RESEARCH TEAMS

The research will be carried out by a diverse group of researchers: 10 faculty members within Greece and 2 Greek faculty members/researchers (Visiting Researchers) outside of Greece with strong complementarity as well as by 7 PhD students to be employed in the project. This core group is augmented by 5 internationally renowned scientists from abroad with expertise on the synthesis (K. Müllen, K. Matyjaszewski, E.W. Meijer) and dynamics (H.W. Spiess, M. Bockstaller) of soft materials.

 

RT1 from the University of Ioannina (UoI) (G. Floudas, A. Avgeropoulos, P. Papadopoulos, 1PhD student) with expertise in molecular and macromolecular self-assembly and dynamics as well as on polymer synthesis and characterization undertake WP1-9. Within these WPs they collaborate closely with the ERT members K. Müllen and H.W. Spiess (both at MPI-P) on the synthesis and characterization of discotic liquid crystals. They investigate the self-assembly (with X-rays, IR) and the dynamics as a function of temperature and pressure (with dielectric spectroscopy, rheology), construct the pertinent phase diagrams for DLCs, investigate the phase transformation kinetics and finally identify structural defects pertinent to electronic applications. At a second stage, they are studying the dynamics of SiO2, Ag and Au polymer functionalized nanoparticles and their self-assembly in the presence and absence of surfaces with dielectric spectroscopy and different microscopy techniques. 

RT2 from the Foundation for Research and Technology-Hellas (FORTH) (U. Jonas, M. Vamvakaki, 1 PhD student) with expertise on the synthesis of polymers and mesoscopic structures. Within WP10-11 they synthesize the supramolecular and mesoscopic systems. To this end they strongly collaborate with the ERT members, K. Matyjaszewski and E.W. Meijer.

RT3 from the University of Crete (UoC) (G. Fytas, D. Vlassopoulos, B. Loppinet, 1 PhD Student) with expertise on polymer dynamics, surface characterization and rheology are responsible for WP12-18. Within the project they characterize the size and shape of the molecular, supramolecular and mesoscopic structures by different light scattering techniques as well as their viscoelastic properties with rheology. They strongly collaborate with the three ERT members: E.W. Meijer, K. Matyjaszewski and M. Bockstaller as well as with RT1, RT2 and RT4.

The members of the Simulation/Theory team (RT4) (D.N. Theodorou, V. Harmandaris, M. Kosmas, Ch. Likos, 4 PhD Students) have distinguished themselves in (a) developing new, efficient theoretical and computational methods, based on statistical mechanics, for the reliable prediction of properties of materials through modelling and simulation;  (b) applying these methods to materials of technological interest. Within the project (WP19-25) and in an effort to address the wide spectra of length- and time-scales that govern the molecular, supramolecular and mesoscopic materials under study, they develop and utilize hierarchical models, by employing systematic coarse-graining to link atomistic, mesoscopic, and macroscopic levels. They closely interact with the experimental teams of UoC and UoI. The Research Teams (RT) and their role in the project are outlined in the Scheme below (the coordinator of each RT is underlined):

 

Scheme I: Overview of the cooperative nature of the proposed work.

The first research team (RT1) will work on:

·           The self-assembly, thermodynamic phase diagrams, the stability and metastability of DLCs as a function of core size, side chains and dipole strength. We employ X-ray scattering (UoI and MPI-P) to determine the unit cell, calorimetry for investigating the thermodynamics of phases and polarizing optical microscopy (UoI) for identifying the mesoscopic textures. The results from the structure analysis are compared with solid state NMR (H.W. Spiess, MPI-P). The orientation of the graphene core with respect to the side chains is further studied by polarizing IR spectroscopy. In addition, IR microscopy allows for the determination of the molecular order parameter within domains of high orientation. The aim here is to identify structural defects pertinent to electronic applications.

·         The study of the disk dynamics in the different phases using dielectric spectroscopy (UoI) and solid state NMR (MPI-P). Dielectric spectroscopy identifies the dipole dynamics that are attached to the core whereas NMR probes the heteronuclear (13C-1H) dipole dynamics located next to the C-X dipoles thus giving complementary information (time scale and geometry of motion) on the disk dynamics. Advanced solid state NMR techniques, X-ray scattering and rheology identify structural defects and the associated dynamics.

