Initiated Chemical Vapor Deposition of Trivinyltrimethylcyclotrisiloxane for Biomaterial Coatings

Abstract

Organosilicon polymers show great utility as both biocompatible and electrically insulating materials. In this work, thin films of a novel organosilicon polymer are synthesized by initiated chemical vapor deposition utilizing trivinyltrimethylcyclotrisiloxane as a monomer and tert-butyl peroxide as a free-radical-generating initiator. Use of an initiator allows for the formation of polymer films at filament temperatures as low as 250 degrees C, significantly lower than those required to thermally polymerize the monomer species. The mild reaction conditions allow for the retention of all siloxane ring moieties within the resulting polymer. Films deposited at filament temperatures of 600 degrees C or higher exhibit damage to this moiety. The all-dry deposition process generates a highly cross-linked matrix material in which over 95% of the vinyl moieties present on the monomer units have been reacted out to form linear polymerized hydrocarbon chains. While each hydrocarbon backbone chain averages 8.9 monomer units in length, as evaluated by X-ray photoelectron spectroscopy analysis, each monomer unit is involved in three independent chains, resulting in polymer films of such high molecular weight that they are completely insoluble. Kinetic analysis of the deposition process indicates that the film formation rate is limited by the adsorption of reactive species to the deposition substrate, with an apparent activation energy of -23.2 kJ/mol with respect to the substrate temperature. These results are consistent with a surface growth mechanism, ideal for the coating of nonuniform or high aspect ratio substrates.

Initiated-chemical vapor deposition of organosilicon layers: Monomer adsorption, bulk growth, and process window definition

“…A list of the absorption modes for both monomer and polymer spectra is reported in Table II , still present in the polymer spectrum, is also attributed to the deformation of the methylene group bonded to silicon. 5 As the polymerization process occurs through the activation of the vinyl groups, the features associated with the generated polyethylene chains, such as the asymmetric and symmetric stretching modes of the methylene groups at 2910 and 2861 cm À1 and the asymmetric bending mode of the methylene groups at 1460 cm À1 , appear in the polymer spectrum. The retention of the other monomer functional groups (i.e.…”

“…In situ SE measurements are acquired at an angle of incidence of 71. 5 with a wavelength range of 245-1000 nm by using a J.A. Woollam Co. M-2000 F ellipsometer.…”

“…In the past years, initiated-chemical vapor deposition (i-CVD) has proven to be a very well suited approach toward vacuum deposition of polymeric films for application in many fields where specific surface and bulk properties are desired, i.e., hydrophobicity/hydrophilicity, 1,2 antimicrobial, 3 binding of biological ligands, 4 biopassive dielectrics, 5 low-k materials 6 and, recently, as responsive materials 7 and organic interlayers in multilayer moisture and oxygen barrier systems. 8,9 The advantage of the i-CVD approach with respect to the widely known hot wire CVD is the lower thermal budget required for the polymerization process to occur.…”

“…Poly(V 3 D 3 ) have proven their potential as biopassivating material being highly cross-linked, showing good adhesion to silicon substrates, and being insoluble both in polar and apolar solvents. 5,29 In our case, poly(V 3 D 3 ) layers were deposited as organic interlayers for an organosilicon-based organic/inorganic multilayer moisture and oxygen barrier system, where highly cross-linked organic interlayers are desirable. 8,9 The use of in situ SE, as a tool to study the polymer growth mechanism during all its stages, is reported for the first time to the authors' knowledge.…”

Conformal coating of poly-glycidyl methacrylate as lithographic polymer via initiated chemical vapor deposition

“…For example, many studies have used i-CVD for polymerization studies of poly-alkyl acrylates, 18 poly-trivinyltrimethoxycyclotrisiloxane, 19 poly-perfluoroalkylethylmethacrylate, 20 poly-glycidyl methacrylate (PGMA), 21,22 etc. In this study, we select PGMA as the lithographic resist.…”