Premium
Is the Reduction in Tracer Diffusivity under Nanoscopic Confinement Related to a Frustrated Segmental Mobility?
Author(s) -
Napolitano Simone,
Rotella Cinzia,
Wübbenhorst Michael
Publication year - 2011
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100029
Subject(s) - thermal diffusivity , nanoscopic scale , tracer , materials science , einstein relation , decoupling (probability) , thin film , polymer , chemical physics , condensed matter physics , nanotechnology , chemistry , thermodynamics , composite material , physics , metric (unit) , operations management , control engineering , nuclear physics , engineering , economics
Abstract We developed an experimental method for the determination of the tracer diffusivity D tr in ultrathin polymer films, and the changes in the segmental mobility of tracer molecules while they diffuse through matrices of different thickness and get adsorbed onto a target substrate. D tr starts decreasing already at 120–150 nm and drops to 1% of its bulk value in films as thin as 7.5 nm. We discuss the results highlighting a strong decoupling between the reduction in mass transport at the nanoscale and the increase in the glass transition temperature determined via capacitive dilatometry together with a breakdown of the Stokes–Einstein relation between orientational and translational degrees of freedom.