3D microfabrication using biomimetic self - folding polymer films
Nature offers an enormous arsenal of ideas for the design of novel materials with superior properties and interesting behaviors. In particular, self-assembly and self-organization, which are fundamental to structure formation in nature, attract significant interest as promising concepts for the design of intelligent materials. Self-folding stimuli-responsive polymers are exemplary biomimetic materials and can be viewed as model systems for bioinspired actuation. Such polymeric objects, on one hand, mimic movement mechanisms in certain plant organs and, on the other hand, are able to self-organize and form complex 3D structures. These self-folding objects consist of two polymers with different properties and one of these polymers, the active one, must change its volume more than the other one in response to changes in the external signals such as temperature, pH or light. Because of this non-equal expansion of polymers, bilayer films are able, for example, to form tubes, capsules or more complex structures. Similar to origami, the self-folding polymeric films provide unique possibilities for the straightforward fabrication of highly complex 3D micro-structures with patterned inner and outer walls that cannot be achieved using other currently available technologies. In this contribution, we demonstrate that the external shape of polymer bicomponent systems is able to direct their folding in a sophisticated manner leading to highly complex hierarchical folding.
College of Engineering, College of Family and Consumer Sciences, University of Georgia, Athens, GA 30602, USA