Fluorescence probes for polymer free-volume

A series of fluorescence probes (p-(N,N-dialkylamino) benzylidene malononitriles) which belong to a class of organic compounds known as “molecular rotors” has been developed. The internal molecular rotation of these compounds can be slowed down by increasing the surrounding media rigidity, viscosity or decreasing the free-volume available for molecular relaxation. Inhibition of internal molecular rotation of the probe leads to a decrease in the non-radiative decay rate and consequently enhancement of fluorescence. This behavior can be used to study both the static and dynamic changes in free-volume of polymers as a function of polymerization reaction parameters, molecular weight, stereo regularity, crosslinking, polymer chain relaxation and flexibility. In addition, the dependence of the fluorescence emission maximum of these probes on media polarity allow continuous monitoring of the probes location in the polymer matrix. These fluorescence materials are capable of simultaneously probing the flexibility and polarity of the surrounding media.

[1]  R. Loutfy,et al.  Spectroscopy of dyes in polymer matrixes: dual fluorescence of p-[(dialkylamino)benzylidene]malononitrile , 1981 .

[2]  R. Humphry-Baker,et al.  Drastic fluorescence enhancement and photochemical stabilization of cyanine dyes through micellar systems , 1980 .

[3]  Rafik O. Loutfy,et al.  Effect of viscosity and temperature on torsional relaxation of molecular rotors , 1982 .

[4]  Rafik O. Loutfy,et al.  Electrochemistry and spectroscopy of intramolecular charge-transfer complexes. p-N,N-Dialkylaminobenzylidenemalononitriles , 1980 .

[5]  J. Jaraudias.  Dependence on the viscosity and the nature of the solvent of the relaxation pathways of the first singlet excited state of 3,3′-Diethyloxadicarbocyanine iodide , 1980 .

[6]  H. Morawetz.  Some Applications of Fluorimetry to Synthetic Polymer Studies , 1979, Science.

[7]  Arthur K. Doolittle,et al.  Studies in Newtonian Flow. II. The Dependence of the Viscosity of Liquids on Free‐Space , 1951 .

[8]  R. Loutfy.  High-conversion polymerization of fluorescence probes. 1. Polymerization of methyl methacrylate , 1981 .

[9]  M. A. Gashgari,et al.  Excimer fluorescence as a molecular probe of blend miscibility. 4. Effect of temperature in solvent casting , 1981 .

[10]  M. Winnik,et al.  The Dynamics of End-to-End Cyclization in Polystyrene Probed by Pyrene Excimer Formation , 1980 .

[11]  G. Johnson.  Intramolecular excimer formation in 1,3‐bis(N‐carbazolyl)propane: Solvent viscosity effects , 1975 .

[12]  G. Oster,et al.  Fluorescence and Internal Rotation: Their Dependence on Viscosity of the Medium1 , 1956 .

[13]  R. Loutfy.  Fluorescence probes for polymerization reactions: Bulk polymerization of styrene, n‐butyl methacrylate, ethyl methacrylate, and ethyl acrylate , 1982 .

[14]  K. Kobs,et al.  Rhodamine B and rhodamine 101 as reference substances for fluorescence quantum yield measurements , 1980 .

[15]  F. Bueche.  Segmental Mobility of Polymers Near Their Glass Temperature , 1953 .

[16]  Arthur K. Doolittle,et al.  Studies in Newtonian Flow. III. The Dependence of the Viscosity of Liquids on Molecular Weight and Free Space (in Homologous Series) , 1952 .

[17]  R. Landel,et al.  The Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-Forming Liquids , 1955 .

[18]  H. Fujita,et al.  Concentration and temperature dependence of diffusion coefficients for systems polymethyl acrylate and n-alkyl acetates , 1960 .