Phase separation in supramolecular and covalent adaptable networks

Kloots, Martijn Hans Paul de Heer; Schoustra, Sybren K.; Dijksman, Joshua A.; Smulders, Maarten M. J.

doi:10.1039/d3sm00047h

Cited by 11 publications

(9 citation statements)

References 219 publications

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“…On the other hand, nanophase separation has been reported for some supramolecular and covalent adaptable networks including vitrimer-like systems and vitrimers (see, e.g., refs − ). Also, microphase separation is found in polymers with transient bonds, in systems that include immiscible chains and functional groups (see, e. g. , ).…”

mentioning

confidence: 99%

Microscopic Evidence for the Topological Transition in Model Vitrimers

Arbe,

Alegría,

Colmenero

et al. 2023

ACS Macro Lett.

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In addition to the glass transition, vitrimers undergo a topological transition from viscoelastic liquid to viscoelastic solid behavior when the network rearrangements facilitated by dynamic bond exchange reactions freeze. The microscopic observation of this transition is elusive. Model polyisoprene vitrimers based on imine dynamic covalent bonds were synthesized by reaction of α,ω-dialdehyde-functionalized polyisoprenes and a tris(2aminoethyl)amine. In these dynamic networks nanophase separation of polymer and reactive groups leads to the emergence of a relevant length scale characteristic for the network structure. We exploited the scattering sensitivity to structural features at different length scales to determine how dynamical and topological arrests affect correlations at segmental and network levels. Chains expand obeying the same expansion coefficient throughout the entire viscoelastic region, i.e., both in the elastomeric regime and in the liquid regime. The onset of liquid-like behavior is only apparent at the mesoscale, where the scattering reveals the reorganization of the network triggered by bond exchange events. The such determined "microscopic" topological transition temperature is compared with the outcome of "conventional" methods, namely viscosimetry and differential scanning calorimetry. We show that using proper thermal (aging-like) protocols, this transition is also nicely revealed by the latter.

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confidence: 99%

Microscopic Evidence for the Topological Transition in Model Vitrimers

Arbe,

Alegría,

Colmenero

et al. 2023

ACS Macro Lett.

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“…This can be expected, as xylylene groups have been applied in other materials to create tougher networks compared to materials made with simpler linear amines . A possible explanation for this might be that π–π stacking of the aromatic rings forms additional (weak) supramolecular cross-links in the polymer network . Next, by comparing the Cad and MeP materials, we observed that branching of the diamine structure significantly improved the solubility of the materials for all tested solvents.…”

Section: Resultsmentioning

confidence: 63%

“…52 A possible explanation for this might be that π−π stacking of the aromatic rings forms additional (weak) supramolecular crosslinks in the polymer network. 53 Next, by comparing the and MeP materials, we observed that branching of the diamine structure significantly improved the solubility of the materials for all tested solvents. In addition, a decrease in the modulus (both in the glassy and rubbery region) and also in the T g (determined from the peak of tan(δ) in temperature sweep measurements) was also observed for MeP compared to Cad, indicating a more flexible network and a lower cross-link density.…”

Section: ■ Results and Discussionmentioning

confidence: 89%

Probing the Solubility of Imine-Based Covalent Adaptable Networks

Schoustra,

Asadi,

Smulders

2023

ACS Appl. Polym. Mater.

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Covalent adaptable networks (CANs) are polymer materials that are covalently cross-linked via dynamic covalent bonds. The cross-linked polymer network is generally expected to be insoluble, as is seen for traditional thermosets. However, in recent years, it has become apparent that�under certain conditions�both dissociative and associative CANs can be dissolved in a good solvent. For some applications (e.g., those that require long-term (chemical) stability), the solubility of CANs can be problematic. However, many forget that (selective) solubility of CANs can also be applied advantageously, for example, in recycling or modification of the materials. In this work, we provide results and insights related to the tunable solubility of iminebased CANs. We observed that selected CANs could be fully dissolved in a good solvent without observing dissociation of imines. Only in an acidic environment (partial) dissociation of imines was observed, which could be reverted to the associated state by addition of a base. By adjusting the network composition, we were able to either facilitate or hamper solubility as well as control the size of the dissolved particles. DLS showed that the size of dissolved polymer particles decreased at lower concentrations. Similarly, decreasing cross-linking density resulted in smaller particles. Last, we showed that we could use the solubility of the CANs as a means for chemical recycling and postpolymerization modification. The combination of our studies with existing literature provides a better understanding of the solubility of CANs and their applications as recyclable thermosets.

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“…Another strategy for controlling creep in vitrimers involves utilizing phase separation. Although the influence of phase separation on viscoelastic properties of polymers is well known, only a handful of studies have explored it for vitrimers. − For example, Epps’ and Sumerlin’s groups investigated block copolymer vitrimers based on vinylogous urethane acrylates . They reported that compared to homogenous counterparts, the microphase-separated vitrimers exhibited lower creep due to lower network strand diffusion.…”

Section: Introductionmentioning

confidence: 99%

Reprocessable Biobased Statistical and Block Copolymer Methacrylic-Based Vitrimers with a Shape Memory Effect

Asempour,

Laurent,

Ecochard

et al. 2023

ACS Appl. Polym. Mater.

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Transitioning to a circular bioeconomy requires shifting away from conventional petroleum-based thermosets to recyclable biobased materials. We developed reprocessable and shape-memory biobased vitrimers with controlled architecture and enhanced creep resistance. A series of prepolymers of lignin-based vanillin methacrylate (VMA), with a mixture of vegetable oil-derived methacrylic esters with an average alkyl side chain length of 13 units (C13MA), and glycidyl methacrylate (GMA) were synthesized: statistical copolymer poly-(C13MA-co-vMA), block copolymer poly(C13MA-block-VMA), and statistical terpolymer poly(C13MA-co-VMA-co-GMA). Reversible addition−fragmentation chain-transfer (RAFT) polymerization allowed control over the backbone structure of statistical and block copolymers with similar overall molecular weights and compositions. Vitrification via aldehyde-functional VMA units with isophorone diamine enabled dynamic imine crosslinking, while adding the epoxy-functional GMA into the statistical terpolymer precursor enabled hybrid static−dynamic crosslinking networks. Vitrimers showed excellent retention of thermomechanical properties after 4× reprocessing cycles. Microphase separation was confirmed in the "hard−soft" type of block vitrimers. While statistical vitrimers showed comparable tensile properties, self-assembled block vitrimers exhibited poor tensile strength. Additionally, we compared the creep control using microphase separation and a hybrid network. Both methods reduced creep (up to 84%), but hybrid crosslinking caused significantly slower stress relaxation. A temperature-triggered shape memory effect was incorporated into the statistical vitrimer with two shape-programming cycles. Combining C13MA and VMA presents a rich platform for greener vitrimers with highly tunable properties and functionalities.

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Phase separation in supramolecular and covalent adaptable networks

Abstract: Phase separation phenomena have been studied widely in the field of polymer science, and were recently also reported for dynamic polymer networks (DPNs). The mechanisms of phase separation in dynamic...

Cited by 11 publications

References 219 publications

Microscopic Evidence for the Topological Transition in Model Vitrimers

Microscopic Evidence for the Topological Transition in Model Vitrimers

Probing the Solubility of Imine-Based Covalent Adaptable Networks

Reprocessable Biobased Statistical and Block Copolymer Methacrylic-Based Vitrimers with a Shape Memory Effect

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