TY - JOUR
T1 - Ionic naphthalene thermotropic copolyesters with para-linked ion-containing units
AU - Xue, Yongpeng
AU - Hara, Masanori
N1 - Funding Information:
We would like to thank Dr H.N. Yoon and Dr L. Cangiano for useful discussions and J. Pickton for his assistance in film extrusion. We acknowledge Hoechst Celanese for support of this research. This research was also supported by the US Army Research Office.
PY - 2005/8/23
Y1 - 2005/8/23
N2 - Novel ionic naphthalene thermotropic polymers (NTPs) based on wholly aromatic copolyesters were synthesized, in which ionic monomer was introduced in the form of para-linked metal hydroquinone disulfonate (HQDS). These ionic NTPs contained ionic groups of up to 4 mol%, with counterions of either monovalent K or divalent Ca, and exhibited thermotropic liquid crystallinity. The K-salts exhibited the crystalline and liquid crystalline behaviors, typically observed for a non-ionic NTP; and they developed excellent thermal and mechanical properties. Testing was made as a function of ionic content under similar processing and testing conditions. The value of glass transition temperature rose as the average molecular weight increased. Both the melting temperature, Tm, and the crystallization temperature, Tc, remained nearly constant over the composition range studied. All the K-salt ionic NTPs showed enhanced tensile properties over a non-ionic NTP. The strength increased significantly as the ionic content increased despite the decrease in the molecular weight, reflecting the dominant effect of ionic interactions over the effect of molecular weight. Enhanced tensile properties arise from enhanced interchain interactions via ionic bonds (cross-links) between highly aligned NTP chains. The incorporation of HQDS-type 'straight' ionic units into a NTP copolyester can provide useful information about the effect of ionic interactions on the thermal/mechanical properties of NTPs.
AB - Novel ionic naphthalene thermotropic polymers (NTPs) based on wholly aromatic copolyesters were synthesized, in which ionic monomer was introduced in the form of para-linked metal hydroquinone disulfonate (HQDS). These ionic NTPs contained ionic groups of up to 4 mol%, with counterions of either monovalent K or divalent Ca, and exhibited thermotropic liquid crystallinity. The K-salts exhibited the crystalline and liquid crystalline behaviors, typically observed for a non-ionic NTP; and they developed excellent thermal and mechanical properties. Testing was made as a function of ionic content under similar processing and testing conditions. The value of glass transition temperature rose as the average molecular weight increased. Both the melting temperature, Tm, and the crystallization temperature, Tc, remained nearly constant over the composition range studied. All the K-salt ionic NTPs showed enhanced tensile properties over a non-ionic NTP. The strength increased significantly as the ionic content increased despite the decrease in the molecular weight, reflecting the dominant effect of ionic interactions over the effect of molecular weight. Enhanced tensile properties arise from enhanced interchain interactions via ionic bonds (cross-links) between highly aligned NTP chains. The incorporation of HQDS-type 'straight' ionic units into a NTP copolyester can provide useful information about the effect of ionic interactions on the thermal/mechanical properties of NTPs.
KW - Ionic polymers
KW - Mechanical and thermal properties
KW - Thermotropic liquid crystalline polymers
UR - http://www.scopus.com/inward/record.url?scp=23744467976&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=23744467976&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2005.05.143
DO - 10.1016/j.polymer.2005.05.143
M3 - Article
AN - SCOPUS:23744467976
VL - 46
SP - 7293
EP - 7300
JO - Polymer
JF - Polymer
SN - 0032-3861
IS - 18
ER -