A new glass-forming molecule having a fluorene skeleton: synthesis and conversion to the polymer with a low dielectric constant, high hydrophobicity and thermostability

2016 ◽  
Vol 7 (38) ◽  
pp. 5925-5929 ◽  
Author(s):  
Yuanqiang Wang ◽  
Jiajia Wang ◽  
Kaikai Jin ◽  
Jing Sun ◽  
Qiang Fang

A new glass-forming molecule having a fluorene skeleton and thermally cross-linkable trifluorovinyl-ether side chains is reported here.

1967 ◽  
Vol 167 (1009) ◽  
pp. 448-448 ◽  

For the first time we have been able to interpret the catalytic activity of an enzyme in stereochemical terms. It seems rash to generalize from the structure of one enzyme, but we may broaden our base by elevating myoglobin and haemoglobin to the rank of honorary enzymes, as Monod has suggested, and call the haem groups their active sites. What these three proteins have in common is the distribution of polar and nonpolar side chains; the interior of the lysozyme as well as that of the globin chains is made up largely of hydrocarbons, providing a medium of low dielectric constant. In each case the active centre lies in a pocket formed by this non-polar medium, and the pocket contains some polar residues which are essential for activity.


1999 ◽  
Vol 565 ◽  
Author(s):  
Y. Shimogaki ◽  
S. W. Lim ◽  
E. G. Loh ◽  
Y. Nakano ◽  
K. Tada ◽  
...  

AbstractLow dielectric constant F-doped silicon oxide films (SiO:F) can be prepared by adding fluorine source, like as CF4 to the conventional PECVD processes. We could obtain SiO:F films with dielectric constant as low as 2.6 from the reaction mixture of SiH4/N2 O/CF4. The structural changes of the oxides were sensitively detected by Raman spectroscopy. The three-fold ring and network structure of the silicon oxides were selectively decreased by adding fluorine into the film. These structural changes contribute to the decrease ionic polarization of the film, but it was not the major factor for the low dielectric constant. The addition of fluorine was very effective to eliminate the Si-OH in the film and the disappearance of the Si-OH was the key factor to obtain low dielectric constant. A kinetic analysis of the process was also performed to investigate the reaction mechanism. We focused on the effect of gas flow rate, i.e. the residence time of the precursors in the reactor, on growth rate and step coverage of SiO:F films. It revealed that there exists two species to form SiO:F films. One is the reactive species which contributes to increase the growth rate and the other one is the less reactive species which contributes to have uniform step coverage. The same approach was made on the PECVD process to produce low-k C:F films from C2F4, and we found ionic species is the main precursor to form C:F films.


2020 ◽  
Author(s):  
Vedanki ◽  
Chandrabhan Dohare ◽  
Pawan KumarSrivastava ◽  
Premlata Yadav ◽  
Subhasis Ghosh

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