Síntesis y caracterización de poliéteres obtenidos con el sistema iniciador poliiminofosfaceno (t-Bu-P4)/3.5-di-terc-butilfenol

Identifier:  TDX:776

Handle: https://hdl.handle.net/20.500.11797/TDX776

Authors:  Peris Campodarbe, Sergio

Abstract:
The polyethers synthesis is an interesting subject of study due to the good physical and chemical properties. Therefore, these polymers are widely used in the polyurethanes chemistry and, recently, in the polymerization of functionalized epoxidic monomers to design and obtain Hi-Tech polymers with specific properties.In this present thesis is studied the synthesis and characterization of polyethers obtained through a initiator system which is based in the mixture of phosphazene base t-Bu-P4 and 3,5-di-tert-buthylphenol. The t-Bu-P4 is a recent reported compound, which is one of the strongest neutral bases known. So, this compound have found different uses in the organic synthesis and, recently, in the polymerization of monomers with very good results. There is only one group reporting the polymerization of epoxides using this base, and they polymerized the simplest monomer, the ethylene oxide.We did the kinetic and mechanistic studies to polymerize the glicidilphenilether, with this initiator system, and we have compared the results with those obtained using conventional anionic initiators. Some of these studies are the evolution of the polyethers' molecular weight using GPC techniques. Also, we determined the molecular weights using 1H NMR after a derivatization of the polyethers that can increase the sensitivity with respect to the end-groups. We studied deeply the microstructure of all the polymers obtained, determining the tacticity, regio-regularity and origin of the end-groups. It was done by the model compounds syntheses, the NMR kinetic studies, derivatization reactions and bidimensional correlation NMR experiments. In the same way, we studied the chain structure and the molecular weight distribution using a MALDI-TOF mass spectrometry, a technique with an increasing interest in the polymer field.The correlation of the obtained results has helped us to state a basic polymerization mechanism and to identify and evaluate different competitive processes in the polymerization which are not reported in the literature yet. Two of these competitive processes are the regio-irregular links formation and the aromatic nucleophilic substitution when the monomer has an electron-withdrawing group in the aromatic ring. We have identified a chain fragmentation processes in the polymerization using the potassium tert-butoxide as initiator.Finally, we applied this initiator system to polymerize monomers with different functionalities, obtaining polymers potentially actives in technological fields.