Identifying the Role of Primary and Secondary Interactions on the Mechanical Properties and Healing of Densely Branched Polyimides

Susa, Arijana; Mordvinkin, Anton; Saalwächter, Kay; Zwaag, Sybrand van der; Garcia, Santiago J.

doi:10.1021/acs.macromol.8b01396

Cited by 25 publications

(37 citation statements)

References 51 publications

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“…70,71 Hydrophobic groups were even used in order to provide self-healing properties by plasticizing effect of alkyl flexible chains. 72 On the other hand, strong metal complex based stickers can also make clusters and lead to nanoscale heterogeneity able to enforce the mechanical strength. 73 Other studied supramolecular polymers bearing carboxylic acid, UPy, or THY side groups can also show phase separation and change polymer dynamics significantly.…”

Section: Phase Separationmentioning

confidence: 99%

A Critical Approach to Polymer Dynamics in Supramolecular Polymers

Golkaram

Loos

2019

Macromolecules

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Over the past few years, the concurrent (1) development of polymer synthesis and (2) introduction of new mathematical models for polymer dynamics have evolved the classical framework for polymer dynamics once established by Doi–Edwards/de Gennes. Although the analysis of supramolecular polymer dynamics based on linear rheology has improved a lot recently, there are a large number of insecurities behind the conclusions, which originate from the complexity of these novel systems. The interdependent effect of supramolecular entities (stickers) and chain dynamics can be overwhelming depending on the type and location of stickers as well as the architecture and chemistry of polymers. This Perspective illustrates these parameters and strives to determine what is still missing and has to be improved in the future works.

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Section: Phase Separationmentioning

confidence: 99%

A Critical Approach to Polymer Dynamics in Supramolecular Polymers

Golkaram

Loos

2019

Macromolecules

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“…An additional proof of the presence of effective supramolecular interactions comes from the measure of G ′ and G ″ slopes in the terminal relaxation region (for HDI_C8DA in Figure 4A, slope G ′ = 1.5, slope G ″ = 0.8), which severely deviate from slopes of ideal Rousian dynamics (2 and 1) as previously reported in comparable branched healing polymers. 26…”

Section: Results and Discussionmentioning

confidence: 99%

Controlling Healing and Toughness in Polyurethanes by Branch-Mediated Tube Dilation

et al. 2019

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In this work, we propose the use of regular branching of polyurethanes as a way to regulate chain dynamics and govern crystallization in highly dense hydrogen-bonded systems. As a result, robust and healable polyurethanes can be obtained. To this end, we synthesized a range of aliphatic propane diol derivatives with alkyl branches ranging from butyl (C4) to octadecanyl (C18). The series of brush polyurethanes was synthesized by polyaddition of the diols and hexamethylene diisocyanate. Polyurethanes with very short (C < 4) and very long (C = 18) brush lengths did not lead to any significant healing due to crystallization. An intermediate amorphous regime appears for polymers with middle branch lengths (C = 4 to 8) showing a fine control of material toughness. For these systems, the side chain length regulates tube dilation, and significant macroscopic healing of cut samples was observed and studied in detail using melt rheology and tensile testing. Despite the high healing degrees observed immediately after repair, it was found that samples with medium to long length brushes lost their interfacial strength at the healed site after being heated to the healing temperature for some time after the optimal time to reach full healing. Dedicated testing suggests that annealed samples, while keeping initial tackiness, are not able to completely heal the cut interface. We attribute such behavior to annealing-induced interfacial crystallization promoted by the aliphatic branches. Interestingly, no such loss of healing due to annealing was observed for samples synthesized with C4 and C7 diols, which is identified as the optimal healing regime. These results point at the positive effect of branching on healing, provided that a critical chain length is not surpassed, as well as the need to study healing behavior long after the optimal healing times.

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“…Some materials achieve self-healing trading off stability [3] while remaining fully autonomous. Others, instead, do not give up their mechanical properties but sacrifice autonomy to earn their healing ability [4], often involving secondary interactions [25][26][27][28]. Alternatively, it is possible to achieve autonomous self-healing embedding healing agents in the material [8][9][10], trading off repeatability and perhaps quality.…”

Section: Discussionmentioning

confidence: 99%

Swap-Driven Self-Adhesion and Healing of Vitrimers

Ciarella

Ellenbroek

2019

Coatings

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Vitrimers are covalent network materials, comparable in structure to classical thermosets. Unlike normal thermosets, they possess a chemical bond swap mechanism that makes their structure dynamic and suitable for activated welding and even autonomous self-healing. The central question in designing such materials is the trade-off between autonomy and material stability: the swap mechanism facilitates the healing, but it also facilitates creep, which makes the perfectly stable self-healing solid a hard goal to reach. Here, we address this question for the case of self-healing vitrimers made from star polymers. Using coarse-grained molecular dynamics simulations, we studied the adhesion of two vitrimer samples and found that they bond together on timescales that are much shorter than the stress relaxation time. We showed that the swap mechanism allows the star polymers to diffuse through the material through coordinated swap events, but the healing process is much faster and does not depend on this mobility.

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Identifying the Role of Primary and Secondary Interactions on the Mechanical Properties and Healing of Densely Branched Polyimides

Cited by 25 publications

References 51 publications

A Critical Approach to Polymer Dynamics in Supramolecular Polymers

A Critical Approach to Polymer Dynamics in Supramolecular Polymers

Controlling Healing and Toughness in Polyurethanes by Branch-Mediated Tube Dilation

Swap-Driven Self-Adhesion and Healing of Vitrimers

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