Making polyvinyl alcohol films iodinated at solution state before casting and its application

Abstract

This research focused on the manufacture a polarizing film with PVA iodinated at solution before casting (IBC) film, which was prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.5, and 1.0 mol/L of I 2 /KI aqueous solution, and I 2 /KI(1:2) with 0, 5, and 10 wt % of PVA. The lights of wavelengths between 450 and 700 nm were polarized in UV analysis. The degree of polarization and transmittance of the IBC polarizing film (10 wt % I 2 /KI and 0.5 mol/L boric acid) are 99.9% and 43.2%, respectively. The resistance of the heat and humidity of IBC polarizing films was higher than that of commercial polarizing films, which were elucidated by changing the transmittance of the films. This can be explained by the fact that the interaction between polyiodine molecules and PVA chains as the state of IBC is higher than that of the commercial state. The effect of boric acid may be strengthened for the resistance of heat and humidity. Crosslinking by boric acid improved thermal properties of the IBC polarizing films, resulting from the increases of degradation temperature in DSC and TG analysis. And the unit cell broadening occurred, which was caused by the intrusion of boric acid into PVA chains in X-ray analysis.

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

“…Namely, the results from the IR spectra confirm that crosslinking by boric acid was formed even in the photocured films. The reaction to the boric acid treatment has been suggested to yield boric acid esters to PVA possessing hydrogen bonding between the polymer chains . In our case, two different kinds of bonds are finally formed in the PVA‐SbQ films by photo‐dimerization and by the boric acid treatment.…”

“…The complexes and structures of polyiodines with poly(vinyl alcohol) (PVA) and other polymers have been studied and discussed for many years, and have been applied to polarizer films for actual use, such as being used as an important component of liquid crystal displays. Aggregation models for PVA–I 3 − and PVA–I 5 − complexes have been suggested, which are enveloped by four PVA segments of syndiotactic configuration with extended conformation .…”

The effect of dye structure on the dyeing and optical properties of dichroic dyes for PVA polarizing film

“…The solution was diluted with water (40 mL) and heated at 100 C for another 2 h. The reaction mixture was cooled to room temperature and poured into ice-water (200 mL). The solid separated was filtered, washed with cold water and dried in a vacuum oven: yield ¼ 95.0%; 1 7-amino-4-hydroxy-2-naphthalenesulfonic acid (5.30 g, 0.02 mol) was dissolved in 100 mL of water at room temperature and pH of the solution was adjusted to 7.0 by adding 10% sodium carbonate solution. The solution was cooled to 0e5 C and 5 mL of 4 M aq sodium nitrite solution was added dropwise.…”

Effect of boric acid and heat treatment for the formation of poly(vinyl alcohol)/iodine complex films iodinated at solution before casting

“…In a previous report,12 polarizing films were prepared with PVA iodinated at the solution before casting (IBC), and the properties were good for the polarizer. However, there are no reports on the role of boric acid and heat treatment in the stabilization of the PVA/iodine complex, particularly manufacture in the PVA solution state.…”

“…In this study, a film was manufactured with PVA iodinated in the solution state before casting (IBC),12, 13 which was produced by casting an aqueous PVA solution, including I 2 /KI and boric acid. The I 2 /KI and boric acid concentrations were varied.…”