STRUCTURE AND MORPHOLOGY CHARACTERIZATION OF POLY(OXYETHYLENE OXYPROPYLENE OXYETHYLENE) COPOLYMER POLOXAMER-407 GEL DURING DEHYDRATION

With the evaporation of water, the crystals precipitated in the Poloxa mer 407 gel. On the optical photograph, the channel-like holes and cra cks were observed, which is a common feature of the solid dried from a gel. By the x-ray and TEM investigations, there existed two crystal s tructures formed by packing of the EO units, which were the monoclinic and triclinic unit cells, respectively. Owing to the presence of the zig-zag conformation of the PEO chains in the dried solid, it was thus suggested that the PEO chains were considerably extended in the gel. However, the crystals formed by packing of the PO units were not decte cted, indicating that the PPO chains of Poloxamer 407 may take the ata ctic configuration. Also, on the bright field electron micrograph, one found the aggregates having the sizes (in radius) in the range 800 an gstrom to 1200 angstrom.