Chemistry Reference
In-Depth Information
6.3.3 Plasma Polymerisation
The polymerisation reaction initiated by plasma is called as “plasma
polymerisation” and is a useful technique to create a biomimetic
interface. Plasma polymerisation is a method encompassing
plasma-assisted chemical vapour deposition of a gaseous species
(monomer) and polymerisation during deposition. This process
consists of activation of the starting materials (monomer) by the
interaction between the gas phase molecules and plasma, followed
by deposition on the substrate. The fundamental components of
a reactor for plasma polymerisation consist of a vacuum system,
plasma generator, controllable gas inlet, and system for in situ
analysis, for example, thickness monitoring or optical emission
spectroscopy [8,59].
A hexamethyldisiloxane (HMDSO) thin film was deposited on
titanium. The film had a thickness of about 0.07-0.35
m after
undergoing plasma polymerisation for 10-60 min and possessed
good stability during 2-week immersion in a phosphate buffer saline
solution. The post-heating process at approximately 250
µ
C favored
fixation of plasma-polymerised HMDSO films onto the substrate. The
quartz crystal microbalance-dissipation measurement suggested
that the film benefitted fibronectin adsorption in the early stage
due to the formation of Si-H, Si-C, C-H, C=O, and Si-O-Si bonds on
the plasma-polymerised HMDSO film as indicated by the Fourier
transform reflection-absorption spectroscopy results in Fig. 6.28
[60].
Allylamine was often chosen as the molecular precursor in the
film deposition because of its good retention of amino groups. A
uniform and smooth plasma-polymerised allylamine (PPAAm)
film with a thickness of around 300 nm was prepared on NiTi (Fig.
6.29) [61]. Rebl et al. studied the effects of the interfacial chemistry
of the PPAAm films on the adhesion behaviour of osteoblasts on
titanium [62]. In comparison with the untreated titanium, adhesion
of human MG-63 osteoblastic cells increased significantly on all the
PPAAm-modified surfaces after culturing for 5 min (Fig. 6.30). The
cell adhesion on the untreated smooth surface was 18
°
±
2% and it
was 54
5% on the PPAAm-modified titanium. In addition, the cells
resembled the underlying structure and blended with the PPAAm-
modified surfaces. The cells spread out over a large area in spite
±
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