Excimer fluorescence as a molecular probe of blend miscibility. 3. Effect of molecular weight of the host matrix

1981 ◽  
Vol 14 (2) ◽  
pp. 443-449 ◽  
Author(s):  
Steven N. Semerak ◽  
Curtis W. Frank
Keyword(s):  
Molecular Weight ◽  
Molecular Probe ◽  
Host Matrix ◽  
Excimer Fluorescence

Pyrene Fluorescence as a Molecular Probe of Miscibility in Organic/Inorganic Hybrid Nanocomposites Suitable for Microelectronic Applications

2002 ◽  
Vol 726 ◽  
Author(s):  
Q. R. Huang ◽  
David Mecerreyes ◽  
James L. Hedrick ◽  
Willi Volksen ◽  
Curtis W. Frank ◽  
...  
Keyword(s):  
Hybrid Nanocomposites ◽  
Molecular Probe ◽  
Excimer Fluorescence ◽  
Neat Polymer ◽  
Loading Level ◽  
Pyrene Fluorescence ◽  
Low Dielectric ◽  
Low Dielectric Constant Materials ◽  
Phase Separation Behavior ◽  
Separation Behavior

AbstractFluorescence spectroscopy has been used to study the miscibility of methyl silsesquioxane (MSSQ)/poly(methyl methacrylate-co-dimethylaminoethyl methacrylate) [P(MMA-co-DMAEMA)] hybrid nanocomposites, which are useful in fabricating the next generation of spin-on, ultra-low dielectric constant materials in the microelectronic industries. In this work, we have attached the pyrene group into the PMMA side chains. MSSQ with different amount of initial -SiOH (silanol) endgroups are used to study the effect of endgroup functionality on the phase separation behavior of the hybrid nanocomposites. Pyrene excimer fluorescence results reveal that MSSQ is miscible with P(MMA-co-DMAEMA) only up to 6 wt% P(MMA-co-DMAEMA) loading level, thus establishing an upper limit on local miscibility with MSSQ. As the P(MMA-co-DMAEMA) loading level increases, the excimer to monomer ratios also increase, suggesting that the MSSQ/P(MMA-co-DMAEMA) hybrid nanocomposites move toward greater immiscibility. This ratio approaches that of the neat polymer for domain sizes > 5 nm (SAXS, SANS). The fluorescence results also show that, the lower the amount of initial silanol groups in MSSQ, the greater the immiscibility of the MSSQ and porogen, which ultimately translates into larger pores upon porogen burnout.

Detection and neutralisation of heparin by a fluorescent ruthenium compound

2009 ◽  
Vol 102 (11) ◽  
pp. 859-864 ◽  
Author(s):  
Helga Szelke ◽  
Job Harenberg ◽  
Roland Krämer
Keyword(s):  
Molecular Weight ◽  
Point Of Care ◽  
Anticoagulant Activity ◽  
Molecular Probe ◽  
Low Molecular Weight ◽  
Serum Samples ◽  
Disease States ◽  
Ruthenium Compound ◽  
Low Sensitivity ◽  
Point Of Care Detection

SummaryHeparin and low-molecular-weight heparin (LMWH) are commonly monitored by determination of activated clotting times or chromogenic assays. Despite their wide use, these assays determine the biological activity and not the concentration of the anticoagulants. They may be inaccurate in some circumstances such as certain disease states. In addition, there is a significant interest in alternative tests for the point-of-care detection of heparin and LMWH. Their binding to small molecules for the detection in biological matrices is poorly explored. We describe here a new optical molecular probe for the detection of LMWH in serum samples. The polycationic ruthenium compound 1 is applicable to the quantification of heparin by monitoring 630 nm fluorescence. In addition, compound 1 is a rare example of a non-polymeric low molecular weight compound which neutralises the anticoagulant activity of heparin and LMWH in plasma samples. Limitation of the method is its low sensitivity currently being improved by structural modification of compound 1.

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