Chemical grafting of silane end-functionalized polymer on silicon surfaces

1993 ◽  
Vol 304 ◽  
Author(s):  
A Karim ◽  
S. K. Satija ◽  
W. Orts ◽  
J. F. Ankner ◽  
C. F. Majkrzak ◽  
...  
Keyword(s):  
Concentration Profile ◽  
Polymer Concentration ◽  
Silicon Surfaces ◽  
Low Molecular Weight ◽  
Neutron Reflectivity ◽  
Exponential Behavior ◽  
Kinetics Of Adsorption ◽  
Chemical Grafting ◽  
Kinetics Of ◽  
Poor Solvent

AbstractX-ray and neutron reflectivity was used to determine the kinetics of adsorption and characterize the concentration profile of a low molecular weight trichlorosilane endfunctionalized polystyrene adsorbed onto polished silicon wafers. Higher adsorbed amounts were obtained from a cyclohexane solution of the polymer rather than toluene, with kinetics that followed a stretched exponential behavior. For moderately high grafting densities the polymer concentration profile in deuterated toluene (a good solvent) was best modelled using a small tailed parabola. In deuterated cyclohexane (a poor solvent) the brush profile steepened but was substantially smoother than a step, while in D20 (a non-solvent) it became step-like.

The Volume Fraction Profile of Terminally Adsorbed Polymers

1991 ◽  
Vol 248 ◽  
Author(s):  
R. J. Composto ◽  
T. Mansfield ◽  
G. Beaucage ◽  
R. S. Stein ◽  
D. R. Iyengar ◽  
...  
Keyword(s):  
Concentration Profile ◽  
Volume Fraction ◽  
Neutron Reflectivity ◽  
Similar Molecular Weight ◽  
Parabolic Profile ◽  
Grafting Density ◽  
Tethered Chains ◽  
Adsorbed Polymers ◽  
Unperturbed Dimension ◽  
Poor Solvent

AbstractWe have used neutron reflectivity to measure the concentration profile of carboxylic acid-terminated polystyrene at the liquid/solid interface. Two isotopic systems were studied: (1) deuterated polystyrene (DPS) in cyclohexane and (2) polystyrene (PS) in deuterated cyclohexane. Although measured at 24°C (a poor solvent condition), the high grafting density of PS tethered chains causes the chains to weakly stretch to 3-5 times its unperturbed dimension. Although of similar molecular weight, the height of the DPS layer is about 50% higher than that of the PS. In both systems, the volume fraction of polymer near the wall is ∼ 0.60. For the DPS system, reflectivity profiles can be simulated using a parabolic profile with a depletion layer at the silicon-liquid interface. However, in the PS system, no depletion is observed. Here, the shape. of the PS concentration profile is parabolic with a rounded tail.

Protamine Neutralization of the Release of Tissue Factor Pathway Inhibitor Activity by Heparins

1993 ◽  
Vol 70 (06) ◽  
pp. 0942-0945 ◽  
Author(s):  
Job Harenberg ◽  
Marietta Siegele ◽  
Carl-Erik Dempfle ◽  
Gerd Stehle ◽  
Dieter L Heene
Keyword(s):  
Tissue Factor ◽  
Binding Sites ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Xa ◽  
Protamine Sulfate ◽  
Low Molecular Weight ◽  
Factor X ◽  
Rebound Phenomenon ◽  
Tissue Factor Pathway ◽  
Kinetics Of

SummaryThe present study was designed to investigate the action of protamine on the release of tissue factor pathway inhibitor (TFPI) activity by unfractionated (UF) and low molecular weight (LMW) heparin in healthy individuals. 5000 IU UF-heparin or 5000 IU LMW-heparin were given intravenously followed by saline, 5000 U protamine chloride or 5000 U protamine sulfate intravenously after the 10 min blood sample. Then serial blood samples for the measurement of TFPI activity and anti-factor Xa- activity were taken, in order to detect a possible relation between the remaining anti-factor X a activity after neutralization of LMW-heparin with protamine and TFPI activity and to establish whether or not a rebound phenomenon of plasmatic TFPI occurs.There was no difference in the release and in the kinetics of TFPI by UF- and LMW-heparin with subsequent administration of saline. After administration of protamine TFPI activity decreased immediately and irreversibly to pretreatment values. There were no differences between protamine chloride and protamine sulfate on the effect of TFPI induced by UF- or LMW-heparin. No rebound phenomenon of TFPI activity occurred. In contrast anti-factor Xa- activity, as measured by the chromogenic S2222-assay, issued the known differences between UF- and LMW-heparin. The half-life of the aXa-effect of LMW-heparin was twice as long as of UF-heparin. Protamine antagonized UF-heparin completely and about 60% of the anti-factor Xa activity of LMW-heparin, using chromogenic S2222-method. No differences could be detected for protamine chloride and sulfate form of protamineIt is assumed that protamine displaces heparins from the binding sites of TFPI. There were no differences between UF- and LMW-heparin. The data indicate that the sustained antifactor Xa activity after antagonization of LMW-heparins as well as heparin rebound phenomena are not mediated by TFPI activity.

The kinetics of adsorption on fractals: A numerical experiment

2007 ◽  
Vol 1 (6) ◽  
pp. 685-691
Author(s):  
Yu. A. Kolbanovskii ◽  
I. V. Bilera ◽  
A. A. Borisov
Keyword(s):  
Numerical Experiment ◽  
Kinetics Of Adsorption ◽  
Kinetics Of

Closure to “Kinetics of Adsorption on Carbon from Solution”

1963 ◽  
Vol 89 (6) ◽  
pp. 53-55 ◽  
Author(s):  
Walter J. Weber ◽  
J. Carrell Morris
Keyword(s):  
Kinetics Of Adsorption ◽  
Kinetics Of
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