GIANT最新文献

Versatile devices with tunable capabilities for controlling lasing wavelength and intensity are in high demand. Liquid crystals (LCs) exhibit immense potential for such applications, offering fine-tuning possibilities through external factors. On the other hand, laser technology is currently a research hotspot in optoelectronics, and also in practical applications. The recent market introduction of laser television marks a significant stride toward making such advanced technology accessible in every household. In synergy with laser pumping, the LCs unquestionably can be rediscovered. This study presents a comprehensive investigation into the crystallization phenomenon within a host-guest device, compact in size, free from moving parts, and integrating the liquid crystalline (LC) matrix doped with 3,4,9,10-tetra-(3-alcoxy-carbonyl)-perylene (THCP) dye. The focus lies in examining the influence of varying dye concentrations on multicolor fluorescence, lasing behavior, and device morphology. The systematic analysis of Random Lasing (RL) energy thresholds and the impact of DC voltage on light intensity modulation is demonstrated. Morphological changes were monitored in real-time using optical microscopy techniques, including crossed polarizer, and fluorescence imaging under 450 nm excitation. Utilizing advanced Transmission Electron Microscopy (TEM) techniques, we explore exceptional insights into our set of devices, providing novel information about the THCP crystallization process for the first time in the literature. To gain a comprehensive understanding of the crystal forming and molecular geometry we examined additionally the THCP dye, using X-ray diffraction and Raman spectroscopy. Furthermore, we showcase that varying the pumping energy enables multicolor tuning in the fabricated systems, presenting an attractive feature in the context of laser display technologies.

In load carrying structures and devices, there is a growing need for shape memory polymer (SMP) metamaterials that are lightweight and have superior strength, remarkable flexibility, and substantial specific recovery force (SFR). One of the challenges is to find optimum lightweight structures with high SFR. To address this challenge, we propose a novel inverse design framework to design plate-lattice structures (PLSs) with user-defined optimum specific maximum compression strength. Consisting of three sub-frameworks, the performance of the inverse design framework was validated before it was utilized to optimize PLSs. The optimum PLSs developed are fabricated with 3D printing using a novel SMP. In addition, we have printed a solid cylinder and Cubic+Octet (control) PLSs to compare their structural capacity with the predicted structures. The optimized PLSs display 30 ∼ 170 % greater SFR compared to the control PLS and solid cylinder. These findings suggest a promising strategy for enhancing the effectiveness of actuators based on SMP mechanical metamaterials. The inverse design framework has the potential to be utilized for generating structures with user-defined optimum mechanical properties.

Fluorinated carbon (CF_x) compounds have extensive applications in lithium primary battery cathodes owing to their high energy density. In this investigation, a novel CF_x compound offering superior electrochemical properties was synthesized via a low-temperature fluorination process, utilizing Pluronic F127 as a template agent and microporous carbon spheres produced through soft template-assisted high-temperature carbonization and chemical activation as precursors, and by regulating the amount of soft template F127 added. The reduction in microsphere size, narrower particle size distribution, and introduction of defects contribute to augmenting the molar ratio of F to C (F/C) of CF_x while preserving the electrochemical activity of C-F bonds. The specific capacity of fluorinated polymer-derived microporous carbon spheres (FPMCSs) with a high fluorination degree rivals that of commercial fluorinated graphite (FG). The microsphere morphology and microporous structure not only furnish abundant sites for fluorination reactions in electrode processes but also facilitate Li⁺ diffusion, ensuring ample rate capability. The synthesized FPMCSs exhibited a peak specific capacity of 1079 mAh g^–1 and a maximum energy density of 2679 Wh kg^–1 (substantially surpassing the 2180 Wh kg^–1 of commercial FG). Hence, the prepared FPMCSs underscore the significance of selecting suitable carbonaceous materials and designing structures deliberately, showing promising potential for achieving high energy density in CF_x cathodes in the future, employing readily available and cost-effective raw materials.

