Unconventional, amphiphilic polymers based on chiral poly(ethylene oxide) derivatives I. Synthesis and Characterization

The first representatives of a new class of synthetic, amphiphilic polymers based on poly(ethylene oxide) are introduced. These polymers are constituted in a similar way to that for coiled-coil-forming peptides: the polymers possess a regular repeat of apolar (A) residues in a polar (P) sequence of residues. The polymers can be characterized by the formula [PAPPAPP']n or [PAPP']n, in which P stands for an ethylene oxide unit, P' stands for a glycolate unit, and A stands for a hydrophobically modified ethylene oxide unit. The prepn. of the polymers comprises the synthesis and dioctyltin-catalyzed ring-opening polymn. of 2-oxo-crown ether monomers. Alternatively, the polymers have been obtained by the polycondensation of their w-hydroxycarboxylic acid precursors. 1H NMR and 13C NMR anal. as well as electrospray mass spectrometry verified the integrity of the synthetic route and confirmed the regular repeat of polar and apolar segments. The crit. aggregation concns. (cac's) of the polymers in H2O at 20 DegC were detd. by a fluorescence study, using pyrene as an apolar fluorescent probe. The cac's (i) were strongly influenced by the size of the hydrophobic segments in the polymer and by the frequency at which these segments were repeated in the polymer and (ii) varied over a wide concn. range