TY - JOUR
T1 - Thin-film polymerization and 'RIS' Metropolis Monte Carlo simulation of fluorinated aromatic copoly(ester-amide)s
AU - Teoh, May May
AU - Chung, Tai Shung
AU - Schiraldi, David A.
AU - Cheng, Si Xue
N1 - Funding Information:
The authors would like to thank NUS for funding this research with a grant number of R-279-000-176-112. Thanks are also due to Dr K. P. Pramoda, Dr C. H. He, Ms Y. Wang, Mr Z. Huang, and Mr X. Y. Xiao who have contributed useful comments and discussion to this study. Special thanks are given to Ueno, Teijin and Sumitomo Chemicals (Japan) for their provision of monomers and LCPs. The authors also thank Mr X. H. Zhang, Ms G. Foo, and Mr M. Masayuki for their useful assistance with the Cerius 2 simulation software.
PY - 2005/5/11
Y1 - 2005/5/11
N2 - In this study, wholly aromatic main chain copoly(ester-amide)s containing tetrafluorophthalic acid (TFPA-ortho), tetrafluoroisophthalic acid (TFIA-meta) and tetrafluoroterephthalic acid (TFTA-para) were synthesized to study the effects of kinks on the formation of mesophase and crystal texture. The effects of kink moieties on these copoly(ester-amide)s were also investigated by the 'RIS' metropolis Monte Carlo simulation. Computational results indicate that all systems form thermotropic liquid crystalline polymers (LCPs) because the calculated persistence ratios for the ortho-, meta- and para-linkage systems are 6.51, 7.64 and 10.49, respectively. Both simulation and experimental results agree that ABA/AAA/TFTA (para) system has the greatest tendency to yield the liquid crystal (LC) phase due to its greater persistence ratio, linearity, and chain stiffness. The incorporation of TFPA (ortho) moiety can effectively reduce 30% of the molar stiffness function and 23% of the persistence length as compared to those of the TFTA (para) system. Yet, the ABA/AAA/TFPA system may form LC texture because of its large, rigid, disk-like TFPA moiety and the crankshaft structure induced by cis-configuration between AAA and TFPA moieties. The meta-linkage system has a slower LC growth rate, but it has a much higher tendency to form LC than the ortho-linkage. Both meta- and para-linkage systems have close critical ABA content to form LC texture. When comparing the requirements of critical ABA content between ABA/AAA/TFIA and ABA/AAA/IA (isophthalic acid) systems, we surprisingly observed that the former has a much lower critical ABA content than the latter. The four fluorine substituents of TFIA definitely help chain rigidity and stabilize the LC mesogens. Even though these fluorinated moieties exhibit different conformations and configurations, they yield similar end-stage crystalline structure. The spherulites are grown from the dark brushes around a single disclination, indicating that these are the lowest energy for crystallization.
AB - In this study, wholly aromatic main chain copoly(ester-amide)s containing tetrafluorophthalic acid (TFPA-ortho), tetrafluoroisophthalic acid (TFIA-meta) and tetrafluoroterephthalic acid (TFTA-para) were synthesized to study the effects of kinks on the formation of mesophase and crystal texture. The effects of kink moieties on these copoly(ester-amide)s were also investigated by the 'RIS' metropolis Monte Carlo simulation. Computational results indicate that all systems form thermotropic liquid crystalline polymers (LCPs) because the calculated persistence ratios for the ortho-, meta- and para-linkage systems are 6.51, 7.64 and 10.49, respectively. Both simulation and experimental results agree that ABA/AAA/TFTA (para) system has the greatest tendency to yield the liquid crystal (LC) phase due to its greater persistence ratio, linearity, and chain stiffness. The incorporation of TFPA (ortho) moiety can effectively reduce 30% of the molar stiffness function and 23% of the persistence length as compared to those of the TFTA (para) system. Yet, the ABA/AAA/TFPA system may form LC texture because of its large, rigid, disk-like TFPA moiety and the crankshaft structure induced by cis-configuration between AAA and TFPA moieties. The meta-linkage system has a slower LC growth rate, but it has a much higher tendency to form LC than the ortho-linkage. Both meta- and para-linkage systems have close critical ABA content to form LC texture. When comparing the requirements of critical ABA content between ABA/AAA/TFIA and ABA/AAA/IA (isophthalic acid) systems, we surprisingly observed that the former has a much lower critical ABA content than the latter. The four fluorine substituents of TFIA definitely help chain rigidity and stabilize the LC mesogens. Even though these fluorinated moieties exhibit different conformations and configurations, they yield similar end-stage crystalline structure. The spherulites are grown from the dark brushes around a single disclination, indicating that these are the lowest energy for crystallization.
KW - Effects of kink linkage
KW - Fluorinated LCPs
KW - Persistence ratio
UR - http://www.scopus.com/inward/record.url?scp=17544371211&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2005.03.028
DO - 10.1016/j.polymer.2005.03.028
M3 - Article
AN - SCOPUS:17544371211
SN - 0032-3861
VL - 46
SP - 3914
EP - 3926
JO - Polymer
JF - Polymer
IS - 11
ER -