writer：Haibing Zeng, Silian Fu, Yongri Liang*, Li Liu*
keywords：Polyurethane, dielectric elastomer
source：期刊
specific source：Smart Materials and Structures, 2023, 32, 015017
Issue time：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