Side-Chain-Controlled Self-Assembly of Polystyrene-Polypeptide Miktoarm Star Copolymers

We show how the self-assembly of miktoarm star copolymers can be controlled by modifying the side chains of their polypeptide arms, using A2B and A2B2 type polymer/polypeptide hybrids (macromolecular chimeras). Initially synthesized PS2PBLL and PS2PBLL2 (PS, polystyrene; PBLL, poly(e-tert-butyloxycarbonyl-l-lysine)) miktoarms were first deprotected to PS2PLLHCl and PS2PLLHCl2 miktoarms (PLLHCl, poly(l-lysine hydrochloride)) and then complexed ionically with sodium dodecyl sulfonate (DS) to give the supramolecular complexes PS2PLL(DS) and PS2(PLL(DS))2. The solid-state self-assemblies of these six miktoarm systems were studied by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and small- and wide-angle X-ray scattering (SAXS, WAXS). The side chains of the polypeptide arms were observed to have a large effect on the solubility, polypeptide conformation, and self-assembly of the miktoarms. Three main categories were observed: (i) lamellar self-assemblies at the block c...