This proposal?s objective is to understand the well-known relaxor ferroelectric phenomenon from a viewpoint of nanoconfinement, and use this knowledge to provide guidance for its future applications. Different from nanoconfined ferroelectric ceramic particles, confined ferroelectric polymers may not exhibit the so-called quantum confinement effect. Instead, their long chain nature and conformational flexibility results in rich and competing ferroelectric polymorphism, when the confinement size gradually decreases from micro- to nano-scales and confinement geometry changes from one-dimensional to two-dimensional, and finally to three-dimensional. In particular, the long-range cooperative interactions among dipoles will be broken or weakened in otherwise normal ferroelectric materials. Both chemical and physical confinement methods will be employed in this project. If successful, this proposed research will contribute to the advancement of fundamental polymer science and education in the field of ferroelectric polymers; 1) Nanoconfined polymer ferroelectricity is a novel concept which has seldom been studied in the polymer field before. 2) This research will lead to new properties and applications for ferroelectric polymers.
NON-TECHNICAL SUMMARY:
Potential impacts of this project are three folds. First, confined polymer ferroelectricity will have a broader impact on electrical energy storage applications, such as high energy density capacitors. Second, through this project, students at all levels, including the undergraduates, graduates, and postdocs, will be well trained for emerging energy-related professional careers. To reach this goal, the PI will recruit undergraduate and REU students, especially underrepresented students, into his research lab. To expose them to the nanoscience of ferroelectric and crystalline polymers, a graduate course, Polymer Structure and Morphology, will be taught with new contents of results from this proposed work. In addition, the PI will also focus on K-12 education by establishing collaborations with local high school science teachers via summer research projects. Interested high school students will also be recruited to stimulate and strengthen their general interest in science and engineering. Finally, research results will be broadly disseminated by collaborations with national laboratories and industries, as well as by publications in quality peer-reviewed journals and presentations at national and international meetings.
The goal of this project is to understand the fundamental mechanism underlying novel ferroelectric behaviors in polymers with enhanced electroactive properties and performance, which are attractive for a variety of electrical applications, such as electrical energy storage, energy harvesting, smart actuators/artificial muscles, and solid-state cooling. The intellectual merit of this project are several folds. First, we understand that incorporating bulky comonomers in ferroelectric polymer crystals is an effective strategy to expand inter-chain distance and allow easier dipole rotation. Second, bulky comonomer units can pin the polymer chains to form nanosized domains in the defect-modified crystals. As a result of both expanded inter-chain distance and nanodomains, ferroelectric hysteresis in electric poling loops is substantially reduced, leading to high dielectric constant and low loss polymer dielectrics. This knowledge is valuable for improving performance of existing electroactive materials, as well as for designing new ferroelectric polymers with even better properties. These high performance electroactive polymers will enable the above-mentioned applications and benefit the society in the future. The broader impacts of this project includes all-level education in polymer science and engineering. High school students and undergraduate students (including Research Experience for Undergraduate students) have participated and been trained in the Principal Investigator’s lab at Case Western Reserve University. Knowledge obtained from this work has been broadly disseminated via referred journal publications (with high school students and undergraduate students as co-authors) and conference presentations. All these experiences will help young students develop interests in the polymer research and prepare them for the scientific profession.
