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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Reprocessable Covalent Adaptable Networks via Free-Radical Polymerization with an Aromatic Disulfide Cross-Linker

ACS Applied Polymer Materials, Год журнала: 2024, Номер 6(15), С. 9209 - 9218

Опубликована: Июль 22, 2024

Aromatic disulfides have seen widespread use in covalent adaptable networks (CANs), though previous studies exclusively used step-growth methods to integrate them into CANs. Here, we describe a case which an aromatic disulfide-based cross-linker, bis(4-methacryloyloxyphenyl) disulfide, also called BiPheS methacrylate or BPMA, is incorporated CAN by nonstep-growth polymerization. Free-radical copolymerization of n-hexyl with 5 mol % BPMA results exhibits full recovery cross-link density and thermomechanical properties across multiple reprocessing cycles. The rubbery-plateau storage modulus directly proportional absolute temperature, characteristic constant density, even at temperatures where the reprocessable. Indeed, BPMA-based thus associative dynamic character, up least 200 °C, enabling it be elevated-temperature applications without risk loss network character. Under 3.0 kPa shear stress, almost total arrest creep 180 °C major suppression its temperature overcoming potential Achilles' heel associated Thus, integration CANs free-radical polymerization provides facile route produce recyclable that maintain character very high contributing polymer sustainability. Finally, determined Arrhenius apparent activation energy ∼100 kJ/mol for stress relaxation viscosity. This value differs substantially from bond dissociation but agrees alpha-relaxation poly(n-hexyl methacrylate) (PHMA). indicates dependence these viscoelastic responses our associative-type defined cooperative segmental mobility PHMA, makes 95 CAN.

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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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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Optimizing Processing Conditions for Additively Reinforced Thermoforming (ART) in Convergent Manufacturing

Опубликована: Янв. 1, 2025

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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Covalent Adaptable Networks with Associative Siloxane Exchange Enabled by Amide‐Based Internal Catalysis: Designing for Reprocessability and Extrudability by Increasing the Cross‐Link Density

Advanced Functional Materials, Год журнала: 2025, Номер unknown

Опубликована: Май 9, 2025

Abstract Replacing non‐recyclable thermosets with covalent adaptable networks (CANs) that recover cross‐link density after reprocessing will reduce waste and contribute to a circular polymer economy. Many CANs undergoing associative dynamic exchange require catalysis. External catalysis often leads harmful effects, e.g., increased creep, accelerated material aging, catalyst leaching. Herein, internally catalyzed siloxane chemistry is demonstrated resulting from amides covalently linked through alkyl chains siloxanes. Small‐molecule studies show the formation of products reaction two amide‐containing molecules. From rubbery plateau modulus, each siloxane‐exchange‐based CAN exhibits temperature‐invariant, or nearly so, characteristic CANs. The length in siloxane‐containing monomer tunes network density. Cross‐link recovery achieved, required time temperature decreasing increasing Stress relaxation also faster dynamics reprocessability arise because second order (i.e., cross‐linker) concentration. Capitalizing on this, melt extrusion highest demonstrated, achieving same extruded compression‐molded Using identical conditions, next‐highest not extrudable.

Язык: Английский

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Biobased Polystyrene Vitrimers for Thermoset Circularity

ACS Applied Polymer Materials, Год журнала: 2024, Номер 6(21), С. 13034 - 13041

Опубликована: Окт. 25, 2024

Thermoset polymers, known for their robust thermomechanical and chemical durability, suffer from poor recyclability due to covalent cross-linking. This study explores the tunability of adaptable networks (CANs), specifically prepolymer-derived vitrimers, which offer both durability through dynamic cross-links. By utilizing biobased vanillin methacrylate (VnMA) Priamine cross-linkers, we synthesized polystyrene (PS) vitrimers with readily tunable viscoelastic properties. The vanillin-derived PS copolymer was cross-linked varying equivalents favor different exchange mechanisms: transamination rapid processability metathesis enhanced dimensional stability. Extending prepolymer chain length above entanglement threshold also introduced physical cross-links that significantly improved creep resistance. Our findings highlight a versatile approach creating biobased, reprocessable thermosets high performance. incorporation primary ability tune mechanisms promising pathway sustainable durable polymer materials suitable various applications. methodology enhances sustainability PS-based materials, broadening commercial utility.

Язык: Английский

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