Portail HAL ENSCP
Not a member yet
9647 research outputs found
Sort by
Construction and deconstruction: recent advances in degradable silicon-based polymers
No full textInternational audienceThis review article presents recent advances in the design, synthesis, degradation, and recycling of degradable silicon-based polymers, with a focus on poly(silyl ether)s, and poly(silyl ester)s. These materials offer a promising route toward sustainable polymer technologies by integrating labile Si–O–C and Si–O–C([double bond, length as m-dash]O) linkages into polymer backbones, enabling controlled degradation without compromising performance. This article details synthetic strategies including step-growth and chain-growth polymerizations, explores degradation mechanisms under various chemical conditions, and highlights emerging catalytic systems, ranging from noble metals to earth-abundant and metal-free catalysts. Challenges and future directions for integrating degradability with high-performance properties are also discussed
Characterization of electronic conductivity by broadband dielectric spectroscopy of positive electrode materials of spinelle-type Li-ion batteries
No full textInternational audienc
Efficient UV Organic Solid‐State Lasers with Ultra‐Short Wavelengths Based on Dispirofluorene‐Indenofluorene Isomers
No full textInternational audienceThe development of efficient UV organic solid‐state lasers (OSLs) remains a significant challenge, yet it is crucial for enabling advanced photonic technologies. This study investigates two dispirofluorene‐indenofluorene regioisomers, (2,1‐a)‐DSF(tBu)4‐IF (DSFIF‐syn) and (1,2‐b)‐DSF(tBu)4‐IF (DSFIF‐anti), to elucidate the impact of subtle structural differences on their solid‐state photophysical and lasing properties. Through a combination of experimental techniques and theoretical approaches, including comprehensive optical characterization and molecular dynamics simulations, it is demonstrated that DSFIF‐syn exhibits significantly reduced intermolecular aggregation compared to DSFIF‐anti, resulting in enhanced optical performance in solid‐state thin films. Remarkably, amplified spontaneous emission (ASE) is achieved at a record‐short wavelength of 365 nm with a low threshold of 4.5 µJ cm−2 (5000 W cm−2) in a PMMA blend film. Moreover, distributed feedback (DFB) laser devices incorporating a blend film of DSFIF‐syn dispersed in polystyrene (PS) enabled lasing at an unprecedentedly short wavelength of 358.5 nm, as well as a low lasing threshold of 0.7 µJ cm−2 (780 W cm−2) at 363.3 nm. These results demonstrate that dispirofluorene‐indenofluorene derivatives are highly promising UV laser dyes, highlighting isomeric control as a valuable molecular design strategy for advancing high‐performance organic lasers
Synthesis of 1,2-Fluorinated Ferrocenes and 1,3-Fluorinated Ferrocenes
No full textInternational audienceSince the discovery of ferroquine and ferrocifen, the incorporation of ferrocene into existing biologically relevant scaffolds has been shown to be an efficient method to unveil new drug candidates with additional modes of action. Concomitantly, it is well-documented that the insertion of a fluorine atom into drugs can help fine-tune their pharmaceutical properties. However, the intersection of both methods remains rather underexplored. In this work, we designed and synthesized the corresponding 1,2-fluorinated ferrocenes and 1,3-fluorinated ferrocenes that could serve as building blocks for drug-like scaffold construction
Internal short circuits in lithium-ion batteries; origins, detection, and experimental reproduction: A review
No full textInternational audienceInternal short circuits constitute a significant risk to the safety and performance of lithium-ion batteries (LiBs). Internal short circuits are among the most problematic failure mechanisms in LiBs because of their ability to cause thermal runaway and catastrophic failure and inherent difficulty of detection. This review provides a comprehensive overview of the types of internal short circuits, their origins, and the experimental methods used to reproduce them. Firstly, the definition and classification of internal short circuits, as well as their associated consequences from minor performance loss to thermal runaway, are described. Secondly, the root causes of internal short circuits are investigated, including a thorough examination of each manufacturing stage where defects can appear, focusing on preventive measures. Finally, the review details experimental approaches to reproduce internal short circuits mentioning their respective advantages and drawbacks with a focus on mechanical internal short circuit reproduction devices, such as nail/needle penetration techniques. These techniques are the easiest to implement but have an important number of variable parameters that can influence the test outcome
Bis-alkenyl compounds from group XIV elements (Si, Ge, Sn): synthesis, reactivity and applications.
No full textInternational audienceThis short review summarizes the state-of-the-art for the synthesis of bis-alkenyl compounds from group XIV elements (Si, Ge, Sn). The reported methods that allow formation of such functionalized reagents are discussed, as well as their use as synthetic building blocks in the synthesis of value-added fine chemical targets, polymers and materials
Supercritical fluid technology to the formulation of quercetin amorphous solid dispersions
No full textInternational audienc
High-triplet-energy polymers via RAFT polymerization: Synthesis and properties
No full textInternational audienceRAFT polymerization of a series of styrene-type dibenzoheterocyclic monomers bearing carbazole, phenoxazine, 9,9-dimethylacridane and phenothiazine moieties using S-dodecyl-S′-(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate as a chain transfer agent has been investigated. The corresponding polymers with the controlled molar mass of up to 30,000 g mol -1 with low to moderate dispersity (Đ = 1.2-1.6) were synthesized. The thermal, photophysical and electrochemical properties of the prepared polymers have been investigated using their solutions, films and in silico to establish the structure-properties relationship. The synthesized polymers were characterized by high values of HOMO (up to -5 eV), singlet (up to 3.8 eV) and triplet (up to 3.2 eV) energies, which are responsible for their unique properties such as formation of excimers with CHCl3 and dichloromethane or the ability to undergo coupling via electrooxidation in case of poly(9,9-dimethyl-10-(4-vinylphenyl)-9,10dihydroacridan). Subsequently, two series of OLEDs based on the synthesized polymers were fabricated in order to study the charge-injecting and charge-transporting properties of these materials as well as to evaluate their performance in solution-processable diodes
The Ascent of Supramolecular Polymers and Gels in Asymmetric Catalysis
No full textInternational audienceSupramolecular polymers (SPs) and gels, formed by the spontaneous assembly of small molecules through various types of noncovalent interactions, are attractive materials for many applications. Their modularity also offers many opportunities in asymmetric catalysis that have been tackled in the last two decades and more intensively in the last one. In this review, strategies adopted to develop efficient asymmetric catalysts supported on SPs and gels are first categorized according to the chiral or achiral nature of the monomers used for their construction and second to their ability to be commuted into different states. Catalytic SPs have been described for which enantioselectivity stems mostly from the molecular chirality located next to the reactive group, or at opposite ends of the spectrum, exclusively from the chiral environment provided by the supramolecular helices. New paradigms revealed by these systems include (i) the organization of catalytic sites at the periphery of modular and well-structured 1D assemblies, (ii) the possibility to conduct asymmetric reactions with a sub-catalytic amount of chiral inducers and even in the absence of chiral monomers, and (iii) the development of a new class of switchable asymmetric catalysts