Synthesis of well-defined star, star-block, and miktoarm star biodegradable polymers based on PLLA and PCL by one-pot azide–alkyne click reaction

Based on the “arm-first” strategy, ring-opening polymerization (ROP) and one-pot azide–alkyne click reaction, well-defined star-shaped polymers with different architectures have been successfully synthesized, including the star homopolymers four-arm star-shaped polycaprolactone (4sPCL) and four-arm star-shaped poly(l-lactic acid) (4sPLLA), star-block copolymer 4sPCL-b-PLLA and miktoarm star-shaped copolymer PCL(2)PLLA(2). The star homopolymers 4sPCL and 4sPLLA were synthesized by a click reaction of an azide small molecule initiator and HC[triple bond, length as m-dash]C-PCL or HC[triple bond, length as m-dash]C-PLLA. The star-block copolymer 4sPCL-b-PLLA was synthesized by a click reaction of an azide small molecule initiator and the block copolymer HC[triple bond, length as m-dash]C-PCL-b-PLLA. The miktoarm star polymer PCL(2)PLLA(2) was synthesized by a one-pot azide–alkyne click reaction of simultaneous addition of equal proportions of HC[triple bond, length as m-dash]C-PCL and HC[triple bond, length as m-dash]C-PLLA. The structures of these star-shaped polymers have been confirmed by NMR, FT-IR and GPC. Furthermore, the melting and crystallization behaviors investigated using DSC and WXRD also confirm the formation of star-shaped polymers with different architectures.