Handbook of Size Exclusion Chromatography and Related ...

was predicted by the mathematical model: (a) the bivariate distribution of
molecular weights and chemical composition of Fig. 3b, (b) the MWD of Fig. 3c,
and (c) the BD of Fig. 3d. The bivariate distribution indicates that the average
composition is almost independent of the molar mass, and that the derived
univariate CCD is expected to be quite broad. The experimental MWD is broader
than the theoretical MWD (Fig. 3c). The experimental BD is quite similar to the
theoretical BD (Fig. 3d).
The mathematical model also predicted the MWDs of the different branched
topologies that integrate the total graft copolymer (Fig. 3c). Each branched
topology b (¼ 1, 2, 3, ...) is characterized by the number of trifunctional grafting
points per molecule. The MWD of the total copolymer is obtained by adding the
individual MWDs (Fig. 3c). The areas under the individual MWDs of Fig. 3c are
represented by vertical bars in the theoretical BD of Fig. 3d. An important
observation is that the MWDs of the individual topologies are relatively little
overlapped at the low molar masses, but moderately overlapped at the high molar
masses. For this reason, a good fractionation according to the number of branches
is expected to be produced at the low molar masses, while a relatively poorer
fractionation is expected to occur at the high molar masses.
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© 2004 by Marcel Dekker, Inc.