A skin inspired bio-smart composite with water responsive shape memory ability

Abstract

Learned from skin, advanced functions have been added to existing materials with applications in regenerative machine and electronic skin. In this study, a skin collagen fiber/polyurethane (SCF/PU) composite with a dual-network based on a skin structural model was successfully prepared by a facile “paper-making” procedure. The first collagen nonwoven network was built up by spontaneous entangling and sticking of collagen fibers recycled from animal skin. Such a fibrous structure was then interpenetrated by waterborne PU. By virtue of chemo-mechanical adaptability of both the collagen fiber and PU elastomeric matrix, a water responsive shape memory with high shape fixation (99%) and shape recovery (>90%) has been achieved. Destruction and reformation of hydrogen bonds within the collagen fiber works as a “switch” to achieve shape deformation and fixation. This “switch” opens under the stimulation of water, while elastic entropy of PU promotes shape recovery. The obtained SCF/PU composite can be degradable in simulated body fluid whilst biological evaluation in vitro (MTT assay) proved that the SCF/PU composite has better biocompatibility than pure PU. The reported work offers a novel, simple and eco-friendly route for fabrication of a bio-smart material, which has potential for biomimetic sensors, regenerative medicine and artificial skins.