NSF Award
2305282
With recent developments in polymer science and conducting polymers, advances are being made in stretchable electronic polymer systems for applications in healthcare, robotics, and entertainment. These systems are attached to clothes or worn directly on the skin for monitoring physical signals, biochemical signals, and motion. Due to the soft, compliant, and complex nature of skin and the natural bending and rotational motion associated with joints, the stretchable electronic polymers should be soft and mechanically robust enough for the wearer to comfortably perform motions such as bending, stretching, and twisting. To prevent long-term performance decline it is desirable for the films to continually heal themselves. Conventional semiconductors, like silicon, are brittle and rigid. Since they are not self-healing, they are unsuitable for many stretchable electronic polymer applications. This work investigates the synthesis, internal structure, self-healing ability, and electrical properties of these dynamic ultra-stretchable systems and utilizes them for wearable electronics, such as sensors. This project's education and outreach activities are combined with the research in a manner that impacts the science, technology, engineering, and mathematics (STEM) workforce. This effort has three main foci: the participation of underrepresented and multi-cultural student groups, improving engineering education at both the undergraduate and graduate level, and outreach to educators & future STEM students. The educational goal of this proposal highlights the role stretchable electronic polymers play in everyday life through the creation of educational YouTube videos reaching thousands of potential STEM students and teachers.<br/><br/>Currently, there is no electronic material that possesses the properties of skin—compliant, elastic, stretchable, and self-healable. This work investigates stretchable electronic polymer systems and the underlying phenomena of these advanced materials—for future applications in healthcare and engineering fields. The fundamental goal of this work is to understand the relationship between synthesis, internal structure, self-healing ability, and electrical properties of dynamic polyaniline/acidic polyacrylamide/small molecule dopant stretchable electronic polymer systems—to fully understand these stretchable electronic polymer materials and apply them specifically to wearable sensor/electronic functionalities. The technical merit of the work provides new insight into the role of both small molecule dopants and polyacrylamides acidic group content and the overall structure of stretchable, self-healable, conductive polyaniline systems. This project elucidates current stretchable electronic polymer systems by unraveling the electrical/self-healing activity in relation to the internal film structure. This knowledge is cross-disciplinary and aids developments in the fields of sensor/surface science, basic materials science and engineering, etc. The research team investigates the effects of small molecule dopants and acidic polyacrylamides on the synthesis/structure/electrical/self-healing properties and working relationships of dynamic polyaniline systems and links this activity to the internal film structure. Investigating the effects of molecular weight, structure, as well as the number and class of the acidic groups of the small molecule dopants allows the investigator to understand how the intermolecular, thermal, morphological, self-healing, and electrical properties depend on the electrostatic interactions and hydrogen bonding within the material. The acidic groups of the polyacrylamides increase the electrostatic interactions within the material and aid the doping of polyaniline, the electrical properties, and the self-healing ability. Varying the amount and type of acidic polyacrylamides enables the researchers to (i) explore their function in the electrostatic interactions of the dynamic systems and (ii) understand how the intermolecular, thermal, morphological, and electrical properties depend on the internal film structure. This understanding allows for a thorough investigation of the basic properties (gauge factor, linearity of response, self-healing) of this class of polymer systems for realizable wearable stretchable electronic polymers for medical diagnosis, prosthetics, e-skins, etc. The research contributes to the current theory relating these functional materials to the fundamental understanding of the electrostatic interactions and internal film properties controlling these autonomous self-healable and ultra-stretchable polymers. The education and outreach components of this work integrate with the research through creative and artistic online media and outreach, and illustrates the importance of stretchable electronic polymers in everyday life to educators & future STEM students.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
