Low-Pressure Plasma Polymerization of AcetyleneaAmmonia Mixtures for Biomedical Applications

• Published in: Plasma chemistry and plasma processing 2013-02, Vol.33 (1), p.147-163
• Main Authors: Contreras-Garcia, Angel, Wertheimer, Michael R
• Format: Article
• Language: English
• Subjects: Acetylene; Bonding; Deposition; Ethylene; Hydrocarbons; Polymerization; Polypropylenes; Solubility
• ISSN: 0272-4324; 1572-8986
• DOI: 10.1007/s11090-012-9409-5

Past research in this laboratory has focused on the deposition of nitrogen- (N)-rich thin organic coatings for biomedical applications; among usual fabrication methods are plasma polymerization (PP) at low- (aLa) or atmospheric- (high-, aHa)-pressure. In the aLa case, ethylene (aEa, C2H4)/ammonia (NH3) feed-gas mixtures with different flow ratios, R, are used, by which the nitrogen- and primary amine concentrations, [N] and [aNH2], respectively, can be reproducibly controlled. The generic symbol we use for that family of deposits is L-PPE:N. In the present research, we used acetylene (aAa, C2H2) as the hydrocarbon feed, because our earlier experience with aHa-type materials (H-PPE:N and H-PPA:N) revealed striking differences in physico-chemical (e.g. [N] and [aNH2], and solubility) characteristics, which are important for applications. We now find that such differences also exist between the L-PPA:N and L-PPE:N families of coatings. This is attributed to the fundamentally different bonding structures of aAa and aEa, namely CH?CH and CH2=CH2; the former leads to more highly cross-linked, [NH2]-leaner deposits, as was also noted for the aHa-type deposits mentioned above.