Effect of Branched Structure on Microphase Separation and Electric Field Induced Bending Actuation Behaviors of Poly(urethane–urea) Elastomers
作者：Haibing Zeng, Silian Fu, Yongri Liang*, Li Liu*
關鍵字：Polyurethane, dielectric elastomer
論文來源：期刊
具體來源：Smart Materials and Structures, 2023, 32, 015017
發表時間：2022年
Polyurethane elastomers as a type of electroactive polymers have wide applications in soft
actuators, soft sensors and energy harvesting due to their high dielectric constant, high
electrostriction coefficients, easy processing and structure adjustability, and superior
biocompatibility etc. However, the relationship between microstructure and electromechanical
properties of EAEs has not been fully understood. In this work, we fabricated the branch
structured poly(urethane–urea) elastomers (PUUs) using hydroxy-terminated polybutadiene as
soft segment, isophorone diisocyanate and 4,4-diaminodicyclohexylmethane as hard segment,
and hydroxyl-terminated four-armed polycaprolactone (PCL410) as branch structured chain
extender for improving bending actuation performances, and understanding the relationship
between structure and electromechanical properties. The degree of branched structure of PUUs
were adjusted by the content of PCL410. The microphase separation kinetics of PUUs was
enhanced as increase of PCL410 content, whereas the degree of microphase separation and hard
domain size of PUUs were reduced. The mechanical loss and bending actuation stress of PUUs
were significantly improved by incorporation of small amount of branched structure into PUU
chains. The PUU with 2.60 mol.% of PCL410 showed 5.16 mm of bending displacement and
5.16 Pa of bending actuation stress at 7.2 kV (corresponding to 180 V mm?1 of the nominal
electric field), which were 76.3, and 79 times higher than that of PUU without PCL410,
respectively. The electric field induced bending actuation mechanism of branch structured PUUs
was suggested that the bending actuation mechanism of branch structured PUUs is caused by
electrostrictive effect from dipole orientation induced bending deformation of constrained
segments and asymmetric charge density distribution on both anode and cathode sides of PUU
films. Our results can provide new insight on design novel electroactive polyurethane
elastomers