Authors: K.W. Lem, D.S. Lee, J.R. Haw, G.S. Song, S. Curran, S. Sund, Z. Iqbal, C. Brumlik
Affilation: Konkuk University, Korea
Pages: 60 - 63
Keywords: polymer film, nano, characterization, domains, size effect, cast
When a film is cast from solution, the volume fraction of polymer in the film increases with increasing drying temperature and/or time. Its viscoelastic behavior transitions from more viscous (where G” > G’) in dilution solution to more elastic (where G’ > G”) as the volume fraction of the polymer (f) increases and finally solidification or gelation when the film is formed. We have used f G”=G’ and fGEL to monitor the transitions of hard segment controlled polyurethane molecules from nanogels/nanocoils to microgels/microgels and finally or hard and soft segmented domains in the bulk. In the early study, we have found that the hard segment weight fraction affects the dilute solution properties of TPU up to a limiting value (Lem et al., 2011). At the regions where f G”=G’ < f <f GEL and f > f GEL, the domain is no longer nano-size but is in the order of micro-scale. However, the size and nature of the nano-scaled domain when f <f G”=G’ greatly affects the structure-property relationship of these segmented domains in concentrated solutions and in the bulk. .
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