73376-32-6Relevant articles and documents
Synthesis and self-assembly behaviours of side-chain smectic thiol-ene polymers based on the polysiloxane backbone
Yao, Wenhuan,Gao, Yanzi,Yuan, Xiao,He, Baofeng,Yu, Haifeng,Zhang, Lanying,Shen, Zhihao,He, Wanli,Yang, Zhou,Yang, Huai,Yang, Dengke
, p. 1425 - 1440 (2016/02/23)
A series of polysiloxane side chain liquid crystal polymers (PSCLCPs) with chiral and achiral substitutions in the side chains, denoted as PMMS-Xchol-n (n = 0, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5 0.6, 0.7. 0.8, 0.9, and 1.0, respectively, the molar content of the chiral cholesteric unit (Xchol) in a specific polymer), were successfully synthesized via thiol-ene click chemistry. The molecular structures of the polymers were confirmed by 1H-NMR, FT-IR, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). Their liquid crystalline (LC) properties and self-assembling behaviors were investigated in detail by a combination of various techniques, such as differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction. The results demonstrated that the phase transition behaviour and the self-assembly structure of the polymers were significantly influenced by Xchol and temperatures. With increased Xchol, the clearing points increased significantly, their mesogenic temperature ranges greatly widened, and abundant mesophases developed. Generally, two different types of LC phase structures and three different molecular arrangements were observed, depending on the two LC building blocks. Polymers with Xchol below 0.3 could self-assemble into a smectic E (SmE)-like structure and a single layer smectic A (SmAs) structure upon heating. When Xchol was between 0.4 and 0.7, a single phase structure of a SmAs or a bilayer smectic A (SmAd) could be observed. While for polymers with Xchol over 0.8, a SmAd phase structure was self-organized, further heating led to a SmAs structure. Moreover, when the molar ratio of the chiral group or achiral group was about 0.1, a microphase-separated smectic morphology could be found, indicating that the introduction of a small amount of any components in the copolymers might destroy the well-ordered structures.
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 (2016/09/23)
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.
