FREE-SURFACE MORPHOLOGY OF BLOCK-COPOLYMERS .1. STYRENE-BUTADIENE DIBLOCK COPOLYMERS

Citation
A. Turturro et al., FREE-SURFACE MORPHOLOGY OF BLOCK-COPOLYMERS .1. STYRENE-BUTADIENE DIBLOCK COPOLYMERS, Polymer, 36(21), 1995, pp. 3987-3996
Citations number
38
Categorie Soggetti
Polymer Sciences
Journal title
ISSN journal
00323861
Volume
36
Issue
21
Year of publication
1995
Pages
3987 - 3996
Database
ISI
SICI code
0032-3861(1995)36:21<3987:FMOB.S>2.0.ZU;2-9
Abstract
The topology and morphology of the free surface of styrene-butadiene d iblock copolymers were investigated by transmission electron microscop y as functions of molecular weight, composition, diene configuration, casting solvent and solvent evaporation rate. It was found that in sol vent-cast thick films the formation of equilibrium free surface depend s on a delicate balance of kinetic and thermodynamic parameters. Fast evaporation rates induce orientation of lamellar and cylindrical micro domains perpendicular to the free surface, while slow rates produce eq uilibrium-like domain orientation, parallel to the free surface. Molec ular mechanisms of such arrangements are discussed, and it is conclude d that to rapidly obtain an equilibrium free surface, the difference b etween critical surface tensions of polystyrene (PS) and polybutadiene blocks must be the greater the higher the affinity between the castin g solvent and the block (PS) with the higher critical surface tension.