Page 36 - Handbook of Adhesion Promoters

2.9 Chemical bonding 29

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moter. Figure 2.30(a) shows very poor
adhesion of the silver nano-ink to the sub-
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strate. Some holes can be observed at the
interface of the two layers produced with-
53
out adhesion promoter. These holes indi-
cate the weak bonding of silver nano-ink to
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the substrate. Figure 2.30(b) shows that,
when the 3-glycidoxypropyltrimethoxysi-
lane is present, highly uniform and dense
layers are formed at interface without any
holes, meaning that the adhesion promoter
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improves interface.
The adhesion between uncured natural
rubber and carbon steel was studied using
the surface modification of the carbon steel
with silane coupling agents comprising
amino, thiol, glycidoxy, and isocyanate
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organic functionality. With each silane,
the carbon steel reacted with the silane
hydroxyl groups, but the reactions between
the natural rubber and the silane coupling
agents depended on the silane functional-
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ity. The adhesion was optimized and
Figure 2.30. (a) The cross-sectional image of film with- cohesive failure achieved when 3-
out 3-glycidoxypropyltrimethoxysilane and (b) film (trimethoxysilyl)propylamine was used to
with 8 wt% 3-glycidoxypropyltrimethoxysilane. modify the carbon steel.
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[Adapted, by permission, from Hong, JU; Kumar,
ABVK; Han, HS; Koo, YH; Kim, HW; Park, JH; Kang, A conductive copper ink contained a
HS; Lee, BC; Piao, L; Kim, S-H, Bull. Korean, Chem. silane coupling agent (3-aminopropyltri-
Soc., 34, 8, 2539-42, 2013.] 55
ethoxysilane) as an adhesion promoter.
The ink that was ink-jet printed on a polyimide film (previously treated by oxygen
o
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plasma) was annealed at 200 C for 2 h at hydrogen atmosphere. The adhesion mecha-
nism is discussed in Figure 2.31. The ink containing 3 wt% silane coupling agent exhib-
55
ited the highest peel strength and low resistivity.

Figure 2.31. Schematic illustration of the adhesion promotion mechanism between the ink-jet printed copper
patterns and polyimide substrate. [Adapted, by permission, from Lee, Y-I; Choa, Y-H, J. Mater. Chem., 22,
12517-22, 2012.]