(10% benzylated) down to R curv ¼ 7.4 nm (100% benzylated). Figure 25 shows no
pronounced difference in R c for the ethylated and benzylated samples.
Finally, an interesting behavior was observed for sample 50PVP47-co50PMMA44-QBB20, i.e., a cylindrical copolymer brush with 50% PMMA and
50% PVP side chains, which were quaternized to 20% with benzyl bromide. The
AFM pictures taken from spin-cast solutions in chloroform are shown in Fig. 26.
Almost exclusively two or three cylindrical brushes are observed to align parallel to
each other, which is also seen for the ethylated sample 50PVP47-co-50PMMA44QEB58 (Fig. 27).
It should be noted that aggregate formation could be confirmed by light scattering
in chloroform solution for the quaternized samples derived from 50PVP47-co50PMMA44, thus qualitatively confirming the conclusion drawn from the AFM
pictures.
Evidence for intramolecular phase separation was not only provided by the AFM
pictures, but also from X-ray investigations on melt extruded samples [95]. Whereas
the unquaternized sample 73PVP47-co-27PMMA35 did not show any scattering
peak, the quaternized sample 73PVP47-co-27PMMA35-QEB70 did show a peak,
which indicates a mean distance between more or less ordered structures of
Fig. 24 Sketch of postulated phase-separated side chains in a horseshoe brush (left) and in a
meandering brush (right) [93]
Fig. 25 Inverse radius of curvature determined from AFM pictures as function of the degree of
quaternization for sample 21PVP47-co-79PMMA44. QBB degree of benzylation, QEB degree of
ethylation. Data taken from [94]
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K. Binder et al.
pronounced difference in R c for the ethylated and benzylated samples.
Finally, an interesting behavior was observed for sample 50PVP47-co50PMMA44-QBB20, i.e., a cylindrical copolymer brush with 50% PMMA and
50% PVP side chains, which were quaternized to 20% with benzyl bromide. The
AFM pictures taken from spin-cast solutions in chloroform are shown in Fig. 26.
Almost exclusively two or three cylindrical brushes are observed to align parallel to
each other, which is also seen for the ethylated sample 50PVP47-co-50PMMA44QEB58 (Fig. 27).
It should be noted that aggregate formation could be confirmed by light scattering
in chloroform solution for the quaternized samples derived from 50PVP47-co50PMMA44, thus qualitatively confirming the conclusion drawn from the AFM
pictures.
Evidence for intramolecular phase separation was not only provided by the AFM
pictures, but also from X-ray investigations on melt extruded samples [95]. Whereas
the unquaternized sample 73PVP47-co-27PMMA35 did not show any scattering
peak, the quaternized sample 73PVP47-co-27PMMA35-QEB70 did show a peak,
which indicates a mean distance between more or less ordered structures of
Fig. 24 Sketch of postulated phase-separated side chains in a horseshoe brush (left) and in a
meandering brush (right) [93]
Fig. 25 Inverse radius of curvature determined from AFM pictures as function of the degree of
quaternization for sample 21PVP47-co-79PMMA44. QBB degree of benzylation, QEB degree of
ethylation. Data taken from [94]
144
K. Binder et al.