Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/68666
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Type: Journal article
Title: Self-assembly of stimuli-responsive water-soluble [60]Fullerene end-capped ampholytic block copolymer
Author: Teoh, S.
Ravi, P.
Dai, S.
Tam, K.
Citation: Journal of Physical Chemistry B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical, 2005; 109(10):4431-4438
Publisher: Amer Chemical Soc
Issue Date: 2005
ISSN: 1520-6106
1520-5207
Statement of
Responsibility: 
Soon Kay Teoh, Palaniswamy Ravi, Sheng Dai and Kam Chiu Tam
Abstract: A well-defined, water-soluble, pH and temperature stimuli-responsive [60]fullerene (C(60)) containing ampholytic block copolymer of poly((methacrylic acid)-block-(2-(dimethylamino)ethyl methacrylate))-block-C(60) (P(MAA-b-DMAEMA)-b-C(60)) was synthesized by the atom transfer radical polymerization (ATRP) technique. The self-assembly behavior of the C(60) containing polyampholyte in aqueous solution was characterized by potentiometric and conductometric titration, dynamic light scattering (DLS), and transmission electron microscopy. This amphiphilic mono-C(60) end-capped block copolymer shows enhanced solubility in aqueous medium at room and elevated temperatures and at low and high pH but phase separates at intermediate pH between 5.4 and 8.8. The self-assembly of the copolymer is different from that of P(MAA-b-DMAEMA). Examination of the association behavior using DLS revealed the coexistence of unimers and aggregates at low pH at all temperatures studied, with the association being driven by the balance of hydrophobic and electrostatic interactions. Unimers and aggregates of different microstructures are also observed at high pH and at temperatures below the lower critical solution temperature (LCST) of PDMAEMA. At high pH and at temperatures above the LCST of PDMAEMA, the formation of micelles and aggregates coexisting in solution is driven by the combination of hydrophobic, electrostatic, and charge-transfer interactions.
Keywords: Fullerenes; Polymethyl Methacrylate; Polymers; Solutions; Microscopy, Electron, Transmission; Chromatography, Gel; Spectrophotometry, Ultraviolet; Magnetic Resonance Spectroscopy; Thermogravimetry; Potentiometry; Temperature; Electric Conductivity; Hydrogen-Ion Concentration; Solubility
Rights: Copyright © 2005 American Chemical Society
RMID: 0020112545
DOI: 10.1021/jp045413r
Appears in Collections:Chemical Engineering publications

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