Dielectric relaxation at the glass transition of confined N-methyl-epsilon-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	2014-03-01T01:47:34Z
dc.date.available	2014-03-01T01:47:34Z
dc.date.issued	1998	en
dc.identifier.issn	0163-1829	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/25263
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	ULTRATHIN POLYMER-FILMS	en
dc.subject.other	CHARACTERISTIC LENGTH	en
dc.subject.other	ALPHA-RELAXATION	en
dc.subject.other	POROUS-GLASS	en
dc.subject.other	LIQUIDS	en
dc.subject.other	DYNAMICS	en
dc.subject.other	TEMPERATURE	en
dc.subject.other	SIZE	en
dc.subject.other	COOPERATIVITY	en
dc.subject.other	SPECTROSCOPY	en
dc.title	Dielectric relaxation at the glass transition of confined N-methyl-epsilon-caprolactam	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	1998	en
heal.abstract	The effects of confinement on the glass transition of the nonassociating glass-forming liquid N-methyl-epsilon-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 ct 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 xi at T-g to xi less than or equal to 10-12 nm.	en
heal.publisher	AMERICAN PHYSICAL SOC	en
heal.journalName	PHYSICAL REVIEW B	en
dc.identifier.isi	ISI:000075720100041	en
dc.identifier.volume	58	en
dc.identifier.issue	9	en
dc.identifier.spage	5336	en
dc.identifier.epage	5345	en