Molecular and spectroscopic properties of a polarizer based on a block copolymer of vinylalcohol and acetylene

The preparation of a high efficiency polarizer derived from the block copol ymer, poly(vinylalcohol-b-acetylene) will be described. The orientations of the polyacetylene chromophore and the polyvinylalcohol matrix have been an alyzed by polarized UV/Vis and FTIR spectroscopy, respectively. For moderat ely stretched films (L/Lo = 3.0-7.0), the degree of orientation for the pol yacetylene segments greatly exceeds that predicted from a simple, pseudoaff ine deformation model. For the visible spectral region, dichroic ratios in the range of 60 to 100 are easily achieved, thus permitting films of this p olymer to function as a high efficiency, polarizing optical element. Data f rom a series of sample tilting experiments utilizing polarized UV/Vis radia tion are consistent with the polyacetylene segments being distributed uniax ially about the stretching direction. However, analogous experiments in the infrared indicate that the PVA matrix has significant biaxial character. O ther novel characteristics of this polarizer will be discussed, such as its thermal and chemical stability.