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The graft copolymers of starch with polycaprolactone (PCL) were prepared through ring opening polymerization of ε‐CL in bulk using N‐methylimidazole (NMI) as catalyst. The graft reaction was detected by FTIR, NMR, and the resultant starch‐g‐PCL copolymers were characterized by DSC, MEB, and XRD. Homopolymerization of CL monomer did not occur during the grafting polymerization and hydrophobicity of the resulting material was highlighted by solvent test and water contact angle measurement.

Ti[O(CH2)4OCHCH2]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)4OCHCH2]4‐initiated bulk polymerization of ε‐caprolactone were investigated. The results demonstrate that Ti[O (CH2)4OCHCH2]4‐initiated polymerization of ε‐caprolactone proceeds through the coordination‐insertion mechanism, and all the four alkoxide arms in Ti[O (CH2)4OCHCH2]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)4OCHCH2]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

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ABSTRACT:The ring-opening polymerization of e-caprolactone initiated by Ti[O(CH 2 ) 4 OCH¼ ¼CH 2 ] 4 was investigated by differential scanning calorimetry (DSC). Both isothermal and dynamic experiments have been applied to obtain the kinetic parameters. The apparent polymerization rate constant for different experiments was determined; the activation energy determined is 76-88 KJ/mol by the isothermal method and 75-86 KJ/mol by the dynamic method. Using the obtained kinetic parameters, a model to predict the polymerization process was developed and can well describe the polymerization process, which demonstrates that DSC is a convenient and reliable method to study the kinetics of ring-opening polymerization. The kinetic results also demonstrate that Ti[O(CH 2 ) 4 OCH¼ ¼CH 2 ] 4 is an efficient initiator in the ring-opening polymerization of e-caprolactone.

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Polycaprolactone (PCL) grafting on vinyl alcohol-co-vinyl acetate) (PVA-Ac), was investigated in the melt at high temperature (1708C), below the PVA-Ac melting point, by ring opening polymerization of e-caprolactone initiated by metal alkoxyde sites present in PVA-Ac: no additional initiator was used. The obtained average structures were determined by 1 H NMR. As expected, small grafts, with low average polymerization degree (DP), were obtained, between 4 and 12 h of reaction. These DP are due to exchange reactions between hydroxyl groups and PCL growing chains. The PVA-Ac was shown to be partially substituted by short PCL grafts. The DP linearly increased with the initial Lactone/PVA-Ac ratio, and the substituted alcohol sites rate were limited to 63%.It was shown that the used reactive system is characterized by a quazi-living polymerization mechanism.