title: Reversible thermosensitive biodegradable polymeric actuators based on confined crystallization.
abstract: We discovered a new and unexpected effect of reversible actuation of ultrathin semicrystalline polymer films. The principle was demonstrated on the example of thin polycaprolactone-gelatin bilayer films. These films are unfolded at room temperature, fold at temperature above polycaprolactone melting point, and unfold again at room temperature. The actuation is based on reversible switching of the structure of the hydrophobic polymer (polycaprolactone) upon melting and crystallization. We hypothesize that the origin of this unexpected behavior is the orientation of polycaprolactone chains parallel to the surface of the film, which is retained even after melting and crystallization of the polymer or the "crystallization memory effect". In this way, the crystallization generates a directed force, which causes bending of the film. We used this effect for the design of new generation of fully biodegradable thermoresponsive polymeric actuators, which are highly desirable for bionano-technological applications such as reversible encapsulation of cells and design of swimmers.
authors: Leibniz-Institut für Polymerforschung Dresden e.V. , Hohe Strasse 6, 01069 Dresden, Germany.
authors: Vladislav
authors: V
authors: Stroganov
authors: Mahmoud
authors: M
authors: Al-Hussein
authors: Jens-Uwe
authors: JU
authors: Sommer
authors: Andreas
authors: A
authors: Janke
authors: Svetlana
authors: S
authors: Zakharchenko
authors: Leonid
authors: L
authors: Ionov
mesh_terms: D063566:Biodegradable Plastics / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004343:Drug Implants / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D008422:Materials Testing; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011091:Polyesters / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature
chemical_list: D063566:Biodegradable Plastics; D004343:Drug Implants; D011091:Polyesters; C016240:polycaprolactone; D005780:Gelatin
keywords: Reversible actuators; confined crystallization; polycaprolactone; stimuli-responsive; thermoresponsive