セルロースエステルにおける溶液キャストフィルムの分子配向制御と光学機能フィルムへの応用

Supervisor:山口　政之マテリアルサイエンス研究科博

Control of Three-Dimensional Refractive Indices of Uniaxially-Stretched Cellulose Triacetate with Low-Molecular-Weight Compounds

A method to control the 3D refractive indices and wavelength dispersion of birefringence of polymer films by uniaxial stretching with addition of various low-molecular-weight compounds (LMCs) with strong polarizability anisotropy is developed. Biomass-derived cellulose triacetate (CTA) films containing a small amount of crystallites at the stretching temperature are found to show planar deformation to some degree only by uniaxial stretching. Although molecular orientation evaluated from the in-plane and out-of-plane birefringences of pure CTA seems consistent with uniaxial deformation, LMC addition pronounces the deviation of the refractive index from uniaxial symmetry. Rod-shaped molecules are found to greatly enhance both in-plane and out-of-plane birefringences because of their marked orientation in the stretching direction. Conversely, the out-of-plane birefringence increases more than the in-plane one upon addition of disk-shaped molecules, because the LMC molecules tend to be embedded in the film plane. Consequently, 3D refractive indices of CTA can be controlled only by uniaxial stretching, not biaxial one, with an aid of an anisotropic LMC

Material design of retardation films with extraordinary wavelength dispersion of orientation birefringence: A review

Orientation birefringence and its wavelength dispersion for various types of cellulose esters are reviewed. Cellulose esters such as cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) show positive orientation birefringence with extraordinary wavelength dispersion, which is determined mainly by the ester groups rather than the main chains. The acetyl group provides negative orientation birefringence with strong ordinary wavelength dispersion, whereas the propionyl and butyryl groups give positive orientation birefringence with weak wavelength dispersion. Although all groups show ordinary wavelength dispersion, the summation of their orientation birefringences gives extraordinary dispersion. Moreover, the wavelength dispersion is dependent on the stretching ratio due to the difference in the orientation relaxation of each group. On the contrary, cellulose triacetate (CTA) shows negative birefringence with ordinary wavelength dispersion because it has no positive contribution. However, doping a plasticizer having positive orientation birefringence changes the orientation birefringence of CTA from negative to positive, and the wavelength dispersion from ordinary to extraordinary. This is attributed to the cooperative orientation of plasticizer molecules to the stretching direction with CTA chains, known as nematic interaction upon a hot drawing process

Birefringence and strain-induced crystallization of stretched cellulose acetate propionate films

We investigated wavelength dependence of birefringence (Δn) for cellulose acetate propionate (CAP) films stretched at various draw ratios (DRs) and strain rates (SRs), by comparing the result of cellulose triacetate (CTA). CAP exhibited an extraordinary wavelength dispersion of Δn although CTA showed an ordinary dispersion, indicating that Δn of CAP is determined by acetyl and propionyl groups. The extraordinary dispersion for CAP became stronger at larger DR and higher SR. The thermal analysis data suggested that the hot-stretching induces the crystallization of CAP and the crystal size increases with increasing DR and SR. Furthermore, two-dimensional X-ray diffraction pattern of CAP exhibited the orientation of the induced crystal as well as that of CTA, which is one of semi-crystalline polymers. These results mean that the acetyl orientation in CAP becomes stronger than the propionyl orientation. This conclusion is reasonable because acetyl group is more tightly confined to a pyranose ring than propionyl

Optical Anisotropy in Solution-Cast Film of Cellulose Triacetate

The out-of-plane birefringence and its wavelength dispersion are studied employing solution-cast films of cellulose triacetate (CTA). In solution-cast process, CTA molecules are induced to align in the film plane. Although refractive index is the lowest in the oriented direction for the CTA films stretched more than 110%, refractive index is found to be the lowest in the normal direction for the unstretched cast film. ATR measurements reveal that in-plane alignment of the acetyl group which provides strong polarizability anisotropy is responsible for the phenomenon. Furthermore, the out-of-plane birefringence is found to increase with increasing wavelength, i.e., extraordinary wavelength dispersion, whereas a stretched CTA film shows ordinary wavelength dispersion. The level of the out-of-plane birefringence in cast films depends on the preparation conditions, which is predictable considering the evaporation rate. Moreover, it is demonstrated for the first time that the out-of-plane birefringence and its wavelength dispersion can be modified by addition of a certain plasticizer such as tricresyl phosphate (TCP). During the evaporation, TCP molecules orient in the film plane accompanying the orientation of CTA chains by intermolecular orientation correlation, called nematic interaction. This technique will widen the scope of material design of retardation films because there are numerous liquid compounds having strong polarizability anisotropy

Sustained Release of Amoxicillin from Ethyl Cellulose-Coated Amoxicillin/Chitosan–Cyclodextrin-Based Tablets

Sustained release mucoadhesive amoxicillin tablets with tolerance to acid degradation in the stomach were studied. The sustained-release tablets of amoxicillin were prepared from amoxicillin coated with ethyl cellulose (EC) and then formulated into tablets using chitosan (CS) or a mixture of CS and beta-cyclodextrin (CD) as the retard polymer. The effects of various (w/w) ratios of EC/amoxicillin, the particle sized of EC coated amoxicillin and the different (w/w) ratios of CS/CD for the retard polymer, on the amoxicillin release profile were investigated. The physicochemical properties of the EC coated amoxicillin particles and tablets were determined by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The result showed that the release profiles of amoxicillin were greatly improved upon coating with EC, while the inclusion of CD to the CS retardant additionally prolonged the release of the drug slightly. Overall, a sustained release of amoxicillin was achieved using amoxicillin coated with EC at a (w/w) ratio of 1:1 and a particle size of 75–100 μm. Therefore, the tablet formulation of amoxicillin may be an advantageous alternative as an orally administered sustained-release formulation for the treatment of peptic ulcers