83953-73-5Relevant articles and documents
Influence of shorter backbone and cholesteric monomer percentage on the phase structures and thermal-optical properties of linear siloxane tetramers containing cholesterol and benzene methyl ether groups
Yao, Wenhuan,Gao, Yanzi,Li, Fasheng,Zhang, Lanying,Yang, Zhou,Yang, Huai
, p. 87502 - 87512 (2016)
A series of new linear polysiloxane tetramers containing cholesterol and benzene methyl ether groups as side chains was successfully synthesized via a typical hydrosilylation reaction. Their chemical structures were confirmed by 1H-NMR, FT-IR and thermogravimetric analysis (TGA). A combination of analysis methods such as differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction was carried out to systematically investigate their phase transition behaviours and phase structures. The results revealed that the mesophase structures of all the polymers were greatly dependent on the molar content of the chiral cholesteric unit (Xchol). Polymers with Xchol below 0.60 or over 0.70 could develop a stable cholesteric phase or smectic A phase, while both smectic A and cholesteric phases could be formed for polymers with Xchol between 0.60 and 0.70. Besides, polymers with Xchol below 0.60, which developed a cholesteric phase with sufficiently wide temperature ranges in the entire mesomorphic state (minimum over 50 °C and maximum over 130 °C), could also exhibit tunable selective reflection wavelengths between 470-560 nm upon heating and arbitrarily regulated glass transition temperatures between 0-40 °C. As a result, a thermochromism liquid crystalline material for temperature sensors was successfully obtained. Surprisingly, different from the results previously reported, an unusual phenomenon of the centre selective light reflection wavelength (λm) vs. Xchol, which decreased dramatically (blue shift) at first, then had a remarkable red shift with increasing Xchol, was first observed.
A series of novel side chain liquid crystalline polysiloxanes containing cyano- and cholesterol-terminated substituents: Where will the structure-dependence of terminal behavior of the side chain reappear?
Yao, Wenhuan,Gao, Yanzi,Zhang, Cuihong,Li, Chenyue,Li, Fasheng,Yang, Zhou,Zhang, Lanying
, p. 1765 - 1772 (2017/04/13)
A series of polysiloxane side chain liquid crystal polymers with strong polarity cyano substitution-terminated achiral side chains and cholesterol-terminated chiral side chains was successfully synthesized via thiol-ene click chemistry. 1H-NMR, FT-IR, and thermogravimetric analysis were used to confirm their chemical structures and thermal stabilities. Their phase transition behaviors and phase structures were systematically investigated by a combination of analysis methods such as differential scanning calorimetry, polarized optical microscopy, and X-ray. Results revealed that attributing to the decisive role of the polarity interaction, all the polymers only developed a monolayer interdigitated SmA phase in which the period arrangement was determined by the cyano-terminated side chains, the increased content of cholesterol-terminated chiral side chains (Xchol) just expanded the distance between neighboring molecules within a layer.
Construction of topological macromolecular side chains packing model: Study unique relationship and differences in LC-microstructures and properties of two analogous architectures with well-designed side attachment density
Han, Li,Ma, Hongwei,Li, Yang,Wu, Jian,Xu, Hanyan,Wang, Yurong
, p. 925 - 941 (2015/06/15)
A new series of linear-comb and 4-arm star-comb side chain liquid crystalline polymers (Lc-/Sc-SCLCPs) have been synthesized and characterized. The treatment of hydride siloxane-containing terminated liquid crystalline and high 1,2-/1,4- (high vinyl, hv/low vinyl, lv) linear or 4-arm star polybutadienes (L-/S-PBs) was conducted via the methods in combination of living anionic polymerization and "reverse" hydrosilylation to obtain SCLCPs with wide mesomorphic temperature range (ΔT) and narrow polydispersity index (PDI). The possible molecular arrangement model of two analogous hv-/lv-architectures was constructed, that was used to systematically investigate the effects of Lc- and Sc- topological morphology on liquid crystalline (LC) properties and molecular microstructures. SCLCPs exhibited the same smectic A phase around room temperature, but thermal properties were significantly different due to differences of interaction force resulting from different macromolecular side chains packing. Surprisingly, the trend of lv-SCLCP displaying the effects of topology on phase transitions and microstructures was just contrary to that of hv-topology. hv-Sc-SCLCPs containing high density mesogenic composition were desired to generate wider ΔT and higher molecular layer order in comparison with Lc analogues, which provided a unexpected analyzed model that are of interest to be explored. In particular, the uniaue differences of macromolecular aggregation state arrangement in liquid crystal state dependent on free cooling between hv-Lc- and Sc-SCLCPs were observed from POM.
