Two series of dendronized polymers (DPs) of generations g ¼ 1–4 with different levels of dendritic
substitution (low and high) and a solvatochromic probe at g ¼ 1 level are used to study their swelling
behavior in a collection of solvents largely differing in polarity as indicated by the Kamlet–Taft
parameters. This is done by measuring the UV-Vis spectra of all samples in all solvents and determining
the longest wavelength absorptions (lmax). The lmax values fall into a range defined by the extreme
situations, when the solvatochromic probe is either fully surrounded by solvent or completely shielded
against it. The former situation is achieved in a model compound and the latter situation is believed to
be reached when in a poor solvent the dendritic shell around the backbone is fully collapsed. We
observe that solvent penetration into the interior of the DPs decreases with increasing g and does so
faster for the more highly dendritically substituted series than for the less highly substituted one.
Interestingly, the swelling of the more highly substituted DP series already at the g ¼ 4 level has
decreased to approximately 20% of that at the g ¼ 1 level which supports an earlier proposal that high g
DPs can be viewed as nano-sized molecular objects. Furthermore, when comparing these two DP series
with a g ¼ 1–6 series of dendrimers investigated by Fr´echet et al. it becomes evident that even the less
substituted series of DPs is much less responsive to solvent changes as assessed by the solvatochromic
probe than the dendrimers, suggesting the branches around the (polymeric) core in DPs to be more
densely packed compared to those in dendrimers, thus, establishing a key difference between these two
dendritic macromolecules.