polarity; stochastic mechanism; Morkov chains; crystals; natural tissues; orientational disorder; pyroelectricity; second harmonic generation; biomimetic materials; Monte Carlo simulations
Burgener Matthias, Aboulfadl Hanane, Labat Gaël Charles, Bonin Michel, Sommer Martin, Sankolli Ravish, Wübbenhorst Michael, Hulliger Jürg (2016), Peculiar orientational disorder in 4-bromo-4'-nitrobiphenyl (BNBP) and 4-bromo-4'cyanobiphenyl (BCNBP) leading to bipolar crystals, in IUCr Journals
, 3(2016), 219-225.
Aboulfadl Hanane, Hulliger Jürg (2015), Absolute polarity determination of teeth cementum by phase sensitive second harmonic generation microscopy, in Journal of Structural Biology
, 192(2015), 67-75.
Burgener Matthias, Putzeys Tristan, Parvinzadeh Gashti Mazeyar, Busch Susanne, Aboulfadl Hanane, Wübbenhorst Michael, Kniep Rüdiger, Hulliger Jürg (2015), Polar Nature of Biomimetic Fluorapatite/Gelatin Composites: A Comparison of Bipolar Objects and the Polar State of Natural Tissue, in Biomacromolecules
, 16(2015), 2814-2819.
Burgener Matthias, Labat Gaël, Bonin Michel, Morelli Alessio, Hulliger Jürg (2013), Pyroelectric and piezoelectric scanning microscopy applied to reveal the bipolar state of 4-iodo-4'-nitrobiphenyl (INBP), in CrystEngComm
, 15(2013), 7652-7656.
Polar symmetry of real objects, molecules and crystals is a fundamental property for establishing complex functions.In the world of crystals, there are two essentially different ways to generate a polar structure:(i) by nucleation and replication, or(ii) by a Markov-type process involving polarity by growth - irrespective of the symmetry crated by nucleation.This completely new concept (ii) for developing/understanding materials by a Markov chain mechanism was independently discovered by Harris et al. and Hulliger et al. in 1997.Since then the group in Berne has elaborated basic theoretical and experimental means to investigate this phenomenon covering all kind of materials: macroscopic heap formation, crystals of low molecular weight and long chain proteins forming tissues. In 2003, the applicant presented a first theoretical model explaining experimentally known pyroelectric effects in collagenous tissues. Nowadays, new scanning probe techniques (e.g. scanning piezoelectric microscopy) reveal more and more of the fine structure of growth induced polarity in tissues.In view of basic features associated with stochastic polarity formation being elaborated in detail, there are still basic issues which merit full understanding and experimental demonstration. In particular the world of biomimetic and real biological materials are fascinating objects to study the generation and function of polar order.The present proposal will thus focus on the following main issues:1) The outcome of our previous SNF proposal (200021_129472) leads us to a new understanding of polarity in condensed molecular matter: Following basic principles, polarity can only exist in antiparallel domains (E=0), yielding zero average polarity for the entire object. This brings us to investigate selected molecular crystals to study their surface near polarization achieved by thermal treatment.2) Biomimetic materials are of great interest for thooth and bone repair. Here we will study apatite and brushite formation in different organic gels and investigate that polar state of the composite.3) Scanning pyroelectric (1), scanning piezoelectric (2) and phase sensitive second harmonic (3) microscopy are the essential techniques to study polar effects in molecular based materials. All these methods (1, 2: Berne; 3: collaboration with MPI Halle) will thus be applied to investigate materials.In essence, a continuation of the former proposal attempts to concentrate research on (i) an essential state of polar molecular matter and (ii) bio- and biomimetic materials.