Dielectric relaxation and thermally stimulated discharge currents in liquid-crystalline side-chain polymethacrylates with phenylbenzoate mesogens having tail groups of different length

Nikonorova, N; Borisova, T; Barmatov, E; Pissis, P; Diaz-Calleja, R

dc.contributor.author	Nikonorova, N	en
dc.contributor.author	Borisova, T	en
dc.contributor.author	Barmatov, E	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Diaz-Calleja, R	en
dc.date.accessioned	2014-03-01T01:18:52Z
dc.date.available	2014-03-01T01:18:52Z
dc.date.issued	2003	en
dc.identifier.issn	0024-9297	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15240
dc.subject	Dielectric Relaxation	en
dc.subject	Liquid Crystalline	en
dc.subject.classification	Polymer Science	en
dc.subject.other	Activation analysis	en
dc.subject.other	Dielectric losses	en
dc.subject.other	Dielectric relaxation	en
dc.subject.other	Electric currents	en
dc.subject.other	Electric discharges	en
dc.subject.other	Liquid crystals	en
dc.subject.other	Polarization	en
dc.subject.other	Thermal windowing techniques	en
dc.subject.other	Polyacrylates	en
dc.title	Dielectric relaxation and thermally stimulated discharge currents in liquid-crystalline side-chain polymethacrylates with phenylbenzoate mesogens having tail groups of different length	en
heal.type	journalArticle	en
heal.identifier.primary	10.1021/ma020832c	en
heal.identifier.secondary	http://dx.doi.org/10.1021/ma020832c	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	Molecular dynamics of six side-chain liquid-crystalline polymethacrylates with phenylbenzoate mesogenic groups having tail groups of different lengths was investigated by dielectric spectroscopy (DS) and by thermally stimulated discharge current (TSDC) methods. In the temperature range from room temperature to 160degreesC, three processes of relaxation of dipole polarization, the beta(1), alpha, and delta processes, were revealed. These correspond, from low to high temperatures, to the mobility of ester groups adjoining the backbone, to the segmental motion, and to the mesogenic group orientation about its short axis. For a quantitative analysis, dielectric spectra were described by a superposition of one or of two Havriliak-Negami functions and of a conductivity term. It was shown that the molecular mobility of the observed relaxation processes does not depend on the mesogen tail length. The comparison of the DS and TSDC data with each other gives good agreement between the temperature position of dielectric loss peaks at the equivalent frequency of TSDC measurements and the temperature position of depolarization current maximum. By using thermal windowing techniques, the activation parameters for the observed processes were determined.	en
heal.publisher	AMER CHEMICAL SOC	en
heal.journalName	Macromolecules	en
dc.identifier.doi	10.1021/ma020832c	en
dc.identifier.isi	ISI:000184398600047	en
dc.identifier.volume	36	en
dc.identifier.issue	15	en
dc.identifier.spage	5784	en
dc.identifier.epage	5791	en