·          The self-assembly and dynamics of core-shell nanoparticles. For the self-assembly we employ wide-angle X-ray scattering with appropriate structural models (i.e., Percus-Yevick) that can provide with the effective radii and volume fraction of spheres. Subsequently, we are studying the dynamics with dielectric spectroscopy (UoI) and identify the shape (through the process of Maxwell-Wagner polarization) and collective dynamics.

·           The self-assembly of the polymer systems and composites which will be prepared by RT2/RT3 with various electron microscopy techniques (high resolution transmission electron microscopy – HRTEM, scanning electron microscopy – SEM and atomic force microscopy or scanning probe microscopy –AFM or SPM respectively). With these techniques the dispersion of the nanoparticles in the polymer matrices will also be visible, leading eventually to conclusions for the potential applications of the proposed systems. At UoI, SEM and AFM instrumentation can be used through the Network of Research Supporting Laboratories whereas HRTEM and SPM will be used through the collaboration with the overseas partners.

 

The second research team (RT2) will work on:

·          The synthesis of polymeric and hybrid structural units that can self-assemble into supramolecular structures in solution and at a surface. 2-ureido-pyrimidone functionalized polynorbornenes carrying nitro-benzene protecting groups will be synthesized by the group of Ε.W. Mejier, whereas the hybrid core-shell nanoparticles comprising a SiO2 core and an inert polystyrene (PS) or a temperature-responsive PNIPAAm shell and the (ii) low symmetry prism shaped Au or Ag particles with a PS or PNIPAAm coating will be synthesized in the Materials Chemistry lab, IESL/FORTH. Both the grafting density and the chain length of the polymer on the inorganic particles will be varied systematically. Polymeric shells with incorporated fluorescent tag molecules will be also prepared in collaboration with the ERT member Κ. Matyjaszewski.

·          Self-assembled supramolecular and mesoscopic structures. The polynorbornene precursors will be first dissolved in an appropriate solvent (H2O, CHCl3) followed by deprotection of the nitro-benzene groups, by UV irradiation, to induce self-assembly via hydrogen bonding of the 2-ureido-pyrimidone groups. On the other hand, the hybrid nanoparticles will be self-assembled by vertical lifting (inert polymer) or upon the application of an appropriate external stimulus (i.e. temperature) (responsive polymer).41

 

The third research team (RT3) will work on:

·          The rheological behavior of DLCs will be investigated in bulk and as monolayer at the air-liquid interface. Shear moduli will shed light into the equilibrium phase transitions of DLCs, the stability of the phases and the kinetics of their transitions. Shear-induced effects on moduli and structure (X-Ray and TEM) will be also investigated (RT1). Nanographene is one of the strongest materials and its deposition at an interface is expected to lead to strong quasi-2D films. It will be deposited at the air water interface and the compression isotherm will be measured. Structural studies will be carried out by AFM and grazing incident X-rays on transferred layers. Rheology will be measured with an interfacial stress rheometer.42

·          Elastic properties of thin DLC films are very crucial for the local structure of DLC. Thickness and direction dependence of the high frequency longitudinal and shear moduli is a sensitive index of possible anisotropy and confinement effects of the DLC film morphology. For such local and direction selective measurements, we will employ Brillouin light scattering (BLS) which was recently developed43 by the RT3 to probe in- and out-of-plane elastic wave propagation in thin polymer films. 

·          The molecular characteristics of the self-assembled constituents in dilute solutions will be determined  via the form factor and the two main transport coefficients. Two main techniques will be utilized: photon correlation (PCS) and fluorescence correlation (FCS)44 spectroscopy; FCS, a single molecule technique, requires inserting a fluorescent probe (RT2). PCS will be employed in both polarization configurations for shape determination with emphasis on the plasmonic nature of Ag and Au particles. Resonance enhanced PCS –the coherent analogue of the resonance enhanced Raman-is still unexplored and its foundation (PCS at different laser wavelengths) will establish a new methodology.   

