Hydroxy-terminated perfluoroethers and polyurethane resins derived from ethers have outstanding chemical resistance and good thermal properties. They can be used as potting compounds, coatings, and seals. The hydroxy-terminated ethers serve as intermediates in the synthesis of highly fluorinated elastomers and adhesives

Rochow, S. E.

Stump, E. C., Jr.

English

NASA Technical Reports Server

September 1970	 Brief 70-10353 
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Preparation of Highly Fluorinated Diols Containing Ether Linkages 
Ll
New hydroxy-terminated perfi uoroethers and poly-
urethane resins derived from ethers possess out-
standing chemical resistance and good thermal 
properties, and can be used in numerous industrial 
applications as potting compounds, coatings, and 
seals. The hydroxy-terminated ethers are also useful 
as intermediates in the synthesis of highly fluorine 
substituted elastomers and adhesives. 
Basically, the precursor materials are prepared by 
the reaction of perfluorinated diacid fluorides with 
hexafluoropropylene epoxide in the presence of a 
suitable catalyst, such as cesium fluoride. The pre-
cursors constitute a fraction of the products obtained 
from the reaction. A specific example of forming the 
precursors involves the reaction of hexafluoropropy-
lene oxide with perfluoroglutaryl fluoride in the pres-
ence of cesium fluoride and a suitable solvent. 
The precursor acid fluoride-terminated ethers are 
converted-to diols by reaction with a reducing agent 
such as an.alkali metal borohydride or an aluminum 
hydride. Reduction takes place in the presence of an 
inert solvent such as dioxane or diethylene glycol di-
methyl ether. The diacid fluoride starting material 
is usually added by drops to the solution of the solvent 
and reducing agent. The temperature at which the re-
duction is carried out is not critical. Normally the 
reactants are heated to a temperature not in excess 
of the boiling temperature of the solvent. The re-
actants are stirred during the reaction for a period 
up to three hours, after which water is added to 
remove any excess borohydride present. This step is 
followed by a separation of the diols from solution.
The diols produced can then be used in reactions 
with suitable diisocyanates to form new polyurethanes. 
Any diisocyanate conventionally used to produce 
polyurethane resins is suitable. These include toluene 
diisocyanate and mixtures of its isomers such as the 2, 
4 and 2, 6 isomers, as well as diphenylmethane-4, 4-
diisocyanate. It is particularly desirable to use a diiso-
cyanate selected to give a maximum number of flu-
orine atoms, such as tetrafluoro-m-phenylene diisocy-
anate, tetrafluoro-p-phenylene diisocyanate, perfluo-
rotrimethylene ¼iiisocyanate, l-chloro-2, 4-diisocyanate 
-3, 5, 6-trifluorobenzene and similar compounds; the 
extremely good thermal properties and nonflamma-
bility of the diols can be attributed to the presence 
of fluorine atoms in the polymer chains. 
The resultant polymers range from sticky semi-
solids to tough, brittle sheets depending upon the 
amount of diisocyanate used in the extension and cross-
linking reaction between it and the diols. Although the 
hardness of the resultant polymers increases with the 
increasing ratio of diisocyanate to diol, the glass tem-
perature of the resultant polyurethanes is not ad-
versely affected. A mole ratio of diisocyanate to diol 
from 1:1 up to 3:1 may be used. The preferred mole 
ratio range is from 1:1 to 2:1. 
The time and temperature of the polymerization 
reaction are dependent upon the molecular weight of 
the prepolymer and type of diisocyanate used. Com-
pletion of polymerization for the given diol-diisocy-
anate can be determined by the increase in viscosity 
of the melt polymer. Generally the temperature of 
curing can vary from 25° to 100°C, while the time of 
the cure can range from 10 to 30 minutes.
(continued overkat) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United 'States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19700000341 2020-03-17T00:41:44+00:00Z
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B70-10353
Patent status: 
This invention is owned by NASA, and a patent

application has been filed. Royalty-free, nonexclusive

licenses for its commercial use will be granted by

NASA. Inquiries concerning license rights should be

made to NASA, Code GP, Washington, D.C. 20546.

Source: E. C. Stump, Jr., and S. E. Rochow of

Peninsular ChernResearch, Inc.

under contract to

NASA Pasadena Office

(NPO- 10768) 
Brief 70-10353	 Category 04


Preparation of highly fluorinated diols containing ether linkages.

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