Nonspherical Assemblies Generated from Polystyrene-b-poly(l -lysine) Polyelectrolyte Block Copolymers
| Autor: | Valeria Castelletto, Christine Wandrey, Harald Nuhn, Anke Lübbert, Harm-Anton Klok, Markus Thomas Scholl, Ian W. Hamley, Laurent Bourdillon |
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| Rok vydání: | 2005 |
| Předmět: |
Analytical chemistry
Centrifugation Neutron scattering Micelle Light scattering Polymerization chemistry.chemical_compound Polymer chemistry Electrochemistry Chemical analysis General Materials Science Static light scattering Micelles Spectroscopy chemistry.chemical_classification Scattering Agglomeration Polymer chains Surfaces and Interfaces Polymer Self assembly Superstructures Condensed Matter Physics Block copolymers Small-angle neutron scattering Solutions chemistry Polystyrenes Structure formation Polystyrene Peptides |
| Zdroj: | Langmuir. 21:6582-6589 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la0502600 |
| Popis: | This report describes the aqueous solution self-assembly of a series of polystyrenem-b-poly(L-lysine)n block copolymers (m = 8-10; n = 10-70). The polymers are prepared by ring-opening polymerization of e-benzyloxycarbonyl-L-lysine AT-carboxyanhydride using amine terminated polystyrene macroinitiators, followed by removal of the benzyloxycarbonyl side chain protecting groups. The critical micelle concentration of the block copolymers determined using the pyrene probe technique shows a parabolic dependence on peptide block length exhibiting a maximum at n = .apprx.20 (m = 8) or n = .apprx.60 (m = 10). The shape and size of the aggregates has been studied by dynamic and static light scattering, small-angle neutron scattering (SANS), and analytical ultracentrifugation (AUC). Surprisingly, Holtzer and Kratky analysis of the static light scattering results indicates the presence of nonspherical, presumably cylindrical objects independent of the poly(L -lysine)n block length. This is supported by SANS data, which can be fitted well by assuming cylindrical scattering objects. AUC analysis allows the molecular weight of the aggregates to be estimated as several million g/mol, corresponding to aggregation numbers of several 10s to 100s. These aggregation numbers agree with those that can be estimated from the length and diameter of the cylinders obtained from the scattering results. © 2005 American Chemical Society. |
| Databáze: | OpenAIRE |
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