Materials that are capable of responding to internal or external stimuli, such as temperature, pH, ionic strength, concentration gradients, electric field, and light, have been of interest for a number of years. Responses include changes in polymer morphology, surface characteristics, and solubility, as well as self-assembly. Potential applications include changes of surface wettability, dimensions, opacity, color, electromagnetic signature, and bioactivity, to name some. Because of the tremendous interest in new materials and their importance for novel technologies, research themes involving stimuli responsiveness have accelerated.