Reinforcement of piezoelectric polymers with carbon nanotubes: Pathway to next-generation sensors

Piezoelectric polymers such as poly(vinylidene fluoride) (PVDF) are being currently utilized as low-cost sensors in many structural vibration control applications and measurements. Their low electromechanical coupling coefficient, however, has always been a concern when utilized in different applications. In order to remedy this, carbon nanotubes, known for their extraordinary properties, can be mixed with such piezoelectric polymers as they have the potential to improve the electromechanical response of these polymers. Along this line of reasoning, different types of nanotubes; namely, single-walled and multiwalled are blended with a copolymer of PVDF. Through extensive experimental vibration testing and theoretical verification, it is found that the nanotube-based polymers yield better response characteristics than those of the plain piezoelectric polymers. More specifically, it is demonstrated that the dominant mechanism responsible for improved sensing performance is the increased Young's modulus of elasticity of the nanotube-based polymer for the samples considered here. The significant change in properties of these piezoelectric polymers with different fabrication conditions and nanotube addition, though provokes doubts about standardization, creates a pathway for the development of next-generation sensors with enhanced or entirely new properties.