence intensity ratio related amide–water hydrogen bonding drastically decrease incorporation an increase Ng. LGPLs pronounced entanglement self-assemble into thermostable lamellae, while other assemblies subjected sphere-to-vesicle vesicle-to-lamella transitions. research affords promising method construct variable architectural parameters achieve topology-dependent behaviors.

Language: Английский

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Large-Scale Synthesis of Polymer Rings by Electrostatic-Mediated Closure of Single-Chain Nanoparticles

Macromolecules, Journal Year: 2025, Volume and Issue: unknown

Published: April 3, 2025

Language: Английский

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Cyclic Poly(Thioester Amide)s via Ring-Opening Copolymerization of Aziridines and Phthalic Thioanhydride: Mechanistic Insights and Enhanced Properties for Sustainable Materials

Macromolecules, Journal Year: 2025, Volume and Issue: unknown

Published: May 7, 2025

Language: Английский

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