Biomimetic preparation and multi-sc ale microstructures of nano-sil ica/polyurethane elastomeric fibers

B i oinspired by t he spinnin g of spider silks, the b iomimetic preparation of nano-silica/polyure than e(n ano-SiO2/TPU) elastomeric fibers with distinctive m ulti-scale m icro structures was successfully implemented. The f ormation m ech an i sm of the nano-SiO2/TPU fibers was considered as the integrated mechanism of diffusion,coagulation, self-assembly, and microp hase separation, same as that of the native s pider silks. The m ass ratio of nano-SiO2to TPU greatly in flu e nced the e xternal a nd inner m icrostructures o f the n ano-SiO2/TPU fibers. The formation process of the nano-SiO2/TPU fibers was simply described as thre e m ain stages , and the second stage,such as the a dding of the e thanol solv en ts an d nano-SiO2in different diameters, was t ho ught to be very crucialfor the final external and inner microstructures of th e prep aredfibers. For example, th e add ing of t he ethanol and the nano-SiO2 spheres i n diameter of 10 nm resulted in the existence of many TPU-self-assemb led microspheres mostly spaced apart by the nano-SiO2 aggregates in the nano-SiO2/TPU fibers, while the a dd ing of the ethanol and t he nano-SiO2 spheres i n diameter of 100 nm resulted i n the existen c e of the nano-SiO2 spheres, instead of the TPU-self-assembled m icrospheres, distrib ted in the nano-SiO2/TPU fibers.