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Selective etching of thermotropic liquid crystalline polyesters
Author(s) -
Hedmark Per G.,
Jansson JanFredrik,
Hult Anders,
Lindberg Henrik,
Gedde Ulf W.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070340226
Subject(s) - copolymer , materials science , ethylamine , thermotropic crystal , scanning electron microscope , etching (microfabrication) , polymer chemistry , propylamine , morphology (biology) , ethylene , chemical engineering , polyester , polymer , chemistry , layer (electronics) , organic chemistry , amine gas treating , liquid crystalline , nanotechnology , composite material , catalysis , engineering , genetics , biology
DSC, IR, ESCA, macroscopic etching rate measurements, analysis of etchant solution, and electron microscopy conclusively show that n ‐alkylamines (ethylamine, n ‐propylamine, n ‐butylamine, and n ‐pentylamine) and NaOH selectively degrade (etch) the ethylene terephthalate (ET)‐rich phase in glassy liquid crystalline poly( p ‐hydroxybenzoic acid‐co‐ethylene terephthalate) [P(HBA–ET)] with molar compositions 0.60:0.40 and 0.80:0.20. ESCA demonstrates the excellent selectivity of the n ‐alkylamine etchants in the 0.60:0.40 copolymer. The 50 Å top layer of the etched samples contains 95 mol% HBA. Treatment with H 2 SO 4 and NH 3 gives ambiguous results, and these compounds are not suitable as etchants. It is demonstrated by electron microscopy on the 0.60:0.40 copolymer, in accordance with earlier reports by Joseph et al., 5–8 that the ET‐rich phase is discontinuous (1–2 μm spheres) and surrounded by an HBA‐rich matrix. SEM is a useful tool for characterization of this morphology. However, both phases have a substracture which is revealed only by TEM. The morphology of the 0.80:0.20 copolymer is fine‐textured, which means that SEM is a less suitable method for the characterization of etched samples.