Hexagonal columnar phase in 1,4-trans-polybutadiene: morphology, chain extension, and isothermal phase reversal

Morphol., lamellar thickening, and the transition between the crystal and the hexagonal columnar phase were studied in 1,4-trans-polybutadiene (I) by optical and electron microscopy, time-resolved synchrotron x-ray diffraction, and DSC. I could form several-thousand-.ANG.-thick lamellas of the extended or nearly extended chain type. These could form either by direct growth from the melt or through annealing of thinner chain-folded lamellas, provided they were in the columnar phase. Lamellar thickness increased by several hundred .ANG. in soln.-crystd. mats immediately upon heating above the crystal-columnar transition, which contrasted with some previous reports on single crystals of I. The low-temp. crystal phase reappeared spontaneously on annealing above the temp. of the initial transition to the high-temp. columnar phase. [on SciFinder (R)]