Covalent Adaptable Networks Made by Reactive Processing of Highly Entangled Polymer: Synthesis-Structure-Thermomechanical Property-Reprocessing Relationship in Covalent Adaptable Networks

Macromolecules, Год журнала: 2024, Номер 57(6), С. 2756 - 2772

Опубликована: Март 6, 2024

Reactive processing provides a simple approach for grafting dynamic covalent cross-linkers onto linear or branched polymers, resulting in adaptable networks (CANs). We synthesized poly(n-hexyl methacrylate) (PHMA) CANs from neat, entangled PHMA using radical-based reactive to graft the cross-linker called BiTEMPS methacrylate (BTMA) between side chains. By tuning BTMA loading, we achieved range of cross-link densities and characterized how stress relaxation, elevated-temperature creep, reprocessability are affected by density. The cross-links chains allowed novel comparison our reversible, polymers described sticky reptation theory, which long-time relaxation occurs unraveling backbone entanglements, process enabled dissociation subsequent exchange side-chain "stickers." observed two regimes that required their fitting combination stretched exponential decay functions extract pertinent parameters. apparent activation energies creep viscosity same within experimental uncertainty these CANs, verifying shared mechanisms governing temperature dependence viscoelastic responses, independent CAN Notably, made linking ∼50–60% those reported previously with chain backbones. These outcomes demonstrate importance synthesis-structure-property-reprocessing relationships may be various methods varying position incorporation structure.

Язык: Английский

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Polypropylene Covalent Adaptable Networks with Full Cross-Link Density Recovery after Reprocessing: Development by Free-Radical Reactive Processing with Resonance-Stabilized, Aromatic Disulfide Cross-Linkers

ACS Macro Letters, Год журнала: 2025, Номер unknown, С. 341 - 348

Опубликована: Март 5, 2025

A single-step method that produces percolated, dynamic covalent cross-links integrated into the PP homopolymer has not been previously demonstrated. Here, we synthesized adaptable networks (CANs) from polypropylene (PP) homopolymers using 180 °C, radical-based, reactive processing with a free-radical initiator, dicumyl peroxide (DCP), and resonance-stabilized, aromatic disulfide cross-linkers, one methacrylate-based another phenyl acrylate-based. Both cross-linkers yielded when reactively processed at 4 wt % relatively high molecular weight (MW) (melt flow index (MFI) = 12) DCP. The acrylate-based cross-linker also other studied DCP/cross-linker concentrations low MW (MFI 35). Notably, our highest cross-link density CAN exhibited full recovery of after three reprocessing steps by compression molding; within experimental uncertainty melt extrusion.

Язык: Английский

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BiTEMPS methacrylate dynamic covalent cross-linker providing rapid reprocessability and extrudability of covalent adaptable networks: high-yield synthesis with strong selectivity for disulfide linkages

Polymer Chemistry, Год журнала: 2024, Номер 15(21), С. 2167 - 2176

Опубликована: Янв. 1, 2024

A dialkylamino disulfide-based dynamic covalent cross-linker (BTMA) was synthesized with high purity and selectivity for disulfides used to produce rapidly reprocessable extrudable adaptable networks n -hexyl methacrylate.

Язык: Английский

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Increasing the cross-link density in a dual dissociative and associative polythiourethane covalent adaptable network improves both creep resistance and extrudability

Polymer, Год журнала: 2024, Номер 306, С. 127232 - 127232

Опубликована: Июнь 1, 2024

Язык: Английский

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Rapidly Self‐Healable and Melt‐Extrudable Polyethylene Reprocessable Network Enabled with Dialkylamino Disulfide Dynamic Chemistry

Macromolecular Rapid Communications, Год журнала: 2024, Номер 45(22)

Опубликована: Июль 24, 2024

Abstract Catalyst‐free, radical‐based reactive processing is used to transform low‐density polyethylene (LDPE) into covalent adaptable networks (PE CANs) using a dialkylamino disulfide crosslinker, BiTEMPS methacrylate (BTMA). Two versions of BTMA are used, BTMA‐S 2 , with nearly exclusively bridges, and n mixture oligosulfide produce S PE CAN CAN, respectively. The two CANs exhibit identical crosslink densities, but the manifests faster stress relaxation, average relaxation times ∼4.5 shorter than those over 130 160 °C temperature range. more rapid dynamics translate compression‐molding reprocessing time at only 5 min (vs 30 for CAN) achieve full recovery density. Both melt‐extrudable within experimental uncertainty density after extrusion. self‐healable, crack fully repaired original tensile properties restored or 60 slightly above LDPE melting point without assistance external forces.

