ABSTRACT
Water-soluble triblock copolymers of the EPE-type [P and E represent poly(oxy-propylene) and poly(oxyethylene), respectively], often abbreviated as POE-POP-POE [or (EO) a (PO) b (EO) c with a, b, c representing the number of repeat units] are commercially available non-ionic macromolecular surfactants and have many uses. In a recent review article on poloxamers, Schmolka [1,2] stated that there were over 1000 articles on many applications in the medical and pharmaceutical industries alone. The commercial names for these triblocks, which find widespread industrial applications in their uses as emulsifying, wetting, thickening, coating, solubilizing, stabilizing, dispersing, lubricating, and foaming agents, are Pluronic® (BASF) or Synperonic® (ICI) polyols. A variety of the EPE-type triblocks are available with varying chain length (total copolymer molecular weight), block length ratio, and chain architecture (e.g., PEP-type, instead of EPE-type). In addition to the EPE-type triblocks, EB-type diblocks and EBE-type triblocks—with B denoting poly(oxybutylene) and being more hydrophobic than E—have been synthesized and studied, and are being marketed by The Dow Chemical Co. The Pluronic polyols are made up of relatively shorter segment blocks. Nevertheless, these nonionic macromolecular surfactants have many properties similar to those of long-chain triblock copolymers. Micelles of block and graft copolymers in selective solvents have been reviewed extensively by Tuzar and Kratochvil [3]. The physical chemistry of nonionic surfactants on earlier studies have also been presented [4]. The main physical methods used in studying Pluronic polyols have been reviewed by Chu [5].
