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Surface immobilized block copolymer micelles with switchable accessibility of hydrophobic pockets

Title data

Gensel, Julia ; Betthausen, Eva ; Hasenoehrl, Christoph ; Trenkenschuh, Katja ; Hund, Markus ; Boulmedais, Fouzia ; Schaaf, Pierre ; Müller, Axel H. E. ; Fery, Andreas:
Surface immobilized block copolymer micelles with switchable accessibility of hydrophobic pockets.
In: Soft Matter. Vol. 7 (2011) Issue 23 . - pp. 11144-11153.
ISSN 1744-6848
DOI: https://doi.org/10.1039/c1sm06338c

Official URL: Volltext

Abstract in another language

We report on a novel approach for the design of stimuli-responsive surfaces based on the immobilization of charged ABC triblock terpolymer micelles. The terpolymer consists of a hydrophobic polybutadiene (B) block, a weak anionic poly(methacrylic acid) (MAA) middle block, and a strong cationic end block of quaternized poly(2-(dimethylamino) ethyl methacrylate) (Dq) (BMAADq). In alkaline solutions, this polymer self-assembles into core-shell-corona micelles with a hydrophobic B core, a pH-sensitive MAA/Dq intramicellar interpolyelectrolyte complex (im-IPEC) shell, and a cationic corona of excess Dq. These micelles were directly adsorbed onto charged silica as a monolayer creating laterally structured surfaces. The adsorption kinetics was found to follow the theoretical model of random sequential adsorption (RSA). Exposure of the adsorbed micelles to external stimuli (at pH < pK(a,apparent) of PMAA) induces im-IPEC dissolution due to protonation of the MAA block resulting in a changed composition of the shell and both the length and charge density of the corona. Two types of conformational response to pH trigger and therefore, two types of dynamics coupled to short and long relaxation times are involved in the system. The response to pH cycling was shown to be reversible on the short-term scale while the long-term exposure to acidic media causes irreversible changes in the morphology of the micelles as a consequence of the micelles' core mobility and slow rearrangement. In particular, we find that exposure to low pH causes a shape transition to a "doughnut"-like morphology, exposing the core parts of the micelles. In contrast, adsorbed micelles with covalently crosslinked B cores show higher stability to irreversible morphology changes while maintaining the reversible response to pH cycling.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors > Chair Physical Chemistry II - Univ.-Prof. Dr. Andreas Fery
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Physical Chemistry II
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 530 Physics
500 Science > 540 Chemistry
Date Deposited: 08 Dec 2014 07:06
Last Modified: 30 Jan 2015 09:29
URI: https://eref.uni-bayreuth.de/id/eprint/3971