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BOUCENNA Imane

Contact - Bureau : 736A

M2 2016-2017 internship : Controlled Aggregation of Nanoparticles In a Crystalline Matrix of Copolymer Micelles

Imane Boucenna, Florent Carn and Ahmed Mourchid

Laboratoire Matière & Systèmes Complexes, UMR Université Paris Diderot-CNRS 7057

Assembly of nanoparticles (NPs) in 1, 2 or 3 D arrays is motivated by the potential use of these structures in bio-sensing, optoelectronics or nanomedecine. Most often, such structures are obtained by aggregation via van der Waals forces or crystallization of binary NP mixtures (i.e. functionalized with complementary ligands). The final aggregates are generally macroscopic faceted crystals with a poorly defined global shape. Recently, several studies have shown that one type of NPs could be assembled into well-defined structures, without carrying out complex surface chemistry. NP confinement is triggered by the crystallization of the surrounding media. Among these methods, the directed assembly of NPs in a micellar crystal offers several control parameters and have been successfully used to assemble spherical silica NPs and nanodisk clays. Surprisingly this approach has never been applied to plasmonic NPs in spite of their potential applications.

Figure 1. a) SEM image of two clusters of AuNPs in a crystalline matrix (not visible)[1] & b) Optical microscopy image of the copolymer crystals obtained at the beginning of crystallization with 3 wt.% NPs.[2]

We propose to study the confinement of model gold NPs (AuNPs) in face centered cubic (fcc) copolymer micellar solutions. The copolymer is a triblock copolymer which has attracted a great deal of attention due to its thermoreversible crystallization. It has been shown that macroscopic ordered crystals with different structures (fcc, bcc,…), are achievable either by temperature or concentration increase whatever the NPs concentration. Previous studies using silica NPs and clays suggest that NPs are aggregated in the grain boundaries between micellar crystallites. Up to now, both the optimal conditions to trigger the NPs confinement and their microstructure are still lacking.

The trainee will synthesizes AuNPs of different sizes and study their confinement as a function of temperature, rate of temperature sweep, NPs and micellar concentration by means of static and dynamic scattering (X-rays, neutrons, light), rheology, light spectroscopy and microscopy techniques (optical and TEM). This work should shed light on the relation between the size, shape and internal structure of AuNPs assemblies and the control parameters. We predict that the rationally designed AuNPs crystals could be tested as heating source under near-infrared laser irradiation and as substrate for surface-enhanced Raman spectroscopy.

Candidate Profile : Chemist with good skills in physics or physicist with good skills in chemistry.

Contact : Imane Boucenna et Ahmed Mourchid (imane.boucennaATuniv-paris-diderot.fr)

Références

[1] Shen et al. Assembly of colloidal nanoparticles directed by the microstructures of polycrystalline ice, ACS NANO 5 (2011) 8426.

[2] Boucenna et al. Temperature directed-assembly of coated-laponite nanoparticles in pluronic micellar solutions, Soft Matter 9 (2013) 170.

Mots-clés

Matériaux et matière molle, Nanoparticules, Polymères, polymères supramoléculaires, polyélectrolytes, cytosquelette, BOUCENNA Imane, CARN Florent, MOURCHID Ahmed, Proposition de stage ou de thèse, Dynamique et Organisation de la Matière Molle


Contact : Published on / Publié le 10 novembre 2016



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