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Cationic Telechelic Polyelectrolytes: Synthesis by Group Transfer Polymerization and Self-Organization in Aqueous Media

George T. Gotzamanis,^† Constantinos Tsitsilianis,*^† Stella C. Hadjiyannakou,^‡ Costas S. Patrickios,^‡ Robert Lupitskyy,^§ and Sergiy Minko^§

Department of Chemical Engineering, University of Patras, 26504 Patras, Greece, and Institute of Chemical Engineering and High-Temperature Chemical Processes, FORTH/ICE-HT; Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus; and Department of Chemistry, Clarkson University, Potsdam, New York 13699-5810

Macromolecules, 2006, 39 (2), pp 678–683

DOI: 10.1021/ma051592e

Publication Date (Web): December 22, 2005

†

University of Patras.

To whom correspondence should be addressed: e-mail ct@chemeng.upatras.gr, Fax +30 2610 997266.

‡

University of Cyprus.

Clarkson University.

Abstract

ABA triblock copolymers comprising a relative long poly(2-(dimethylamino)ethyl methacrylate) end-capped by short poly(methyl methacrylate) blocks (PMMA-b-PDMAEMA-b-PMMA) were synthesized using group transfer polymerization (GTP), and their aqueous solution properties were explored in aqueous media. At low pH these copolymers behaved as cationic telechelic polyelectrolytes (TP) and were self-organized through hydrophobic interactions among the PMMA blocks (stickers). Two types of associates were observed by atomic force microscopy (AFM) at very low concentrations: end-to-end linear associates and star like “hairy” loose aggregates where the one end of the TP was located in an irregular hydrophobic core and the other remained as a dangling end (absence of looping chains). By increasing the concentration, finite size clusters (microgels) were formed, the size of which changed continuously, leading eventually to the formation of an infinite transient network. All the structures were visualized by AFM with molecular resolution.

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