Abstract
High-performance films with almost zero-birefringence and zero-wavelength dispersion were succeeded to prepare from pullulan esters derivatives (PLEs) without any additives. Optical transmittance analysis, birefringence measurement of PLE cast film and hot stretched films, and infrared dichroism analysis were conducted to characterize optical properties of PLE films comparing with cellulose triacetate which is commercially used as low-birefringence in optical devices. The aims of this study, characterization of optical properties of pullulan esters, can develop a deep understanding of the fundamental knowing and applicability of polysaccharides. Accordingly, authors believe this paper will open the gate for researches in the application of polysaccharides.
Highlights
Biomedical fields[11,12,13]
We investigated pullulan esters (PLEs) films with small acyl carbon number (N) values such as pullulan acetate (PLAc: N = 2), pullulan propionate (PLPr: N = 3) and pullulan acetate propionate (PLAcPr: N = 2,3) with high transparency
High-performance films with high optical transparency, almost zero birefringence and zero wavelength dispersion were prepared from natural polysaccharide derivatives
Summary
Nx, ny, and nz, along three principal axes must be taken into consideration when assessing the optical anisotropy of films. Refractive index anisotropy mainly results from the orientation of the polymer chains, and is called orientation birefringence (Δn(λ)). Using the Herman’s orientation function, orientation birefringence is expressed by the following equation (1):. Where λ,∆n0 (λ), and F are the wavelength of light, the intrinsic birefringence of the polymer, and the orientation function, respectively. The intrinsic birefringence is the asymmetry in the refractive indices that originates from the chemical structure of the repeating units of the polymers[2,9]. Three-dimensional assessment of refractive indices is required to characterize birefringence properties
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