A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC, DSC, TG, POM, X-ray di...A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC, DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whin they were heated to their melting temperatures (T-m) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM. All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.展开更多
Fluorinated smectic liquid crystals each with a biphenyl benzoate rigid core are investigated. Molecular structures of the studied compounds have difference only in fluorine position and the length of the carbon chain...Fluorinated smectic liquid crystals each with a biphenyl benzoate rigid core are investigated. Molecular structures of the studied compounds have difference only in fluorine position and the length of the carbon chain. Dielectric relaxation study and electro-optical measurements are carried out with the classical SSFLC geometry. The field-induced phase transitions are studied and the（E,T） phase diagram is established.展开更多
A series ofpolypeptides bearing biphenyl mesogenic side-chains and oligo-ethylene-glycol （OEG） tails （PPLGn-g- BPOEGm, n = 26 and 63, m = 2, 3, and 7） has been synthesized via a 1,3-dipolar cycloaddition with quan...A series ofpolypeptides bearing biphenyl mesogenic side-chains and oligo-ethylene-glycol （OEG） tails （PPLGn-g- BPOEGm, n = 26 and 63, m = 2, 3, and 7） has been synthesized via a 1,3-dipolar cycloaddition with quantitative grafting density. FTIR results revealed that the polypeptides adopted highly stable a-helix in the temperature range of 25-200 ℃. DSC, POM and WAXS analysis revealed that PPLGn-g-BPOEGm （m ≤ 3） samples with short OEG tail length showed two main phase transitions including crystal to liquid crystalline （smectie C, SmC） phase transition and the melting transition of crystalline E-phase, while PPLG,-g-BPOEG7 with longer OEG tail length （m = 7） exhibited the melting transitions without the formation of liquid crystalline phase.展开更多
5-[（4＇-Heptoxy-4-biphenylyl）carbonyloxy]-1-pentyne（A-3,7） was synthesized and the phase structures and transitions were investigated by differential scanning calorimetry（DSC）,wide angle X-ray diffraction（WAXD...5-[（4＇-Heptoxy-4-biphenylyl）carbonyloxy]-1-pentyne（A-3,7） was synthesized and the phase structures and transitions were investigated by differential scanning calorimetry（DSC）,wide angle X-ray diffraction（WAXD）,polarized light microscopy（PLM） and the molecular packing in the crystal and liquid crystalline phases were simulated by molecular dynamic simulation.The results showed that the sample formed thermodynamically metastable SmA and SmC_2 phases before crystallized during cooling and the crystal phase directly transformed into isotropic phase during heating.展开更多
Dielectric relaxation and spontaneous polarization studies have been carried out in a low molar mass organosiloxane liquid crystal, TSi10PPBN4 which displays a wide temperature range of de Vries Smectic A* and chiral ...Dielectric relaxation and spontaneous polarization studies have been carried out in a low molar mass organosiloxane liquid crystal, TSi10PPBN4 which displays a wide temperature range of de Vries Smectic A* and chiral Smectic C* phases. The temperature variation of the permittivity and dielectric loss studied are found to have anomalous variations in the vicinity of the phase transitions. The frequency variation of permittivity and dielectric loss are also studied in the de Vries Smectic A* and Smectic C* phases. The relaxation frequency, fR is found to decrease with decreasing temperature. Temperature variation of fR is found to follow an Arrhenius shift from which the activation energy is estimated. The thermal variation of the spontaneous polarization, Ps is measured using the polarization reversal technique in the Smectic C* phase. Ps increases initially, reaches a peak value and then drops drastically in the vicinity of the SmC*-SmA*de Vries phase transition.展开更多
A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three di...A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three dimentional, tree-like, starburst structure.Its phase behavior was K64 Sx115 SA123N138I. Compared with its AZO-meso-unit, 4-nitro-4’- (llydroxyhexyl)-azobenzene, whose phase behavior was K122N132I, its phase range was enlarged about 64 ℃ and two more liquid crystalline phases SA Sx were found.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 29674025) and the Natural Science Foundation of Henan Province.
文摘A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC, DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whin they were heated to their melting temperatures (T-m) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM. All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.
文摘Fluorinated smectic liquid crystals each with a biphenyl benzoate rigid core are investigated. Molecular structures of the studied compounds have difference only in fluorine position and the length of the carbon chain. Dielectric relaxation study and electro-optical measurements are carried out with the classical SSFLC geometry. The field-induced phase transitions are studied and the（E,T） phase diagram is established.
基金financially supported by the National Natural Science Foundation of China(No.21204075)Hunan Provincial Natural Science Foundation of China(No.13JJ6042)Xiangtan University start-up fund(No.12QDZ06)
文摘A series ofpolypeptides bearing biphenyl mesogenic side-chains and oligo-ethylene-glycol （OEG） tails （PPLGn-g- BPOEGm, n = 26 and 63, m = 2, 3, and 7） has been synthesized via a 1,3-dipolar cycloaddition with quantitative grafting density. FTIR results revealed that the polypeptides adopted highly stable a-helix in the temperature range of 25-200 ℃. DSC, POM and WAXS analysis revealed that PPLGn-g-BPOEGm （m ≤ 3） samples with short OEG tail length showed two main phase transitions including crystal to liquid crystalline （smectie C, SmC） phase transition and the melting transition of crystalline E-phase, while PPLG,-g-BPOEG7 with longer OEG tail length （m = 7） exhibited the melting transitions without the formation of liquid crystalline phase.
基金the financial supports of National Natural Science Foundation of China (No21074073)Shenzhen Key Laboratory of Functional Polymers(NoFP20100011)
文摘5-[（4＇-Heptoxy-4-biphenylyl）carbonyloxy]-1-pentyne（A-3,7） was synthesized and the phase structures and transitions were investigated by differential scanning calorimetry（DSC）,wide angle X-ray diffraction（WAXD）,polarized light microscopy（PLM） and the molecular packing in the crystal and liquid crystalline phases were simulated by molecular dynamic simulation.The results showed that the sample formed thermodynamically metastable SmA and SmC_2 phases before crystallized during cooling and the crystal phase directly transformed into isotropic phase during heating.
文摘Dielectric relaxation and spontaneous polarization studies have been carried out in a low molar mass organosiloxane liquid crystal, TSi10PPBN4 which displays a wide temperature range of de Vries Smectic A* and chiral Smectic C* phases. The temperature variation of the permittivity and dielectric loss studied are found to have anomalous variations in the vicinity of the phase transitions. The frequency variation of permittivity and dielectric loss are also studied in the de Vries Smectic A* and Smectic C* phases. The relaxation frequency, fR is found to decrease with decreasing temperature. Temperature variation of fR is found to follow an Arrhenius shift from which the activation energy is estimated. The thermal variation of the spontaneous polarization, Ps is measured using the polarization reversal technique in the Smectic C* phase. Ps increases initially, reaches a peak value and then drops drastically in the vicinity of the SmC*-SmA*de Vries phase transition.
文摘A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three dimentional, tree-like, starburst structure.Its phase behavior was K64 Sx115 SA123N138I. Compared with its AZO-meso-unit, 4-nitro-4’- (llydroxyhexyl)-azobenzene, whose phase behavior was K122N132I, its phase range was enlarged about 64 ℃ and two more liquid crystalline phases SA Sx were found.
