Synthesis, structure, and mesomorphism of novel liquid crystalline acrylate monomers and polymers
摘要:
A series of novel liquid crystalline monomers (M-1-M-8) and side chain polymers base polyacrylate backbone were synthesized. The chemical structures were characterized by FT-IR and H-1-NMR spectra. The mesomorphism and thermal behavior was investigated by polarizing optical microscopy, differential scanning calorimetry, and thermogravimetric analysis. The relationships of structure and mesomorphism are discussed in detail. The eight monomers and their corresponding polymers all show enantiotropic nematic phase. With increasing the spacer length or flexibility of the terminal group, the melting temperature (T-m) and isotropic temperature (T-i) of the corresponding monomers and polymers all decreased. However, with increasing the rigidity of the mesogenic core, T-m and T-i of the corresponding monomers and polymers all increased. TGA showed that all the polymers obtained in this study had excellent thermal stability.
Synthesis, structure, and mesomorphism of novel liquid crystalline acrylate monomers and polymers
摘要:
A series of novel liquid crystalline monomers (M-1-M-8) and side chain polymers base polyacrylate backbone were synthesized. The chemical structures were characterized by FT-IR and H-1-NMR spectra. The mesomorphism and thermal behavior was investigated by polarizing optical microscopy, differential scanning calorimetry, and thermogravimetric analysis. The relationships of structure and mesomorphism are discussed in detail. The eight monomers and their corresponding polymers all show enantiotropic nematic phase. With increasing the spacer length or flexibility of the terminal group, the melting temperature (T-m) and isotropic temperature (T-i) of the corresponding monomers and polymers all decreased. However, with increasing the rigidity of the mesogenic core, T-m and T-i of the corresponding monomers and polymers all increased. TGA showed that all the polymers obtained in this study had excellent thermal stability.
Cross Redox Coupling of Aryl-Aldehydes and <i>p</i>-Benzoquinone
作者:Anima Bose、Prasenjit Mal
DOI:10.1021/acs.joc.5b02175
日期:2015.11.6
unprecedented Cross Redox Coupling (CRC) reaction catalyzed by Cu(OAc)2·H2O. As a proof-of-concept, directcoupling of aromatic aldehydes (or alcohols) and p-benzoquinone led to an ester in the presence of the Cu(II)–TBHP combination. During the coupling process, the C–H bond of the aldehydes was converted directly to a C–O bond. Mechanistically, we propose that the reaction proceeded via a radical pathway
The transformation kinetics of a series of liquid-crystallines based on 1,4-phenylene 4-n-alkybenzoate-4-allyloxybenzoate (PABAOB) was studied by nonisothermal methods using differential scanning calorimetry. These determinations led to the values of activation energy of transformation from 691.3 to 628.3 kJ/mol, respectively The values of the Avrami exponent n were from 3.0 to 2.6. The values of transformation activation energy decreased with the ascending of alkyl. The result shows that the process of transformation of PABAOB is a constant number of nuclei growing in three dimensions at constant rate and the crystal growth being controlled probably by a diffusion process. (C) 1997 John Wiley & Sons, Inc.