Poly(ionic liquid) Grafted MXene via Si-ATRP and its Polyurethane Composite Foam: Mechanical, Flame Retardant and Sensing Properties

Abstract

Compared with other types of sensors, capacitive flexible pressure sensors (CFPS), with low sensitivity, are more susceptible to environmental changes. It is still a considerable challenge to achieve high sensitivity, excellent mechanical properties and long-time structural stability simultaneously. Targeting the aforementioned issues, herein, Ti3C2 (MXene) with high dielectric constant was firstly chemically modified with a poly(ionic liquid) (PIL) via surface-initiated ATRP, and then combined with a porous polyurethane foam (PUF) 3D network structure via a one-step blending foaming method. Thanks to the organic-inorganic hybrid network based on the PU/MXene porous structures and the uniformly distributed micro-capacitor structure provided by MXene@PIL, the mechanical properties, structural stability, flame retardancy and dielectric properties of the composite foam were all significantly enhanced. When the content of MXene@PIL was 10%, the sensitivity of CFPS based on this dielectric were 17.1, 5.2, and 2.5/KPa in the pressure ranges of 0-1 KPa, 1-12 KPa and 12-100 KPa, respectively. In addition, the sensor showed the response and recovery times of 88 and 82 ms under a low pressure of 355 Pa. The light, flexible sensor prepared in this work is expected to be used in wearable devices to monitor physiological signals, and it should also be a good candidate for the next generation of man-machine interface characterization devices.