Tuning the macroscopic properties of polymer nanocomposites is essential for applications in various sectors. In order to design and engineer materials with highly desirable properties, it is crucial to have a strong control over the morphology of filler particles within the composite. In our lab, we use both computational and experimental techniques to understand the phase behavior and self-assembly of nanoparticles in polymer/nanoparticle blends. In a recent work (Figure), we observed that the spatial arrangement of ‘bare’ nanoparticles in a polymer matrix can be controlled by adding polymer-grafted nanoparticles. Figure: a) The ‘bare’ particles (pink) are pulled away from the top and bottom surfaces by the grafted particles (orange) in films and b) anisotropic structures of ‘bare’ particles facilitated by grafted particles in the bulk.
Active-layer morphology in polymer-based solar cells
Polymer-based solar cells have attracted much attention in recent years due to their low cost and ease of handling. But, the major problem preventing large scale production is their low efficiency compared to their inorganic counterpart. Several strategies ranging from development of new materials to advanced surface coating techniques have been explored to improve their efficiency. Our work has been focused on achieving the right morphology of PCBM in P3HT films by exploring novel techniques to direct its assembly in the film. In a recent work, we observed that addition of P3HT-grafted silica nanoparticles (SiNP) not only improves the PCBM morphology but also the crystallinity of P3HT domains. Figure a) shows isolated PCBM clusters in P3HT-PCBM blends and b) shows the formation of well-defined percolated network of PCBM upon addition of SiNP.
Hydrogen storage in carbon-based materials
Hydrogen is one of the most environmental-friendly and renewable sources of energy. Unlike conventional fossil fuels, vehicles powered by hydrogen may have zero-emission and therefore, leave no carbon footprint on the environment. However, the prime challenge in this development is the efficient on-board storage and release of hydrogen. We study the fundamental aspects of hydrogen adsorption on various carbon-based materials that have shown a promising potential to meet the energy storage goals outlined by the US Department of Energy. We recently discovered that the adsorption energy changes with the type of defect present on carbon nanotubes. This is one of the cases where defects can be useful.
Locomotion and behavior of C. elegans
The 1 mm long soil-dwelling nematode, Caenorhabditis elegans has been extensively studied and used as a model organism due to its simple nervous system yet complex maneuverability. The highly developed chemosensory system in these nematodes is used not only to detect food but also to avoid danger. Such an implementation of advanced locomotory behavior with only 302 neurons is extremely exceptional. Our research on these organisms focuses on understanding their locomotion and behavior in complex environment that will not only help in decoding the language of nematode motion but will also enable a fundamental understanding of such behavior in small organisms. a) C. elegans undergo durotaxis to agar with silica nanoparticles (right), which is the stiffer region. b) Flawless navigation of C. elegans through an array of PDMS pillars Polymer membranes for gas separation
Membrane-based gas separation is an active area of research due to its high demand in industrial applications, such as preparation of nitrogen or oxygen-enriched air, mitigation of CO2 from greenhouse gas-producing sources. However, high material cost, low product purity, and limited thermal/chemical stability are some of the major challenges that limit the development of polymer-based membranes. In our lab, we use atomistic molecular simulations to design and develop novel polymeric materials with high permeability and good selectivity, required for cost-effective large-scale separation applications. The figure shows a polymer membrane containing triphenylamine (left) and the free volume (right) that are interconnected, which improve the permeability of gas molecules.
