Two glass transitions associated to different dynamic disorders in the nematic glassy state of a non-symmetric liquid crystal dimer dopped with gamma-alumina nanoparticles

Diez-Berart, Sergio ; López, David.O. ; Salud, Josep ; Diego, José Antonio ; Sellarés, Jordi ; Robles-Hernández, Beatriz ; De la Fuente, M.Rosario ; Ros, M.Blanca (Universidad de Zaragoza)

Resumen: In the present work, the nematic glassy state of the non-symmetric LC dimer a-(4-cyanobiphenyl-4'-yloxy)-¿-(1-pyrenimine-benzylidene-4'-oxy) undecane is studied by means of calorimetric and dielectric measurements. The most striking result of the work is the presence of two different glass transition temperatures: one due to the freezing of the flip-flop motions of the bulkier unit of the dimer and the other, at a lower temperature, related to the freezing of the flip-flop and precessional motions of the cyanobiphenyl unit. This result shows the fact that glass transition is the consequence of the freezing of one or more coupled dynamic disorders and not of the disordered phase itself. In order to avoid crystallization when the bulk sample is cooled down, the LC dimer has been confined via
the dispersion of ¿-alumina nanoparticles, in several concentrations.

Idioma: Inglés

DOI: 10.3390/ma8063334

Año: 2015

Publicado en: MATERIALS 8, 6 (2015), 3334-3351
ISSN: 1996-1944

Factor impacto JCR: 2.728 (2015)

Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 63 / 271 = 0.232 (2015) - Q1 - T1

Factor impacto SCIMAGO: 0.83 - Materials Science (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E04
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2012-38538-C01-02

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Química Orgánica (Dpto. Química Orgánica)