Mechanically robust and highly elastic thermally induced shape memory polyurethane based composites for smart and sustainable robotic applications

Abstract

AbstractIn the present study, polyurethane (PU) was prepared using a pre‐polymer (two‐shot) process with a novel phloroglucinol chain extender. PU nanocomposite was prepared by incorporating acid‐FMWCNTs in pristine‐PU. Polystyrene (PS) was functionalized with the nitro group through our previously reported method. The ternary blend composites (PU/PS‐NO2/FMWNTs) were prepared using acid functionalized multiwall carbon nanotubes (FMWCNTs) for enhanced properties and selectivity. Nitro‐functionalized‐PS/PU composite properties were compared with pristine‐PU and its blend composite. The structure of the pre‐designed PU polymer and its composites were confirmed by the FTIR and the degree of crystallinity and amorphous state was determined with XRD analysis. Excellent thermal stabilities were confirmed through a TGA thermogram with an increase in the loading amount of FMWCNTs. Excellent tensile strength 59.2 ± 2.6 MPa with 0.1 g loading amount of FMWCNTs with enhanced flexibilities was achieved. The significant change in surface morphologies and porosity suggested enhanced interaction (physical and chain entanglement) of FMWCNTs and nitrated‐PS with PU chain as the loading amount of filler increased. The resulted porous spongy cluster (as seen in SEM images) provides efficient shape recovery strain with excellent flexibility to the composite material without compromising repeatability. Almost 100% shape recovery was observed for all samples with repeated recoveries. The recovery time of PU nanocomposite observed is shorter than neat polyurethane and PU/PS‐NO2 blends because of their better conductive nature but causes brittleness, which can easily initiate a crack in the sample compared to a blended sample.