Synergistic influence of keratin and TPU: An approach towards bioinspired artificial skin

Abstract

Inspired from the keratin-elastin composition of the human skin, here we have developed a robust, flexible and biocompatible composite film of thermoplastic polyurethane (TPU) and bio-waste human hair keratin using extrusion-based melt-mixing method for artificial skin applications. During the melt-mixing, the molecules of TPU and keratin forms H-bonding among their polar functionalities. The H-bonding interaction between TPU and keratin molecules was studied and verified by FTIR and H-1 NMR results. Because of both the H-bonding interaction (between TPU and keratin) and lubricating behavior of cysteine-rich keratin, TPK exhibits unique mechanical and tribological performances. Hygroscopic keratin enhances the hydrophilicity and the porous morphology allows the moisture permeability of TPK. TPK containing 1 wt% keratin (i.e., 1% TPK) shows elastic modulus of 31.44 MPa, ultimate tensile strength (UTS) of 18.52 MPa, coefficient of friction (COF) of 0.18 and water contact angle of 85 degrees which are closer to that of the human skin of different body parts. Also, the 1% TPK shows very high toughness value of 77.5 J*m(-3)*10(6), which is similar to that of the mammalian collagen fibrils.