Tr. Gengenbach et Hj. Griesser, Aging of 1,3-diaminopropane plasma-deposited polymer films: Mechanisms andreaction pathways, J POL SC PC, 37(13), 1999, pp. 2191-2206
Citations number
34
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
In the course of plasma deposition of organic-polymeric thin films, radical
s are incorporated into the growing film. These radicals initiate spontaneo
us oxidation reactions that continue over many weeks when the plasma polyme
rs are stored in air. These reactions and their products have been previous
ly studied in detail for spectroscopically simple, hydrocarbon-based plasma
polymers. In this investigation, the aging of 1,3-diaminopropane (DAP) pla
sma polymer samples was monitored by XPS and FTIR in order to study how the
oxidative reaction pathways might differ in a plasma-deposited material th
at is initially rich in amine groups. The freshly deposited DAP plasma poly
mer consisted of a random hydrocarbon network with a considerable amount of
unsaturation and a high concentration of nitrogen-containing functional gr
oups, mainly primary/secondary amines and imines. These groups strongly inf
luenced the aging reactions: in contrast to hydrocarbon-based material wher
e hydrogen abstraction and reaction of carbon-centered radicals with in-dif
fusing oxygen result in a wide range of oxidative products, both XPS and FT
IR identified a rather narrow range of products (mainly amides and similar
groups) in DAP plasma polymers even after extensive aging for more than 2 y
ears. Reaction routes based on oxidation and/or hydrolysis of nitrogen func
tional groups, and involving primary as well as secondary reactions, are pr
oposed to account for the spectroscopic data. The structure of the aged DAP
plasma polymer appeared to be stable, and did not undergo more extensive o
xidation, in contrast to hydrocarbon plasma polymers. In particular, carbox
ylic acid groups and carbamates were not detected. (C) 1999 John Wiley & So
ns, Inc. J Polym Sci A: Polym Chem 37: 2191-2206, 1999.