Thermoplastic polyurethanes with controlled morphology based on methylenediphenyldiisocyanate/isosorbide/butanediol hard segments

• Published in: Polymer international 2015-11, Vol.64 (11), p.1607-1616
• Main Authors: Javni, Ivan, Bilić, Olivera, Bilić, Nikola, Petrović, Zoran S, Eastwood, Eric A, Zhang, Fan, Ilavský, Jan
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Butanediol; chain extender; isosorbide; Morphology; Phase boundaries; Polyurethane resins; segmented polyurethanes; Segments; Small angle X ray scattering; Urethane thermoplastic elastomers
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.4960

The effects of isosorbide chain extender on the microstructural morphologies of two series of thermoplastic polyurethanes were systematically investigated using small‐angle X‐ray scattering and optical and atomic force microscopy. Isosorbide, a cyclic, rigid and renewable diol, was used as a chain extender in two series of thermoplastic polyurethanes (PUs). Isosorbide was used alone or in combination with butanediol to examine the effects on the morphology of PU. Two series of materials were prepared – one with dispersed hard domains in a matrix of polytetramethylene ether glycol soft segments of molecular weight 1400 g mol−1 (at 70 wt% soft segment concentration, SSC) and the other with co‐continuous soft and hard phases at 50 wt% SSC. We investigated the detailed morphology of these materials with optical and atomic force microscopy, as well as ultra‐small‐angle X‐ray scattering. The atomic force microscopy measurements confirmed the different morphologies in PUs with 50 wt% SSC and with 70 wt% SSC. Small‐angle X‐ray scattering data showed that in PU with 70 wt% SSC, the hard domain size varied between 2.4 and 2.9 nm, and decreased with increasing isosorbide content. In PU with 70 wt% SSC, we found that the correlation length and average repeat distances became smaller with increasing isosorbide content. We estimated the thickness of the diffuse phase boundary for PU with 70 wt% SSC to be ca 0.5 nm, decreasing slightly with increasing isosorbide content. © 2015 Society of Chemical Industry