Study on Copolymerization of Potassium Chloroacetate and Potassium N-Chloroacetyl-6-Aminohexanoate
Tutor / director / avaluadorPuiggalí Bellalta, Jordi
Tipus de documentProjecte Final de Màster Oficial
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In the present work a series of copolymers derived from potassium chloroacetate (MGL) and potassium N-chloroacetyl-6-aminohexanoate (MEA) comonomers have been synthesized. As a result, a variety of degradable copolymers containing different percentage of glycolic acid units and different ratio between amide and ester groups were obtained. Firstly, MGL and MEA halogenate salts comonomers were synthesized and their thermal stability was measured by thermogravimetric analysis due to the high temperatures needed for their polycondensation. The polymerization kinetics of MGL, MEA and their mixtures was studied by FTIR-ATR spectroscopy with temperature control and calorimetric assays. These assays allowed acquiring kinetic data of the polymerization process by applying an approximation to the Avrami model. FTIR-ATR studies revealed that the bulk polycondensation reaction was faster for MEA than for MGL but kinetic differences in the selected temperature range were not large enough to make unfeasible copolymerization of both monomers. DSC data also showed significant differences in the exothermic polycondensation peaks that suggested an effective copolymerization reaction and favored the kinetic process over the corresponding homopolymerization in consistency with the FTIR-ATR studies. Once the different potassium-salt mixtures were polymerized by thermal polycondensation and copolymers of poly[(glycolic acid)-alt-(6-aminohexanoic acid)] (PGL/PEA) were obtained, the resulting poly(ester amide)s were characterized by FTIR-ATR spectroscopy and thermal analysis (DSC and TGA). 1H-NMR spectra of the copolymers allowed to know experimental conformation and also revealed the existence of hetero-sequences whose ratio was slightly lower than that expected for a random polymerization of the two monomers in samples with high MEA content. By means of GPC it was determined that samples with high molecular weights were only attained when the MGL molar ratio in the monomer mixture was lower than 65%.
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