Encapsulation and release by star-shaped block copolymers as unimolecular nanocontainers

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2008-01, Vol.46 (2), p.650-660
• Main Authors: Kul, Dilek, Van Renterghem, Lieven M, Meier, Michael A.R, Strandman, Satu, Tenhu, Heikki, YIlmaz, Sevil S, Schubert, Ulrich S, Du Prez, Filip E
• Format: Article
• Language: English
• Subjects: amphiphiles; Applied sciences; atom transfer radical polymerization (ATRP); Exact sciences and technology; host-guest systems; nanocontainer; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; star-block copolymer
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.22413

A five-arm star-shaped poly(ethylene oxide) (PEO) with terminal bromide groups was used as a macroinitiator for the atom transfer radical polymerization of tert-butyl acrylate (tBA), resulting in five-arm star-shaped poly(ethylene oxide)-block-poly(tert-butyl acrylate) block copolymers. The polymerization proceeded in a controlled way using a copper(I)bromide/pentamethyl diethylenetriamine catalytic system in acetonitrile as solvent. The hydrolysis of the tBA blocks of the amphiphilic star-shaped PEO-b-PtBA block copolymer resulted in dihydrophilic star structures. The encapsulation of the star-block copolymers and their release properties in acid environment have been followed by UV-spectroscopy and color changes, using the dye methyl orange as a hydrophilic guest molecule. Characterization of the structures has been done by ¹H NMR, size exclusion chromatography, MALDI-TOF, and differential scanning calorimetry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 650-660, 2008