Multiphase Structure and Electromechanical Behaviors of Aliphatic Polyurethane Elastomers
writer：Dong Xiang,? Jingjing He,? Tongtong Cui,§ Li Liu,? Qi Song Shi,? Lan Chao Ma,? and Yongri Liang
keywords：介電彈性體，聚氨酯彈性體，結構與性能關系
source：期刊
Issue time：2018年
Understanding the relationship between multiphase structure and electromechanical property of thermoplastic
dielectric elastomers is significantly important in the developments of high-performance and novel dielectric elastomers. In this
work, we fabricated a series of aliphatic polyurethane elastomers (PUEs) based on hydroxyl-terminated butadiene-acrylonitrile
copolymer (HTBN), hexamethylene diisocyanate (HDI), and various lengths of linear aliphatic diols and investigated effect of
their microstructure and morphology on dielectric and electromechanical properties. The FTIR, WAXS, SAXS, and viscoelastic
AFM results showed that the PUEs existed in crystalline phase, hard domain (HD) and soft domain (SD) phases composed
HD-rich region and few HDs and SD composted SD-rich region by crystallization and microphase separation. Also, the crystal
morphology and crystallinity of PUEs are strongly influenced by the length of chain extender due to the chain extender adopting
various conformations by hydrogen bonding. The mechanical and electric fields induced responses of segment motions in PUEs
at below room temperature were relative to the constrained SS motions from HD-rich and SD-rich regions. The electric field
induced strain of PUEs was actuated by both Maxwell stress and electrostriction effect, of which contribution of electrostriction
effect was above 64% in total actuation strain. In addition, we found that the effect of electrostriction on the actuation strain
played an important role in improving the actuation strain of PUEs at lower electric field. Our results showed that the dielectric
and electromechanical properties of PUEs can be adjusted by controlling the crystallization and microphase separation.