Abstract
Isotactic-poly(1-butene) (iPB1) shows superior mechanical properties after crystal-crystal transitions. Recently, Miyoshi et al. found that crystalline stems in metastable tetragonal crystal perform uniaxial rotational diffusions accompanying side-chain conformational transitions in the fast motional limit (correlation time <tau(c)> <10(-7) s; Macromolecules 2010, 43, 3986-3989.). In this study, molecular dynamics in stable trigonal crystal is investigated by solid-state nuclear magnetic resonance, which indicates that crystalline stems and side-chain conformations are completely fixed up to melting points (<tau(c)> > 10 s). In addition, lamellar thickness, < I > of iPB1 and a low isotacticity iPB1 (low_iPB1) with < mmmm > = 78%, respectively, were investigated by small-angle X-ray scattering. The low_iPB1 sample shows very week supercooling dependence of < I > (similar to 5 nm), whereas iPB1 shows strong supercooling dependence of < I > (10-28 nm). On the basis of molecular dynamics and < I > results, molecular dynamics effects on structures and unique mechanical property of iPB1 are discussed. Polymer Journal (2012) 44, 65-71; doi:10.1038/pj.2011.66; published online 10 August 2011