GIANT最新文献

To achieve all-organic polymer with high dielectric performances, we have designed a novel side-chain liquid crystalline polymer (P7) with strong polar mesogen of (Z)-4-(2-cyano-2-phenylvinyl)benzonitrile (CSCN) attached to polycyclooctene backbone. The bis-cyano-substituted CSCN is board-shaped and exhibits a large dipole moment (8.54 D) which tilts ∼34.2° away from its molecular long axis. Consequently, CSCN shows unique dual molecular anisotropy: one from biaxial shape anisotropy and the other from polarization anisotropy. The complex phase behaviors of P7 were investigated employing mainly the techniques of differential scanning calorimetry and X-ray diffraction. Four liquid crystal (LC) phases are identified as K0, K1, K2 and K3, which are SmA, highly-ordered biaxial SmA, B5-like and B7-like, respectively, with the thermal stability increased in sequence. The experimental results indicate that the different LC phases are arisen from the competition and balance between π-π stacking and dipole-dipole interaction. While the face-to-face π-π stacking is dominant in K0 and K1, optimizing the dipole-dipole interaction causes the CSCN mesogens within the smectic layer to tilt and rotate, resulting in K2 and K3. We further investigated the dielectric properties of P7 films using polarization-electric field loops test. The dielectric constant (ε_r) of P7 is found to be LC structure dependent, which is increased when the LC phase is varied from K0 to K3. With an average ε_r of 9.7 achieved in K3 and the low dielectric loss (tan δ = 0.001), P7 film offers a promising material in advanced applications like energy storage and electronic devices.

This paper describes the two-dimensional (2D) crystallization of side-chain giant molecules (SCGMs) having the fixed number ratio of two types of functionalized building blocks with 1:1. SCGMs are regarded to a certain degree as size-amplified versions of universal synthetic polymers that are prepared by precisely connecting molecular nanoparticles (MNPs) to polymer chains. Our previous experimental results have shown that individually changing the number ratio of one of the building blocks would significantly affect the structural parameters of molecular crystals, mainly the longitudinal thickness. Herein, we systematically discussed the 2D crystallization of two categories of POSS-based SCGMs with constant building blocks ratio. Solution self-assembly of such SCGMs resulted in well-defined 2D nanosheets with similar structural configurations, showing great tolerance in the number of building blocks. Subsequently, we proposed a “sandwiched-type” mode to illustrate the bilayer 2D supramolecular framework, in which crystalline blocks pack in head-to-head manner. In addition, sequence isomers provide an ideal platform to further verify that the thickness of 2D nanocrystal is linked with the tethering density determined by the number ratio of building blocks. We believe that this study could be a better complement to our previous work and then make us to be more in-depth understand the crystallization mechanism of SCGMs.

Organic electrochemical transistors (OECT) have shown great potential in diverse applications; however, in many OECTs, their slow transient response has thus far limited their practical use. One reason for the slow response is the complex interplay between lateral and vertical ion transport that has so far been poorly understood. In this work, we study the impact of lateral ion transport on OECT transient response, introduce a robust pre-charging method to manipulate the slow lateral ion transport. This approach leads to quicker ion redistribution and improved switching speeds. We show the general utility of pre-charging method in enhancing the switching speeds across various material systems, characterized by both low and high ion mobilities, and across different device architectures, achieving nearly symmetric speeds for both on-switching and off-switching. Moreover, we showcase the efficacy of the pre-charging method in enabling slow OECTs to capture rapid signals in real-world applications. Our findings present a groundbreaking strategy for enhancing the response times of OECT devices and deepening our understanding of the transient mechanisms in OECT device.

The recent discovery of liquid-matter ferroelectrics not only opens a door to explore novel polar matter states and properties in the term of condensed matter physics but also provides unprecedented opportunities for developing new liquid crystal materials and technologies. The progression from the ferroelectric nematic phase to many other liquid-matter ferroelectrics represents a remarkable journey in emerging polar soft matter. In this perspective, we briefly introduce the latest quick rise and advancements of liquid-matter ferroelectrics that display the nematic and smectic characteristics. We summarize the recently-discovered new polar phases, their new physics, and potential technological innovations, and then give some hints that we consider critical for further exploration. More importantly, we seek to delve into broader discussions on chemical structure design, the underlying physical interactions driving various polar states, and their connections to a range of intriguing phenomena.

Biomimetic damping materials have emerged as promising candidates for various applications due to their ability to mimic the exceptional damping properties observed in biological systems. This review provides a comprehensive overview of recent advances in the field of biomimetic damping gel materials. The conceptual framework of biomimetic damping materials is discussed, the synthesis methods inspired by biological principles are elucidated, and key considerations in material selection are highlighted. The latest research findings on the mechanical properties, biocompatibility and practical applications of these materials are synthesized and insights into the future directions of biomimetic damping gel materials are offered.

