Molecular weight distribution of poly(dimethylsiloxane) by combining matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with gel-permeation chromatography fractionation

Authors

  • Giorgio Montaudo,

    Corresponding author
    1. Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria, 6–95125 Catania, Italy
    • Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria, 6–95125 Catania, Italy
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  • Maurizio S. Montaudo,

    1. Istituto per la Chimica e la Tecnologia dei Materiali Polimerici, Consiglio Nazionale delle Ricerche, Viale A. Doria, 6–95125 Catania, Italy
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  • Concetto Puglisi,

    1. Istituto per la Chimica e la Tecnologia dei Materiali Polimerici, Consiglio Nazionale delle Ricerche, Viale A. Doria, 6–95125 Catania, Italy
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  • Filippo Samperi

    1. Istituto per la Chimica e la Tecnologia dei Materiali Polimerici, Consiglio Nazionale delle Ricerche, Viale A. Doria, 6–95125 Catania, Italy
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Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows detection of large molecules such as those present in synthetic and natural macromolecules. Until recently, it was reported that MALDI-TOF measurements can provide correct molecular weight (MW) estimates only for nearly monodisperse polymer samples. We have now developed a methodology for polydisperse samples. We recorded the gel-permeation chromatography (GPC) trace of a polydisperse polymeric sample of poly(dimethylsiloxane) (PDMS), collecting 42 fractions. Selected fractions were analyzed by MALDI-TOF and the average MW of each fraction was determined, allowing a calibration of GPC curves against absolute MW. The calibrated GPC trace was then used to compute average MW and molecular-weight distribution (MWD) of the unfractionated poly(dimethylsiloxane) sample. In the spectra of low molecular-weight fractions, the resolution is high enough to resolve the contributions of the various PDMS oligomers as separate signals.

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