INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Nanostructured polymer networks based on amphiphilic monomers
Autor/es:
R. J. J. WILLIAMS; J. PUIG; C. E. HOPPE; I. A. ZUCCHI; A. LEDO-SUÁREZ; M. J. GALANTE
Lugar:
San José, Costa Rica
Reunión:
Simposio; XII Simposio Latinoamericano de Polímeros (SLAP 2010); 2010
Institución organizadora:
Poliuna-LANOTEC
Resumen:
Linear amphiphilic epoxy polymers synthesized by the polyaddition of diglycidyl ether of bisphenol A (DGEBA) with alkylamines like octylamine (OA), dodecylamine (DA) and hexadecylamine (HA), undergo a physical gelation process through tail-to-tail association of alkyl chains (1,2). SAXS spectra showed that tail-to-tail associations of alkyl chains were present since the beginning of polymerization and remained in the final materials. Initially, these associations correspond to micelles of the alkylamines dispersed in the solvent (DGEBA). In the course of polymerization micelles are disaggregated as the individual alkylamine chains become part of the linear amphiphilic polymer. However, tail-to-tail associations among alkyl chains attached to the polymer backbone persisted in the final materials. Reactions were followed by rheometry at 100 ºC. For every system, a significant discontinuity in the increase in the storage modulus observed at advanced conversions was assigned to a phase inversion process produced by depletion of the reactive solvent. By annealing prolonged times at the reaction temperature a cross-over of storage and loss modulus was observed due to the increase in the extent of associations among alkyl chains. Times for physical gelation varied in the order OA < DA < HA. Both DGEBA-DA and DGEBA-HA polymers could be reversibly transformed from gel to liquid states by appropriate heating-cooling cycles; however, the DGEBA-OA polymer showed no thermoreversibility. Physical gels exhibited a high swelling capacity in different solvents (HA > DA > OA).