Dichroism Of Poly Research Articles

Formation and dichroism of poly(vinyl alcohol)–iodine complex in photocurable film

The formation of polyiodine complexes was investigated in a photocurable poly(vinyl alcohol) modified N‐methyl‐4(4′‐formylstyryl)pyridinium methosulfate acetal (PVA‐SbQ), which is a photofunctional group that causes photodimerization. PVA‐SbQ films with polyiodine complexes were prepared to be photocured, iodinated and soaked in a boric acid solution. The formation of PVA–polyiodine complexes was studied during iodinating and while in the boric acid treatment through UV–vis absorption spectrometry, resonance Raman spectrometry and IR absorption spectrometry. As a result, polyiodines were formed in the photocurable PVA‐SbQ films, and the formation of PVA–polyiodine complexes was enhanced by boric acid treatment. It was found that the SbQ‐ratio of PVA‐SbQ affects the formation of PVA–polyiodine complexes. The photocrosslinking by the dimerization of SbQ groups helps to form the PVA–I5− complex during the boric acid treatment. Based on this effect, we demonstrated a unique recording method by the PVA–polyiodine complex formation. The PVA‐SbQ film cured by the irradiation of the liner polarized light showed that dichroism of the PVA–polyiodine complexes formed after iodination. Copyright © 2015 John Wiley & Sons, Ltd.

Coil-helix transition in poly(L-glutamic acid): Evidence for a 3-state non-cooperative process

A careful analysis of measurements of circular dichroism of poly(L-glutamic acid) (PGA) shows that the data can be very accurately described by introducing a third state for the PGA configuration, in addition to the helix and coil ones, and considering a simple equilibrium between these three states, without cooperativity. The third state is more conspicuous when high molecular weight polyethyleneglycol (PEG) is added. Excluded-volume effects shown by differences in the presence of short and long PEG chains suggest a direct interaction of PEG and PGA rather than an osmotic effect.

Dichroism of Poly(Methyl Methacrylate) Thin Films Doped with Disperse Orange 11 Molecules

We investigate the absorption spectra of poly (methyl methacrylate) (PMMA) thin films doped with Disperse Orange 11 (DO11) dye molecules which change under illumination with visible light. Dichroism measurements of the kinetics of the transmission changes at 472 nm at room and low temperatures (−60◦C ± 2◦C) have been investigated. Our data show that the photoisomerisation reaction and the light-induced polar orientation depend on the molecular structure of the polymer. Simultaneous UV-visible spectroscopy at low temperature confirms the existence of two forms of DO11 molecules (keto and enol forms), which are responsible for the interaction with irradiating laser light and forming an anisotropic structure inside the PMMA/DO11 thin film.

Dichroism of Poly(vinylalcohol) Films Containing Gold Nanorods Induced by Polarized Pulsed-Laser Irradiation

Gold nanorods (NRs) dispersed in a poly(vinylalcohol) film were transformed into spherical particles by one shot of a pulsed-laser light (1064 and 532 nm, 6–7 ns). Irradiation by the linearly polarized laser light distinctly induced orientation-selective transformation of the NRs, which resulted in large dichroic properties of the film. The degree of the transformation depended on the wavelength as well as the polarization direction of the pulsed-laser light.