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: 624 - 627
Keywords: polymer, nano, characterization, domains, size effect
Many useful polyurethane components, such as films, are prepared from solution, in the form of dispersion, emulsion, or suspension. The ultimate properties of such films depend on the effect of nano scaled structures in the hard and soft segments. When a film is cast from solution, the volume fraction of polymer in the film increases with increasing drying temperature and/or time. Consequently, the viscoelastic behavior of the polymer solution transitions from viscous (where G” > G’) in dilute solution to elastic (where G’ > G”) as the volume fraction of the polymer (f) increases and finally solidification or gelation occurs when the film is formed. We have used f G”=G’ and at fGEL to monitor the transition of hard segment controlled domains in the polyurethane molecules from nanogels/nanocoils to microgels/microgels and finally hard and soft segmented domains in bulk. We have continued our effort to study the effect of size on properties of nano-structured polymers during the transition from the nanoscale to the macroscale (Lem et al., 2010). A systematic study has illustrated the effect of hard segment molecular weight induced nanosized domains on solution and bulk properties of thermoplastic ether based polyurethanes (TPUs).