Fast Triggering of Shape Memory Polymers using an Embedded Carbon Nanotube Sponge Network.

Guoxiang Zhou,Shuping Xu,Nikhil Koratkar,Heng Zhang,Jinsong Leng,Jing Zhong,Xuchun Gui,Hongqiu Wei

doi:10.1038/srep24148

Abstract

In this work, a 3-D porous carbon nanotube sponge (CNTS) was embedded within a shape memory polymer (SMPs) matrix. We demonstrate complete infiltration and filling of the SMPs into the CNTS by capillary force without any damage to the CNTS structure. With only ~0.2 wt% carbon nanotube loading, the glass transition temperature is increased by ~20 °C, indicating strong interaction between CNTS and the SMPs matrix. Further, we find that the uniform distribution of the carbon nanotubes in the nanocomposite results in high electrical conductivity, and thus highly effective electricity triggering capability. The carbon nanotube sponge shape memory polymer (CNTS/SMPs) nanocomposite could be triggered within ~10 seconds by the application of ~10 volts. Results from finite element simulations showed good agreement with the experimental results, and indicated that for our system the interface thermal energy loss does not have a significant effect on the heating rate of the polymer matrix.

Highlights

The advancement of smart materials and structures has broad impact on aeronautics, civil engineering construction, gas and steam turbines, as well as wind power generators[1]
Due to the relatively strong interaction between individual nanotubes in the sponge, the capillary forces associated with polymer filling do not induce any visible collapse of the carbon nanotubes sponge (CNTS), which is frequently observed in the case of carbon nanotube (CNT) forests[17]
The outstanding electrical conductivity of the CNTS can be successfully inherited by the CNTS/Shape memory polymers (SMPs) nanocomposite[18]

Summary

Introduction

The advancement of smart materials and structures has broad impact on aeronautics, civil engineering construction, gas and steam turbines, as well as wind power generators[1]. Coating of carbon paper on the SMPs surface can allow the electrical triggering of SMPs within ~400 seconds by a voltage of ~16 volts, and further adding carbon nanofibers in the SMPs matrix can decrease the recovery time to ~180 seconds[16] This strategy could limit the deformation capability of SMPs since the weakly bonded conductive layer are prone to delamination from the SMPs under relatively small tensile/bending strain. From the above discussion it is clear that there is a need to develop new approaches to synthesize highly conductive SMPs nanocomposite with low nanoparticles loading This will ensure that the thermal actuation of the SMPs can be efficiently triggered without compromising on the deformation capability of the SMPs. In this study, we employed a pre-formed nano-porous carbon nanotubes sponge (CNTS) which is synthesized via chemical vapor deposition (CVD) as a 3-D conductive backbone[17]. The simulation results indicated that the interface thermal diffusion layer has marginal effect on the heat transport from the CNTS backbone to the SMPs matrix

Methods

Results

Conclusion