A facile method to produce PBS-PEG/CNTs nanocomposites with controllable electro-induced shape memory effect

Abstract

A facile method to develop electro-induced shape memory polymer composites with good location- and process-controlled shape recovery performance is proposed. The poly(butylene succinate) (PBS)–poly(ethylene glycol) (PEG) multiblock copolymer (PBSEG), which has excellent flexibility, was chosen as the matrix of the composites. The conducting medium, carbon nanotubes (CNTs), was introduced to this copolymer by in situ polycondensation. The fine dispersion of CNTs in the PBSEG matrix, which was confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, enabled it to form a percolation network when only 0.5 wt% filler was loaded. DSC analysis revealed another important role played by CNTs in this system, as a nucleating agent for both PBS and PEG segments, and it caused an increase in crystallization temperature and crystallinity of both segments. The tensile properties test showed that the nanocomposite still exhibits good ductility with the addition of no more than 1 wt% CNTs, which allows it to undergo large deformation during shape programming. The electrical actuation shape memory performance was evaluated by a bending test, and the recovery process was recorded with a camera and an infrared video camera. The effect of CNTs loading, segment content and chain length upon the fixity ratio, recovery ratio and speed was studied, and the temporary shape control and localized shape memory response were also investigated. The results showed that the PBSEG/CNTs nanocomposites possess good shape memory performance with high shape fixity (more than 93.77%) and recovery ratio (more than 97.04%), and the shape recovery process can be adjusted by tailoring the polymer chain structure, the content of CNTs and the mode of how the samples are put in a circuit. In present work, we successfully achieved an electro-induced shape memory device which can be well controlled to remain at any stage during the recovery process and respond at any local position.