pH-triggered reversible sol–gel transition in aqueous solutions of amphiphilic gradient copolymers

0366060 - ÚMCH 2012 RIV GB eng J - Journal Article
Borisova, O. - Billon, L. - Zaremski, M. - Grassl, B. - Bakaeva, Zulfiya - Lapp, A. - Štěpánek, Petr - Borisov, O.
pH-triggered reversible sol–gel transition in aqueous solutions of amphiphilic gradient copolymers.
Soft Matter. Roč. 7, č. 22 (2011), s. 10824-10833. ISSN 1744-683X. E-ISSN 1744-6848
R&D Projects: GA ČR GAP208/10/1600
Institutional research plan: CEZ:AV0Z40500505
Keywords : small angle neutron scattering * triblock copolymer * self-organized structure
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 4.390, year: 2011

We demonstrate the possibility of reversible pH-controlled sol–gel transition in aqueous solution of associating amphiphilic triblock copolymer poly(styrene-grad-acrylic acid)-b-poly(acrylic acid)-b-poly(styrene-grad-acrylic acid), synthesized via nitroxide-mediated radical copolymerization. The presence of pH-sensitive co-monomer units of the acrylic acid in the terminal blocks ensures the dynamic nature of the styrene-rich hydrophobic nano-domains which are formed at low pH. At small polymer concentrations the association triggered by lowering the pH gives rise to flower-like micelles stabilized by partially ionized PAA coronae. The pH-controlled association was monitored by DLS-titration and manifested in the evolution of a correlation peak in the SANS spectra. Above the micelle overlap concentration a decrease in pH provokes macroscopic gelation where the styrene-reach domains perform as pH-controllable cross-links in the transient network.
Permanent Link: http://hdl.handle.net/11104/0201153