Dual-Plasticized PVC-Gels with High Dissipation Factor for Smart Wearable Thermotherapy and Sensing Devices

Abstract

Multifunctional wearable heaters are widely used from smart healthcare to soft interactive electronics requiring high transparency and stretchability while operating at low voltage. Here, this study presents novel dual-plasticizer strategy by synergistically incorporating dibutyl adipate (DBA) as the primary plasticizer with propylene carbonate (PC) and ethylene carbonate (EC) as high-dielectric secondary plasticizers to polyvinyl chloride (PVC). The dual-plasticized PVC-gel achieves superior dielectric loss and dissipation factor exceeding 3 × 10³ and 295, facilitating efficient dielectric heating. The heater simultaneously exhibits exceptional stretchability (300%) and optical transparency (>90%) for maintaining visual aesthetics. The heater reaches over 60 °C at an operating voltage (350 V) with rapid heating rate of 0.76 °C s⁻¹ and exhibits excellent power efficiency (1.015 W cm⁻²). Moreover, it demonstrates uniform heat distribution and achieves saturation temperature within 1 min at every voltage. The heater exhibits remarkable thermal stability with sustained performance during 20000 s and maintains stable heating performance without temperature degradation under stretching. These capabilities enable both therapeutic heating and thermal sensing functionalities, demonstrating adaptive wearable applications while maintaining conformal contact and consistent heating under complex wrist movements. Furthermore, this heater implements thermal sensing system capable of gesture recognition, establishing potential for next-generation wearable electronics.