## 3 Results and Discussion
### Dynamic Light Scattering Measurements
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Copolymer**} & \multicolumn{2}{c}{**PBG Core (DMF) 1 **} & \multicolumn{2}{c}{**Graft Copolymer (DBF) 2 **} \\ \cline{2-7}  & \(d_{\text{h1}}\) (nm) 3 **} & \(d_{\text{h2}}\) (nm) 4 ** \\ \hline G1 PBG-_eg_-PGly & \(11.7\pm 1\) & \(10.0\pm 1\) & \(30.3\pm 1\) & \(26.3\pm 1\) & \(78.9\pm 1\) & \(54.6\pm 1\) \\ G2 PBG-_eg_-PGly & \(18.9\pm 1\) & \(17.3\pm 1\) & \(39.7\pm 1\) & \(35.5\pm 1\) & \(72.5\pm 1\) & \(53.0\pm 1\) \\ G3 PBG-_eg_-PGly & \(28.4\pm 1\) & \(26.8\pm 1\) & \(39.9\pm 1\) & \(38.9\pm 1\) & \(43.5\pm 1\) & \(39.8\pm 1\) \\ G1 PBG-_eg_-PEO & \(11.7\pm 1\) & \(10.0\pm 1\) & \(46.8\pm 1\) & \(42.1\pm 1\) & \(61.7\pm 1\) & \(54.4\pm 1\) \\ G2 PBG-_eg_-PEO & \(18.9\pm 1\) & \(17.3\pm 1\) & \(43.9\pm 1\) & \(39.4\pm 1\) & \(45.8\pm 1\) & \(41.7\pm 1\) \\ G3 PBG-_eg_-PEO & \(28.4\pm 1\) & \(26.8\pm 1\) & \(38.3\pm 1\) & \(35.4\pm 1\) & \(56.9\pm 1\) & \(50.5\pm 1\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: DLS measurements for chain end CuAAC-grafted arborescent copolymers. Figure 7: SEC traces in DMF with 0.1% LiCl for (top to bottom) G3 PBG-_eg_-PGly, G3 PBG-_eg_-PEO, G2 PBG-_eg_-PGly, G2 PBG-_eg_-PGly, G2 PBG-_eg_-PGly, G1 PBG-_eg_-PGly, G1 PBG-_eg_-PEO, G3 PBG, G2 PBG, and G1 PBG. in PBS, and a large (24 nm) difference between \(d_{\rm h1}\) and \(d_{\rm h2}\), consistent with the presence of aggregated species. This was confirmed by CONTIN analysis (Figure S1), yielding a bimodal distribution corresponding to what are likely unimolecular micelles (with a population around 20 nm) and aggregated species (above 100 nm). While the size distribution for sample G1 PBG-_eg_-PEO is unimodal in DMF and in PBS, the populations are rather large in comparison to the G1 PBG substrate (ca. 10 nm) and centered around 40 nm and 60-70 nm (Figure S1), respectively, which is consistent with the formation of aggregates in PBS, and possibly also in DMF. As before, aggregate formation by the G1 copolymers is attributed to the relatively open structure of these molecules facilitating interactions between the G1 PBG cores. Interestingly, samples G2 PBG-_eg_-PEO, G3 PBG-_eg_-PGly, and G3 PBG-_eg_-PGly have comparable \(d_{\rm h1}\) and \(d_{\rm h2}\) values in PBS and in DMF, and displayed modest size increases when the hydrophilic shell components were grafted onto the PBG substrates (Figures S2 and S3), suggesting that these arborescent copolymers behave like unimolecular micelles in PBS. It is clear from the DLS data in PBS that chain-end CuAAC grafting is more useful for the synthesis of arborescent copolymers containing PEO: not only are all the copolymers soluble, but there is good agreement between the \(d_{\rm h1}\) and \(d_{\rm h2}\) values for each generation, and the CONTIN size distributions are unimodal although, as stated above, G1 PBG-_eg_-PEO appears to be aggregated. These trends were also observed when comparing arborescent copolymers obtained by the random versus chain-end carbodiimide-promoted peptide coupling techniques [16]: the randomly-grafted arborescent copolymers containing PEO were either insoluble or displayed extensive aggregation, whereas the chain end-grafted copolymers yielded unimolecular micelles. Given the good agreement between the \(d_{\rm h1}\) and \(d_{\rm h2}\) values in the DLS results for G1 PBG-_eg_-PEO and G2 PBG-_eg_-PEO in both DMF and PBS, it seems likely that artefacts occurred in the SEC measurements of these copolymers (Figure 7). While the exact nature of these artefacts is not clear, they could be related to aggregation and/or column interactions during the SEC measurements.