Characterization of poly(ε-caprolactone) by size exclusion chromatography/matrix-assisted laser desorption ionization-mass spectrometry (SEC/MALDI-MS)

Chemical structure and molecular weight distribution of individual components in a commercially, available poly(E -caprolactone) (PCL). sample were characterized by off-line coupled size exclusion chromatography (SEC)/matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). The main component of the sample was identified to, be PCL-diol, whose chains extended from two hydroxyl groups of diethylene glycol as an initiator. This component was distributed over a wide molecular weight range of ca. 1000similar to40000. On the other hand, in the lower molecular weight region (less than or equal toca. 5000), cyclic PCL and alpha-carboxy-omega-hydroxyPCL were also present as byproducts. In addition, the formation of PCL-diol byproduct yielded through incomplete chain propagation at one side was also suggested. On the basis of the observed results, the formation mechanisms of the byproducts were discussed.