Synthesis of zwitterionic diblock copolymers without protecting group chemistry

Vo, Cong-Duan, Armes, Steven P., Randall, David P., Sakai, Kenichi and Biggs, Simon (2007) Synthesis of zwitterionic diblock copolymers without protecting group chemistry. Macromolecules, 40 2: 157-167. doi:10.1021/ma062648n

Author Vo, Cong-Duan
Armes, Steven P.
Randall, David P.
Sakai, Kenichi
Biggs, Simon
Title Synthesis of zwitterionic diblock copolymers without protecting group chemistry
Journal name Macromolecules   Check publisher's open access policy
ISSN 0024-9297
Publication date 2007-01-01
Year available 2006
Sub-type Article (original research)
DOI 10.1021/ma062648n
Open Access Status Not yet assessed
Volume 40
Issue 2
Start page 157
End page 167
Total pages 11
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Abstract A two-step route was used to prepare a range of zwitterionic diblock copolymers in which both blocks are weak polyelectrolytes. In the first step, low polydispersity diblock copolymers of 2-hydroxypropyl methacrylate (HPMA) with either 2-(diethylamino)ethyl methacrylate (DEA) or 2-(diisopropylamino) ethyl methacrylate (DPA) were prepared by atom transfer radical polymerization in protic media under mild conditions in a convenient one-pot synthesis. Block copolymers with varying compositions were prepared by adjusting the comonomer/initiator molar ratio. In the second step, the hydroxyl groups of the diblock copolymers were esterified with excess succinic anhydride (SA) to produce the corresponding zwitterionic diblock copolymers, which exhibit complex pH-dependent behavior (isoelectric points and "schizophrenic"-type micellization) in aqueous solution. The electrostatic adsorption of "cationic corona" micelles onto near-monodisperse anionic silica particles was successful at pH 3.5, as evidenced by aqueous electrophoresis, FT-IR studies, thermogravimetric analysis, and scanning electron microscopy. The same "cationic corona" micelles were also adsorbed onto planar mica at pH 3.5. More surprisingly, inverted "anionic corona" micelles prepared from the same diblock copolymer could be adsorbed onto mica at pH 10. Presumably, this latter adsorption arises from relatively weak hydrophobic interactions due to the micelle cores, rather than strong electrostatic interactions due to the micelle corona. Both types of adsorbed micelles could be imaged by in situ atomic force microscopy.
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Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Engineering, Architecture and Information Technology Publications
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