Title:
Side-Chain-Controlled Self-Assembly of Polystyrene–Polypeptide Miktoarm Star Copolymers
Languages of Item:
English
Abstract:
We show how the self-assembly of miktoarm star copolymers can be controlled by modifying the side chains of their polypeptide arms, using A 2B and A 2B 2 type polymer/polypeptide hybrids (macromolecular chimeras). Initially synthesized PS 2PBLL and PS 2PBLL 2 (PS, polystyrene; PBLL, poly(ε-tert-butyloxycarbonyl-l-lysine) ) miktoarms were first deprotected to PS 2PLLHCl and PS 2PLLHCl 2 miktoarms (PLLHCl, poly(l-lysine hydrochloride)) and then complexed ionically with sodium dodecyl sulfonate (DS) to give the supramolecular complexes PS 2PLL(DS) and PS 2(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 copolymer length scale with packed layers of α-helices in PS 2PBLL and PS 2PBLL 2; (ii) charge-clustered polypeptide micelles with less-defined conformations in a nonordered lattice within a PS matrix in PS 2PLLHCl and PS 2PLLHCl 2; (iii) lamellar polypeptide-surfactant self-assemblies with β-sheet conformation in PS 2PLL(DS) and PS 2(PLL(DS)) 2 which dominate over the formation of block copolymer scale structures. Differences between the 3- and 4-arm systems illustrate how packing frustration between the coil-like PS arms and rigid polypeptide conformations can be relieved by the right number of arms, leading to differences in the extent of order. © 2012 American Chemical Society.
Authors:
Susanna Junnila
Nikolay Houbenov
Anastasis Karatzas
Nikos Hadjichristidis
Akira Hirao
Hermis Iatrou
Olli Ikkala
Publisher:
American Chemical Society (ACS)
Keywords:
Fourier transform infrared (FTIR) spectroscopies; l-Lysine hydrochloride; Length scale; Miktoarm star copolymers; Number of arms; Side-chains; Small- and wide-angle X-ray scatterings; Sodium dodecyl sulfonate; Supramolecular complexes; Transmission electron microscopy (TEM), Amino acids; Block copolymers; Conformations; Fourier transform infrared spectroscopy; Polystyrenes; Self assembly; Sodium; Supramolecular chemistry; Surface active agents; Synthesis (chemical); Transmission electron microscopy, Lamellar structures
Main subject category:
Science
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