(323f) Oligothiophene-Containing Polymers for Dielectric Energy Storage

This presentation describes the synthesis, characterization, and dielectric properties of a new class of nano-dipolar, π-conjugated oligomer-containing polymers for use as dielectric materials for high-density energy storage.  We used reversible addition fragmentation transfer (RAFT) polymerization to synthesize polymethacrylate homopolymers with terthiophene side chains (PTTEMA) as well as block copolymers of PTTEMA with polystyrene (PTTEMA-b-PS).  Data for PTTEMA from wide-angle X-ray diffraction and differential scanning calorimetry indicate the formation of small crystalline domains of electrically conductive terthiophene side chains dispersed in amorphous matrix.  We hypothesize that when electrically polarized, charge migrates through these nanoscale domains and accumulates at domain boundaries, creating nano-dipoles.  Impedance spectroscopy data indicates that the PTTEMA homopolymer has high relative permittivity and low dielectric loss over a wide frequency range (100 Hz – 10 MHz).  Polarization testing indicates energy density values (1.56 J/cc at 200 MV/m) among the highest measured for any homopolymer.  Ongoing studies of PTTEMA-b-PS and blends with PS, rationalized with theoretical models, enable us to investigate the relationship among crystallinity, nanoscale domain structure, and dielectric performance.  Ultimately this work will lead to a deeper understanding of structure-property-performance relationships in nanodielectric materials for high density energy storage and pulse power applications.