Nanostructuration of PS-b-PEO Block Copolymers in a Crosslinked Epoxy: Influence of Molar Mass and Cure Cycle

AGUSTINA B. LEONARDI; ILEANA A. ZUCCHI; ROBERTO J.J. WILLIAMS

Porto de Galinhas

Congreso; SLAP 2014; 2014

Two commercial PS-b-PEO block copolymers (BCP) containing 25 wt% PEO and different molar masses (Mn = 43000 and 136000), were used as modifiers of a crosslinked epoxy based on diglycidylether of bisphenol A (DGEBA) and 4,4? methylenebis (2,6-diethylaniline) (MDEA). Both blocks were initially miscible at the reaction temperature (135 ºC) but the PS block was phase separated during polymerization leading to a transparent nanostructured network. At 20 wt% concentration the low molar mass BCP was nanostructured as hexagonally packed cylinders (HPC) while the high molar mass BCP produced a high density of wormlike micelles. At 40 wt% concentration the low molar mass BCP generated a combination of lamellar (L) and HPC domains. A postcure at 190 ºC produced an L to HPC transformation due to the partial phase separation of PEO from the epoxy matrix, corroborated by FTIR spectra.