(a)
1
0.1
0.01
βfσ3∕A
0.001
0.0001
W5
0 0.2 0.4 0.6 0.8 1
q
Figure 6.8: (a) Interaction force between the two grafted monolayers in the absence of
free polymer as a function of the compression ratio (q = H∕2Hq) for pgσ2 = 0.01 (■), pgσ2
= 0.03 (A) and pgσ2 — 0.1 (▼), at fixed Ns = 101. (b) Interaction force between the two
grafted monolayers in the absence of free polymer as a function of the compression ratio for
Ng = 51 (■), Ng = 101 (a) and Ng = 151 (▼), at fixed pgσ2 = 0.1.
(b)
1
0.1
0.01
βfσ3∕A
0.001
0.0001
105
О 0.2 0.4 0.6 0.8 1
q
6.3.4 Interaction between two grafted monolayers in the pres-
ence of free polymer
The presence of free polymer around the grafted monolayers significantly affect
their structure and the interactions between them. For large separations between
them, they do not interact and behave as two independent monolayers immersed in
the free polymer solution. These monolayers and the free polymer interpenetrate each
other and the monolayers are compressed. The degree of interpenetration depends
upon the chain lengths of the grafted (Ng) and free (Nf) polymers, grafting density
(pg) and the bulk free polymer density (pf) for σg = σf(= σ), where σg and σf are the
segments sizes of the grafted and free polymer chains, respectively. As all the polymer
166