Design, fabrication and self-assembly of anisotropic and patchy particles

Resume : Inverse patchy colloids (IPCs) are heterogeneously charged particles characterized by a non-trivial interplay between attractive and repulsive directional interactions [1]. Within this class of systems, we consider IPCs with two charged polar regions and one oppositely charged equatorial belt. We first investigate the assembly of these colloids under planar confinement in thermodynamic conditions such that the formation of extended structures is favored: (i) a general tendency to form quasi two-dimensional aggregates is observed irrespective of the confinement size, (ii) a clear distinction between the formation of ordered versus disordered aggregates is possible based on the specific features of the inter-particle interaction, and (iii) a simple way to tune via experimentally accessible parameters the ordering of IPCs in the vicinity of a possibly charged substrate is presented. Second, we consider an IPC system that exhibits a bulk phase diagram characterized by a broad region where a structure composed by parallel monolayers is stable and we report about the the effect of the parameters featured in the particle-particle interaction potential on the whole phase diagram [4]. [1] Soft Matter 7, 8313 (2011) [2] ACS Nano 7, 4657 (2013) [3] NANO letters 14, 3412 (2014) [4] Soft Matter 10, 8464, (2014)

Resume : We present a model of assembly of superparamagnetic iron oxide nanoparticles into size-controlled nanoparticle clusters. In the process, the steric repulsion of the nanoparticles is gradually reduced by competitive stabilizer desorption arising from the presence of a tertiary silica phase.[1,2] The kinetics of assembly is analysed using Smoluchowski aggregation equation and Fuchs stability ratio dependent on nanoparticle-nanoparticle colloidal interactions. We show that by including a rigorous treatment of van der Waals, steric and magnetic interactions the experimental evolution of the size distribution obtained by dynamic light scattering can be reproduced. The model can be extended to other nanoparticle systems including multicomponent clusters (e.g. gold and iron oxide). We also show that the model of nanoparticle interactions can be of great use to predict the magnetic and colloidal properties of the resulting clusters as well as to design novel multifunctional nanoparticle clusters. 1.J. K. Stolarczyk et al, Angew. Chem. Int. Ed. 2009,48,175. 2.C.J. Meledandri et al, ACS Nano 2011,5,1747

Resume : Today, many recognized methods exist to measure the size and size distribution of nano-particles [1]. Among these methods, Dynamic Light Scattering (DLS) also known as Photon Correlation Spectroscopy (PCS) is certainly one of the prevalent techniques of choice in colloidal sciences [2, 3]; Until today, all commercial DLS setups require batch sampling which is not adapted for in situ and real time process monitoring (time consuming operation, sample stability issues, reproducibility issue, etc) . Addressing this challenge implies a change of paradigm: if you cannot bring your sample to the measurement, you have to bring the measurement to your process. With that idea in mind, we have developed a unique fully agile in situ DLS probe system based on an innovative approach using integrated optics and single mode optical fibers. The new probe is designed to be integrated into various environments. We present here the principle of this probe and different examples of integration in concrete applications: (i) real time monitoring and control of NPs synthesis in mili-fluidic reactor with combined and simultaneous SAXS-DLS measurement; (ii) NP synthesis kinetics monitoring into a microwave reactor;(iii) Polymer nano-emulsion control in super critical CO2 reactor, (iv) Magnetic Hyperthermia experiments, etc.

