A Study On The Epitaxial Crystallization Behavior Of Isotactic Poly(1-Butene)

In this work,the epitaxial crystallization behavior of isotactic poly(1-butene)(iPBu)has been investigated by means of transmission electron microscope(TEM),polarized optical microscopy(POM),fourier transform infrared(FTIR)and atomic force microscopy(AFM).Mainly homoepitaxial crystallization of iPBu from melt on its highly oriented form I crystals with different morphologies and heteroepitaxy between iPBu and isotactic polystyrene(iPS)were studied.Following results have been obtained.1.Highly oriented form I iPBu thin films with highly oriented fibril crystals were prepared by a melt-draw technique.By vacuum vapor evapolation of an ultrathin carbon layer and subsequent melt-recrystallization of the melt-drawn iPBu thin film,highly oriented form I iPBu thin film with chain fold lamellae has been obtained after a period of aging at room temparature.The melt crystallization of iPBu on its oriented thin films with fibril and lamellar structure indicates that both films can induce epitaxial crystallization of iPBu in its form ?.The epitaxy leads to the melt crystallized form II crystals with molecular chain or chain segments aligning parallel to the chain direction of iPBu in the substrate films and having a(010)contact plane.This has been attributed to a one-dimensional lattice matching.2.By cold crystallizing the iPS from amorphous glassy state on melt-drawn iPBu form I films at 130? results also in an oriented growth of the iPS crystals.The epitaxially grown edge-on iPS lamellae aligned perpendicular to the molecular chain direction of iPBu substrate,indicating a parallel chain orientation of both iPBu and iPS.The heteroepitaxy of iPS on form I iPBu can be ascribed to a two-dimensional lattice matching between iPS and iPBu.3.Using the cold crystallized iPS/iPBu double layer,by selective melting and subsequent melt-recrystallization of the iPBu,the melt crystallization behavior of iPBu on oriented iPS has been studied.It was found that the oriented iPS thin film generated by the oriented iPBu form ? film can in turn induce the epitaxial crystallization orientation of iPBu in its form ? rather than in form ?.Nevertheless,the molecular chains or chain segments of both polymers are still parallel oriented.The contact plane of the form ? iPBu is also the(010)lattice plane.These results indicate that the epitaxy of iPBu on iPS is the synergistic effect of matching and crystallization kinetics.While the crystallization kinetics of iPBu determines the polymorphic behavior of iPBu,the lattice matching determines the crystal orientation during epitaxial crystallization.