Enhanced Mechanical and Dielectric Properties of Polyurethane Elastomers Containing Modified SiO₂

A novel and straightforward approach was employed to augment the dielectric constant and diminish the elastic modulus of polyurethane (PU) through the integration of modified silica (NSiO₂) into the matrix. The incorporation of NSiO₂ resulted in the disruption of N-H/C=O hydrogen bonds between the PU chains, which subsequently led to an enhancement in the polarizability of the chains and an increase in the dielectric constant of PU. Concurrently, the addition of NSiO₂ resulted in a reduction of the elastic modulus (Y) of PU, which was attributed to the disruption of the hard domains of PU. The concurrent increase in the dielectric constant and reduction in Y give rise to a 60% enhancement in electromechanical sensitivity at 10³ Hz. Furthermore, PU/NSiO₂ displays robust electrical breakdown strength due to the insulation properties of SiO₂. At a NSiO₂ content of 3%, the breakdown strength of PU/NSiO₂-3 increases to 145.12 MV/m, which is 1.6 times that of PU (91.03 MV/m). This study presents a novel approach to the design and preparation of PU with a high dielectric constant and enhanced electrical breakdown strength.