In recent years, 3D hydrogels based on alginate (Alg) have undergone substantial advancements, holding transformative potential for biomedicine and regenerative medicine. Nevertheless, the viscosity of Alg needs to be further increased, in order to print complex 3D structures. Attempts to adjust printability often employ rheological modifiers like methylcellulose (MC), but these still lack mechanical integrity for broader biomedical applications. Our study sought to chemically modify Alg/MC to create a photopolymerizable hydrogel by incorporating acrylate-based monomers, which would enhance the curing ability of the base hydrogel, leading to better mechanical properties of Alg/MC, such as stretchability and stability with shape recovery. Comprehensive mechanical assessments unveiled remarkable tensile properties, achieving a notable specific strength benchmark of 44.72 kPa/(g.cm^-3) before reaching the point of fracture. This represents a substantial 250 % improvement compared to samples lacking the acrylate monomer. Biomedical assessments confirmed the hydrogel's promising potential, especially with the MG-63 cell line, underscoring its suitability for advanced applications like tissue engineering.

Elastomeric polyurethane (EPU) is characterised by distinctive mechanical properties, including high toughness, low glass transition temperature, and high impact resistance, that render it indispensable in diverse engineering applications from soft robotics to anti-collision devices. This study presents a thermo-mechanically coupled constitutive model for EPU, systematically incorporating hyperelasticity, viscoelasticity, thermal expansion, and self-heating effect in a thermodynamically consistent manner. Experimental data, obtained from previous studies, are then used for parameter identification and model validation, including iterative updates for temperature parameters considering the self-heating effect. Subsequently, the validated model is integrated into finite element codes, i.e., user subroutine to define a material’s mechanical behaviour (UMAT) based on the commercial finite element software ABAQUS, for the computation of three-dimensional stress-strain states, facilitating the analysis of the structural response to various mechanical loads and boundary conditions. The results obtained from simulations are compared with analytical solutions to confirm the precision of Finite Element Method (FEM) implementation. The self-heating effect is further analysed under different strain rates and temperatures. To validate the engineering significance of the FEM implementation, a plate with a hole structure is also simulated. In conclusion, this research provides a robust tool for engineers and researchers working with soft materials, enhancing their understanding and predictive capabilities, notably addressing the self-heating effect in thermo-mechanical behaviours.

The demand for novel bio-based materials in UV-curing additive manufacturing has surged due to increasing environmental concerns and a growing emphasis on sustainable practices in the manufacturing industry. However, at the moment, their thermomechanical performance is not equal to that of their fossil-based counterparts and this impedes the acceptance of these materials within the industrial community. Therefore, in this study, a series of nanocomposite polyesters based on itaconic acid was synthesized for the first time with in-situ polymerization, in an attempt to leverage the unique properties of nanofillers and improve the overall performance of the material. A variety of reinforcing agents were utilized, namely cellulose nanocrystals (CNC), montmorillonite (MMT), graphene nanoplatelets (GNP) and titanium dioxide (TiO₂), to understand the effect of each filler on the physicochemical properties of the polyester. Formulations of these polyesters were then prepared and processed on a digital light processing (DLP) 3D printer to prepare test specimens. Extensive thermomechanical characterization showed that the interference of the fillers with the UV curing process was the main parameter determining the mechanical performance of the 3D printed materials.

Shape memory polymers (SMPs) and their composites have broad application prospects in multiple fields due to their unique shape memory effects. However, they still face challenges in accurately controlling the shape recovery process, improving the stability of shape memory loops, and achieving the manufacturing of complex shapes and functions. At present, theoretical models, molecular dynamics (MD) simulations, and additive manufacturing technologies have been widely applied. Theoretical models and MD simulations provide theoretical foundations at both macro and micro levels, respectively. Meanwhile, by combining SMPs and their composites with additive manufacturing, some complex structures can be produced. This not only verifies the accuracy of the theoretical foundation, but also further expands its application. This review aims to review the application and intersection of theoretical models, MD simulations, and additive manufacturing in the research of SMPs and their composites, and analyze how they jointly promote the leap from theory to application, providing valuable insights for future development trends.

