Controlled Topological Structure of Copolyphosphates by Adjusting Pendant Groups of Cyclic Phosphate Monomers

A convenient method was reported to control the topological structure of copolyphosphates by adjusting the pendant group of cyclic phosphate monomers (CPMs) in the ring-opening polymerization (ROP), including linear block, star block, and hyperbranched multiarm structure. Linear block copolyphosphate (PEP-b-PIPP) was prepared by a two-step ROP procedure of CPMs with different pedant groups, i.e., monofunctional propargyl alcohol first initiated the ROP of the CPM with ethyl and then the CPM with isopropyl M turn. Similarly, star block copolyphosphate (SPEP-b-PIPP) was also synthesized when the monofunctional propargyl alcohol was replaced by a trifunctional trimethylolpropane. When the pendant group of CPM was changed into 2-hydroxyethyl, hyperbranched polyphosphate (HPHEP) was obtained first through the self-condensing ring-opening polymerization (SCROP) of such CPM, and then the terminal hydroxyls of HPHEP further initiated the ROP of CPM with ethyl to produce hyperbranched multiarm copolyphosphate (HPHEP-star-PEP). The resulting copolyphosphates were characterized by NMR. GPC, FTIR, and DSC techniques M detail, and the results confirmed their topological structures. Moreover, methyltetrazolium assay and AO/EB double staining methods indicated that all copolyphosphates with different topological structures had excellent biocompatibility against NIH 3T3 cells and would be applied as novel biomedical materials.