Excimer emission in protonated pyridine systems—5. Molecular weight dependence of dimer-like excimer and normal excimer fluorescence of poly(2-vinylpyridine) in solution in the presence of trifluoroacetic acid

Utena, Yoshio; Yajima, Hirofumi; Ishii, Tadahiro; Handa, Takashi

doi:10.1016/0014-3057(88)90129-2

Cited by 11 publications

(2 citation statements)

References 34 publications

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“…In a previous study we presented similar results for a shorter chain ( N = 25), and adding the present results, we have now a range of chain lengths, extending from oligomer to high polymer, for a discussion of molecular weight dependence. The influence of molecular weight on the fluorescence of polymers showing excimer emission has been studied in a number of systems. − Most of these studies refer just to stationary data (the excimer to monomer intensity ratio), and only very few report on decays as a function of molecular weight. Thus, the influence of chain length on kinetic data is still lacking, in general.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of molecular weight on the fluorescence of polymers showing excimer emission has been studied in a number of systems. [21][22][23][24][25][26][27][28][29][30][31] Most of these studies refer just to stationary data (the excimer to monomer intensity ratio), and only very few report on decays as a function of molecular weight. Thus, the influence of chain length on kinetic data is still lacking, in general.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of Linear Poly(methylphenylsiloxane) by Time-Resolved Fluorescence: Slow vs Fast Relaxations and Low-Temperature Behavior in Chains of Different Lengths

et al. 2002

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Three linear poly(methylphenylsiloxane) chains (PMPSN) with different number of skeletal bonds (N ) 82, 284, 1285) were studied by time-resolved fluorescence spectroscopy in the temperature range 20 to -60 °C. Fluorescence decays obtained for all the samples could be fitted only with sums of three exponential functions. Two different time regimes of excimer formation are detected in these polymers (the same as was previously obtained for a shorter oligomer, PMPS25). A fast relaxation, which is connected to unrestricted skeletal motions at the dyad level, and a slower relaxation, which is attributed to segmental chain rearrangements needed to release temporary isolated hindered monomers. The rate constants of the fast relaxation (k a ) 14-17 ns -1 , at 20 °C) are one order of magnitude larger than the rate constants of the slower relaxation (ku ) 1.2-1.6 ns -1 , at 20 °C), and the activation energies of this slow relaxation (Eu) are about 3 kcal mol -1 larger than the activation energies of the fast relaxation (Ea ) 2.0-2.2 kcal mol -1 ). These rate constants and activation energies are practically constant in all samples, which means that internal dynamics (local or segmental) is not affected by chain length. The fraction of temporary isolated hindered monomers at 20 °C (β ) 0.03) is also constant for all chain lengths, but its low-temperature behavior is systematically dependent on chain length. With decreasing temperature, β first decreases and then increases, the temperature for this trend reversal being higher the longer the chain. At still lower temperatures aggregation takes place, and this is also dependent on chain length.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamics of Linear Poly(methylphenylsiloxane) by Time-Resolved Fluorescence: Slow vs Fast Relaxations and Low-Temperature Behavior in Chains of Different Lengths

et al. 2002

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Complexation of polyacrylamide and poly(N‐isopropylacrylamide) with poly(acrylic acid). The temperature effect

Staikos

Karayanni

Mylonas

1997

Macro Chemistry & Physics

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SUMM A F~We present potentiometric and viscometric results on the interpolymer complexation between polyacrylamide (PAAM) and poly(N-isopropylacrylamide) (PNIPAAM) with poly(acry1ic acid) (PAA) in dilute aqueous solution. A potentiometric procedure for the determination of the complex stoichiometry in monomeric units has been proposed. The temperature dependence of the strength of the complexes formed has been investigated. From the results obtained it has been concluded that hydrogen bonding is the main factor stabilizing the PAAMRAA complex, strengthened by decreasing the temperature while the much stronger PNIPAAMPAA complex, strengthened by increasing the temperature, is stabilized by hydrophobic interaction.

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UV–VIS emission properties of poly(4-vinylpyridine) and its derivatives: Solid state ionization and quaternization of the pyridine rings

2006

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Excimer emission in protonated pyridine systems—5. Molecular weight dependence of dimer-like excimer and normal excimer fluorescence of poly(2-vinylpyridine) in solution in the presence of trifluoroacetic acid

Cited by 11 publications

References 34 publications

Dynamics of Linear Poly(methylphenylsiloxane) by Time-Resolved Fluorescence: Slow vs Fast Relaxations and Low-Temperature Behavior in Chains of Different Lengths

Dynamics of Linear Poly(methylphenylsiloxane) by Time-Resolved Fluorescence: Slow vs Fast Relaxations and Low-Temperature Behavior in Chains of Different Lengths

Complexation of polyacrylamide and poly(N‐isopropylacrylamide) with poly(acrylic acid). The temperature effect

UV–VIS emission properties of poly(4-vinylpyridine) and its derivatives: Solid state ionization and quaternization of the pyridine rings

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