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Multi‐arm star block copolymers based on ε ‐caprolactone with hyperbranched polyglycerol core
Author(s) -
Burgath Armin,
Sunder Alexander,
Neuner Ingo,
Mülhaupt Rolf,
Frey Holger
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(20000401)201:7<792::aid-macp792>3.0.co;2-k
Subject(s) - copolymer , polymer chemistry , dispersity , monomer , caprolactone , polymerization , polymer , chemistry , ring opening polymerization , materials science , organic chemistry
Multi‐arm star block copolymers based on ε ‐caprolactone have been prepared by a core‐first approach using propoxylated hyperbranched polyglycerol P(G 52 PO 3 ) as a polyfunctional initiator. Various monomer/initiator ratios were employed in the Sn‐catalyzed polymerization in order to vary the length of the caprolactone arms ( DP n (arm) = 10 to 50). The molecular weights of the block copolymers were in good aggreement with the calculated values. Careful NMR analysis revealed that the monomer/initiator ratio not only controls the arm length, but also influences the degree of functionalization. Poly( ε ‐CL) stars with 52 arms and absolute molecular weights between 69 200 and 360 400 g/mol have been prepared. SEC measurements showed that the narrow polydispersity of the core molecule ( M w / M n = 1.24) could be maintained upon block copolymerization. The resulting star polymers exhibited polydispersities between 1.21 and 1.33.