| 簡(jiǎn) 介： |
In recent years, polymers based on dielectric materials with high dielectric constant and low dielectric loss have attracted considerable interest due to their potential applications in artificial muscles, energy storage, flexible electronics, and sensors, etc. In most cases, ceramic fillers or metal particles or carbon nanotubes were added into the polymer matrix to increase the dielectric constant. However, this inevitably led to the obvious increase in dielectric loss. To solve this problem, in this work, orientated multiwall carbon nanotubes (MWNTs) array/Polyvinyl alcohol (PVA) nanocomposite films were prepared by using an electrospun-in-situ film-forming technique. For comparison purpose, the composite films with MWNTs randomly dispersed in PVA matrix were also prepared by solution casting. The results showed that the two types of composites had greatly different microstructures and dielectric properties. Compared with solution casting composite films, MWNTs in electrospun-in-situ composite films were not only uniformly dispersed in PVA matrix, but also aligned in one direction, which effectively prevented MWNTs to curl, wind and form the connecting networks, and thus dramatically increased the percolation threshold from 0. 5 wt% t0 2. 8 wt%. As a result, the dielectric constant of the electrospun-in-situ formed films was significantly increased up t0 105 for the films with 4. 0 wt%
MWNTs. More importantly, a rather low dielectric loss (一0. 8) was successfully achieved with the incorporation of 4. 0 wt% MWNTs. However, for the composites films prepared by solution casting, although a higher dielectric constant (～ 400) was obtained by adding 4. 0 wt% MWNTs, the dielectric loss reached a particularly high value (一i5). Our work indicates that polymer/MWNTs dielectric materials with high dielectric constant and low dielectric loss could be successfully obtained by using electrospinning in-situ film-forming technique due to the well-dispersion and alignment of MWNTs in polymer matrix. |
