Fluorescence Study of the Coil−Globule Transition of a Poly(ε-caprolactone) Chain Labeled with Pyrenes at Both Ends

Piçarra, Susana; Gomes, Pedro T.; Martinho, J. M. G.

doi:10.1021/ma992106o

Cited by 49 publications

(72 citation statements)

References 29 publications

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“…In 1980, Winnik applied the Birks scheme to analyze the fluorescence decays of a series of pyrene end-labeled polystyrenes (Py 2 -PS) and retrieve k EEC quantitatively [79]. The procedure introduced by Winnik to determine k EEC was then expanded to numerous polymeric backbones such as polydimethylsiloxane [81,96,97], poly(bisphenol A-diethylene glycol carbonate) [84], poly(tetramethylene oxide) [86], or poly(ε-caprolactone) [94]. At about the same time, it was also realized that k EEC provided not only information about the EEC process, but maybe more importantly, also a measure of the long range internal dynamics of the polymer chain.…”

Section: Analysis Of the Kinetics Of Excimer Formation For Pyrene-labmentioning

confidence: 99%

Internal Dynamics of Dendritic Molecules Probed by Pyrene Excimer Formation

Duhamel

2012

Polymers

147

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Abstract:This review exposes the current poor understanding of the internal segmental chain dynamics of dendrimers in solution probed by monitoring the process of excimer formation between pyrene labels covalently attached to the chain ends of dendrimers. The review begins by covering the bases of fluorescence and the kinetics of pyrene excimer formation before describing a procedure based on the Model Free (MF) analysis that is used to analyze quantitatively the fluorescence decays acquired for dendrimers, the ends of which have been fully and covalently labeled with pyrene. Comparison of the various trends obtained by different research groups describing the efficiency of pyrene excimer formation with the generation number of dendrimers illustrates the lack of consensus between the few studies devoted to the topic. One possible reason for this disagreement might reside in the presence of minute amounts of unattached pyrene labels which act as potent fluorescent impurities and affect the analysis of the fluorescence spectra and decays in an uncontrolled manner. The review points out that the MF analysis of the fluorescence decays acquired with pyrene-labeled dendrimers enables one to account for the presence of unattached pyrene and to retrieve information about the internal segmental dynamics of the dendrimer. It provides guidelines that should enable future studies on pyrene-labeled dendrimers to yield results that are more straightforward to interpret.

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Section: Analysis Of the Kinetics Of Excimer Formation For Pyrene-labmentioning

confidence: 99%

Internal Dynamics of Dendritic Molecules Probed by Pyrene Excimer Formation

Duhamel

2012

Polymers

147

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“…Fluorescence spectroscopy is a powerful technique for studying microenvironment changes of isolated chains in solution and can be used to study the chain mobility and detect the CGT. [1,[14][15][16][17][18] Wu identified two intermediate states appearing above the y temperature, namely, the crumpled coil and molten globule Summary: The effect of salts on the conformational behavior of acenaphthylene labeled poly(N,N-diethylacrylamide) (PDEA/ACE) has been investigated in dilute aqueous solution using UV-vis and fluorescence spectroscopy. It is demonstrated here that the effectiveness of various salts in changing the lower critical solution temperature (T LCS ) of the PDEA/ ACE solution followed the Hoffmeister series.…”

Section: Introductionmentioning

confidence: 99%

The Effect of NaCl on the Conformational Behavior of Acenaphthylene Labeled Poly(N,N‐diethylacrylamide) in Dilute Aqueous Solution

Chen

Liu

Bian

et al. 2005

Macro Chemistry & Physics

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Summary: The effect of salts on the conformational behavior of acenaphthylene labeled poly(N,N‐diethylacrylamide) (PDEA/ACE) has been investigated in dilute aqueous solution using UV‐vis and fluorescence spectroscopy. It is demonstrated here that the effectiveness of various salts in changing the lower critical solution temperature (TLCS) of the PDEA/ACE solution followed the Hoffmeister series. The addition of NaCl linearly lowered the TLCS. In dilute aqueous solution, the PDEA/ACE adopted a loose coil conformation below its TLCS. The PDEA/ACE adopted a compact globule conformation above the temperature at which the coil to globule transition (CGT) was completed. A fluorescence anisotropy investigation suggested that a molten globule conformation existed during the CGT of the PDEA/ACE solution. In all of the above three conformations, the PDEA/ACE was more compact in the presence of NaCl than in the absence of any salt.

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“…This confirms that the incorporation of %2 mol-% of pyrene moieties along the chain does not significantly affect the solution properties of PNIPAM. Relevant reports by Martinho et al [19,21,81,82] and Winnik [83] also revealed that the incorporation of %1 -5 mol-% of pyrene units into PNIPAM chains does not result in discernible effects on their phase behavior.…”

Section: Resultsmentioning

confidence: 92%

“…This is also in agreement with the excimer fluorescence results for pyrene-labeled PNIPAM reported by Winnik. [83] Note that Martinho et al [19,21,81,89] also typically observed the decrease of I e /I m during equilibrium coil-to-globule transitions.…”

Section: Fluorescence Studies Of Pnipam-py-f 3 In Methanol/ Water MIXmentioning

confidence: 89%

“…For pyrene-labeled polymer chains, the latter is determined by the chain mobility and local pyrene concentrations. [86,87] Martinho and Duhamel et al [19,21,81,82] employed equilibrium excimer fluorescence to investigate the coil-toglobule transition thermodynamics of individual chains and a blob model was proposed accordingly. [86,87] The fluorescence technique enabled them to study the equilibrium collapsing transitions of short chains when labeled with appropriate fluorescent dyes.…”

Section: Fluorescence Studies Of Pnipam-py-f 3 In Methanol/ Water MIXmentioning

confidence: 99%

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Contraction and Collapsing Kinetics of Single Synthetic Polymer Chains at Small Quench Depths

Wang

et al. 2010

Macro Chemistry & Physics

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Chain contraction and collapsing kinetics of pyrene‐labeled poly(N‐isopropylacrylamide) (PNIPAM) single chains ($\overline {M} _{{\rm n}} $ = 3.64 × 105 g · mol−1, $\overline {M} _{{\rm w}} /\overline {M} _{{\rm n}} $ = 1.17) were investigated by employing the stopped‐flow technique coupled with fluorescence and light scattering detections, which can achieve millisecond jumping of solvent quality from good to above and below the θ‐solvent condition at small quench depths. It was found that the coil‐to‐crumpled globule transition proceeds via an isotropic one stage process and the obtained characteristic relaxation times exhibit a monotonic decrease with increasing quench depths. The obtained experimental results were in qualitative agreement with previous theoretical considerations. magnified image

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Fluorescence Study of the Coil−Globule Transition of a Poly(ε-caprolactone) Chain Labeled with Pyrenes at Both Ends

Cited by 49 publications

References 29 publications

Internal Dynamics of Dendritic Molecules Probed by Pyrene Excimer Formation

Internal Dynamics of Dendritic Molecules Probed by Pyrene Excimer Formation

The Effect of NaCl on the Conformational Behavior of Acenaphthylene Labeled Poly(N,N‐diethylacrylamide) in Dilute Aqueous Solution

Contraction and Collapsing Kinetics of Single Synthetic Polymer Chains at Small Quench Depths

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