The effect of particle surface modification on electric-field-induced modulus control and actuation strain of polyurethane/TiO2 elastomers

초록

A new type of electro-responsive composite elastomer was prepared using polyurethane (PU) as the matrix and TiO2 nanoparticles as the active dispersed phase. The TiO2 nanoparticles with different surface chemical structures (TiO2-IL: modified by ionic liquid; TiO2-IL-AA: dual-modified by ionic liquid and acetic acid) were used in the PU matrix in order to study the effect of interface structure on the electro-responsive performance of the elastomers. Fourier transform infrared spectroscopy, X-ray diffraction, and small-angle X-ray scattering were used to examine the structures of the elastomers to verify the impact of nanoparticles on the microphase of PU matrix. Rheological analysis was conducted under a controlled electric field, indicating that the elastomers showed an improved modulus under an electric field and that the elastomer contained 20 wt% TiO2-IL nanoparticles (TiO2-IL-20wt%) exhibited the highest electrorheological (ER) efficiency of 247% at 3.0 kV/mm. Dielectric analysis indicated that the TiO2-IL nanoparticles induced a stronger interfacial polarization than the TiO2-IL-AA nanoparticles. In addition, the PU/TiO2-IL elastomer also presented a significant electrostriction effect. The highest deformation in the thickness, up to 14 % was achieved in the sample of TiO2-IL-20wt%; however, the elastomers containing TiO2-IL-AA nanoparticles showed negligible actuation thickness strain; this might be related to the low dielectric constant and loose nature of TiO2-IL-AA nanoparticles. This research indicated that both electric field-controlled modulus and electric field-actuated deformation can be obtained in one system: the PU/TiO2-IL elastomer, indicating its great potential in dual or multi-functional actuators.

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