TEMPERATURE EFFECT ON EPITAXIAL-GROWTH OF POLY(P-OXYBENZOATE)

A series of epitaxial polymerizations of poly(p-oxybenzoate) (POBA) on substrates of single-crystal mica, potassium bromide (KBr), and uniax ially aligned poly(tetrafluoroethylene) (PTFE) was performed at temper atures from 200 degrees C to 270 degrees C. As the temperature rose, n ot only did the POBA domain dimension in the polymer chain direction a nd the thickness of the epitaxial layer increase, but also the domain morphology changed correspondingly. The POBA domains tended to grow mo re three dimensionally at low temperatures, accompanied by a decreased epitaxial order. Thus, a high temperature favored epitaxial crystalli zation of POBA onto crystalline substrates. The POBA film grown on KBr substrate at 220 degrees C revealed a low density layer consisting of lamellaelike plates. Subsequent annealing at 320 degrees C produced a fibrous morphology in which the POBA fibrils were aligned, forming a 90 degrees C cross-hatched network. More interestingly, a POBA film on KBr substrate, prepared by melt condensation reaction at 180 degrees C for 24 h followed by annealing at 280 degrees C for 1 h and then at 320 degrees C for 2 h, produced laminae with both square and rectangul ar patterns with domain boundaries that aligned with KBr crystal axes. The electron diffraction (ED) pattern showed a phase I crystal patter n with the POBA polymer chains perpendicular to the substrate surface with very high crystallinity.