Abstract
A new series of liquid-crystalline poly(azomethine)s (PAMEs), containing different numbers n of ethylene glycol flexible spacers, has been studied. It has been observed that, after crystal melting, all specimens show nematic liquid-crystalline phases before they reach their isotropic melts. The polymers can form single liquid-crystalline glassy phases after quenching ( n = 1) or on cooling ( n = 2, 3 and 4). The heat capacities of the polymers in solids, nematic liquid crystals and isotropic melts have been measured in the temperature range 230–620 K. Calculations of the solid heat capacities of the polymers have been carried out based on their vibrational spectra. The liquid-crystalline glass transitions of the polymers have been investigated. Pre-glass transitions of the PAMEs have been distinguished in lower-temperature regions, and they are attributed to the contributions of flexible spacers. Broadness of the semicrystalline PAMEs in the glass transition regions is reported. Hysteresis effects of PAMEs show a dependence on the number of flexible spacers. Both transitions from rigid crystals to nematic liquid crystals and from nematic liquid crystals to isotropic melts were studied. The enthalpy and entropy changes are discussed systematically.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
