Role Of Polymer Matrix Research Articles

Role of polymer matrix in large enhancement of dielectric constant in polymer-metal composites

Dielectric behavior of polymer (polar/nonpolar)-metal nanocomposites (PMCs) prepared under identical processing conditions have been compared. A high effective dielectric constant (ɛeff>2500) with a moderate loss and a lower ɛeff (74) with low loss was observed, respectively, for polar and nonpolar PMC at their respective percolation thresholds (fc). The results have been explained with the help of percolation theory and dipolar polarization. Similar value of fc observed in both the PMC is attributed to the same order of conductivity of polymer matrices. The dipolar polarization present in the polymer plays a major role in the enhancement of ɛeff.

Role of Polymer Matrix in Polymer/Silver Complexes for Structure, Interactions, and Facilitated Olefin Transport

The role of the polymer matrix in facilitated olefin transport through polymer/silver salt complex membranes was investigated, particularly its influence on the structure and interactions of polymer/silver salt complexes and hence on the interactions of silver ions with olefin molecules. This role was assessed for complexes of silver salts with polymeric ligands containing three different carbonyl groups, specifically, amide, ketone, and ester groups. It was found that the threshold concentration of silver salt for facilitated olefin transport depends on the polymeric ligand and has the following order: amide > ketone > ester. This dependence of the threshold concentration on the polymeric ligand is explained in terms of the differences between the comparative strengths of the interactions of silver ions with the different carbonyl oxygens and that of silver ions with olefin molecules. It is concluded that when the former interaction is stronger than the latter, the threshold concentration for facilitate...

Thin layers of ET 2I 3 obtained by in situ crystallization — the role of polymer matrix

Unconventional method of preparation of thin layers of organic crystals by in situ crystallization consists in using a polymer matrix as a reservoir of molecular compounds and also as a medium of crystallization. We discuss an influence of properties of the polymer matrix on the crystallization and properties of the C1-ET 2I 3 polycrystalline layers, and on their transformation by annealing into the layers of superconducting β t-ET 2I 3 phase. Polycarbonate, polystyrene and poly(methyl methacrylate) were used as the matrices. The properties and structure of the polycrystalline layers were investigated by means of direct current and microwave conductivity measurements in a broad temperature range, by Raman spectroscopy, AFM and SEM. It was found that in the systems with polymer matrices of lower Tg, the α->β t transformation occurs easier and at lower temperatures, yielding metallically conducting layers which show in some cases an onset of superconducting transition at liquid helium temperatures.

Role of polymer matrix on the conductivity of polymers doped with tetracyanoquinodimethane (TCNQ) salts of polycations

AbstractThe influence of interactions with polymer matrix on the critical concentration and stability of heterogeneous conductive polymer films was investigated. These films were obtained by reticulate doping of polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA) and polycarbonate (PC) with complex salts of tetracyanoquinodimethane (TCNQ) with polycations having sulfonium groups in the main chain, Ks[4,6]. It was found that the chemical structure of the matrix influences the conductivity of such systems. The PMMA matrix is most suitable for obtaining conducting systems at low concentration of the dopant. In PMMA the absorption spectra of moleculary dispersed Ks[4,6] do not change with time. The strong influence of PAN matrix was confirmed by the study of absorbance changes of Ks[4,6] with time in this matrix and particularly by investigation of absorption of this salt in solutions containing acrylonitrile/methyl methacrylate copolymers of various composition.