SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3872-3
Flexoelectricity, the generation of electrical polarization in response to a strain gradient, is a fundamental electromechanical coupling mechanism that has gained significant attention due to its enhanced effects in ferroelectric materials, which exhibit large dielectric permittivities. This review comprehensively examines the classical theories and recent advances in flexoelectricity, with a primary focus on ferroelectric materials. We discuss the advantages and limitations of various characterization techniques, computational models for determining flexoelectric coefficients, and the mechanisms that enhance flexoelectricity in different ferroelectric systems. Furthermore, we explore the applications of flexoelectricity in devices, highlighting its potential to overcome the dimensional and stability limitations of piezoelectricity, particularly at the micro- and nanoscale. The review concludes by outlining future research directions, aiming to provide valuable insights for advancing both the fundamental science of flexoelectricity and the development of high-performance practical devices.
The Chinese Journal of Process Engineering•2026•DOI: 10.12034/j.issn.1009-606X.225172
The increasing discharge of oily wastewater from oil extraction and anthropogenic activities necessitates the development of efficient oil-water separation technologies to safeguard ecological and environmental safety and ensure sustainable resource utilization. Membrane separation technology, owing to its high efficiency and operational convenience, has emerged as a viable solution for treating oily wastewater. To enhance the hydrophilic and oleophobic properties of hydrophobic separation membranes, this study employed polyvinylidene fluoride (PVDF) hydrophobic microfiltration membranes with robust mechanical properties as substrates. Through a biomimetic coating approach, dopamine (DA) was first polymerized to form polydopamine (PDA) on the membrane surface, which subsequently reacted with polyvinyl alcohol (PVA) to construct a dense hydrophilic layer, yielding modified membranes with hydrophilic/oleophobic surface characteristics. The morphology and chemical composition of the modified membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Oil-water separation performance was comprehensively evaluated by measuring water contact angle, underwater oil contact angle, emulsion flux, and oil rejection. Under optimal conditions, the modified membrane M3 exhibited a pure water flux of 4893.2 ± 70.2 L/(m²·h), an emulsion flux of 2138.1 ± 29.4 L/(m²·h) for toluene-in-water emulsion, and an oil rejection of 98.5% ± 0.1%. Simulated fouling and regeneration tests using bovine serum albumin (BSA) solution demonstrated a flux recovery rate of 92.0% for M3, indicating excellent antifouling performance. Immersion tests in acid, alkali, and salt solutions confirmed the modified membrane's outstanding chemical stability. The designed PVDF modified membrane offers advantages of simplicity, environmental friendliness, and high efficiency, showing significant application potential in oil-water separation and providing a novel strategy for membrane development.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3986-2
Organic/molecular ferroelectrics exhibiting spontaneous polarization have attracted increasing attention due to their flexibility, light weight, low-temperature processability, environmental friendliness, and biocompatibility. Among them, organic donor-acceptor cocrystals, self-assembled from two or more components, offer new insights into ferroelectricity. This review systematically examines recent progress in organic donor-acceptor cocrystal ferroelectrics, focusing on microscopic origins of ferroelectricity, structure modulation strategies, and underlying mechanisms. Ferroelectric origin mechanisms, including intermolecular charge transfer, proton transfer, and order-disorder transitions, are analyzed in detail. Structure-property relationships in crystal engineering are summarized, and recent advances in theoretical simulations, experimental characterization techniques, and practical applications are introduced. Finally, current challenges and future research perspectives are outlined. The review highlights that weak intermolecular interactions often lead to low Curie temperatures (Tc), limiting practical applications. Strategies to enhance Tc involve introducing stronger molecular interactions to increase transition energy barriers. Notably, room-temperature ferroelectricity in organic cocrystals has been achieved, as demonstrated by Wiscons et al. (Angew Chem Int Ed, 2018, 57: 9044–9047). The review underscores the potential of organic cocrystal ferroelectrics for flexible and wearable electronics, while addressing the need for higher Tc and robust switching performance.