Supersonic nanoblowing: a new ultra-stiff phase of nylon 6 in 20–50 nm confinement

The 20–50 nm nanofibers hold great promise as functional fabrics, biomedical materials, filters, fuel cell membranes, ultra-speed fiber optics, electronics and sensorics. In our novel process of supersonic solution blowing of nylon-6, 20–50 nm nanofibers are obtained. Here we found a new phase of nylon-6, which differs from the known α-, β-, γ-, δ- and λ-phases, presenting itself as a novel χ-phase. It is characterized by the decrease of CH2 stretching, a shift of –NH stretching, a different type of hydrogen bond and a ten-fold increase in Young's modulus compared to those of post-processed macroscopic nylon fibers.