The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are det...The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are determined by infrared absorption spectroscopy (IR),nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing opticalmicroscope (POM) and differential scanning calorimetry (DSC).展开更多
Poly(3-hydroxybutyrate-co-10%3-hydroxyhexanoate)(PHBHHx) thin films were prepared by means of spin-coating PHBHHx/chloroform solutions on the silicon substrate. The crystalline morphologies of PHBHHx thin films were o...Poly(3-hydroxybutyrate-co-10%3-hydroxyhexanoate)(PHBHHx) thin films were prepared by means of spin-coating PHBHHx/chloroform solutions on the silicon substrate. The crystalline morphologies of PHBHHx thin films were observed by atomic force microscopy(AFM) at room temperature. A novel crystalline morphology, that is like sunflower was found when the film is very thin and named as sunflower-like crystalline morphology. Compared with usual PHBHHx spherulites, there are obvious differences in aspects of nucleation, crystal growth process and crystalline morphology for the sunflowers. The PHBHHx/chloroform solution properties and the substrate have great effects on the formation of the sunflower. A circular boundary that may result from a liquid-liquid phase separation in PHBHHx solution first formed in the thin film during the spin-coating process, then it induced the formation of the sunflowers.展开更多
The hydrogenated diamond like carbon(DLC) films were formed on conductive glass substrate by deposition in DMF using a pulse modulated source. The X ray photoelectron spectroscopy results of the films showed that the ...The hydrogenated diamond like carbon(DLC) films were formed on conductive glass substrate by deposition in DMF using a pulse modulated source. The X ray photoelectron spectroscopy results of the films showed that the main composition of the films are carbon. The Raman and IR spectra indicated the existence of hydrogen in form of sp 3 C in the film. From the Raman spectra indicated the formation of DLC in most regions of the film and also possible diamond deposits. The films showed high transmission ratio (>70%) in 330～2000 nm and electrical resistivity of 10 10 Ω·cm.展开更多
Two bowlic cyclotriveratrylene CTV-1 and CTV-2, with different peripheral groups of -OCH3 and -OCH2CH3 for CTV-1 and -OCH3 and -OCH2COOCH3 for CTV-2, respectively, were synthesized by typical trimerization via a multi...Two bowlic cyclotriveratrylene CTV-1 and CTV-2, with different peripheral groups of -OCH3 and -OCH2CH3 for CTV-1 and -OCH3 and -OCH2COOCH3 for CTV-2, respectively, were synthesized by typical trimerization via a multistep sequence from vanillin. Both bowlic CTV molecules were thermotropic liquid crystals, and presented typical grainy textures of the nematic phase and homogeneous texture of the single domain nematic phase. It is of interest to observe the regular and beautiful mosaic-like morphologies after cooling from liquid crystalline phases, which appeared and vanished repeatedly in several circles of cooling and heating. The size of each mosaic was several dozens of micron. In nature, the mosaic-like morphologies are the optical pattern of cracks formed by the shrinking, due to the crystallization of frozen texture of nematic phases. By means of scanning electron microscopy, the mosaic-like morphologies were observed to consist of lamellae, and each mosaic is a rectangular multi-layer lamella, which is composed of packed single-layered lamellae. The fibrils in the diameter of about 1 μm were observed, which are the structural units of lamellae and would be the bundles of the bowlic molecular columns. The mosaic-like morphologies decorate the bowlic molecular columnar nematic phase, therefore, a novel mosaic-like morphologies decoration method was applied to reveal the director distribution of several kinds of point disclinations, such as s = +1(δ =0°and δ =90°) and s = ±1/2, and Nèel domain walls. It was shown that the bowlic molecular columnar nematic phase behaved as normal nematic phases; however, the basic structural units ordered were the bowlic molecular column or the bundles of bowlic molecular column (i.e. fibrils), but not the bowlic molecules themselves. The bowlic molecular columns acted as the rod-like molecules in a normal nematic phase. Therefore, a new term BCN (bowlic columnar nematic phase) is used to describe the anomalous nematic phase in this paper.展开更多
文摘The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are determined by infrared absorption spectroscopy (IR),nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing opticalmicroscope (POM) and differential scanning calorimetry (DSC).
文摘Poly(3-hydroxybutyrate-co-10%3-hydroxyhexanoate)(PHBHHx) thin films were prepared by means of spin-coating PHBHHx/chloroform solutions on the silicon substrate. The crystalline morphologies of PHBHHx thin films were observed by atomic force microscopy(AFM) at room temperature. A novel crystalline morphology, that is like sunflower was found when the film is very thin and named as sunflower-like crystalline morphology. Compared with usual PHBHHx spherulites, there are obvious differences in aspects of nucleation, crystal growth process and crystalline morphology for the sunflowers. The PHBHHx/chloroform solution properties and the substrate have great effects on the formation of the sunflower. A circular boundary that may result from a liquid-liquid phase separation in PHBHHx solution first formed in the thin film during the spin-coating process, then it induced the formation of the sunflowers.
文摘The hydrogenated diamond like carbon(DLC) films were formed on conductive glass substrate by deposition in DMF using a pulse modulated source. The X ray photoelectron spectroscopy results of the films showed that the main composition of the films are carbon. The Raman and IR spectra indicated the existence of hydrogen in form of sp 3 C in the film. From the Raman spectra indicated the formation of DLC in most regions of the film and also possible diamond deposits. The films showed high transmission ratio (>70%) in 330～2000 nm and electrical resistivity of 10 10 Ω·cm.
基金Supported by the National Natural Science Foundation of China (Grant No. 20774077)the Natural Science Foundation of Fujian, China (Grant Nos. E0510003 & E0710025)the Project of Science and Technology of Xiamen, China (Grant No. 3502Z20055013)
文摘Two bowlic cyclotriveratrylene CTV-1 and CTV-2, with different peripheral groups of -OCH3 and -OCH2CH3 for CTV-1 and -OCH3 and -OCH2COOCH3 for CTV-2, respectively, were synthesized by typical trimerization via a multistep sequence from vanillin. Both bowlic CTV molecules were thermotropic liquid crystals, and presented typical grainy textures of the nematic phase and homogeneous texture of the single domain nematic phase. It is of interest to observe the regular and beautiful mosaic-like morphologies after cooling from liquid crystalline phases, which appeared and vanished repeatedly in several circles of cooling and heating. The size of each mosaic was several dozens of micron. In nature, the mosaic-like morphologies are the optical pattern of cracks formed by the shrinking, due to the crystallization of frozen texture of nematic phases. By means of scanning electron microscopy, the mosaic-like morphologies were observed to consist of lamellae, and each mosaic is a rectangular multi-layer lamella, which is composed of packed single-layered lamellae. The fibrils in the diameter of about 1 μm were observed, which are the structural units of lamellae and would be the bundles of the bowlic molecular columns. The mosaic-like morphologies decorate the bowlic molecular columnar nematic phase, therefore, a novel mosaic-like morphologies decoration method was applied to reveal the director distribution of several kinds of point disclinations, such as s = +1(δ =0°and δ =90°) and s = ±1/2, and Nèel domain walls. It was shown that the bowlic molecular columnar nematic phase behaved as normal nematic phases; however, the basic structural units ordered were the bowlic molecular column or the bundles of bowlic molecular column (i.e. fibrils), but not the bowlic molecules themselves. The bowlic molecular columns acted as the rod-like molecules in a normal nematic phase. Therefore, a new term BCN (bowlic columnar nematic phase) is used to describe the anomalous nematic phase in this paper.
