Control of the molecular weight of hyperbranched polyglycerols

Hyperbranched polyglycerols exceeding M_n > 15,000 g/mol (DP_n > 270) have been prepared, using a modified version of the synthetic protocol reported earlier. In the optimized process polydispersities recorded by SEC remained narrow, with M_w/M_n < 1.7 over a large molecular weight range. The drastic increase of viscositity in the course of the reaction, was found to be responsible for the increased fraction of cycles (MALDI‐TOF MS) at high molecular weights.