Nanostructural organization of thin films prepared by sequential dip-coating deposition of poly(butylene succinate), poly(ε-caprolactone) and their copolyesters (PBS-ran-PCL)

Fabrication electro-spun Poly(vinyl alcohol)-Melamine nonwoven membrane composite separator for high-power lithium-ion batteries

Current commercial separators used in lithium-ion batteries have inherent flaws, especially poor thermal stability, which pose substantial safety risks. This study introduces a high-safety composite membrane made from electrospun poly(vinyl alcohol)-melamine (PVAM) and polyvinylidene fluoride (PVDF) polymer solutions via a dip coating method, designed for high-voltage battery systems. The poly(vinyl alcohol) and melamine components enhance battery safety, while the PVDF coating improves lithium-ion conductivity. The dip-coated PVDF/Esp-PVAM composite separators were evaluated for electrolyte uptake, contact angle, thermal stability, porosity, electrochemical stability and ionic conductivity. Notably, our Dip 1 % PVDF@Esp-PVAM composite separator exhibited excellent wettability and a lithium-ion conductivity of approximately 7.75 × 10⁻⁴ S cm⁻1 at room temperature. These separators outperformed conventional PE separators in half-cells with Ni-rich NCM811 cathodes, showing exceptional cycling stability with 93.4 % capacity retention after 100 cycles at 1C/1C, as compared to 84.8 % for PE separators. Our Dip 1 % PVDF@Esp-PVAM composite separator demonstrates significant potential for enhancing the long-term durability and high-rate performance of lithium-ion batteries, making it a promising option for long-term energy storage applications.

Influence of Surface Chemistry of Fiber and Lignocellulosic Materials on Adhesion Properties with Polybutylene Succinate at Nanoscale

The production of bio-based composites with enhanced characteristics constitutes a strategic action to minimize the use of fossil fuel resources. The mechanical performances of these materials are related to the specific properties of their components, as well as to the quality of the interface between the matrix and the fibers. In a previous research study, it was shown that the polarity of the matrix played a key role in the mechanisms of fiber breakage during processing, as well as on the final properties of the composite. However, some key questions remained unanswered, and new investigations were necessary to improve the knowledge of the interactions between a lignocellulosic material and a polar matrix. In this work, for the first time, atomic force microscopy based on force spectroscopy measurements was carried out using functionalized tips to characterize the intermolecular interactions at the single molecule level, taking place between poly(butylene succinate) and four different plant fibers. The efficiency of the tip functionalization was checked out by scanning electron microscopy and energy-dispersive X-ray spectroscopy, whereas the fibers chemistry was characterized by Fourier-transform infrared spectroscopy. Larger interactions at the nanoscale level were found between the matrix and hypolignified fibers compared to lignified ones, as in control experiments on single lignocellulosic polymer films. These results could significantly aid in the design of the most appropriate composite composition depending on its final use.

Rheology and Tack Properties of Biodegradable Isodimorphic Poly(Butylene Succinate)-Ran-Poly(e-Caprolactone) Random Copolyesters and Their Potential Use as Adhesives

The sole effect of the microstructure of biodegradable isodimorphic poly(butylene succinate)-ran-poly(ε-caprolactone) random copolyesters on their rheological properties is investigated. To avoid the effect of molecular weight and temperature, two rheological procedures are considered: the activation energy of flow, E_a, and the phase angle versus complex modulus plots. An unexpected variation of both parameters with copolyester composition is observed, with respective maximum and minimum values for the 50/50 composition. This might be due to the peculiar chain configurations of the copolymers that vary as a function of comonomer distribution within the chains. The same chain configuration variations are responsible for the isodimorphic character of the copolymers in the crystalline state. Tack tests, performed to study the viability of the copolyesters as environmentally friendly hot melt adhesives (HMA), reveal a correlation with rheological results. Tackiness parameters, particularly the energy of adhesion obtained from stress-strain curves during debonding experiments, are enhanced as melt elasticity increases. Based on the carried-out analysis, the link microstructure-rheology-tackiness is established, allowing selecting the best performing HMA sample considering the polymer chemistry of the system.