ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The morphology of cast and annealed films from poly[bis(trifluoroethoxy)phosphazene] \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \{ PBFP,\rlap{--} [(CF}_{\rm 3} {\rm CH}_{\rm 2} {\rm O)}_{\rm 2} {\rm P = N\rlap{--} ]}_{\rm n} {\rm \} } $\end{document} has been studied by electron, scanning electron and optical microscopy. Several polymorphic forms and one mesophase (hexatic) have been established. From THF solution, PBFP has a chain folded morphology (α-orthorhombic) which transforms into a chain extended 2D hexagonal mesophase at T(1). It remains in this state until final melting occurs at Tm = 245°C approximately. Upon cooling the melt, it quickly reverts to the hexagonal mesophase again, but then passes into a chain extended (3D) γ-orthorhombic modification. This material is much more stable thermodynamically than the α-form, which is friable or brittle. PBFP cannot be quenched to a glassy form from the molten state, but it can be disordered as assessed by its reduced T(1) enthalpy and less well defined morphology assessed by electron microscopy. Another crystal modification (β-monoclinic) has been found in solution cast low molecular weight PBFP films.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1985.021860318
