TY - JOUR
T1 - Synthesis and characterization of a thermotropic liquid-crystalline poly[2,5-bis(4′-alkoxycarbonylphenyl) styrene]
AU - Zhu, Zhiguo
AU - Zhi, Junge
AU - Liu, Anhua
AU - Cui, Jiaxi
AU - Tang, Hui
AU - Qiao, Wenqiang
AU - Wan, Xinhua
AU - Zhou, Qifeng
PY - 2007/3/1
Y1 - 2007/3/1
N2 - We report the synthesis and characterization of a series of novel mesogen-jacketed liquid-crystalline polymers, poly[2,5-bis(4′- alkoxycarbonylphenyl)styrene]s (1-m, where m is the number of carbon atoms in the alkyl tails), along with the corresponding monomers, 2,5-bis(4′- alkoxycarbonylphenyl)styrenes (2-m), and their precursors, 2,5-bis(4′- alkoxycarbonylphenyl)toluenes (3-m). The influence of the tail length on the thermotropic properties of the two types of low-molecular-mass compounds and macromolecules was investigated with a combination of differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray diffraction techniques. Except for compound 3-3, which exhibited a monotropic nematic phase, all members of the low-molar-mass molecules developed no mesophase during both heating and cooling processes. The glass-transition temperatures of the polymers decreased as the tail lengths increased. The 5% weight loss temperatures of all the polymers under a nitrogen atmosphere were above 360 °C, indicating quite high thermal stability. Although polymers 1-1 and 1-2 were non-liquid-crystalline, columnar nematic phases were observed for the remaining homopolymers with longer alkyl tails. The mesophases of 1-3 to 1-9 that developed at high temperatures remained upon cooling to room temperature, whereas those of 1-10 to 1-12 disappeared during the cooling process.
AB - We report the synthesis and characterization of a series of novel mesogen-jacketed liquid-crystalline polymers, poly[2,5-bis(4′- alkoxycarbonylphenyl)styrene]s (1-m, where m is the number of carbon atoms in the alkyl tails), along with the corresponding monomers, 2,5-bis(4′- alkoxycarbonylphenyl)styrenes (2-m), and their precursors, 2,5-bis(4′- alkoxycarbonylphenyl)toluenes (3-m). The influence of the tail length on the thermotropic properties of the two types of low-molecular-mass compounds and macromolecules was investigated with a combination of differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray diffraction techniques. Except for compound 3-3, which exhibited a monotropic nematic phase, all members of the low-molar-mass molecules developed no mesophase during both heating and cooling processes. The glass-transition temperatures of the polymers decreased as the tail lengths increased. The 5% weight loss temperatures of all the polymers under a nitrogen atmosphere were above 360 °C, indicating quite high thermal stability. Although polymers 1-1 and 1-2 were non-liquid-crystalline, columnar nematic phases were observed for the remaining homopolymers with longer alkyl tails. The mesophases of 1-3 to 1-9 that developed at high temperatures remained upon cooling to room temperature, whereas those of 1-10 to 1-12 disappeared during the cooling process.
KW - Alkyl tail length
KW - Columnar nematic phase
KW - Mesogen-jacketed liquid-crystalline polymer
KW - P-terphenyl
KW - Poly[2,5-bis(4′- alkoxycarbonylphenyl) styrene]
KW - Radical polymerization
KW - Structure-property relations
UR - http://www.scopus.com/inward/record.url?scp=33847729005&partnerID=8YFLogxK
U2 - 10.1002/pola.21845
DO - 10.1002/pola.21845
M3 - Article
AN - SCOPUS:33847729005
SN - 0887-624X
VL - 45
SP - 830
EP - 847
JO - Journal of Polymer Science, Part A: Polymer Chemistry
JF - Journal of Polymer Science, Part A: Polymer Chemistry
IS - 5
ER -