MORPHOLOGICAL CHARACTERIZATION OF WELL DEFINED METHACRYLIC BASED DIBLOCK AND TRIBLOCK IONOMERS

A detailed morphological investigation of methacrylic based block ionomers was conducted. In the case of the triblock systems, the end blocks were based on t-butyl methacrylate while the elastomeric centre block was either n-hexyl methacrylate or 2-ethylhexyl methacrylate. Upon hydrolysis of the end block the acid form of the block polymer was obtained. Neutralization of this component led to the ionic block polymer. The effect of ionic block length and the consideration of either di- or triblock architecture was studied. Though the diblock materials exhibited poor tensile properties relative to the triblock systems, the morphological features of the diblock materials were very interesting when in ionic form. Multiple scattering peaks were observed in the diblock ionomers using SAXS and this was attributed to the well ordered regions that were also observed utilizing TEM measurements. In general, good correspondence between the TEM and SAXS results was obtained. Surprisingly, long range order was less pronounced in the triblock ionomer with similar ion content when compared with its diblock analogue. Finally, the interdomain distance between the ionic domains was found to be highly dependent on ionic block length.