Phase Separation and Gelation in Solutions and Blends of Heteroassociative Polymers

Macromolecules, Год журнала: 2023, Номер 56(14), С. 5661 - 5677

Опубликована: Июль 10, 2023

An equilibrium statistical mechanical theory for the formation of reversible networks in two-component solutions associative polymers is presented to account phase behavior due hydrogen-bonding, metal–ligand, electrostatic, or other pairwise heterotypic interactions. We derive explicit analytical expressions binding statistics, gelation condition, and free energy, which we consider types A B with many associating groups per chain only A–B association between groups. The energy approximated at mean-field level, considering overlapping polymer chains an ideal gas "stickers" capable intermolecular association. It shown that number associations maximized stoichiometric conditions Accordingly, homogeneous are most easily formed near groups, resulting a re-entrant sol–gel–sol transition as overall composition altered. Association network found be accompanied by tendency separation. These results demonstrate reversibly have large parameter space terms molecular design, mixture compositions. Our predictions expected useful rational design interacting mixtures networks.

Язык: Английский

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Microstructure, Viscoelasticity, and Extensional Rheology of Ethylene–Propylene Copolymer Vitrimers

Macromolecules, Год журнала: 2024, Номер 57(6), С. 2729 - 2745

Опубликована: Март 14, 2024

Vitrimers of ethylene–propylene (EP) copolymers were synthesized by postreactor melt reactions with a dynamic covalent cross-linker (diacrylate bis(dioxoborolane), DBDA) and dicumyl peroxide (DCP). A novel two-step synthetic route to prepare DBDA is presented. The EP vitrimer melts show the expected chain relaxation delay due network formation. This manifests as significant increase in elasticity, viscosity, extensional strain hardening. However, it was found that degree depends not only on amount added but also comonomer ratio (E/P) copolymer precursor. E/P determines cure kinetics well-known side (i.e., beta scission, branching, cross-linking) induced DCP copolymers. AFM SAXS studies reveal formation spherical nanodomains during curing. nonoccurrence macrophase separation cured vitrimers led us postulate are made clustered poly(DBDA) chains grafted onto backbones. complex topology, resulting from DCP-induced combined nanoclusters, possibly acting nanofillers, has strong effect structure–rheology correlations.

Язык: Английский

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Upcycling of PET from recycled food packaging trays via vitrimers chemistry

Polymer, Год журнала: 2022, Номер 266, С. 125618 - 125618

Опубликована: Дек. 16, 2022

Язык: Английский

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Vitrimer-like elastomers with rapid stress-relaxation by high-speed carboxy exchange through conjugate substitution reaction

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Окт. 5, 2024

We report vitrimer-like elastomers that exhibit significantly fast stress relaxation using carboxy exchange via the conjugate substitution reaction of α-(acyloxymethyl) acrylate skeletons. This network design is inspired by a small-molecule model shows even at ambient temperature in presence 1,4-diazabicyclo[2.2.2]octane (DABCO). The and acrylic acid copolymers are cross-linked bis[α-(bromomethyl)acrylates] doped with 10 wt% DABCO, exhibiting processability to obtain transparent film hot pressing. high-speed bond network, validated stress-relaxation tests, allows quick molding household iron. In addition, material applied as an adhesion sheet for plastic metal substrates. Because dynamic cross-linking proposed mechanism can be implemented any polymer bearing carboxyl pendants, our approach versatile backbones, which must thus meaningful practical sense.

Язык: Английский

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Dynamics of Associative Polymers with High Density of Reversible Bonds

Physical Review Letters, Год журнала: 2023, Номер 130(22)

Опубликована: Май 31, 2023

An associative polymer carries many stickers that can form reversible associations. For more than 30 years, the understanding has been associations change shape of linear viscoelastic spectra by adding a rubbery plateau in intermediate frequency range, at which have not yet relaxed and thus effectively act as crosslinks. Here, we design synthesize new classes unentangled polymers carrying unprecedentedly high fractions stickers, up to eight per Kuhn segment, strong pairwise hydrogen bonding ∼20kBT without microphase separation. We experimentally show bonds significantly slow down dynamics but nearly do spectra. This behavior be explained renormalized Rouse model highlights an unexpected influence on structural relaxation polymers.Received 3 May 2022Revised 2 February 2023Accepted 19 April 2023DOI:https://doi.org/10.1103/PhysRevLett.130.228101© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHydrogen bondsRheologyPhysical SystemsPolymer meltsPolymer networksTechniquesPolymer theoryRouse modelPolymers & Soft Matter

Язык: Английский

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