Characterization from PMMA average

One possibility is that although averages for polystyrene standards require correction, those for PMMA would not According to symmetrical axial dispersion theory (5) the correction depends upon both the slope of the calibration curve (different for each polymer type) and the variance of the chromatogram of a truly monodisperse sample. Furthermore, the calibration curve to be utilized can be obtained from a broad standard as well as from monodisperse samples. The broad standard method may itself incorporate some axial dispersion correction depending upon how the standard was characterized. 

The average time determined experimentally from the slope of linear dependence Y Tln) is given by Eq. (5,5.3). The data on PMMA listed in Table 21 show how the structure of the side chain bonding the LG to the main PMMA chain and the position of the attachment of this side chain to LG (to the anthracene ring) affect the times characterizing the rate of rearrangements in side chains with LG. 

However, such a strategy can be applied only for block copolymers. Molecular weight characterization of random amphiphilic copolymers currently poses its own analytical challenges. Giordanengo et al. [92] used a methylation reaction to transform methacrylic acid (MAA)/methyl methacrylate (MMA) copolymer samples that could not be properly ionized by MALDI into PMMA homopolymers. Weight average molecular weight (MJ parameters of the copolymers were then derived from values obtained for the methylated MAA-MMA molecules by MALDI, which were also validated by NMR. 

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