A journey into the chemistry of silicon – from molecules to materials

A l’occasion de la venue exceptionnelle du Professeur Richard M. Laine de l’Université de Michigan, le pôle Chimie de l’Université de Montpellier vous invite à un symposium sur la chimie du silicium.

Intitulé « A journey into the chemistry of silicon – from molecules to materials » il sera également l’occasion de présenter quelques travaux de recherche des instituts composant le pôle chimie et de rassembler les acteurs de cette thématique.

Outre les conférences, un moment d’échange sera organisé avec les doctorant.e.s.

Résumé des conférences

9h-10h Session plénière (1) Prof. Richard Laine
Silicon Carbide (SiC) Anodes Derived from the Biowaste Product, Rice Hull Ash (RHA), for Lithium-ion Batteries: Performance and Mechanisms.

Description 

Biomass-derived materials offer a low to neutral carbon approach to energy storage. We explore here the use of SiC with (SiC/HC) and without hard carbon (SiC/O), derived from rice hull ash (RHA) as Li+ battery anodes. Galvanostatic cycling of SiC/HC and SiC/O shows capacity increases eventually to >950 and >740 mAh g-1, respectively, after 600 cycles. These values suggest lithiation at ≈ 1.4Li:SiC[LR1] . Room temperature Li+ diffusion coefficients are of the order of 10-22-10-14 cm2 s−1.

Post-mortem studies using XRD and MAS NMR reveal partial phase transformation from 3C to 6H SiC, with no significant unit cell size changes observed. SEM images show cycled electrodes maintain their integrity, implying almost no volume expansion on lithiation/delithiation. No evidence for lithium silicide was observed in MAS NMR or XPS. Computational modeling reveals that Li+ prefers an all C environment due to electrostatic interactions, and 3C to 6H phase transformation is possible at high Li content.

Session plénière (2) Prof. Richard Laine
Further proof of unconventional conjugation via disiloxane bonds. Double decker silsesquioxanes and half cages.

Description

In this work, we continue efforts to expand the family of silsesquioxane (SQ)-based oligomers and polymers that exhibit through-cage conjugation in the excited state and to map structure-property relationship for practical applications. We recently reported synthesizing a series of double decker (DD), expanded DD and half cage derived copolymers prepared via Heck cross-coupling that exhibit unconventional conjugation as evidenced by exceptional red-shifted emissions relative to model compounds. When copolymerized with biphenyl, terphenyl and stilbene, the SQ polymers typically emit ca. 400 nm with quantum yields ≥ 0.6.

Entre 10h et 13h

Exemple de travaux réalisés entre l’IBMM  et l’ICGM
Ahmad Mehdi – Gilles Subra
When the inorganic polymerization of silicon meets biomolecules. A successful combination

Description

This lecture will present a collaboration between IBMM and ICGM involving the development of biocompatible sol-gel catalyst and a wide range of hybrid building blocks consisting in silylated peptides, dyes, drugs and biopolymers, that can be combined and engaged in sol-gel hydrolysis and condensation. This allowed us to prepare biomimetic hydrogels for cell encapsulation and bioinks for 3D bioprinting. During the last 10 years, several challenges were tackled including the preparation of bioactive titanium or silicon medical devices and dressings, multiligands fluorescent nanoparticles for cancer targeting, hyaluronic and collagen-based hydrogels and foams for tissue engineering; protein-imprinted magnetic nanoparticles, sensors able to detect specific MMP enzyme activity.

Exemple de travaux réalisés à l’ICGM
Lorenzo Stievano
Development of silicon negative electrodes for lithium batteries

Description

With its high theoretical capacity and reasonable cost, silicon is a promising negative electrode material for lithium-ion batteries. The large volume expansion observed during the electrochemical lithiation process, however, is a serious obstacle for its practical application. Several strategies have been proposed for the development of practical silicon electrodes, including modification of the silicon chemistry, morphology as well as electrode engineering. Some of these aspects are currently under investigation at ICGM in the framework of academic and industrial collaborations, in order to obtain viable high performance silicon electrodes.

Exemple de travaux réalisés à l’IEM
Anne Julbe
Silicon Carbide- An attractive material for membrane applications

Description

Non-oxide ceramic membranes based on silicon carbide (SiC) and silicon carbonitride (SiCN) materials recently received significant attention in the membrane community, for both liquid and gas phase separations.

Whatever the considered application, understanding and controlling the SiC-material microstructure and its original surface/interface properties are strategic research areas for boosting the developments of these membranes in industry.

This presentation will provide examples of the approaches developed at the IEM for a rational design and investigation of these versatile membrane materials.

A propos de Prof. Richard Laine


Richard M. Laine is Professor at Dept. of Materials Science and Engineering, Macromolecular Science and Engineering Center at the University of Michigan

 

Research interests

Major research areas for the Laine group include the synthesis and processing of inorganic/organic hybrids, metalloorganic and organometallic polymers, and in the production of mixed-metal oxide nanopowders from them. We are particularly interested in polyfunctional macromonomers (octahedral silsesquioxanes or cubes) synthesized in one or two steps from simple starting materials, e.g. silica. These macromonomers are then processed into shapes whose properties are defined by the attached organic functionality. The effects of processing conditions and polymer architecture on macroscopic or global properties are of specific interest for nm x nm construction of nanocomposites. Processing of metalloorganic polymers into mixed-metal oxide nanopowders via liquid-feed flame spray pyrolysis (LF-FSP) represents another area of significant interest. LF-FSP provides a means of escaping the tyranny of thermodynamics by producing nanopowders at temperatures in excess of 1500°C and then quenching them to < 400°C in microseconds, trapping kinetic products. We are also interested in the effects of processing conditions on mechanical, optical and electronic properties of these nanopowders. Two companies have been spun out of these technologies.

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