Molecular dynamics in nanophase-separated comb-like poly(alpha-n-alkyl beta-L-aspartate)s.
Eur Phys J E Soft Matter
; 15(4): 383-93, 2004 Dec.
Article
em En
| MEDLINE
| ID: mdl-15565501
A series of poly(alpha-n-alkyl beta-L-aspartates) which are nanophase self-assembled comb-like polymers has been studied by dielectric spectroscopy in a broad frequency range (10(-2) < or = nu < or = 3 x 10(6) Hz), with n-alkyls side chains of various lengths, 10 < or = n < or =18. In every member of the series the same relaxations were identified after the decomposition of the experimental isothermal trace in up to three peaks with relaxation times distributions. The strength, width and average relaxation time for all the relaxation modes were determined for each material. Besides the local low temperature, Arrhenius modes, two relaxation modes, alpha and alpha(PE), present a cooperative character whose dynamics are not affected by the side chains melting. The alpha(PE) relaxation is a polyethylene-like glass transition of the amorphous side chains and its dynamics is strongly dependent on the n value due to the increasing restrictions imposed by the self-assembled confinement. The strength of the alpha(PE) relaxation mode increases as the lateral chains loose their 2D order. The restricted chopstick motion of the rigid rods is thought to be the origin of the alpha mode; this motion is hindered at temperatures where the cage size decreases as a result of the increasing disorder with temperature.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Análise Espectral
/
Materiais Biocompatíveis
/
Teste de Materiais
/
Ácido Aspártico
/
Cristalização
/
Modelos Químicos
Tipo de estudo:
Evaluation_studies
Idioma:
En
Revista:
Eur Phys J E Soft Matter
Assunto da revista:
BIOFISICA
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Venezuela
País de publicação:
França