Epitaxy of isotactic poly(1-butene): new substrates, impact and attempt atrecognition of helix orientation in form I ' by AFM

Epitaxial crystallization of isotactic poly(1-butene) (iPBu) is performed o n different substrates, which help expand the range of interactive substrat es used in a previous study. All three crystal forms of iPBu1, which rest o n different helix and unit-cell geometries and symmetries, have been produc ed by epitaxial crystallization. The different epitaxial interactions are d iscussed. Epitaxial crystallization of form I' yields an exposed (110) cont act plane. The films have true single crystal structure; they display elect ron diffraction patterns with sharp peaks, but also characteristic streaks due to the co-existence of up and down helices in the crystal structure (an ticline helices). The streaks are modelled with a 'Diffraction faulted' pro gram. Further, this same (110) contact face of Form I' provides the potenti al to observe in direct space (i.e. by AFM) the up or down orientation of h elices. Such a possibility would require differentiation by AFM of a methyl group from an ethyl group of the side chains. The AFM resolution reached i n our investigation falls short of doing so, but the problematics could be adapted to other, more suitable polymers. (C) 2001 Elsevier Science Ltd. Al l rights reserved.