Improving the heat resistance of bio-based and biodegradable polyesters is of great significance to extend their applications. Herein, N,N’-trans-1,4-cyclohexane-bis(pyrrolidone-4-methyl carboxylate) (T-CBPMC) was prepared through efficient Michael-addition reaction between dimethyl itaconate and trans-1,4-cyclohexanediamine. The obtained T-CBPMC was copolymerized into aliphatic poly(butylene succinate) (PBS), and a series of PBSPs copolymers with T-CBPMC (BP) molar percentages between 41−80 mol % and weight average molecular weight (M_w) values ranging between 5.77*10⁴ and 6.67*10⁴ g/mol were prepared. BP units efficiently facilitated the melting temperature (203-251 °C) and isothermal-crystallization rate (t_1/2 < 20 s) of PBSPs, endowing the highest heat resistance among commercial biodegradable polyesters, which helps maintain stable in pasteurization, high-temperature disinfection, and microwave environments. Moreover, these copolymers displayed remarkable mechanical, gas barrier properties and degradability. PBSP40-PBSP60 obtained high elastic modulus (335–872 MPa) and tensile strength (24.7–31.5 MPa), and good toughness simultaneously. Multiple-ring structures and large steric hindrance of BP units resulted in superior O₂ barrier performance than that of non-degradable PET films. Importantly, the PBSP copolyesters showed obvious degradation in water environments and relatively better enzymatic degradation. It was interesting to find that even with 70 % of the BP units, the PBSP copolyesters still retained hydrolysis ability. The resulting PBSP copolyesters open the way for alternative candidates of biodegradable packaging materials with rapid crystallization, high heat-resistance and gas barrier.

The combination of well-balanced mechanical performance, high transparency and appealing eco-friendly attributes endows poly(lactic acid) (PLA) with significantly potential for wide-ranging applications in high-value packaging sectors. However, effectively toughening PLA without compromising its transparency and stiffness remains a formidable challenge. In this study, we synthesized a series of graft copolymers by incorporating hydroxyl-functionalized linear low density polyethylene (LLDPE_OH) and copolymers of cycloolefin (COC_OH) as the main chain and PLA as the side chain, which were subsequently employed as novel toughening agents for commercial PLA. The achievement of high-performance PLA blends with a balanced combination of toughness, strength, and transparency can be realized through meticulous tuning of the structure and mass fraction of the blended graft copolymers. The maximum elongation at break for the PLA blends increased by about 50 times that of neat PLA, reaching up to 300 %. Furthermore, these materials retained their high strength (54 MPa) and excellent transparency (light transmittance up to 90 %). The excellent properties of PLA blends could be ascribed to the well-designed chain structure of the graft copolymer which leaded to and excellent compatibility with the PLA matrix and unique phase morphology. This work is significant in guiding the design and synthesis of graft copolymers as toughening agents for PLA, thereby expanding its application range in areas where high transparency and toughness are required.

To enhance the nitrogen utilization efficiency of fertilizers, we developed a novel slow-release fertilizer hydrogel through free radical polymerization, incorporating lignin-containing cellulose nanofiber (LCNF), clinoptilolite (CL), urea, and acrylic acid (AA)-co-acrylamide (AAm) polymer. Various analytical techniques were utilized to examine the structure, swelling, and release behaviors of the fabricated hydrogels with varying LCNF concentrations. The results indicated that the addition of 10% LCNF led to a decrease in water absorption from 72.44 g g⁻¹ to 24.04 g g⁻¹. However, re-swelling was significantly enhanced, with a reduction in re-swelling capacity loss from 32.91% to 23.52%. Concurrently, water retention capacity notably increased from 18.03% to 39.20%. The hydrogel containing 10% LCNF exhibited a slower urea release over 30 days. The kinetic studies revealed that the swelling and urea release behaviors align well with the second-order kinetics model and the Peppas-Sahlin model, respectively. In summary, the developed LCNF/CL/(AA-co-AAm)/urea hydrogel nanocomposites present a novel strategy for the future production and utilization of slow-release fertilizers in agricultural and horticultural fields.