Preparation and characterization of soft and ultra-stretchable multifunctional thermoplastic elastomeric materials

Soft materials with incredible stretchability, thermal, electrical, and dielectric properties are crucial for soft matter technological applications, like flexible electronics and soft robotics. However, fabricating such multifunctional materials for advanced applications remains a challenge. In this work, new kind of soft and ultra-stretchable multifunctional thermoplastic elastomeric composite materials were successfully fabricated by integrating nickel ferrites (NFO) nanoparticles with styrene–isoprene-styrene block copolymers (SIS) matrix by exploiting polymer processability. The resulting materials showed excellent electrical (dielectric, ac conductivity), magnetic and thermal properties. The resulting fabricated composites exhibited ~ 200% enhancement in dielectric response at room temperature as compared to neat SIS. This can be attributed to the interfacial polarization, where large numbers of space-charge accumulated at the interface between the NFO nanofillers and the SIS matrix leading to enhanced the polarization with filler loading. Interestingly, the initial diamagnetic SIS exhibited superparamagnetic behaviour upon incorporation of NFO nanofillers possessing a high magnetic moment. The net magnetization of the composites was also enhanced with the magnetic filler loading. Apart from these multifunctional attributes, the composites showed ultra-high stretchability (elongation at break of up to ∼3500%) and elasticity. Functional properties of the resulting materials were also explained using theoretical models like modified Cole–Cole model, Universal Dielectric Response model, and Agari model. This work provides a facile and scalable pathway to fabricate multifunctional thermoplastic elastomeric materials that could influence their potential applications in soft-matter engineering.