Micellization in pH-sensitive amphiphilic block copolymers in aqueous media and the formation of metal nanoparticles

Maria Vamvakaki; Lampros Papoutsakis; Vasilios Katsamanis; Theodora Afchoudia; Panagiota G. Fragouli; Hermis Iatrou; Nikos Hadjichristidis; Steve P. Armes; Stanislav Sidorov; Denis Zhirov; Vasilii Zhirov; Maxim Kostylev; Lyudmila M. Bronstein; Spiros H. Anastasiadis

doi:10.1039/B403414G

Micellization in pH-sensitive amphiphilic block copolymers in aqueous media and the formation of metal nanoparticles

Maria Vamvakaki,^ab Lampros Papoutsakis,^ac Vasilios Katsamanis,^ac Theodora Afchoudia,^ac Panagiota G. Fragouli,^d Hermis Iatrou,^d Nikos Hadjichristidis,^d Steve P. Armes,^e Stanislav Sidorov,^f Denis Zhirov,^f Vasilii Zhirov,^f Maxim Kostylev,^g Lyudmila M. Bronstein^fg and Spiros H. Anastasiadis*^ac

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* Corresponding authors

^a Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1527, Heraklion Crete, Greece
E-mail: spiros@iesl.forth.gr

^b Department of Materials Science and Technology, University of Crete, Heraklion Crete, Greece

^c Department of Physics, University of Crete, Heraklion Crete, Greece

^d Department of Chemistry, University of Athens, Panepistimiopolis Zografou, Zografou Athens, Greece

^e School of Chemistry Physics and Environmental Science, University of Sussex, Falmer, Brighton, UK

^f Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, Russia

^g Chemistry Department, Indiana University, Bloomington, IN, USA

Abstract

Dynamic light scattering, potentiometric titration, transmission electron microscopy and atomic force microscopy have been used to investigate the micellar behaviour and metal-nanoparticle formation in poly(ethylene oxide)-block-poly(2-vinylpyridine), PEO-b-P2VP, poly(hexa(ethylene glycol) methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate), PHEGMA-b-PDEAEMA, and PEO-b-PDEAEMA amphiphilic diblock copolymers in water. The hydrophobic block of these copolymers (P2VP or PDEAEMA) is pH-sensitive: at low pH it can be protonated and becomes partially or completely hydrophilic leading to molecular solubility whereas at higher pH micelles are formed. These micelles consist of a P2VP or PDEAEMA core and a PEO or PHEGMA corona, respectively, where the core forming amine units can incorporate metal compounds due to coordination. The metal compounds (e.g., H₂PtCl₆, K₂PtCl₆) can either be introduced in a micellar solution, where they are incorporated within the micelle core via coordination with functional groups, or can be added to a unimer solution at low pH, where they lead to a metal-induced micellization. In these micellar nanoreactors, metal nanoparticles nucleate and grow upon reduction with sizes in the range of a few nanometers as observed by TEM. The effect of the metal incorporation method on the characteristics of the micelles and of the synthesized nanoparticles is investigated.

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Micellization in pH-sensitive amphiphilic block copolymers in aqueous media and the formation of metal nanoparticles

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Micellization in pH-sensitive amphiphilic block copolymers in aqueous media and the formation of metal nanoparticles

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