AbstractTi[O(CH2)4OCHCH2]4, used for the ring‐opening polymerization (ROP) of ε‐caprolactone, was synthesized through the ester‐exchange reaction of titanium n‐propoxide and 1,4‐butanediol vinyl ether, and its chemical structure was confirmed by nuclear magnetic resonance (1H NMR) and thermogravimetric analysis (TGA). The mechanism and kinetics of Ti[O(CH2)4OCHCH2]4‐initiated bulk polymerization of ε‐caprolactone were investigated. The results demonstrate that Ti[O (CH2)4OCHCH2]4‐initiated polymerization of ε‐caprolactone proceeds through the coordination‐insertion mechanism, and all the four alkoxide arms in Ti[O (CH2)4OCHCH2]4 share a similar activity in initiating ROP of ε‐caprolactone. The polymerization process can be well predicted by the obtained kinetic parameters, and the activation energy is 106 KJ/mol. Then, the rheological method was employed to investigate the feasibility of producing the crosslinked poly(ε‐caprolactone)‐poly (n‐butyl acrylate) network by using Ti[O(CH2)4OCHCH2]4 as the ROP initiator. The tensile test demonstrates that the in situ generated crosslinked PCL‐PBA network in PMMA matrix provides the possibility of ameliorating the tensile properties of PMMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7773–7784, 2008