Detailed multitechnique spectroscopic surface and bulk characterization of plasma polymers deposited from 1-propanol, allyl alcohol, and propargyl alcohol

Abstract

Three monomers with different degrees of unsaturation, 1-propanol, allyl alcohol, and propargyl alcohol, are plasma-deposited to obtain alcohol functions containing polymers. To obtain information on the behaviors of these monomers in the plasma, the polymers deposited in the reactor and in the postdischarge region are characterized by high-energy resolution XPS, IR, HREELS, elemental analysis, and chemical derivatization. XPS results show that oxygen-rich polymers can be obtained from the unsaturated monomers at low power for both regions or at high power in the postdischarge region. In the reactor at high power, fragmentation of the monomer leads to the elimination of oxygen fragments and ablation reactions during the polymerization process. Detailed structural information on the chemical structure and content of functional groups are obtained by simulation of the XPS C1s core levels of the polymers before and after derivatization with trifluoroacetic anhydride. In soft conditions, allyl alcohol leads to the formation of polymers with a relatively low degree of crosslinking and a high hydroxyl content (53–72%). However, the high resolution of the XPS spectrometer allows one to detect the presence of secondary or tertiary alcohol functions resulting from chain branching reactions in this polymer. Results from this multitechnique characterization indicate also that the hydroxyl conversion and crosslinking reactions are more pronounced for poly(1-propanol) and poly(propargyl alcohol). Alcohol, ether, and carbonyl functions are present in equivalent quantities in poly(propargyl alcohol) while poly(1-propanol) contains mainly ether functions (50%). The presence or absence of alcohol functions at the extreme surface of the polymers in relation to the chain mobility and the tendency of hydrogen bonding between hydroxyl groups was studied by HREELS. © 1996 John Wiley & Sons, Inc.