Self external stimuli

Microcrack formation and crack propagatiOTi are a common cause of material failure. To overcome this problem, supramolecular polymer networks have been developed that can self-heal on the basis of the dynamic nature of their reversible cross-links [268]. The healing can either occur in an autonomous fashion or upmi exposure to an external stimulus such as heat, light, pressure, or mechanical stress. 

Liquid crystalline elastomers (LCEs) are materials that combine the properties of polymeric elastomers (entropy elasticity) with those of liquid crystals (self-organi-zation). They are the subject of several reviews and books [1-10]. Their most interesting property is the ability to change their shape reversibly after the application of a certain external stimulus. This feature was predicted by de Gennes as early... 

The first step of a cooperative molecular event is to receive an external stimulus, i.e., proton, metal ion, small molecule, light, heat, or pressure to produce conformational and configurational change, formation of self-assembly, or other aggregation. Subsequently, a change of structural, chemical, and/or physical properties (acidity, basicity, reactivity, binding affinity, redox potential, photophysical properties, magnetic properties) of the molecular system occurs and eventually results in cooperative events. 

Conditions prevailing inside the pit make it self-propagating without any external stimulus. Once initiated, the pit grows at an ever-increasing rate. 

This is the least violent type of munition response where any reaction is self-extinguished immediately upon the removal of the external stimulus. 

Self-actuating Actuation in response to an external stimulus Hwang and Lee (2006) and Datla et al. (2014)... 

Upon the first reduction, the voltammetric wave shifts by 20-30 mV, presumably due to donor-acceptor interactions resulting from the naphthalene and cyclophane moieties.39 The second reduction remains relatively unaffected, indicating that the complex disassembles prior to the second reduction of the cyclophane. Alternatively, the complex can disassemble through competitive binding interactions with a tetrathiafulvalene derivative. Thus, Cooke and coworkers demonstrate that self-assembly at exo-active surfaces can be reversibly controlled via an external electrochemical stimulus or competitive binding interactions. 

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