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Spectroscopic evidence of the polymer tacticity as an important parameter for the configuration of the adsorbed pmma layer
Author(s) -
Grohens Yves,
Brogly Maurice,
Labbe Clorinthe,
Schultz Jacques,
Prud'homme Robert E.
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971190117
Subject(s) - tacticity , materials science , polymer , adsorption , layer (electronics) , infrared spectroscopy , methylene , polymer chemistry , aluminium , substrate (aquarium) , analytical chemistry (journal) , chemistry , composite material , organic chemistry , polymerization , oceanography , geology
Abstract PMMAs with a racemic fraction (f r ) ranging from 0.07 to 0.9 and a molecular weight of about 40000 Dalton are adsorbed on aluminum mirrors and alumina powder. The fraction of bonded carbonyl group ( p ) linked to the substrate by acid‐base interactions is determined by infrared spectroscopy in reflectance mode (IRAS for aluminum mirrors, DRIFT for alumina powder). Calculated values of p range from 0.5 to 0.2 from isotactic to syndiotactic isomers. Ellipsometric thickness (h) of PMMA films are measured on aluminum surfaces and provide values increasing with the average syndiotactic sequence length (n s ). Solid state 13 C NMR is performed on PMMA adsorbed on alumina powder to provide experimental evidence of interfacial conformational changes. The changes in methylene carbon chemical shift, due to a lowering in the γ‐gauche effect, are more pronounced for isotactic PMMA than for the syndiotactic form. These experimental results lead to the conclusion that the extent of flattening of polymer chains on the substrate depends on the PMMA stereoregularity.