We report a simple and low-cost strategy to enhance the dielectric permittivity of polystyrene by up to an order of magnitude via incorporating an oligoaniline trimer moiety at the end of the polymer chains. The oligoaniline-capped polystyrene was prepared by a copper-catalyzed click reaction between azide-capped polystyrene and an alkyne-containing aniline trimer, which was doped by different acids. By controlling molecular weight of polystyrene, the end-capped polymers can be induced to form nanoscale oligoaniline-rich domains embedded in an insulating matrix. Under an external electric field, this led to an increase in dielectric polarizability while maintaining a low dielectric loss. At frequencies as high as 0.1 MHz, the dielectric permittivity and dielectric loss (tan δ) were ∼22.8 and ∼0.02, respectively. This strategy may open a new avenue to increasing the dielectric permittivity of many other commodity polymers while maintaining relatively low dielectric loss.

Graphene-based ion sensitive field effect transistors (GISFETs) with high sensitivity and selectivity for K + ion detection have been demonstrated utilizing valinomycin based ion selective membrane. The performance of the GISFET for K + ion detection was studied in various media over a concentration range of 1 µM-2 mM. The sensitivity of the sensor was found to be > 60 mV/decade, which is comparable to the best Si-based commercial ISFETs, with negligible interference found from Na + and Ca 2+ ions in high concentration. The sensor performance did not change significantly in Tris-HCl solution or with repeated testing over a period of two months highlighting its reliability and effectiveness for physiological monitoring. The performance of the sensor also remained unchanged when fabricated on biocompatible polyethylene terephthalate (PET) substrate, showing significant potential for developing flexible bio-implantable graphenebased ISFETs.

This paper reports a strategy for controlling surface chemistry of barium titanate (BaTiO 3 ) using surfaceinitiated reversible addition−fragmentation chain transfer (RAFT) polymerization of an oligothiophene monomer. The modular chemistry on the engineering of nanoparticles provides a facile pathway to compatibilizing dielectric nanofillers in a matrix of oligothiophene polymers, leading to the formation of nanodielectric composites with permittivity at ∼20 and dielectric loss <0.02 over a wide range of frequencies (1 kHz to 1 MHz). This approach could be generalized to a variety of nanoparticles with tunable dipolar polymer shells for the development of novel dielectric nanocomposite systems for energy storage.

This paper presents a novel strategy to modify the surface chemistry of barium titanate (BaTiO3, BT) with a bimodal population of oligothiophene polymer brushes using step-by-step reversible addition–fragmentation chain transfer (RAFT) polymerization. Compared with a previous strategy based on monomodal surface-tethered brushes, these hybrid nanoparticles, BaTiO3 coated with bimodal oligothiophene polymer brushes, demonstrate extremely good dispersion behaviors as dielectric nanofillers in a matrix of oligothiophene polymers. These nanodielectric composites exhibit greatly improved dielectric performance and maintain linear displacement–polarization (D–E) profiles under high applied electric fields. This promising bimodal strategy could be generalized to a variety of nanoparticles for the development of novel dielectric nanocomposite systems.

This work explores the dielectric and polarization properties of block copolymers and homopolymer blends containing a terthiophene-rich, electronically polarized block (PTTEMA) and an insulating polystyrene block (PS). PTTEMA-b-PS block copolymers were synthesized by reverse addition-fragmentation chain transfer (RAFT) polymerization, and PTTEMA/PS homopolymer blends with the same PTTEMA weight percentages were produced by solution blending. DSC and XRD characterization show that crystallinity increases with PTTEMA content, indicating the presence of terthiophene-rich crystalline domains. Under an applied electric field, these domains are electronically polarized, but the insulating PS block inhibits current leakage, resulting in enhanced dielectric properties. Impedance measurements show that relative permittivity increases with PTTEMA content. The permittivity values are higher in PTTEMA-b-PS copolymers with moderate PTTEMA content due to the ability of the PS block to inhibit PTTEMA association, resulting in a higher density of isolated, terthiophene-rich polarizable domains. Freestanding PTTEMA/PS blend films containing up to 40 wt % PTTEMA have almost 40% greater recoverable energy density compared to pure PS films polarized to the same electric field strength.