Toward Truly Water-Soluble Rodlike Polyelectrolytes: Synthesis of Poly(para-phenylenes) Wrapped in Ethylene Oxide and Amino Side Groups

摘要

Suzuki and Yamamoto cross-coupling protocols are applied to synthesize water-soluble poly(p-phenylene) (PPP) derivatives decorated with oligoethylene oxide (OEO) and tertiary amino side groups. It is shown that constitutionally well-defined PPPs can be obtained having degrees of polycondensation, P-n, of 30-60. In some cases, however the heteroatoms in the side chains affect the monomer synthesis and prevent proper chain growth through coordination of metal species present in the reaction medium. It is shown that essentially uncharged but still water-soluble PPPs result if (i) the side groups bear their heteroatoms in the right position, and (ii) if the water-soluble segments of the lateral substituents prevent intermolecular hydrophobic interactions of the apolar main chains reliably. In other words, the lateral substituents have to wrap the PPP core structure tightly in a closed outer shell of water-soluble OEO moieties. These PPPs constitute a valuable new pool of model systems for future polyelectrolyte research, being highly complementary to what has been available so far.