### Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)Analytical strategy for the molecular weight determination of random copolymers of poly(methyl methacrylate) and poly(methacrylic acid)

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 Author Giordanengo, Rémi ♦ Viel, Stéphane ♦ Hidalgo, Manuel ♦ Allard Breton, Béatrice ♦ Thévand, André ♦ Charles, Laurence Source SpringerLink Content type Text Publisher Springer-Verlag File Format PDF Copyright Year ©2010 Language English
 Subject Domain (in DDC) Natural sciences & mathematics ♦ Chemistry & allied sciences Subject Keyword Analytical Chemistry ♦ Biotechnology ♦ Organic Chemistry ♦ Proteomics ♦ Bioinformatics Abstract Molecular weight characterization of random amphiphilic copolymers currently represents an analytical challenge. In particular, molecules composed of methacrylic acid (MAA) and methyl methacrylate (MMA) as the repeat units raise issues in commonly used techniques. The present study shows that when random copolymers cannot be properly ionized by MALDI, and hence detected and measured in MS, one possible analytical strategy is to transform them into homopolymers, which are more amenable to this ionization technique. Then, by combining the molecular weight of the so-obtained homopolymers, as measured by MS, with the relative molar proportion of the MMA and MMA units, as given by $^{1}$H NMR spectrum, one can straightforwardly estimate the molecular weight of the initial copolymer. A methylation reaction was performed to transform MAA-MMA copolymer samples into PMMA homopolymers, using trimethylsilyldiazomethane as a derivatization agent. Weight average molecular weight (M $_{w}$) parameters of the MAA-MMA copolymers could then be derived from M $_{w}$ values obtained for the methylated MAA-MMA molecules by MALDI, which were also validated by pulsed gradient spin echo (PGSE) NMR. An alkene function in one of the studied copolymer end-groups was also shown to react with the methylation agent, giving rise to MMA-like polymeric by-products characterized by tandem mass spectrometry and which could be avoided by adjusting the amount of the trimethylsilyldiazomethane in the reaction medium. ISSN 10440305 Age Range 18 to 22 years ♦ above 22 year Educational Use Research Education Level UG and PG Learning Resource Type Article Publisher Date 2011-11-22 Publisher Institution The American Society for Mass Spectrometry Publisher Place New York e-ISSN 18791123 Journal Journal of The American Society for Mass Spectrometry Volume Number 21 Issue Number 6 Page Count 11 Starting Page 1075 Ending Page 1085