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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"mechanophores"”.
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Spiropyrans as color-generating mechanophores
… bond changes in force-sensitive molecules called mechanophores potentially allows a much wider range of polymer responses to be accessed. In an effort to show the feasibility of this concept, a series of spiropyran-based mechanophores were designed which were expected to undergo a 6-π …
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Synthesis and Development of Novel Cyclobutane Mechanophores
… mechanically active chemical moieties known as mechanophores. These mechanophores could then be utilized for localized self-healing or self-repair of polymer composites. To date there have been few attempts at systematically investigating the effects of mechanophore structure upon rates of …
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Control of mechanochromic reactions in a polymer matrix
Mechanophores are force sensitive molecules that undergo productive chemical transformations under a mechanical force including color change, small molecule release, and cross-linking. Productive chemical transformations depend on the intrinsic molecular structure as well as the extrinsic …
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Polymer architecture effects on mechanochemical reactions
… to undergo site-specific bond cleavage, termed mechanophores. An overarching theme in polymer mechanochemistry is that the polymer chains are the link between macroscopic energy and the mechanophore. Therefore, polymer architecture is thought to play a significant role in influencing these types …
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Mechanical and optical characterization of force induced chemical reactions in solid state linear polymers
… By linking force-sensitive chemical species (mechanophores) into polymer backbones, mechanical force can drive chemical reactions. Mechanophores have been developed with potential as damage sensing, self-healing, and self-reinforcing materials. This research investigates the conditions for …
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Investigating Shear-induced Damage during Hydrogel Extrusion-based Manufacturing: Rheological Insights and Mechanophore Incorporation
… printing conditions. The introduction of mechanophores into hydrogel structures was made to visually monitor and quantify shear-induced damage under different flow conditions. Hydrogels showed mechanochromic behaviour during extrusion due to the activation of spiropyran moieties, where …
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Mechanophore activation at heterointerface and surface crowdedness as a determining factor
… embedded polymers. However, behavior of mechanophores at heterointerfaces is particularly interesting, as interfaces in composite materials are often the weakest point where damage-reporting and self-healing are applicable. To achieve this goal, a model system was constructed to allow …
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The photochemical and mechanochemical ring opening of cyclobutene from first principles
… Finally, we apply AISMD and NEB to other new mechanophores that are currently being studied including gem-difluorocyclopropane and dicyano-cyclobutane. Both of these methods can be used to screen new mechanophores, which will aid in designing new polymeric materials that respond favorably to …
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Design and synthesis of mechanoresponsive materials and multivalent polymer-peptide conjugates
… examples of intrinsic functionalization. First, mechanophores are incorporated into polymers and impart function when materials are subjected to mechanical force. Second, multivalent polymer-peptide conjugates (mPPCs) are synthesized by the post polymerization modification of a polymer backbone …
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Electrospinning applications in mechanochemistry and multi-functional hydrogel materials
… productive when stress-sensitive molecules, or mechanophores, are incorporated into materials. One mechanophore that has been heavily investigated is spiropyran, a molecule that exhibits a color change when activated, although large strains are required to achieve this activation in elastomeric …
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Junctions and Strands: Breaking Property Tradeoffs in Polymer Networks and Composite Polymer Electrolytes
… incorporation of forceresponsive molecules (mechanophores) that may either toughen or weaken the material depending on network construction and topology. The first part of this thesis identifies a new class of mechanophores called tetrafunctional cyclobutanes (TCBs), which can be used to …
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Mechanochemical Reaction Development for Addition, Elimination, and Isomerization
… 2-methoxy-gem-difluorocyclopropane (MeO-gDFC) mechanophores in polymers. Pulsed ultrasonication of a MeO-gDFC containing polymer leads to one equivalent of HF release per MeO-gDFC activation. We further quantify the mechanochemical reactivity of MeO-gDFC by single molecule force spectroscopy, …
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Synthesis, Characterization, and Theory of Polymer Gels to Elucidate Topology-Property Relationships
… the revised fracture theory. Weak and strong mechanophores were used as crosslinkers in an end-linked network where the tearing energy was shown to correlate directly to the force-coupled reactivity of the linker. Tearing energy of mixed reactivity networks demonstrated that depercolation of …
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Controlling and Exploiting Spiropyran-based Mechanochromism
… reactions. These functionalities, known as mechanophores,</p><p>react to unveil a new molecular structure and triggering a constructive response. This</p><p>strategy has been explored for a variety of purposes, including stress sensing, stress</p><p>strengthening, small molecule release, …
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Towards reversible mechanochemically triggered strengthening, toughening and assembly of soft materials
… times. With the exception of color switching mechanophores, the majority of mechanochemical reactions developed in the lab are completely irreversible, thus limiting their function to a one time use. Spiropyran (SP) is a unique mechanophore that reversibly switches from a ring-closed state to …
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Force-induced mechanochemical reactions in polymeric systems
Chemical reactions traditionally rely on energy from stimuli such as heat, light, or electric fields to overcome activation barriers separating desired products from starting materials. In the field of mechanochemistry, the energy from mechanical force is harnessed to induce and direct chemical …
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Fracture-induced mechanophore activation and solvent healing in poly(methyl methacrylate)
… in engineering materials. The potential of using mechanophores, stress-sensitive molecules, as material stress sensors has been established through tensile, compressive and shear tests. Spiropyran (SP) has been the chosen mechanophore and this molecule undergoes a ring opening reaction …