INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Thermodynamic analysis of the reaction-induced phase separation of random copolymers of methyl methacrylate and N,N-dimethylacrylamide in a polythiourethane network
Autor/es:
E. R. SOULÉ; B. JAFFRENNOU; F. MÉCHIN; J. P. PASCAULT; J. BORRAJO; R. J. J. WILLIAMS
Lugar:
Río de Janerio, Brasil
Reunión:
Congreso; Macro 2006 World Polymer congress; 2006
Institución organizadora:
IUPAC
Resumen:
Poly(methyl methacrylate) (PMMA) and random copolymers of methyl methacrylate (MMA) and N,N-dimethylacrylamide (DMA) containing 7.5, 15 and 20 wt % DMA were dissolved in a stoichiometric mixture of m-xylylene diisocyanate and 4-mercapto-methyl-3,6-dithia-1,8-octanedithiol, precursors of a polythiourethane network. Phase separation that took place during polymerizations at 60, 90 and 120 ºC, exhibited a lower-critical-solution-temperature (LCST) behavior. Cloud-point conversions were determined by iodometric titration of free thiol groups of samples chilled in ice at the cloud-point. A thermodynamic analysis was performed using the Flory-Huggins equation, taking into account the polydispersities of both the thermoplastic and thermoset polymers, and using an interaction parameter depending on temperature and on the composition of the random copolymer. A reasonable fitting of experimental curves was obtained with negative values for the interaction energies of the MMA-thermoset and DMA-thermoset pairs, and a positive value for the MMA-DMA pair.