The discovery of nanodipolar π -conjugated oligomer-containing polymers as high performance nanodielectric materials with high permittivity and low dielectric loss over a wide range of frequency (100 Hz-4 MHz) is reported. Terthiophene-containing methacrylate polymers are synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Both X-ray and thermal studies indicate the formation of small crystalline domains of terthiophene side chains dispersed in amorphous matrix. The highly polarizable and fast-responsive nanodipoles from the nanoscale crystalline domains ( < 2 nm) are believed to dictate the performance. These polymers uniquely satisfy nanodipole architectures conjectured two decades ago to guide the design of high performance nanodielectric materials. This unprecedented approach can be generalized to a variety of π -conjugated oligomer-containing polymers for the development of high energy density capacitor materials.

The development of hemostatic technologies that suit a diverse range of emergency scenarios is a critical initiative, and there is an increasing interest in the development of absorbable dressings that can be left in the injury site and degrade to reduce the duration of interventional procedures. In the current study, β-cyclodextrin polyester (CDPE) hydrogels serve as sacrificial macroporous carriers, capable of degradation under physiological conditions. The CDPE template enables the assembly of imprinted chitosan honeycomb-like monolithic mats, containing highly entangled nanofibers with diameters of 9.2 ± 3.7 nm, thereby achieving an increase in the surface area of chitosan to improve hemostatic efficiency. In vivo, chitosan-loaded cyclodextrin (CDPE-Cs) hydrogels yield significantly lower amounts of blood loss and shorter times to hemostasis compared with commercially available absorbable hemostatic dressings, and are highly biocompatible. The designed hydrogels demonstrate promising hemostatic efficiency, as a physiologically-benign approach to mitigating blood loss in tissue-injury scenarios.

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Polyvinyl polymers bearing pendant hole transport functionalities have been extensively explored for solution-processed hole transport layer (HTL) technologies, yet there are only rare examples of high anisotropic packing of the HT moieties of these polymers into substrate-parallel orientations within HTL films. For small molecules, substrate-parallel alignment of HT moieties is a well-established approach to improve overall device performance. To address the longstanding challenge of extension from vapor-deposited small molecules to solution-processable polymer systems, a fundamental chemistry tactic is reported here, involving the positioning of HT side chains within macromolecular frameworks by the construction of HT polymers having bottlebrush topologies. Applying state-of-the-art polymer synthetic techniques, various functional subunits, including triphenylamine (TPA) for hole transport and adhesion to the substrate, and perfluoro alkylsubstituted benzyloxy styrene for migration to the air interface, were organized with exquisite control over the composition and placement throughout the bottlebrush topology. Upon assembling the HT bottlebrush (HTB) polymers into monolayered HTL films on various substrates through spin-casting and thermal annealing, the backbones of HTBs were vertically aligned while the grafts with pendant TPAs were extended parallel to the substrate. The overall design realized high TPA π-stacking along the out-ofplane direction of the substrate in the HTLs, which doubled the efficiency of organic light-emitting diodes compared with linear poly(vinyl triphenylamine)s.

High‐performance nanodielectric materials are built by C. Tang and co‐workers based on nano‐dipolar π‐conjugated oligomer thiophenecontaining polymers that exhibit high permittivity and low dielectric loss over a wide range of frequencies (100 Hz to about 10 MHz). Highly polarizable and fast‐responsive nano‐dipoles from nanoscale crystalline domains from π–π stacked oligomer thiophenes are believed to dictate the performance. These materials could be used to construct high energy‐density capacitors. The cover image is courtesy of Xiaodong Yin and Mitra Ganewatta.

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We review recent progress on reduced coating diameter fibers for increasing core density for optical interconnect applications. We discuss design considerations on microbending and mechanical reliability and present new experimental results.