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(6k) Controlling Interactions at Nanoscale: A Versatile Tool for Assembling Multifunctional Future Materials

Bharti, B., North Carolina State University
Findenegg, G., Technische Universität Berlin
Kaneko, K., Shinshu University
Velev, O. D., North Carolina State University

The interactions between nanoscale objects play an essential role in various industrial and biomedical processes. These interactions determine the material's physical properties such as tensile strength, flexibility, electrical and thermal conductivity of the resulting macroscopic material. My research focuses on the fundamental understanding of the interactions at the nanoscale in order to develop new multifunctional hybrid materials. During my doctoral studies at Technische Universität, Berlin in the group of Prof. Gerhard Findenegg, I investigated the effects of modulating the interaction between soft and hard nanomaterials. The influence of surface energy and curvature on the self-assembly of nonionic surfactant at silica nanoparticles[i] and in the nanopores of SBA-15 silica material[ii],[iii] were studied. In addition we also investigated the interaction of biologically relevant entities such as globular proteins with silica nanoparticles[iv]. We revealed how the adsorbed protein induces a pH-dependent completely reversible bridging aggregation of silica particles[v]. Earlier in 2014, I visited the group of Prof. Katsumi Kaneko at Shinshu University, Japan as a JSPS postdoctoral fellow for short period of time. My research in Japan was focused on the development of single walled carbon nanotube (SWCNT) and silica hybrid materials which can further be used as precursors for energy efficient electrodes. In this work we used the approach of dispersing the tubes in liquid and its subsequent drying to form highly porous hybrid aerogel[vi].

Since 2012, I am working in the group of Prof. Orlin Velev at North Carolina State University and Triangle Materials Research and Engineering Center (ΔMRSEC) deals with the programmed assembly of isotropic and anisotropic particles into chains as actuators for soft micro-robotic applications. We demonstrated that heteroaggregating particle pairs can be assembled into rigid permanent chains using dielectrophoresis (DEP) as a structure directing tool[vii]. We proposed a combinatorial based approach for predicting the chain length distribution and established the rules for permanent chain assembly[viii]. Recently, we developed a novel method for assembling superparamagnetic nanoparticles covered by lipid shell into magnetically responsive ultraflexible chains[ix]. Initial application of external magnetic field aligns the particles into linear chains, after which the particles are bound by the soft attractive potential induced by the surface condensed lipid. We demonstrated that the surface wetting lipid governs the formation of nanocapillary bridges and hence enables the ultraflexible chain assembly. We also established that the chains can be assembled in the form of self-repairing networks and a number of other hierarchal structures. In the future, this research field will be extended into the design of new functional materials with unusual optical, electrical and heat transport properties.

In future I plan to continue my research in the field of nanoscience with the aim to fabricate new materials with unusual physical and chemical properties. Based on my previous research experience on self- and directed assembly, I plan to establish my independent research team which would focus on both fundamental and applied aspects nanoscience and nanotechnology. In particular I am very interested in extending my research for assembling carbon based energy harvesting materials. In addition, I would also like to continue my research efforts towards developing a better understanding between nonentities and biological matter.

[i] B. Bharti; J. Meissner; U. Gasser;  G. H. Findenegg Soft Matter, 2012, 8, 6573

[ii] B. Bharti; M. Xue; J. Meissner; V. Cristiglio; G. H. Findenegg J. Am. Chem. Soc., 2012, 134, 14756

[iii] B. Bharti, T. Shin; B. Deme; G. H. Findenegg in-preparation

[iv] B. Bharti; J. Meissner; S. H. L. Klapp; G. H. Findenegg Soft Matter, 2014, 10, 718

[v] B. Bharti; J. Meissner; G. H. Findenegg Langmuir, 2011, 27, 9823

[vi] B. Bharti; R. Kukobat; D. Minami; K. Kaneko in-preparation

[vii] B. Bharti; G. H. Findenegg; O. D. Velev Sci. Rep. (Nature), 2012, 2,1004

[viii] B. Bharti; G. H. Findenegg; O. D. Velev accepted, 2014

[ix] B. Bharti; A.-L. Fameau; M. Rubinstein; O. D. Velev submitted