Polyethylene-block-hyperbranched polyglycerol diblock copolymers: synthesis, thermal property and compatibilization

The linear-b-hyperbranched copolymers (LHBCs) consisting of linear polyethylene (PE) block and hyperbranched polyglycerol (hbPG) segment were synthesized with a sequential method starting with V(III)-catalyzed coordination polymerization and followed by ring-opening multibranching polymerization (ROMBP). The hydroxyl groups in hbPG block are further modified to benzoyl groups to improve the solubility. Ultimately, the structures and thermal properties of LHBCs were clearly characterized by ¹H/¹³C NMR, GPC, TGA and DSC. The SEM images show that the LHBCs are effective compatibilizers in LLDPE/PCL blends. This paper represents the first case of generation of LHBCs combining hbPG with nonpolar and crystalline polyethylene block instead of polar and/or noncrystalline linear blocks. As a result, the crystallinity of linear polyethylene can be combined with low viscosity and a large number of terminal functional groups of hbPG.