Synthesis and radical polymerization of methacrylic monomers with crown ethers in the ester residue:1,4,7,10-tetraoxacyclododecan-2-ylmethyl methacrylate

摘要

The synthesis and radical polymerization of 1,4,7,10-tetraoxacyclododecan-2-ylmethylmethacrylate (CR4MA) is described.The polymerization reactions to CR4MA were carried out at different temperatures and the kinetic curves of monomer depletion against time were obtained by direct measurements of the instantaneous monomer concentrations by using nuclear magnetic resonance (NMR) spectroscopy.At the same time electron paramagnetic resonance (CPR) spectroscopy was used to determine the actual polymer radical concentration during all the reaction time.The conjunction of both techniques (NMR and EPR) allowed the determination of the polymerization rate parameter (2fk_p/~(1/2) and separately of k_p and /f,where f,k_p and are,respectively,the initiator efficiency factor and the overall averages of propagation (K_p is considered to be practically indepdent of the chain length) and termiantion rate constants.The values found for this ratio and for k_p were comparatively higher than those recently reported in the literature for its lateral open chain counterpart,the methacrylic monomer with equal number of oxyethylene units in the residue ester (TTEMA).However the vaules were similar for the polymerization of both monomers CR4MA and TTEmA.The polymer,PCR4MA,is solbule in water as its open chain homologous,and exhibits a glass transition temperature in the vicinity of the ambient temperature (about 35 deg C),much higher than the value found for the homologous polymethacrylate derived from the TTEMA.