Ms
Junjie Yin
(University of Waterloo)
Polydispersity can significantly affect the physics properties of polymers. In this study we show the differences in poly(ethylene oxide) oligomer crystallization between monodisperse and polydisperse samples as an example. Commercial polymers even with a low polydispersity index (PDI) of about 1.01, still contain a rather broad distribution of different molecular weights. In this study we produced highly monodisperse PEO through evaporative purification of a M 600 PEO sample, achieving a PDI significantly lower than the as purchased sample, as measured by mass spectroscopy. Melting temperatures were obtained using differential scanning calorimetry (DSC). Based on the Gibbs Thomson relation, we show that during crystallization, some monodisperse samples form crystal lamellae with both extended chains and once-folded chains. In contrast, polydisperse samples have been shown to only contain extended chains in the crystal form. The fact that we are able to tune the melting temperature through annealing treatment on the crystal validates the existence of both folded and extended chains in the monodisperse samples.
Ms
Junjie Yin
(University of Waterloo)
Dr
Adam Raegen
(University of Waterloo)
Prof.
James Forrest
(University of Waterloo)
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