Abstract: Tri- and tetra-arm star poly(ε-caprolactone)s have been successfully synthesized by ring-opening polymerization of ε-caprolactone using triethanolamine or N,N,N′,N′-tetrakis-(2-hydroxyethyl) ethylenediamine (HEA) as the multifunctional initiator and lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(DBMP)3) as the catalyst. In1HNMR analysis, compared with triethanolamine and HEA molecules, the chemical shifts of the hydrogen (N(CH2CH2O)n, n=3, 4) in star poly(ε-caprolactone)s moved from 3.65 to 4.10, suggesting the direct linkage between the poly(ε-caprolactone) arm and the initiator. When the molar ratio of triethanolamine to La(DBMP)3 ranged from 1.7 to 6.4, pure tri-arm star poly(ε-caprolactone) could be prepared, which indicates that one catalyst molecule could co-work with several initiator molecules. The molecular weights of star poly(ε-caprolactone) were determined by1HNMR end group analysis, which are very close to the values calculated from the molar ratio of ε-caprolactone to the initiator.

Key words: star poly(ε-caprolactone), ε-caprolactone, ring-opening polymerization, lanthanum complex, triethanolamine, N, N, N′, N′-tetrakis-(2-hydroxyethyl) ethylenediamine