Encapsulation and Release by Star-Shaped Block Copolymers as Unimolecular Nanocontainers

Kul, Dilek; van Renterghem, Lieven M.; Meier, Michael; Strandman, Satu; Tenhu, Heikki; Yilmaz, Sevil S.; Schubert, Ulrich S.; Prez, Filip E. Du

Abstract:

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)-blockpoly( 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.

Year:

2008

Type of Publication:

Article

Keywords:

amphiphiles; atom transfer radical polymerization ATRP; host-guest systems; nanocontainer; star-block copolymer

Journal:

Journal of Polymer Science: Part A: Polymer Chemistry

Volume:

46

Pages:

650 - 660