Язык: Английский

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Synthesis of polyethylene-based covalent adaptable networks including 1,2,3-triazolium or imine dynamic cross-links by reactive processing

Polymer, Год журнала: 2024, Номер 307, С. 127281 - 127281

Опубликована: Июнь 12, 2024

Язык: Английский

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Extrudable and Highly Creep-Resistant Covalent Adaptable Networks Made from Polyethylene and Ethylene/1-Octene Copolymers by Reactive Processing with Aromatic Disulfide Cross-Links

ACS Applied Polymer Materials, Год журнала: 2024, Номер unknown

Опубликована: Дек. 3, 2024

Polyolefins like polyethylene (PE) and ethylene-based copolymers are widely used in consumer industrial applications due to their versatility, the diversity tunability of properties, theoretical recyclability at elevated temperatures. However, recycling rates markedly low, and, though cross-linking PE enhances its properties through creation a networked architecture, resulting thermoset known as PEX is rendered completely unrecyclable. Incorporating associative or dissociative dynamic covalent bonds cross-links into plastics promising route both make use spent (via "upcycling" them) generate recyclable alternatives unrecyclable thermosets PEX. Such materials adaptable networks CANs (also called vitrimers if exclusively associative). Here, we present method for imbuing polymers with aromatic disulfide cross-links, robust, reprocessable CANs. Radical-based reactive processing ethylene/1-octene-based 1 wt % dicumyl peroxide 5 bis(4-methacryloyloxyphenyl) (BiPheS methacrylate BPMA) successfully resulted which fully recovered cross-link densities associated thermomechanical after multiple reprocessing cycles. These demonstrate remarkable elevated-temperature creep resistance high-temperature thermal stability high temperatures required exchanges BiPheS-based cross-links. copolymer also enable (re)processability via extrusion temperatures, property recovery demonstrated 260 °C, thereby indicating feasibility extending our approach scales processes well other rigorous applications.

Язык: Английский

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Reprocessable Polymer Networks Containing Sulfur‐Based, Percolated Dynamic Covalent Cross‐Links and Percolated or Non‐Percolated, Static Cross‐Links

Macromolecular Rapid Communications, Год журнала: 2024, Номер unknown

Опубликована: Июль 11, 2024

Abstract One method to improve the properties of covalent adaptable networks (CANs) is reinforce them with a fraction permanent cross‐links without sacrificing their (re)processability. Here, simple synthesize poly( n ‐hexyl methacrylate) (PHMA) and ‐lauryl (PLMA) containing static dialkyl disulfide (utilizing bis(2‐methacryloyl)oxyethyl disulfide, or DSDMA, as cross‐linker) dynamic dialkylamino sulfur‐sulfur BiTEMPS methacrylate dissociative presented. The robustness (re)processability CANs are demonstrated, including full recovery cross‐link density after recycling. authors also investigate effect content on stress relaxation responses percolated, cross‐links. As PHMA PLMA have very different activation energies respective cooperative segmental mobilities, it shown that dominated by dissociation rather than relaxations backbone segments, i.e., alpha relaxation. In cross‐links, side chains, beta relaxation, critical in allowing for large‐scale governs

Язык: Английский

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Reprocessable Polypropylene Covalent Adaptable Networks via Free-Radical Reactive Processing with Vinyl Aromatic Additives

Macromolecules, Год журнала: 2025, Номер unknown

Опубликована: Апрель 23, 2025

Язык: Английский

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Increasing the Cross-Link Density in a Dual Dissociative and Associative Polythiourethane Covalent Adaptable Network Improves Both Creep Resistance and Extrudability

Опубликована: Янв. 1, 2024

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Язык: Английский

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