Novel ferroelectric behaviors, namely, narrow single and double polarization loops, have been observed in semicrystalline polar polymers and are promising for advanced electrical applications. Based on recent finding from poly(vinylidene fluoride)-based random copolymers, it is proposed that repeating-unit isomorphism having bulky comonomers inside ferroelectric crystals is an effective strategy to expand interchain distance and pin nanosized ferroelectric domains (i.e., nanodomains). In this proposal, the hypothesis of pinned nanodomains via crystal isomorphism is employed to rationally design new ferroelectric nylon copolymers and testify the working mechanism. First, nylon 11 random copolymers with various n-nylon comonomers will be synthesized to mismatch amide groups in the crystal, disrupting hydrogen-bonding interactions for enhanced ferroelectricity. Second, N- or C-methylation will be further employed in nylon 11 random copolymers to expand the interchain distance and facilitate faster dipole switching. Third, nanodomains will be pinned either physically (by larger comonomers) or chemically (by UV-crosslinkable comonomers) in ferroelectric nylon crystals to realize narrow polarization loops. If successful, this study will not only confirm the mechanism of pinned nanodomains responsible for novel ferroelectric behaviors, but also provide better polymeric materials for various electroactive applications.
NON-TECHNICAL SUMMARY:
Electroactive polymers with high field response are smart soft materials, which are highly attractive for numerous electrical applications in electrical energy storage, smart actuators/artificial muscles, and energy harvesting. However, comparing with electroactive ceramic materials, current electroactive polymers show inferior electric field responses. This impairs their usage in practical applications, despite the superior processability, light weight, and low-cost characteristics for polymers. Stimulated by recent research results, this project aims to realize a nanoconfinement effect on electric responsiveness of semicrystalline polar polymers via rational polymer design, synthesis, and electrical property characterization. If successful, these novel electroactive polymers will be able to achieve ultrahigh electric field responses and the above-mentioned applications will become practically feasible to benefit society. In addition to the scientific research activities, this project also provides a broad education and training platform for minority and under-represented high school students, and undergraduate and graduate young professionals. An interactive feedback educational theme, involving faculty members, graduate students, undergraduates and high school students, will be implemented and emphasized throughout the proposed project to enhance the awareness of nano-science and technology of polymers in the general community.
