Processable photonic polymers with controllable properties

A series of polyethers consisting of a conjugated segment connected with a nonconjugated spacer were synthesized and characterized. On the basis of the chemical structure of the conjugated moiety, controllable light emission was obtained. The thermal properties were influenced from the structure of the conjugated segment, the type of substituents used, and the length of the flexible spacer used. Additionally, coil‐rod‐coil block copolymers having conjugated segments as the rod block were prepared with atom transfer radical polymerization of α,ω‐modified conjugated oligomers. The optical properties of these copolymers were examined with respect to their aggregation behavior. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2485–2491, 2003     

The higher rank numerical range of nonnegative matrices

In this article the rank-k numerical range ∧ _k (A) of an entrywise nonnegative matrix A is investigated. Extending the notion of elements of maximum modulus in ∧ _k (A), we examine their location on the complex plane. Further, an application of this theory to ∧ _k (L(λ)) of a Perron polynomial L(λ) is elaborated via its companion matrix C _L .     

Synthesis and characterization of conjugated polymers and their blends for optoelectronic applications

Various polymeric blends of hole transporting materials, (such as MEH-PPV and P3HT) and electron transporting materials (such as poly(phenyl-vinyl-quinoline) and poly[2-(4-methacryloxyphenyl)-5-phenyl)-1,3,4-oxadiazole]) have been prepared and investigated. Moreover a soluble, main chain oxadiazole bearing polyether has been synthesized, aiming towards an efficient electron transporting polymeric material which was also used for blend preparation together with P3HT. A deeper investigation into their spectroscopic characteristics using, primarily, FT-IR spectroscopy, but also UV-Vis spectroscopy has been conducted. The surface morphology of these blends was investigated using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in an attempt to gather information for their solid state properties and morphologies. Finally, DSC measurements provided additional insight into the thermal behaviour of these materials.