Resume : Recently few research groups have turned their attention toward the possibility to graft conjugated polymer at the surface of inorganic, carbon (nanotube or graphene) and metallic substrates in order to create new electro-active materials.(1) Another new challenge is then now to develop the so-called “low band gap” LBG polymer, macromolecules able to harvest more photons. This presentation will deal with the elaboration of new hybrid core@corona nanoparticles. Different strategies have been developed by our group to covalently anchored conjugated polymers to metal oxide particles. Herein the “grafting onto” and the “grafting from” methodologies will be describe and apply for the synthesis of reference P3HT (2) and a low band gap LBG poly[(4,4′-bis(2-ethylhexyl)dithieno-[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT) brushes on ZnO nanorods. (3) Moreover, for the first time, we will present, the elaboration of a biomimetic mussel adhesive inspired anchor group for the design of Zinc Oxide ZnO nanoparticles grafted by Poly(3-HexylThiophene). The synthetic methodology is based on the synthesis of a catechol derivated moiety from dopamine able to be “click” on an alkyne terminated P3HT. (4) ZnO/Conjugated polymers combined materials are of great interest in organic electronics and more especially in hybrid photovoltaic materials. The corona thickness by Transmission Electronic Microscopy will be discussed with regard to the grafting density and the molecular weight of the conjugated polymers. Photoluminescence measurement in solution was used to prove an efficient electron transfer from the P3HT donor to the ZnO acceptor upon grafting. (1) A. Bousquet, H. Awada, R.C. Hiorns, C. Dagron-Lartigau, L. Billon, Prog. Polym. Sci., 39, 1847-1877, 2014 (2) H. Awada, H. Medlej, S. Blanc, M.H. Delville, R.C. Hiorns, A. Bousquet, C. Dagron-Lartigau, L. Billon, J. Polym. Sci. Polym. Chem. : Part A, 52, 30-38, 2014. (3) H. Awada, A. Bousquet, C. Dagron-Lartigau, L. Billon, asap, 2015 (4) H. Awada, L. Mezzassalma, S. Blanc, D. Flahaut, C. Dagron-Lartigau, J. Lyskawa, P. Woisel, A. Bousquet, L. Billon , asap, 2015

Resume : Magnetic nanoparticles became recently of high potential to develop advanced applications such as mass storage media and ultrasensitive sensors. Although the intrinsic properties of nanoparticles are controlled by their shape, isotropic shapes such as spherical nanoparticles bring some limits to enhance efficiently their magnetic anisotropy. This issue can be overcome by addressing self-assembling of nanoparticles into anisotropic assemblies onto substrates.[1-3] The self-assembling is triggered by specific chemical interactions between functional groups located at both nanoparticles and substrates which surfaces are chemically addressed by self-assembled monolayers (SAMs) of organic molecules.[5] Therefore, reducing the dimensionality of nanoparticle assemblies has a strong impact on their collective properties. In contrast to powder state which corresponds to 3D isotropic random assemblies, 2D monolayers favor stronger coupling of magnetic nanoparticles thanks to shape anisotropy. While self-assembly can be controlled by chemical interactions through “click” chemistry,[3,6] magnetic interactions also take part to the assembling process and address the spontaneous formation of highly anisotropic assemblies such as 1D chains of nanoparticles which result in strong enhancement and unexpected magnetic properties.[4] [1] M. Pauly et al, J. Mater. Chem. 2011, 21, 16018 and J. Mater. Chem. 2012, 22, 6343 [2] B.P. Pichon et al, Chem. Mater. 2011, 23, 3668 [3] D. Toulemon et al, Chem. Commun., 2011, 47, 11954 [4] D. Toulemon et al, To be published [5] B. P. Pichon et al, J. Phys. Chem. C, 2011, 114, 9041 (2010) [6] D. Toulemon et al. Chem. Mater., 2011, 25, 2849 (2013)

Resume : In the last decades nanoscale inorganic objects emerged as a novel type of matter with unique functional properties and a plethora of prospective applications. Although a broad range of nano-synthesis methods has been developed, our abilities to organize these nano-components into designed architectures and control their transformations are still limited. In this regard, an incorporation of bio-molecules into a nano-object structure allows establishing highly selective interactions between the components of nano-systems. Such bio-encoding may permit programming of complex and dynamically tunable systems via self-assembly: biomolecules act as site-specific scaffolds, smart assembly guides and reconfigurable structural elements. I will discuss our advances in addressing the challenge of programmable assembly using the DNA platform, in which a high degree of addressability of nucleic acids is used to direct the formation of structures from nanoscale inorganic components. Our work explores the major leading parameters determining a structure formation and methods for creating targeted architectures. The principles and practical approaches developed by our group allow for assembly of well-defined three-dimensional superlattices, two-dimensional membranes and finite-sized clusters form the multiple types of the components. I will also discuss how interplay of polymeric and colloidal effects can result in the novel interactions effects in these systems. Finally, our recent progress on the assembly by-design, including super-lattices with pre-defined crystallographic symmetries and particle clusters with pre-determined architectures will be demonstrated. Research is supported by the U.S. DOE Office of Science and Office of Basic Energy Sciences under contract No. DE-AC-02-98CH10886.