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Exploring the loading capacity of generation six to eight dendronized polymers in aqueous solution

Aspects of size, structural (im)perfection, inner density, and guest loading capacity of dendronized polymers (DPs) of high generation g (6≤g≤8) in aqueous solution were studied using electron paramagnetic resonance (EPR) spectroscopy on amphiphilic, spin- labeled guest molecules. The presented results show that the interior of the charged DPs is strongly polar, especially in comparison to their lower generation analogues 1-4. This is a direct sign of large amounts of water penetrating the DP surface, which in return mirrors structural imperfections and much lower than theoretically achievable segmental densities of these high generation DPs. Images obtained with atomic force microscopy (AFM) reveal that the high g DPs show no aggregation and give further insights into structural (im)perfections. EPR- spectroscopic data further show that despite their structural imperfections, these DPs can bind and release large numbers of amphiphilic molecules. It can be concluded that attention should be paid to synthesis which needs to develop a protocol that avoids the relatively large amount of defects generated in the direct conversion of PG4 to PG6 which had to be employed here.

dendronized polymers ; AFM ; EPR ; loading capabilities ; release

DOI: 10.1002/cphc.201600580