Preparation and properties of shape memory polyurethane filaments triggered by human body temperature

To utilize the human body heat to trigger the shape memory smart textiles, shape memory polyurethane filaments (SMPUF) with three different transition temperatures were prepared based on modified polycaprolactone diol (PCL) by dry spinning. The chemical structure was characterized systemically. The shape memory properties, tensile properties, resilience, and viscoelasticity were studied comprehensively. The results revealed that the phase transition temperatures were close to human body temperature which measured 19.97°C, 27.33°C, and 30.37°C, respectively. Additionally, the fraction of hydrogen bonds in the samples was about 30% less than that of polyurethane filaments (PUF). The best shape fixity ratio was 88.5% and the shape recovery ratio was 96.7% belonging to samples with a transition temperature of 30.37°C. At 55°C, the elastic recovery was 45.2% higher than that at 22°C. As the temperature rose, the elastic modulus of SMPUF decreased until it reached that of PUF. The static and dynamic viscoelasticity of SMPUF indicated that the phase transition of the soft segment affects the movement of the molecular chain. SMPUF can be used as compression garments, and wearable orthopedic devices, such as the elastic bands prepared in this work.