·          Morphology and dynamics of supramolecular and hybrid mesoscopic self assembled systems as studied by X-ray scattering, PCS, FCS, shear rheometry and cryo-TEM (ERT member M. Bockstaller and RT1). The influence of preparation protocol, shear strain, electric field (anisotropic particles) and temperature (for the thermo-responsive PNIPAAm core-shell particles) on the morphology of the assembly(ies) will be mapped on a non-conventional phase diagram for the two different systems. This will be contrast with the thermodynamic phase diagram of DLC (RT1).

·         Behavior near solid surfaces (confinement effects). It is anticipated that all systems will modify their properties in the vicinity of solid surfaces and only the strength of the modification should be system dependent. Here, we will examine the role of the surface (glass) on the self-assembly. Evanescence wave-PCS and resonance enhanced-PCS (developed by the RT345), as well total reflection X-Ray scattering, will be employed respectively, for dynamical and structural characterization, respectively.

·          Particulate  polymers (hybrid particles with polymers). This is a new direction where the thermo-elastic properties of such thin films are of fundamental and technological interest. The film formation and the necessary SEM characterization will be performed by the ERT. The structure of the core/shell particles will be studied by X-Ray by the RT1 whereas for the measurement of the in-plane and normal to the film elastic constants at different temperatures, will be investigated by RT3. In the case of PNIPPAm particles the response will be examined in the vicinity of the collapse temperature. The exploitation for potential applications (coatings, actuators, plasmonics) will be examined together with the ERT.

 

The laboratories of the 4th research team (RT4) (NTUA, UoC, UoI, U. Vienna) will conduct:

·            Atomistic simulations of the DLCs with molecular dynamics (MD) methods, aimed at predicting structure in the crystalline and liquid crystalline phases, the volumetric properties and the modes of motion of the aromatic rings and side chains for short times (< 1 μs). 

·            Mesoscopic simulations of the DLCs.  Starting from a detailed atomistic model for each DLC system, we will develop a corresponding coarse-grained model which will be used to predict the phase diagram and quantify the rates of slow dynamical phenomena.

·            Atomistic MD simulations of supramolecular hybrid core-shell nanoparticles. The simulations of nanoparticles of relatively small size (5-10 nm) will allow a study of their structure, thermodynamics, and short-time (~1 μs) dynamics. 

·            Mesoscopic simulations of core-shell nanoparticles.  Starting from detailed microscopic simulations, we will develop a coarse-grained model. A critical step in this coarse-graining effort will be the computation of the effective potential to be used at the coarse-grained level. The coarse-grained model will be used to study larger systems of hybrid nanoparticles and their collective dynamics.

·            Theoretical work for the development of a microscopic model, which will be used to calculate the macroscopically observed behaviour of DLC systems with methods of statistical thermodynamics. We will write down a Hamiltonian involving the effect of microscopic and mesoscopic interactions and use our past knowledge and experience to solve the problem in the framework of statistical mechanics.

·           Study of DLC modified with electric dipoles. Using analytical theory and simulation, a potential of interaction will be computed, which depends on both distance and orientation.  Based on this interaction potential, we will predict the thermodynamically stable, self-organising phases of DLCs.

·            In all cases, results from the above simulations will be compared against scattering, rheology, and spectroscopic measurements to be conducted by RT1 and RT3. 

 

The first Visiting Researcher (member of RT4) Prof. C. Likos will carry out:

·           Theoretical/Computational study of DLC modified with electric dipoles.  Using analytical theory and simulation, a potential of interaction will be computed, which depends on both distance and orientation.  Based on this interaction potential, we will predict the thermodynamically stable, self-organising phases of the DLCs. Subsequently, with appropriate computational methods we will calculate the activation energies for creating a stable nucleus and the characteristic times for transitions between the phases.

·           Density functional theory as well as mode coupling theory to predict the (ideal) glass transition of the core-shell particles.

   Conclusions                                                                          .

META-ASSEMBLY is positioned at the interface of two well-established hitherto not cross-fertilizing fields with strong impact to microelectronics and the biological world. It involves novel and unconventional fabrication and characterization strategies that will enable us to achieve a fundamental understanding of the underlying mechanisms controlling the self-assembly of soft matter systems and associated phase and state transitions. This unified research approach will open up new routes for both scientific and technological research by tackling simultaneously structural, thermodynamic and kinetic issues over a broad spatio-temporal range. The research program will be implemented by an interdisciplinary team headed by the PI, 3 complementary research groups, 5 international leading scientists, 2 renowned visiting scientists and 7 PhD students. We envisage significantly contributing to the new emerging field of metastable soft matter, where the many outstanding challenges are only now just being addressed.

