The Preparation And Study Of Polyurethane With Organic Molecules Dielectric Elastomer Composites

Dielectric elastomer actuators (DEAs) have been receiving much attention in the past two decades because DEAs can give rise to surprisingly large deformations by applying an electric field. By virtue of the low modulus, large strain, fast response, lightweight, reliability, high energy density, and high electromechanical coupling efficiency, DEAs find many applications in industry. A key limitation for the practical application of DEAs is the requirement of high operating electric field (>100kV/mm), which could be harmful to humans and damage equipment, particularly in biological and medical fields. Getting a large actuated strain at a low electric field is the biggest challenge for DEAs. A novel approach was used to largely increase the electromechanical sensitivity (β) and the actuated strain of a thermalplastic polyurethane(TPU) dielectric elastomer (DE) at a low electric filed by introducing polyethylene glycol (PEG) oligomer or diaminonaphthalene (DAN) into the matrix. The results showed that PEG or DAN disrupted the N-H/C=O hydrogen bonds in TPU, leading to the large increase in dipole rotation of TPU chains. As a result, a321-fold increase in dielectric constant at low frequency over that of pure TPU was obtained with the addition of80parts per hundred resin (phr) of PEG and a11-fold increase in dielectric constant with the addition of50parts per hundred resin (phr) of DAN. Meanwhile, the elastic modulus of TPU was sharply decreased owing to the plasticizing effect of PEG on TPU matrix by the disruption of hydrogen bonds in hard segment of TPU as well as the Van der Waals interaction between PEG and TPU in soft segment. The simultaneous increase in dielectric constant and decrease in elastic modulus resulted in4700%increase in β at5000Hz and7500%increase in actuated strain at quite a low electric field (3V/μm) by adding80phr PEG and330%increase in β at5000Hz and520%increase in actuated strain at a electric field (20V/μm) by adding50phr DAN.To the best of our knowledge, the actuated strain (5.22%at3V/μm) is much higher than that of other dielectric elastomers at the same electric field reported in the literature. Our work provides a simple and effective method to obtain a DE with large actuated strain at a low electric field, facilitating the application of DE in biological and medical fields, where a low electric field is required.