Oligo(p-benzamide)s – Versatile Synthons for Nanoscale Organization of Polymers

摘要

The advances in living polymerization techniques have enabled polymer chemists to create polymers, esp. block copolymers, with increasing precision as far as molecular weight and molecular weight distribution are concerned. Block copolymers can routinely be prepared from a wide range of different monomer structures. Coil-coil block copolymers and their solution and bulk structures have been studied in great detail. Amphiphilic coil-coil diblock copolymers typically form phase-separated morphologies with domain sizes between 10 and 100 nm. One way to obtain smaller domain sizes is via rod-coil block copolymers in which a discrete oligomeric rod-block is attached to a polydisperse coil-block. This allows the generation of domain sizes on similar length scales as that of the oligomeric rod itself. Such precisely defined oligomers can be synthesized and attached to polymeric coil blocks using the tools of classical multi-step organic synthesis. In recent years, this boundary between classical organic synthesis and polymer chemistry has been crossed by many groups with the aim of creating new block-copolymer architectures in which at least one block is precisely defined. Recently, we described the synthesis and aggregation behavior of a series of oligo(p-benzamide)-b-poly(ethylene glycol)monomethyl ethers in which strong directional hydrogen bonds are responsible for the formation of nanoscale solution structures. Here we present an overview over different organic synthetic strategies aiming at precisely defined oligo(p-benzamide)-coil-block copolymers. The nanoscale aggregates formed by these polymers in non-polar solvents were analyzed using scanning probe microscopy (SPM) as well as light scattering techniques.