Page 79 - Handbook of Adhesion Promoters

72 Substrates - Surface Condition and Treat-

Figure 4.21. Chemical modification strategies on various substrates for HSQ adhesion. [Adapted, by permission,
from Zhang, Z; Duan, H; Wu, Y; Zhou, W; Liu, C; Tang, Y; Li, H, Microlectronic Eng., 128, 59-65, 2014.]

expected changes in polymers on their exposure to UV can be found in the monograph on
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the subject.
UV treatment found applications in medical and dental fields. Titanium and its alloys
are used extensively in orthopedic implants. They have excellent biocompatibility,
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mechanical properties and corrosion resistance. Application of these implants is not free
of complications because of poor osseointegration and bacterial infections, which may
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lead to implant failure. Preparing a biomaterial surface to enhance the interactions with
host cells and inhibit bacterial adhesion is the key to the prevention of implant failure. 52
Combination of acid etching and UV irradiation improved the cell adhesion and inhibited
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bacterial adhesion. Figure 4.20 shows results of acid etching and UV radiation on con-
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tact angle.
UV irradiation of the Ti6Al4V surface causes wettability increase while preserving
the properties of the alloys that are crucial for its performance as an orthopedic and dental
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implant. The adhesion of bacterial strains related to clinical orthopedic infections, i.e.,
Staphylococcus aureus and Staphylococcus epidermidis was reduced by UV irradiation
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which did not affect human cell adhesion.
4.2.9 CHEMICAL MODIFICATION
Hydrogen silsesquioxane is an excellent negative-tone resist for electron beam lithogra-
phy but its adhesion on different types of substrates varies, thus limiting its application in
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etching masks or metal lift-off process on various substrates. The 3-mercaptopropylt-