MWD affects both processing and properties of polymers.  Engineering polymers incorporate rigid structures which increase Tg and mechanical properties but may also induce limited solubility, making the characterization of the (MWD) more challenging.  We have characterized the MWD of random and multiblock SPAES and sulfonated poly(arylene ether ketones) copolymers, using SEC.  These materials were soluble in N-Methylpyrrolidone (NMP), but the hydrophilic/hydrophobic nature, rigidity, or aggregation lead to interactions affecting the separations.  SEC of SPAES homo and copolymers will be presented comparing the results using light scattering (LS) and universal calibration (UC).  Analysis of the MWD of highly sulfonated polymers suggests aggregation and column interaction.  Figure 1 shows SEC chromatograms of 15,000 g/mole (NMR Mn) SPAES oligomers.  SEC with LS provides weight average molecular weight (Mw) of 22,000 and 28,000 g/mole for 1 and 2 respectively; however, the tailing observed at high elution times indicates column interaction.  Asymmetric flow field flow fractionation (AF4) of SPAES copolymers is expected to provide improved results by eliminating column interaction.  100% SPAES are soluble in both aqueous and NMP solvents, partially sulfonated copolymers have limited solubility in aqueous systems so have been analyzed in NMP/0.05M LiBr.  Development of AF4 is underway for SPAES with the intention of performing separations in both aqueous and NMP/0.05M LiBr solvents.  The limitations of the methods with respect to the level and distribution of the hydrophilic monomers will be reported.  

Size exclusion chromatography (SEC) and molecular weight distribution (MWD) analysis of sulfonated polyarylene ether sulfone (SPAES) copolymers in N-methylpyrrolidone (NMP)

247th National Meeting (2014)

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