PHASE-BEHAVIOR OF DIBLOCK COPOLYMERS - PRESSURE AND TEMPERATURE-DEPENDENCE STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING

Citation
K. Mortensen et al., PHASE-BEHAVIOR OF DIBLOCK COPOLYMERS - PRESSURE AND TEMPERATURE-DEPENDENCE STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING, Macromolecular symposia, 121, 1997, pp. 245-262
Citations number
38
Categorie Soggetti
Polymer Sciences
Journal title
ISSN journal
10221360
Volume
121
Year of publication
1997
Pages
245 - 262
Database
ISI
SICI code
1022-1360(1997)121:<245:PODC-P>2.0.ZU;2-L
Abstract
The structure factor of a poly(ethylene-propylene)poly(dimethylsiloxan e) diblock copolymer has been measured by SANS as a function of temper ature and pressure. In contradiction to the random phase approximation the conformational compressibility exhibits a pronounced maximum at t he order-disorder phase transition. The phase boundary shows an unusua l shape: with increasing pressure it first decreases and then increase s. Its origin is an increase in, respectively, the entropic and the en thalpic part of the Flory-Huggins interaction parameter. The Ginzburg parameter describing the limit of the mean-field approximation is not influenced by pressure.