Aca - Departamento de Física - Universidad Técnica Federico Santa ...

Relative diameter (a.u.)
V Encuentro Sud Americano de Colisiones Inelásticas en la Materia
1.2
1
batch 1
batch 2
0.8
0.6
0.4
0.2
0
0 5 10 13 1 10 14 1.5 10 14 2 10 14
(cm -2 )
Figure 2. Relative diameter of the etched pores (D()/D(0)) as a function of H + fluence , for two batches of
samples.
The observation of a minimum in the
diameter curve is compatible with the existence
of two competitive effects: one that
causes the decrease in radius and is dominant
at low fluences (i.e. with a large crosssection)
and another that tend to increase the
radial etching rate and is dominant at high
fluences (with a small cross-section).
The physico-chemical mechanism behind
the observed effect is unclear at present.
The decrease in pore size due to the proton
irradiation is consistent with a reduction in
the radial or bulk etch rate v B or an increase
in the etching induction time. A reduced v B
could be caused by e.g., crosslinking of the
PC matrix induced by the proton beam. However,
the GPC curves indicate the predominance
of chain scission in the irradiated samples.
Also negligible changes in the contact
angle of the proton irradiated foils were detected,
indicating similar wetting properties.
Thus the proton irradiation seems to affect
the etching process in a more complex way
by changing the surface properties of the PC
foils.
Key-words: ion track etching, polymers,
polycarbonate.
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