Search results for "MOLECULE"

Synthetic approaches to new polymers

1990

A plenary lecture should be an introduction into the main topic of the symposium and a review about the state of art. Therefore, in the first part of this presentation different possibilities for the preparation of new polymers are briefly discussed from a chemical point of view. Some selected examples from the literature show how methods of organic chemistry can be utilized for polymer science: new catalytic systems, new monomers, modification of polymers, new poly-reactions. In the second part, several polyelectrolytes are described: polymers with sec., tert. and quart. N-atoms in the main chain, block copolymers and block polyampholytes. The third part deals with the problems of rod-like…

Interpolymer complexes and polymer compatibility.

2012

A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [η] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, …

Derivatization of Plasma Polymerized Thin Films and Attachment of Biomolecules to Influence HUVEC-Cell Adhesion

2011

Insights into the Dynamics of Grotthuss Mechanism in a Proton-Conducting Chiral bioMOF

2016

Proton conduction in solids attracts great interest, not only because of possible applications in fuel cell technologies, but also because of the main role of this process in many biological mechanisms. Metal–organic frameworks (MOFs) can exhibit exceptional proton-conduction performances, because of the large number of hydrogen-bonded water molecules embedded in their pores. However, further work remains to be done to elucidate the real conducting mechanism. Among the different MOF subfamilies, bioMOFs, which have been constructed using biomolecule derivatives as building blocks and often affording water-stable materials, emerge as valuable systems to study the transport mechanisms involve…

Magneto-Transport Results in SAM Based MTJs

2015

This chapter is dedicated to the description of the magneto-transport results obtained in LSMO/SAM/Co magnetic tunnel nanojunctions fabricated by nanoindentation lithography technique. We started by focusing on the study of LSMO/C12P/Co MTJs. This because C12P is a medium size alkyl chain: long enough to avoid short-circuits in the junction but short enough to give a device resistance in the order of few tens of MO and thus easier to measure. Next, we started to tune the molecule thickness from C10P to C18P (from 10 carbon atoms in the alkyl chain to 18). This allowed on one hand to validate our system by comparing the exponential increase of the junction resistance to the one reported in t…

Theoretical Design of Organic Metals Based on the Phthalocyanine Macrocycle

1990

Phthalocyanine molecular crystals and cofacially linked polymers are well documented as low-dimensional materials that may attain high electrical conductivities. Air-stable conductivities on the order of 1 to 1000 S/cm after partial oxidation by iodine have been reported.1–3 These conductivity studies indicate that the electrical conductivity has very little dependence on the identity of the atom complexed in the cavity, but is strongly dependent on the orientation and spacing of the phthalocyanine rings. A columnar stacking with minimum spacing leads to a maximum interaction between π-molecular orbitals on adjacent rings and promotes the highest conductivity. More effective π-interactions …

Structure of bottle-brush brushes under good solvent conditions: a molecular dynamics study.

2011

We report a simulation study for bottle-brush polymers grafted on a rigid backbone. Using a standard coarse-grained bead-spring model extensive molecular dynamics simulations for such macromolecules under good solvent conditions are performed. We consider a broad range of parameters and present numerical results for the monomer density profile, density of the untethered ends of the grafted flexible backbones and the correlation function describing the range that neighboring grafted bottle-brushes are affected by the presence of the others due to the excluded volume interactions. The end beads of the flexible backbones of the grafted bottle-brushes do not access the region close to the rigid…

Spectroscopic Investigations Of LB Mono- And Multilayers Of 2-docosylamino 5-nitropyridine; Promising Candidates For Non-linear And Integrated Optics

2005

Alkylamino-5-nitropyridineshavemently been introduced forthepreparation of a novel type of non-centrosymmetric Langmuir-Blodgett (LB) multilayer (1,2). Hitherto, second order non-linear optical investigations have been resmcted toLB-films oftwomaterialsinaltematinglayerstructureand to films of a single material with head to tail arrangement of the molecules, both of whicharedifficulttoobtain (seerefs. quotedin 1 and2.1. Incontrast,allpresent data indicate that LB-filmsof 2-aUcylamino-5-nitropyridines are head-to-head and tail-to-tail (Y-type) multilayers with a rather strong tilt-angle of the alkyl chains (Fig. I). The most effective substance for second order non-linear optical experiments…

Electrochemical biosensing using hydrogel nanoparticles

2014

Abstract Biology and medicine have seen great advancements in the development of nanobiosensors capable of characterizing and quantifying biomolecules. This review reports a systematic study of the usefulness of hydrogel nanoparticles (HNPs) in the different steps of the electroanalytical process developed in electrochemical biosensing systems. We illustrate the advantages offered by HNPs in detection of analytes with representative recent examples that highlight the scientific interest in widening the use of HNPs in electrochemical biosensing methods. We review different types of HNP-based electrochemical biosensors, such as enzyme, protein, and nucleic acids, in terms of their sensing per…

Mesoporous silica-based materials for use in biosensors

2012

Abstract There have been great advancements in the development of biosensors capable of characterizing and quantifying biomolecules. This article gives an overview of the formation, the properties and the electrochemical applications of ordered mesoporous silica-based materials in electrocatalysis, electrosorption, matrix immobilization, construction of systems for controlled release of active compounds, sensors, biosensors and immunosensors. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on the evaluation of models.