acid) (PEI/PAC). Half-sphere morphologies were obtained due to flattening of
the soft PEC particles. The PEC particles appeared to form more of an emulsion
than a suspension.
2.1.5 Scanning Force Microscopy
One of the first SFM studies on PEC particles was reported by Wolfert and Seymour
[39], whereby complexes of poly(L-lysine) (PLL) and DNA were deposited and
their size determined. Early SFM studies on spherical PEC particles consisting of
synthetic PEI and poly(maleic acid-co-propylene) adsorbed onto mica came also
from Kramer et al. [40]. Singularized particles were obtained, whose size could
be related to that measured with DLS (166 nm). Similar adsorbed singularized
spherical particles of PDADMAC/PMA-MS were reported [16, 17], showing an
improvement with respect to monomodal size distribution.
Fig. 6 SEM images of
adsorbed PEC particles at a
silicon support modified by
PEM-6 of PEI/PAC. (From
[21] with kind permission of
Elsevier)
Fig. 5 SEM images of the
PEC system consisting of an
integral type polycation and
polymethycrylic acid. (From
[38] with kind permission of
ACS)
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