A novel polyelectrolyte PNANT functionalized with electron donor-acceptor type azobenzene chromophores has been synthesized through post-polymerization azo coupling reaction and characterized by 1H-NMR,FTIR and UV-Vis...A novel polyelectrolyte PNANT functionalized with electron donor-acceptor type azobenzene chromophores has been synthesized through post-polymerization azo coupling reaction and characterized by 1H-NMR,FTIR and UV-Vis spectroscopy.The degree of functionalization (DF) of PNANT was 20% measured by elemental analysis.The degree of polymerization and its distribution were determined by GPC to be X n=251 with a polydispersion index 1.53.A glass transition temperature of 119℃ was observed from DSC thermogram. H-aggregation of azo chromophores of PNANT in spin-coated film and self-assembled film were detected from UV-Vis spectra,and the degree of H-aggregation of PNANT in the self-assembled film was found to be higher than that in the spin-coated film.Dichroism was optically induced in the spin-coated film and self-assembled film upon the irradiation of a polarized Ar + laser beam at 488 nm.The orientational order parameter obtained was 0.15 for spin-coated film and 0.07 for the self-assembled film.The resulting dichroism detected by UV-Vis spectra exhibited long-term stability.展开更多
On polyhydroxybutyrate banded spherulites, concentric rings were observed between cross polarizers or without polarizers. The rings used to be considered as cracks. In this paper, we provide evidences to distinguish t...On polyhydroxybutyrate banded spherulites, concentric rings were observed between cross polarizers or without polarizers. The rings used to be considered as cracks. In this paper, we provide evidences to distinguish the concentric rings from cracks observed on PHB spherulites. Furthermore, atomic force microscopy confirmed that these concentric rings with varying spacing were growth terraces rather than cracks. The height of the terraces reached up to several hundred nanometers. It was observed that the external terraces were higher than the internal terraces, which was proposed to result from layer by layer growth. This is the first report on the new microscopic feature of polyhydroxybutyrate spherulites. Spherulites with birefringent bands, wavy fluctuation of height were also observed.展开更多
With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period w...With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period was about 670 nm.The quartz slides covered with SRG films were assembled to liquid crystal (LC) cell to study the LC alignment behavior.Homogeneous liquid crystal alignment was observed in the surface relief gratings regions of the LC cell.Alignment of LC molecules was monitored by measuring the transmittance passing through the cell between crossed polarizers as a function of the angle of the cell rotating around the experiment optical axis.The transmittance changed periodically with a regular 90° separation of the rotational angle and the pretilt angle of the cell was found to be 3.2°.This alignment technique could have useful applications in the future LC displays.展开更多
文摘A novel polyelectrolyte PNANT functionalized with electron donor-acceptor type azobenzene chromophores has been synthesized through post-polymerization azo coupling reaction and characterized by 1H-NMR,FTIR and UV-Vis spectroscopy.The degree of functionalization (DF) of PNANT was 20% measured by elemental analysis.The degree of polymerization and its distribution were determined by GPC to be X n=251 with a polydispersion index 1.53.A glass transition temperature of 119℃ was observed from DSC thermogram. H-aggregation of azo chromophores of PNANT in spin-coated film and self-assembled film were detected from UV-Vis spectra,and the degree of H-aggregation of PNANT in the self-assembled film was found to be higher than that in the spin-coated film.Dichroism was optically induced in the spin-coated film and self-assembled film upon the irradiation of a polarized Ar + laser beam at 488 nm.The orientational order parameter obtained was 0.15 for spin-coated film and 0.07 for the self-assembled film.The resulting dichroism detected by UV-Vis spectra exhibited long-term stability.
文摘On polyhydroxybutyrate banded spherulites, concentric rings were observed between cross polarizers or without polarizers. The rings used to be considered as cracks. In this paper, we provide evidences to distinguish the concentric rings from cracks observed on PHB spherulites. Furthermore, atomic force microscopy confirmed that these concentric rings with varying spacing were growth terraces rather than cracks. The height of the terraces reached up to several hundred nanometers. It was observed that the external terraces were higher than the internal terraces, which was proposed to result from layer by layer growth. This is the first report on the new microscopic feature of polyhydroxybutyrate spherulites. Spherulites with birefringent bands, wavy fluctuation of height were also observed.
文摘With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period was about 670 nm.The quartz slides covered with SRG films were assembled to liquid crystal (LC) cell to study the LC alignment behavior.Homogeneous liquid crystal alignment was observed in the surface relief gratings regions of the LC cell.Alignment of LC molecules was monitored by measuring the transmittance passing through the cell between crossed polarizers as a function of the angle of the cell rotating around the experiment optical axis.The transmittance changed periodically with a regular 90° separation of the rotational angle and the pretilt angle of the cell was found to be 3.2°.This alignment technique could have useful applications in the future LC displays.