 

 

 References                                                                                    .

[1] Debenedetti, P.G. Metastable Liquids: Concepts and Principles (Princeton Univ. Press. 1996).

[2] Muthukumar, M.; Ober, C.K.; Thomas, E.L. Science 277, 1225 (1997).

[3] Sijbesma, R.P.; Bijer, F.B.; Brunsveld, L.; Meijer, E.W. Science 278, 1601 (1997).

[4] Breen, T.L.; Tien, J.; Oliver, S.R.; Hadjik, T.; Whitesides, G.M. Science 284, 948 (1999).

[5] Roh, K.H.; Martin, D.C.; Lahann, J. Nature Mater4, 759 (2005).

[6] Grzelczak, M.;  Vermant,J.; Furst, E.M.; Liz-Marzán, L.M. ACS Nano 4, 3591 (2010)

[7] Kennedy, D.; Norman, C. Science 309, 75 (2005); Service R.F. Science 309, 95 (2005).

[8] Kumar, S. Chem. Soc. Rev. 35, 83 (2006).

[9] Wu, J.; Pisula, W.; Muellen, K. Chem. Rev. 107, 718 (2007).

[10] de Gennes P.G. J. de Physique Letters 44, L-657 (1983).

[11] Grigoriadis, C.; Haase, N.; Butt, H-J.; Müllen, K.; Floudas, G. Adv. Mater22, 1403 (2010).

[12] Elmahdy, M.M.; Floudas, G.; Mondeshki, M. et al. Phys. Rev. Lett. 100, 107801 (2008).

[13] Möller, M.; Wendorff, J.H.; Werth, M.; Spiess, H.W. J. Non- Cryst. Solids 170, 295 (1994).

[14] Tasios, N. ; Grigoriadis, C.; Hansen, M.R. et al. J. Am. Chem. Soc. 132, 7478 (2010).

[15] Elmahdy, M.M.; Dou, X.; Mondeshki, M.; Floudas, G. et al. J. Am. Chem. Soc. 130, 5311 (2008).

[16] Elmahdy, M.M.; Mondeshki, M.; Dou, X., et al. J. Chem. Phys. 131, 114704 (2009).

[17] Floudas,G. et.al, Molecular Dynamics of Glass-Forming Systems. Effects of Pressure (Springer, 2011).

[18] Alivisatos, A.P. et al. Nature 382, 609 (1996).

[19] Wojtecki, R.J.; Meador, M.A.; Rowan, S.J. Nature Materials 10,15 (2011)

[20] Christian, D.A. ; Liu, A.; Discher, D.E. et al. Nature Materials 8, 843 (2009).

[21] Herman, T.M.; Broeren, M.A.C.; Gomopoulos, N. et al.  Nature Nanotechnology 4, 721 (2009).

[22] Manoharan, V.N.; Elsesser, M.T.; Pine, D.J. Science 301, 483 (2003).

[23] Wagner, C.S.; Lu, Y.; Wittemann, A. Langmuir 24, 12126 (2008).

[24] Zhanng, Z.; Glotzer, S.C. Nano Lett. 4, 1407 (2004).

[25] Bianchi, E.; Largo, J.; Tartaglia, R.; Zaccarelli, E.; Sciortino, F. Phys. Rev. Lett. 100, 168301 (2008).

[26] Pappu, R.V.; Wang, X.; Vitalis, A.; Crick, S.L. Arch. Biochem. Biophys. 469, 132 (2008).

[27] Zhang, F. et al. Phys. Rev. Lett. 101, 125701 (2008).

[28] Tang, Z.; Kotov, N.A.; Giersig, M. Science 297, 237 (2002).

[29] Foster, E.J.; Berda, E.B.; Meijer E.W. J. Am. Chem. Soc. 131, 6964 (2009).

[30] Russo, J.; Tavares, J.M.; Teixeira, P.I.C.; Sciortino, F. Phys. Rev. Lett. 106,085703 (2011)

[31] Versteegen, R.M.; van Beek, D.J.M.; Sijbesma, R.P. et al. J. Am. Chem. Soc. 127,13862 (2005).

