Cecile Malardier-Jugroot

Self-assembly of alternating copolymers and the role of hydrophobic interactions: characterisation by molecular modelling

This paper describes the characterisation and the properties of amphiphilic alternating copolymers and their self-assembly into nanoarchitectures in aqueous solution. To investigate the role of the nature of the hydrophobic groups on the association, the self-assembly of two different polymers are compared: poly(isobutylene-alt-maleic anhydride) (IMA) and poly(styrene-alt-maleic anhydride). A structural analysis using computational methods is performed to investigate and characterise the behaviour of IMA chains at different pH values. The optimisation of IMA at different pH values is performed using a complete conformational method which applied both semi-empirical and ab initio molecular modelling methods. The present paper describes in detail the conformational analysis of IMA, the association among IMA chains to form the nanostructures and discusses the influence of the nature of the hydrophobic groups on the association. The theoretical prediction is also compared to experiment.

Theoretical investigation of the use of doped graphene as a membrane support for effective CO removal in hydrogen fuel cells

Carbon monoxide poisoning of the anode catalyst is currently a big problem facing the use of hydrogen fuel cells. This study uses density functional theory to model the interaction between a filter membrane and carbon monoxide to optimise the removal of CO from the H2 feed gas. The membranes studied are graphene/metal surfaces of nickel, platinum and iridium/gold over undoped or boron-, nitrogen- or oxygen-doped graphene. It was found that graphene doping improved the efficiency of the filter membrane in hydrogen fuel cells because addition of a dopant increases metal/graphene binding and causes metal/H2 binding to become negligible while only decreasing metal/CO binding slightly. Platinum and iridium/gold systems show slightly stronger binding to graphene and CO than nickel systems. However, nickel is a non-precious metal, so membranes produced with this active centre could lead to a reduction in the cost of fuel cell production by increasing the lifetime of the platinum anode catalyst.

Physisorption of molecular hydrogen in curved carbon nanomaterials: a computational study

Hydrogen physisorption on carbon nanomaterials is a promising method of hydrogen storage because carbon materials are cheap, abundant and light weight. However, storage is difficult because dispersion forces between C and H are weak. Curved carbon substrates are more promising than planar systems because the increased level of sp 3 -hybridization enhances H2 physisorption. The present study uses density functional theory to model large fullerenes, single-walled carbon nanotubes and graphene to investigate the interaction with H2; decorating platinum is also considered. We conclude that H2 can be stored in fullerenes without an energy input if the H2 molecules are more than 3 A from the carbon surface and more than 2 A from each other. In addition, confinement effects are observed when hydrogen is stored in fullerenes rather than nanotubes – storage in nanotubes is more favourable for systems with small diameters.

Synthesis of polypyrrole under confinement in aqueous environment

Conducting polymers are used in a wide variety of applications such as electronic devices, batteries, functional electrodes and optical switching devices. Polypyrrole in particular has attracted interest recently due to the versatility of its applications, high conductivity and capacity for energy storage. Density functional theory is used to characterise the polymerisation process of polypyrrole in aqueous environment. The theoretical characterisation of the synthesis and the number steps involved showed the essential role of water in this confined polymer template for the activation as well as the polymerisation of pyrrole. This study is expected to have an important impact on a novel, environmentally friendly synthesis of nanostructures.

Synthesis and characterization of a pH responsive folic acid functionalized polymeric drug delivery system

We report the computational analysis, synthesis and characterization of folate functionalized poly(styrene-alt-maleic anhydride), PSMA for drug delivery purpose. The selection of the proper linker between the polymer and the folic acid group was performed before conducting the synthesis using Density Functional Theory (DFT). The computational results showed the bio-degradable linker 2, 4-diaminobutyric acid, DABA as a good candidate allowing flexibility of the folic acid group while maintaining the pH sensitivity of PSMA, used as a trigger for drug release. The synthesis was subsequently carried out in multi-step experimental procedures. The functionalized polymer was characterized using InfraRed spectroscopy, Nuclear Magnetic Resonance and Dynamic Light Scattering confirming both the chemical structure and the pH responsiveness of PSMA-DABA-Folate polymers. This study provides an excellent example of how computational chemistry can be used in selection process for the functional materials and product characterization. The pH sensitive polymers are expected to be used in delivering anti-cancer drugs to solid tumors with overly expressed folic acid receptors.

Optimising the platinum–carbon bond in nitrogen-doped single-walled carbon nanotubes

The durability, high surface area and metallic properties demonstrated by single-walled carbon nanotubes (SWCNTs) show potential as a catalyst support. In this work, the effects of nitrogen doping of SWCNTs are examined using density functional theory. It will be shown that by adding nitrogen, the durability of a platinum catalyst, measured by the binding energy it has with the surface, increases with the number and proximity of N atoms to the carbon–platinum bond. A twofold increase in binding energy is measured and is due to the disruption that the N atoms cause locally in the surface at the C–Pt bond.

Investigation of a Dual Electrostatic Colloid Micropropulsion System for Space Applications

Electric propulsion is an advanced form of spacecraft propulsion with many advantages compared to chemical propulsion. It can be considered for operations such as stationkeeping, attitude control, and possibly de-orbiting of small satellites at end-of-life. An electrostatic colloid thruster is investigated in the present paper via numerical and experimental studies. The objective is to test the concept of a dual colloid system with a positively and a negatively charged beam thereby operating without the use of a neutralizer. Dual and multiplexed configurations are also investigated and a laboratory model has been designed and tested with the aid of simulation results. Both simulation and experimental results are assisting in the understanding of dual beam effects and the testing of doped propellants.

Biomimetic Soft Polymer Nanomaterials for Efficient Chemical Processes

Nanostructured soft materials combine structure and function to produce effects inspired by natural systems. Recent innovations in polymer science and supramolecular chemistry have led to the development of materials that can respond to and control their microenvironment, allowing them to increase the efficiency of chemical processes while decreasing their ecological impact. Size effects are profound at the nanoscale, allowing for a broad range of applications. This chapter features synthetic biomimetic nanosystems at different size regimes and match them with biological counterparts from tissues through cell walls to vesicles and proteins. The application of soft, bioinspired nanomaterials in fields ranging from medicine to sustainable energy represents a fundamental advancement in science and technology.