State Key Laboratory of Polymer Physics and Chemistry

Altering the properties of polymer chains under confinement represents fundamental challenges in polymer science. Molecular bottlebrushes (MBs), with their densely grafted architecture, create a unique constrained environment that serves as an ideal model system for exploring the structure–property relationships of confined molecular chains. In this work, we employed a Me6TREN/CuBr-catalyzed CuAAC click chemistry to synthesize precisely defined MBs with ultrahigh grafting densities (up to 6.2 side chains (SCs) per C–C repeating unit) via a reaction-enhanced reactivity of intermediates (RERI)-driven grafting-onto strategy. Using this approach, we prepared 65 MBs bearing tetraphenylethylene (TPE) units, a fluorescent moiety sensitive to mechanical strain, at tailored positions along poly(ethylene glycol) (PEG) SCs, including the interior segment, middle portion, and terminal end of the side chains. By systematically varying grafting density (Gdst), molecular weight, composition, and TPE location of SCs, as well as the backbone length, and correlating these with the luminescent behavior in both good and poor solvents, we elucidated the local segmental motion within the SCs. The results demonstrate that the mobility of the interior SC segments decreases initially in a linear manner with an increase of Gdst. Beyond a critical threshold, however, the decline in the mobility of segments follows a steeper linear trend. Moreover, the mobility of the SC segments away from the backbone increases significantly, even under dense grafting. This work not only clarifies how molecular parameters influence side-chain dynamics but also provides a theoretical basis for the design of advanced functional materials based on MBs.

The integration of crystallographic control into solution-processed perovskite films remains a challenge for efficient light emission, as disordered optical dipoles fundamentally limit photon extraction, a bottleneck constraining both classical and quantum planar optoelectronic devices. Here, we address this by developing an in situ formation strategy for oriented quasi-2D perovskite nanosheets within films via ligand-engineered crystallization. By designing and orchestrating steric hindrance and π-π interactions of ligands, we direct the crystallization kinetics to yield regular face-on nanosheets exhibiting enhanced horizontal transition dipole moment orientation compared to conventional isotropic films. The in situ architectural control also elevates both the photoluminescence quantum yield beyond 90% and carrier mobility comparable to 3D perovskite levels. These synergies enable perovskite light-emitting diodes (PeLEDs) with an external quantum efficiency (EQE) of 31.2% for pure-red emission at 635 nm, comparing favorably to other pure-red PeLEDs. Concurrently, the peak luminance and operational stability of the in situ nanosheet PeLEDs exhibit significant improvements.

Dipole interactions are ubiquitous in nature and constitute a fundamental force governing the conformational behavior, stability, and self-assembly of polyelectrolyte systems. While the study of polyelectrolytes has traditionally been anchored in the language of long-range Coulombic interactions, this mean-field perspective often fails to capture complex many-body effects and short-range correlations that are critical to molecular function. This review provides a comprehensive examination of dipoles in polyelectrolyte systems, arguing that dipole interactions often represent a more universal framework than simple electrostatics in describing complex fluids. We analyze the diverse origins of dipoles─ranging from intrinsic molecular polarity and ion-pair formation to zwitterionic dipole–dipole associations─and demonstrate theoretical evidence that dipole potentials can create significantly deeper energy wells than screened Coulomb potentials at the ion-pair scale. Structured along a continuum of increasing confinement, we systematically explore dipole-driven behaviors in solutions, gels, interfaces, nanopores, and melts/glasses. By elucidating the mechanisms by which dipoles modulate phase transitions and transport properties across these environments, this work offers essential insights for decoding physiological functions and guiding the rational design of advanced functional materials with tailored properties.

The synthesis of novel functional polymers used for high-temperature proton exchange membranes is of fundamental interest and practical significance. But the direct synthesis is still difficult because expected materials are heteroatom-containing stereoregular polymers, and heteroatom-containing monomers usually show serious poisoning toward catalysts. In this work, we report the syndioselective polymerization of 8-vinylquinoline (8-VQ) by the combination of yttrium catalysts with alkylaluminum and [Ph3C][B(C6F5)4] via the heteroatom-assisted polymerization process. Y-4 with a pyridinyl ligated fluorenyl group shows high activity and high syndioselectivity (rr > 99%) for 8-VQ polymerization. The resultant polymers have high molecular weight (Mn 33,000–134,000 g mol–1) and high glass-transition temperature (Tg 139–147 °C), which have the application prospect of a high-temperature proton exchange membrane. The polymerization mechanistic aspect is elucidated by density functional theory calculations. We find that the σ–π coordination mode between 8-VQ and the catalytic center can weaken the difference of interaction energy between syndio- and iso-selectivity and improve the influence of steric hindrance to further promote the synthesis of highly syndiotactic P(8-VQ). We expect that our new findings could provide guidance for the synthesis of stereoregular polymers containing heteroatoms.