Studies on Novel C60-anchored Polymers and Their Optoelectronic Properties
Date Issued
2005
Date
2005
Author(s)
Chu, Chih-Chien
DOI
zh-TW
Abstract
Synthesis of novel C60-anchored telechelic and star-shaped polymers has been demonstrated. First, multi-armed poly(tert-butyl acrylate) (PtBA) bearing a malonate ester core and well-controlled molecular weight was synthesized through atom transfer radical polymerization (ATRP). Based on ‘arm-first’ strategy, the highly effective Bingel reaction between C60 and the polymers was then introduced to yield the novel macromolecules anchored to a C60 core. The GPC profiles obtained by UV and RI dual detectors indicated that C60 had been covalently bonded to the polymers. The molecular weights of the C60-bonded telechelic and star-shaped polymers ((PtBA)n-C60, n = 2, 4, 8) were similar to that of the homopolymers (PtBA), and these results strongly suggested that the C60-bonded polymers were monosubstituents. 1H-NMR analysis demonstrated the clear down-field-shift of the benzylic protons in the relating C60-based polymeric structures due to the electron-withdrawing properties of C60 moiety. Thus, the results reinforced the conclusion that C60 had been covalently bonded to the polymers. Furthermore, UV-vis studies showed an apparent blue shift and a sharp band atλmax = 426 nm for C60-bonded telechelic and star-shaped polymers in comparison with C60 molecule. The absorption phenomenon seems to be highly characteristic for ‘closed’ 6-6-ring-bridged methanofullerene derivatives. Moreover, the C60 contents in these polymers can be determined by facile quantitative calculation based on Beer’s law from the absorbance atλmax = 326 nm. The results were consistent with the theoretical values calculated based on the assumption that C60-derived polymers was a monoadduct. Subsequent acidic hydrolysis of multi-armed C60-anchored PtBA successfully led to corresponding water-soluble multi-armed C60-anchored poly(acrylic acid) (PAA). The aggregation behavior for the novel water-soluble C60-anchored polymers in aqueous solution was carefully examined using GPC-MALLS-RI technique, dynamic light scattering (DLS), and atomic force microscopy (AFM). Based on preliminary calculation of the average aggregation numbers, Rg and Rh values for these polymers, two-armed C60-anchored PAA revealed apparent primary intermolecular association which corresponds to the individual micelle-like aggregates, but eight-armed C60-anchored PAA still remained unimers in aqueous solution since hydrophobic/hydrophilic balance was easily achieved through intramolecular association. Moreover, AFM images also showed that the dimensions of the micelle-like aggregates comprising of two-armed C60-anchored PAA range from 10 to 60 nm. Finally, donor-acceptor nanoensembles were prepared via electrostatic interactions of multi-armed C60-anchored PAA and water-soluble porphyrin derivative (TMPyP). The fluorescence quenching efficiency monitored by PL studies for the two-armed C60-anchored PAA/TMPyP nanoensembles was a 2-fold increase than that for the eight-armed C60-anchored PAA/TMPyP nanoensembles. Such enhancement of the fluorescence quenching, observed for the two-armed C60-anchored PAA/TMPyP nanoensembles, implied that the electron transfer takes place intramolecularly as well as intermolecularly due to the unique micelle-like aggregation behavior of two-armed C60-anchored PAA.
Subjects
碳六十
紫質
原子轉移自由基聚合
光激發電子轉移
fullerene
polymer
porphyrin
ATRP
PET
Type
thesis
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