Dielectric relaxation at the glass transition of confined N-methyl-ε-caprolactam

Daoukaki, D; Barut, G; Pelster, R; Nimtz, G; Kyritsis, A; Pissis, P

dc.contributor.author	Daoukaki, D	en
dc.contributor.author	Barut, G	en
dc.contributor.author	Pelster, R	en
dc.contributor.author	Nimtz, G	en
dc.contributor.author	Kyritsis, A	en
dc.contributor.author	Pissis, P	en
dc.date.accessioned	2014-03-01T01:13:41Z
dc.date.available	2014-03-01T01:13:41Z
dc.date.issued	1998	en
dc.identifier.issn	01631829	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/12655
dc.subject	Dielectric Relaxation	en
dc.subject	Glass Transition	en
dc.title	Dielectric relaxation at the glass transition of confined N-methyl-ε-caprolactam	en
heal.type	journalArticle	en
heal.identifier.primary	10.1103/PhysRevB.58.5336	en
heal.identifier.secondary	http://dx.doi.org/10.1103/PhysRevB.58.5336	en
heal.publicationDate	1998	en
heal.abstract	The effects of confinement on the glass transition of the nonassociating glass-forming liquid N-methyl-ε-caprolactam were studied in detail by means of broadband dielectric relaxation spectroscopy, 5 Hz-2 GHz, and thermally stimulated depolarization current measurements, 77-300 K. The liquid was two dimensionally confined in the pores of controlled porous glasses with mean pore diameter d = 2.5, 5.0, 7.5, and 20.0 nm (Gelsil glasses) and d = 4.0 nm (Vycor glass) and three dimensionally confined in butyl rubber with mean droplet diameter d=7.6 nm. The confined liquid is classified into two fractions: a relatively immobile interfacial layer close to the wall and the inner layer (volume liquid). For the volume liquid the a relaxation associated with the glass transition becomes faster and the glass transition temperature decreases compared to the bulk liquid. These effects increase with decreasing d and are stronger for three- than for two-dimensional confinement. They can be understood on the basis of the cooperativity concept and the configurational entropy model of Adam and Gibbs. The systematic variation of d allows the determination of the cooperativity length ξ at Tg to ξ≤s10-12 nm.	en
heal.journalName	Physical Review B - Condensed Matter and Materials Physics	en
dc.identifier.doi	10.1103/PhysRevB.58.5336	en
dc.identifier.volume	58	en
dc.identifier.issue	9	en
dc.identifier.spage	5336	en
dc.identifier.epage	5345	en