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Séminaire Chimie ED459 / Chaire Total

Metal adhesives from copper-catalysed azide-alkyne cycloaddition [and other seminars]

Prof. David Díaz-Díaz (Institute of Organic Chemistry, Universität Regensburg [Ratisbone], Germany)

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Le Jeudi 26 mars 2015 à 13h45
UM Fac des Sciences, salle de cours SC-16.01 (campus Triolet)

Abstract of March 26th ED459 Seminar :

Metal adhesives from copper-catalysed azide-alkyne cycloaddition

Polymers generated in situ from the copper(I)-catalyzed cycloaddition (CuAAC) reaction between multivalent azides and alkynes have been identified as strong metal-binding adhesives. Some of these adhesives have shown much higher strength than commercially available glues for the same purpose. The performance of these ‘click’-adhesives can be remarkably improved by the incorporation of a flexibility-inducing difunctionalized component and a tertiary amine additive, among different formulation parameters. Moreover, these adhesives can be made electrically conductive by the inclusion silver-coated copper flakes and further improved by the incorporation of carbon nanotubes into the formulation.

Additional seminars (Chaire Total Fondation Balard)

During his stay in Montpellier, David Díaz-Díaz will give three additional seminars in the scope of the Chaire Total :

1. Thursday, March 12th, 2015, 10.30 am, MACS seminar room (104 rue de la Galéra, Montpellier)

The delicate balance between gelation and crystallisation

Understanding the delicate phase boundary between gelation and crystallization is important for crystal engineering and for the development of new gel-based material with superior properties. This elusive interface can be exemplified using a multicomponent gelator solution of an ammonium tartrate salt in MeOH/HCl. Solubilization of the salt occurs due to an ionic dissociation-exchange process induced by HCl. In this process, a transient chloride-containing assembly of the tartrate salt in solution, resembling that in its crystalline state, can serve as a supramolecular synthon for the growth of gel networks in the presence of different organic solvents at low temperature. These gels have very short lifetimes as a consequent of the thermodynamic formation of insoluble diaminocyclohexane dihydrochloride salt. However, a more robust formulation can be obtained by replacing MeOH by DMSO, which in the presence of HCl provides similar solubilization of the ammonium tartrate salt, but it remarkably delays the destabilization of solvated supramolecular aggregates.

2. Wednesday, March 18th, 2015, 2 pm, MACS seminar room (104 rue de la Galéra, Montpellier)

Hydrogels based on surfactant-free ionene polymers

The manifold applications of ionene-based materials such as hydrogels in daily life, biomedical sciences, and industrial processes are a consequence of their unique physical and chemical properties, which are governed by a judicious balance between multiple non-covalent interactions. However, one of the most critical aspects identified for a broader use of different polyelectrolytes is the need of raising their gelation efficiency. This presentation will focuses on the preparation of new surfactant-free ionene polymers containing DABCO and N,N′-(x-phenylene)dibenzamide (x = ortho-/meta-/para-) linkages as model systems. These ionenes were used to develop a combined computational-experimental approach aiming to improve their hydrogelation efficiency through a better understanding of the gelation mechanism. The gelation efficiency of these systems can be correlated with molecular dynamic simulations with explicit water molecules.

3. Wednesday, April 1st, 2015, 2 pm, Faculté de Pharmacie, amphithéâtre D

Controlling self-assembly of low molecular weight peptides by side-chain functionalization

The incorporation of azobenzene residues into the side chain of low-molecular-weight peptides can modulate their self-assembly process in organic solvents leading to the formation of stimuli responsive physical organogels. The major driving forces for the gelation process are hydrogen bonding and π–π interactions, which can be triggered either by thermal or ultrasound external stimuli, affording materials having virtually the same properties. The obtained viscoelastic materials exhibited interconnected multistimuli responsive behaviors including thermal-, photo-, chemo- and mechanical responses. Structure–property relationship studies of a designed peptide library have demonstrated that the presence and position of the azobenzene residue can be operated as a versatile regulator to reduce the critical gelation concentration and enhance both the thermal stability and mechanical strength of the gels. Compared with other approaches, this strategy is advantageous in terms of structural flexibility since it is compatible with a free, unprotected amino terminus and allows placement of the chromophore at any position of the peptide sequence.

Contact local ICGM : Dr. Françoise Quignard, D.R. CNRS (équipe MACS)


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