[32] Hermans, T.M.; Broeren, M.A.C.; Gomopoulos, N. et al. J. Am. Chem. Soc. 129,15631 (2007).

[33]  Burnworth, M.; Tang, L.; Kumpfer, J.R. et al. Nature 472, 335 (2011)

[34]  Sciortino F., Nature Materials 1, 145 (2002).

[35]  Mayer, C.; Zaccarelli, E.; Stiakakis, E.;  Likos C.N. et al. Nature Materials7, 780 (2008).

[36]  Zaccarelli, E.; Valeriani, C.; Sanz, E. et al. Phys. Rev. Lett. 103, 135704 (2009).

[37]  Pham, K. N., Puertas, A. M., Bergenholtz, J. et al. Science 296, 104 (2002).

[38] Akcora, R.; Liu, H.; Kumar, S.K. et al. Nature Materials 8, 354 (2009).

[39] Voudouris, P.; Choi, J.; Dong, H.; Bockstaller, M.R. et al. Macromolecules 42,  2721 (2009).

[40] Mateescu, A.; Ye, J.; Narain, R.; Vamvakaki, M. Soft Matter 5, 1621 (2009).

[41] Vogel, N.; de Viguere, L.; Jonas,U.  et al. Adv. Funct. Mat.  (DOI:1002/adfm2011000414).

[42] Klein, O.C.; Jonas,U.; Muellen K.; Vlassopoulos, D. Soft Matter (DOI: 10.1039/C1SMO53570.)

[43] Gomopoulos, N.; Saini, G.; Efremov, M. et al. Macromolecules 43,1551 (2010).

[44] Raccis, R.; Nikoubashman, Likos, C.N.; Fytas. G. et al. ACS Nano (DOI:10.1021/nn200767xx).

[45] Plum, M.; Steffen, W.; Fytas, G.; Knoll, W.; Menges, B. Optics Express 177, 10364 (2009).

[46] Marcon, V.; Vehoff, T.; Kirkpatrick, J. et al. D. J. Chem. Phys129, 094505 (2008).

[47] Megariotis, G.; Vyrkou, A.; Leygue, A.; Theodorou, D.N. Ind. Eng. Chem50, 546 (2011).

[48] Romanos, N.A.; Theodorou, D.N. Macromolecules43, 5455 (2010).

[49] Doxastakis, M.; Theodorou, D.N.; Fytas, G. et al. J. Chem. Phys. 119, 6883 (2003).

[50] Ahumada, O. ; Theodorou, D.N.; Triolo, A. et al. Macromolecules 35, 7110 (2002).

[51] Reith, D.; Pütz, M.; Müller-Plathe, F. J. Comput. Chem. 24, 1624 (2003).

[52] Spyriouni, T.; Tzoumanekas, C.; Theodorou, D. N. et al. Macromolecules 40, 3876 (2007).

[53] Izvekov, S.; Voth, G.A. J. Phys. Chem. B 109, 2469 (2005).

[54] Allen, M.P.; Tildesley, D.J. Molecular Simulation of Liquids; Clarendon: Oxford, 1987.

[55] Hijón, C.; Español, P.; Vanden-Eijnden, E.; Delgado-Buscalioni, R. Faraday Discuss.144, 301 (2010).

[56] Harmandaris, V.A. et al. Macromolecules 40, 7026 (2007).

[57] Harmandaris, V.A. and Kremer, K., Macromolecules 42, 4858 (2009).

[58] Harmandaris, V.A. and Kremer, K., Soft Matter 5, 3920 (2009).

[59] Likos, C.N. Phys. Rep. 348, 267 (2001).

[60] Gottwald, D.; Kahl, G.; Likos, C.N. J. Chem. Phys. 122, 204503 (2005).

[61] Bolhuis, P.G.; Chandler, D.; Dellago, D.; Geissler, P.G. Annu. Rev. Phys. Chem. 53, 291 (2002).

[62] Götze, W. in Liquids, Freezing and Glass Tranistion, ed. by J.-P. Hansen, D. Levesque, and J. Zinn-Justin (North-Holland, Amsterdam, 1991).