Process yields difunctional isobutylene polymers ranging in molecular weight from 1150 to 3600. These polymers have the potential for copolymerization and cross-linking with other monomers to form elastomeric materials

Midler, J. A., Jr.

English

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August 1970	 Brief 70-10334 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
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be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Difunctional Polyisobutylene Prepared by Polymerization 
of Monomer on Molecular Sieve 
A process has been devised for producing difunc-
tional polyisobutylene by polymerization of the iso-
butylene monomer on a molecular sieve catalyst. The 
new polymer is difunctional in that it has a double 
bond (unsaturated group) at each end of the hydro-
carbon chain. The process is relatively simple and can 
be easily controlled to yield difunctional isobutylene 
polymers (or prepolymers) ranging in molecular 
weight from 1150 to 3600. These polymers show a 
potential for copolymerization and cross-linking with 
other monomers to form new and useful elastomeric 
materials. 
Experimental quantities of the difunctional poly-
isobutylenes were prepared in a 300 ml flask equipped 
with a magnetic stirrer and a side filling tube which 
could be sealed to a vacuum manifold. In beginning 
a run, a weighed amount of molecular sieve granules 
having 5 A pores is placed in the flask and the system 
is degassed under vacuum (10 -4 to 10_6 torr), with 
intermittent heating to 100°C. The flask is then placed 
in a liquid nitrogen bath and a measured volume of 
reagent grade isobutylene is condensed onto the molec-
ular sieve. The contents of the flask are degassed at 
10 torr, quickly warmed to reaction temperature 
(at which isobutylene is liquid), and finally stirred at 
autogenous pressure for a given period. After distilla-
tion of excess isobutylene and other low-boiling frac-
tions from the flask, the molecular sieve is washed 
with pentane to dissolve the adsorbed polyisobutylene. 
The resultant solution is washed with water in a sep-
aratory funnel and dried over anhydrous magnesium 
sulfate. The solution is then decanted from the drying 
agent and evaporated at reduced pressure until the 
polymer appears. It is recovered as a clear, colorless, 
viscous liquid after final vacuum drying at 50°C. The 
molecular weight and percentage yield of the polyiso-
butylene were found to increase as the reaction period 
(contact time on the molecular sieve) increased or the 
temperature increased over the range from -141° to 
+35°C. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP70-10334 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. A. Midler, Jr. of 
Caltech/JPL 
under contract to 
NASA Pasadena Office 
(N P0-10893) 
Category 04 
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 owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000322 2020-03-17T00:42:48+00:00Z


Difunctional polyisobutylene prepared by polymerization of monomer on molecular sieve

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