ATRP synthesis and association properties of thermoresponsive anionic block copolymers |
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| Authors: | Giancarlo Masci Marco Diociaiuti Vittorio Crescenzi |
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| Institution: | 1. Department of Chemistry, University of Rome “La Sapienza,” P.le A. Moro 5, 00185 Rome, Italy;2. Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanita, Viale R. Elena 299, 00161, Roma, Italy |
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| Abstract: | Thermosensitive anionic block copolymers of sodium 2‐acrylamido‐2‐methylpropanesulfonate (AMPS) and N‐isopropylacrylamide (NIPAAM) with different block lengths were prepared by atom transfer radical polymerization (ATRP). Controlled polymerization was achieved by using ethyl 2‐chloropropionate (ECP) as initiator and CuCl/CuCl2/tris(2‐dimethylaminoethyl)amine (Me6TREN) catalytic system in DMF:water 50:50 (v/v) mixtures at 20 °C. Blocks lengths ranging from 36 to 98 repeating units were obtained. The association properties in aqueous solutions at different NaCl ionic strengths were studied as a function of temperature and polymer concentration by dynamic light scattering, fluorescence spectroscopy, and energy‐filtered transmission electron microscopy. The block copolymers with a higher pNIPAAM/pAMPS ratio formed spherical core‐shell type micelles independently of the ionic strength. The block copolymers with lower pNIPAAM/pAMPS ratio formed core‐shell type micelles at high ionic strength. Larger particles were observed at low ionic strength, which could be due to the formation of vesicles or compound micelles/micellar clusters. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4830–4842, 2008 |
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| Keywords: | anionic atom transfer radical polymerization (ATRP) block copolymers micelles thermosensitive vesicles |
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