Preparation of enediyne-crosslinked networks and their reactivity under thermal and mechanical conditions

Hickenboth, Charles R.; Rule, Joseph D.; Moore, Jeffrey S.

doi:10.1016/j.tet.2008.04.106

Cited by 32 publications

(35 citation statements)

References 44 publications

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“…These motifs are however well known to dissociate upon heating, exposure to light, and ultrasonication, and have previously been incorporated into various polymers. The latter were used as radical macroinitiators for the synthesis of well-defined block copolymers, [14][15][16][17][18][19][20][21] the fabrication of crosslinked PMMA microspheres, 22 and for the release of molecules grafted onto nanoparticles in imaging or delivery applications. 23,24 It was also shown that the azo-motif can be used to create mechanoresponsive materials that can be degraded upon ultrasonication in solution.…”

Section: Introductionmentioning

confidence: 99%

Azo-Containing Polymers with Degradation On-Demand Feature

2016

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ABSTRACT. Molecules comprising aliphatic azo moieties are widely used as radical polymerization initiators, but only few studies have explored their usefulness as stimuliresponsive motifs in macromolecular constructs. The controlled degradation of azo-containing polymers has indeed remained largely unexplored. Here we present the syntheses of linear azocontaining polyamides and polyurethanes and report on their thermally and optically induced responses in solution and the solid state. We show that the stimuli-induced degradation behavior depends strongly on the nature of the polymer backbone, the state of matter, and in solution, on the nature of the solvent. The stimuli-responsive solid-state properties of the azo-containing materials may be particularly useful. In the case of the polyurethanes studied here, temperatureor light-induced cleavage of the azo motifs led to a controllable decrease of the molecular weight, which in turn caused a reduction of the elongation at break, modulus and strength. The controlled degradation of the polymer in well-defined areas can be readily achieved via photopatterning, and this approach was shown to be useful to produce solid structures with graded mechanical properties.2

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Section: Introductionmentioning

confidence: 99%

Azo-Containing Polymers with Degradation On-Demand Feature

2016

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“…But COGEF (COnstrained Geometries simulating External Force modelling has predicted that under mechanical load, the enediyne ring can be distorted towards its cycloaromatisation transition state, lowering the activation barrier enough to spontaneously cyclise at ambient temperatures (mechanophore 3 in Table 2). 219 In an attempt to empirically prove this model, enediyne rings were incorporated into bulk poly(methyl methacrylate) as a cross-linker, and the cross-linked polymer was swelled with methyl methacrylate monomer. It was hypothesised that, if the dimensional expansion of the swollen polymer provided adequate force to elongate the enediyne cross-links enough to spontaneously cyclise, the resulting cyclised adducts could initiate detectable amounts of polymerisation of the methyl methacrylate monomer.…”

Section: Virgin Property Strengtheningmentioning

confidence: 99%

Self-healing polymers and composites

Mauldin¹,

Kessler²

2010

International Materials Reviews

231

136

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Inspired by the unique and efficient wound healing processes in biological systems, several approaches to develop synthetic polymers that can repair themselves with complete, or nearly complete, autonomy have recently been developed. This review aims to survey the rapidly expanding field of self-healing polymers by reviewing the major successful autonomic repairing mechanisms developed over the last decade. Additionally, we discuss several issues related to transferring these self-healing technologies from the laboratory to real applications, such as virgin polymer property changes as a result of the added healing functionality, healing in thin films v. bulk polymers, and healing in the presence of structural reinforcements.

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“…[8] The design of such materials in general requires a profound knowledge of the underlying dynamics, [2,[9][10][11][12] either those of individual chains or chain segments, intra-or intermolecular interactions as well as knowledge of the kinetics of chemical reactions, [4,5,[13][14][15][16][17][18][19][20][21][22] if they are involved.…”

Section: Introductionmentioning

confidence: 99%

Azide/Alkyne‐“Click”‐Reactions of Encapsulated Reagents: Toward Self‐Healing Materials

Gragert

Schunack

Binder

2011

Macromol. Rapid Commun.

120

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The successful encapsulation of reactive components for the azide/alkyne-"click"-reaction is reported featuring for the first time the use of a liquid polymer as reactive component. A liquid, azido-telechelic three-arm star poly(isobutylene) (M(n) = 3900 g · mol⁻¹) as well as trivalent alkynes were encapsulated into micron-sized capsules and embedded into a polymer-matrix (high-molecular weight poly(isobutylene), M(n) = 250,000 g · mol⁻¹). Using (Cu(I)Br(PPh₃)₃) as catalyst for the azide/alkyne-"click"-reaction, crosslinking of the two components at 40 °C is observed within 380 min and as fast as 10 min at 80 °C. Significant recovery of the tensile storage modulus was observed in a material containing 10 wt.-% and accordingly 5 wt.-% capsules including the reactive components within 5 d at room temperature, thus proving a new concept for materials with self-healing properties.

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Preparation of enediyne-crosslinked networks and their reactivity under thermal and mechanical conditions

Cited by 32 publications

References 44 publications

Azo-Containing Polymers with Degradation On-Demand Feature

Azo-Containing Polymers with Degradation On-Demand Feature

Self-healing polymers and composites

Azide/Alkyne‐“Click”‐Reactions of Encapsulated Reagents: Toward Self‐Healing Materials

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