We developed a cost-effective silica gel-supported palladium nanocatalyst in a three-step reactions process. Initially, silica gel (60–120 mesh) underwent amino group functionalization using 3-aminopropyltriethoxysilane, leading to the formation of a Schiff base through a reaction with the 1,10-phenanthroline-2,9-dicarboxaldehyde ligand. Subsequently, palladium nanocatalyst was introduced to the silica matrix ligand in the presence of palladium salt and hydrazine hydrate, resulting in the formation of the silica gel-supported Schiff-base palladium nanocatalyst (Si@SBPdNPs 3). Successful functionalization of the silica matrix was confirmed using various spectroscopic techniques. FT-IR spectra demonstrated the incorporation of organic moieties onto the silica surface, while SEM images revealed the modified spherical shape of the silica gel. TEM and XRD analyses confirmed the presence of palladium on the silica matrix. ICP and EDX measurements validated the anchoring of 0.55 mmol/g of palladium to the catalyst. Additionally, XPS analysis showed the complexation of Pd⁽⁰⁾ with the organic ligand on the silica matrix, confirming the successful integration of palladium into the system. This nanocatalyst demonstrated outstanding performance in Mizoroki-Heck reactions, yielding high product outputs in the cross-coupling of various aryl halides and olefins under mild conditions. Additionally, the nanocatalyst was effectively utilized in synthesizing Ozagrel, a thromboxane A2 synthesis inhibitor used for treating noncardioembolic stroke patients. Remarkably, the catalyst demonstrated excellent reusability, maintaining high productivity across five consecutive cycles, underscoring its economic and sustainable potential for industrial applications.

Solid polymer electrolytes (SPEs) with wide electrochemically stable window and high lithium-ion transference number (t_Li⁺) are a requirement for high energy density lithium batteries. Here, we construct a copolymer electrolyte (PDA) with ether-ester bifunctional groups that exhibits a low highest occupied molecular orbital (HOMO) energy level by in situ polymerization. Compared to the poly(1,3-dioxolane) (PDOL) pure polyether electrolyte, the weakening of the ion-dipole interaction between lithium salt and polymer in the PDA electrolyte promotes the formation of a “weak solvation” structure. Therefore, the electrolyte achieves high oxidative stability (4.6 V vs. Li⁺/ Li with a standard leakage current of 10 μA), high Li⁺ transference number (0.60), and importantly, derives a stable LiF-rich composition on high voltage cathode surface. Which ultimately enables stable cycling of Li||LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) batteries at a range of 3.0–4.3 V. This work provides a fundamental understanding of the design of antioxidant SPEs to achieve high energy density lithium batteries.

Dissipative solitons in liquid crystals (LCs) are represented by three-dimensional solitary waves of director deformation called directrons. The only one exception on the quasi-static counterparts of directrons has ever been observed in achiral nematics. In this work, quasi-static solitons and their fission are identified in chiral nematics. The structure, distribution and fission of quasi-static solitons are closely related to the pitch of samples. The critical pitch is about 7.0 µm for LC cells with thickness of ∼10.0 µm. Quasi-static solitons are transformed from directrons by stepping down voltage to facilitate locating solitons. Successive two-soliton fission with increasing fission time occurs for all quasi-static solitons in samples of relatively larger pitches. Multi-soliton fission is also found in some quasi-static solitons when the voltage is stepped up back to the directron domain, leaving behind a region that can modify the trajectories of surrounding directrons. The fission of quasi-static solitons in chiral nematics has predictable fission location, adjustable fission time, and controllable fission number, may acting as an excellent model system for studying general principles of soliton fission in nonlinear systems.

Spiro-OMeTAD is a primary hole transport material (HTM) employed in most state-of-the-art regular perovskite solar cells (PSCs). The essential reliance on hygroscopic ionic dopants to enhance the conductivity and mobility of Spiro-OMeTAD has dramatically compromised the stability of PSCs. Here, we demonstrated excellent photovoltaic performance of PSCs by developing two dopant-free polymers, namely L1 and L2, using thieno[3,2-b]thiophene as a building block. It is found that the n-hexyl-modified thiophene side chains endow the polymer L2 with favorable crystallinity, unique self-assembly behavior, and a preferable face-on stacking orientation. After the addition of a small amount (10 %) of PM6 to create a polymer alloy named LPA, the above properties were further improved, and the resulting film exhibited a distinct fibrous morphology, resulting in increased hole mobility and effective defect passivation. Consequently, PSCs employing LPA as a dopant-free HTM afforded a high efficiency of 23.81 %. Importantly, LPA-based PSCs exhibit significantly enhanced operational stability with a T80 lifetime of 1572 h at 55 °C. This work provides a crucial guideline for the design of dopant-free polymers, thereby advancing the practical application of PSCs.

The twist-bend nematic (N_TB) phase of achiral liquid crystals (LCs) manifests a unique self-assembled heliconical structure with nanometer-scale pitch length, mirroring the chiral symmetry-breaking phenomena in nature, thus sparking widespread research interest. However, the ingenious N_TB phase is only stable at high temperatures within a very limited temperature interval, often undergoing inevitable crystallization at low temperatures. Herein, room temperature supercooled N_TB material systems composed of meticulously designed LC dimer mixtures with varying molecular curvatures and central flexibility were developed, resulting in complete resistance to crystallization even after 1 year of storage. Furthermore, the proposed N_TB material systems demonstrated exceptional compatibility with common nematic LCs, facilitating the tailoring of overall physical parameters, particularly to achieve a sufficiently low bend elastic constant with excellent stability. This work represents a paradigmatic advancement forward in realizing stable N_TB phase materials with a broad temperature range and resistance to crystallization, thereby tackling the enduring and seemingly insurmountable challenge while providing impetus for further exploration of their applications in soft matter, crystallography, and advanced photonics.