Cross-linked polyphenylene oxides comprise the reaction product of alkyl halogenated phenylene oxide polymer and primary monoamines, such as methylamine, ethylamine, propylamine, butylamine and aniline. Such cross-linked polyphenylene oxide compositions are useful as membranes.

BACKGROUND OF THE INVENTION 
This invention relates to cross-linked polyphenylene oxide compositions. 
More particularly, it relates to such compositions where polyphenylene 
oxide chains are cross-linked with benzylamine bonding provided by 
reaction with a primary monoamine. 
The polyphenylene oxides are a body of thermoplastics disclosed in U.S. 
Pat. Nos. 3,306,874 and 3,306,875, incorporated herein by reference. They 
are characterized by a unique combination of chemical, physical and 
electrical properties over a temperature range of more than 600.degree. 
F., extending from a brittle point of minus 275.degree. F. to a heat 
distortion temperature of 375.degree. F. In particular, the polyphenylene 
oxides combine high tensile strength and tensile modulus with a high 
softening temperature, and excellent resistance to water, steam, strong 
acids and alkalies. 
Some polyphenylene oxides also exhibit exceptional transport properties 
making them useful as membranes for separation processes such as ion 
exchange, ultra filtration, reverse osmosis, pervaporation and even gas 
permeation. 
However, the polyphenylene oxides also have certain undesirable 
characteristics that are common to most thermoplastic materials. For 
example, their resistance to most common organic solvents is low. Aromatic 
and chlorinated hydrocarbon solvents dissolve phenylene oxide polymers, 
while other solvents and solvent vapors induce crazing in molded 
polyphenylene oxide parts under stress, causing loss of strength. The 
tensile properties of the resins decrease steadily with increasing 
temperature, and drop off sharply at about 200.degree. C. Further, under 
extreme prolonged stresss, molded parts formed from the polyphenylene 
oxides tend to creep, causing permanent deformation. 
It is known that these disadvantages which are common to most thermoplastic 
materials, may be overcome by cross-linking the individual polymer 
molecules during, or after, the forming of the material into its final 
shape. Thus, if a sufficient number of cross-linking sites are present, 
the material can be cross-linked and will then no longer be soluble, but 
only swell to a greater or lesser extent. Also, while the phenomenon of 
solvent crazing is not fully understood, it appears to involve 
crystallization of the polymer molecules. As the mobility of the polymer 
molecule is limited by cross-linking, crystallization is no longer 
possible, and thus the problem of solvent crazing is removed. The 
limitation on molecular mobility also prevents the polymer from flowing, 
even above its melting point, the preventing, to a large degree, creep and 
loss of tensile properties at increased temperature. 
The polyphenylene oxides are, to a high degree, chemically inert, a 
desirable characteristic from a materials standpoint. However, because of 
this inertness the prior art has experienced difficulty in introducing 
cross-links between polymer chains, and structurally different units 
generally, by simple chemical processes. For example, prolonged heating in 
air will render the polymer insoluble in aromatic or chlorinated 
hydrocarbon solvents, but the degree of cross-linking accomplished is 
quite low, and the materials produced swell to a considerable degree. 
Cross-linked polyphenylene oxides have been disclosed by Borman in U.S. 
Pat. No. 3,330,806 and by Schmukler in U.S. Pat. No. 3,406,147. Borman 
disclosed a cross-linkable polyphenylene oxide without the disadvantages 
of degradation and brittleness resulting from heat-induced cross-linking 
by introducing hydroxyl radicals into the polyphenylene oxide resin. The 
hydroxyl substituted polyphenylene oxide could then be cross-linked by 
reaction, for instance with a formaldehyde-releasing substance such as 
hexamethylenetetramine. Schmukler attempted to overcome deficiencies in 
cross-linked polyphenylene oxides by providing a plurality of side chain 
acyloxy groups on the polymer chain. Cross-linking could then be induced 
at elevated temperatures by aromatic substitution in the presence of a 
Lewis acid or by transesterification with a difunctional material reactive 
with the acyloxy group. A disadvantage of such cross-linked polyphenylene 
oxides as disclosed by Borman or Schmukler is that the cross-linked resin 
comprises by-products of the cross-linking reaction which are detrimental 
to the utility of such cross-linked resins for gas permeation purposes. 
Ward et al. in U.S. Pat. No. 3,780,496 disclose sulfonated polyxylelene 
oxide membranes for use in gas separations where the hydrogen ion form of 
the sulfonate substituent can be converted to a metal counter ion form. 
Ward et al. disclose that such membranes have some utility in gas 
separation. A principal disadvantage is that the presence of water can be 
detrimental in membrane formation. Accordingly, the preparation of such 
membranes in a water-based coagulating system is impractical. 
SUMMARY OF THE INVENTION 
The present invention provides a cross-linked phenylene oxide polymer 
composition comprising the reaction product of an alkyl halogenated 
phenylene oxide polymer and a primary monoamine. Preferred monoamines 
include methylamine, ethylamine, n-propylamine, n-butylamine and aniline. 
Preferred cross-linked phenylene oxide polymer compositions include the 
reaction product of brominated poly(2,6-dimethyl-1,4-phenylene oxide) and 
a primary monoamine where there are from 0.01 to 2.0 benzylic bromine 
atoms per phenylene oxide unit. Such cross-linked phenylene oxide polymer 
compositions have cross-linkage between phenyl groups represented by the 
structural formula --CH.sub.2 NRCH.sub.2 --, where R is methyl, ethyl, 
propyl, butyl or phenyl. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
This invention provides cross-linked phenylene oxide polymer compositions 
comprising the reaction product of an alkyl halogenated phenylene oxide 
polymer and a primary monoamine. The alkyl halogenated phenylene oxide 
polymer which is useful in such a cross-linked phenylene oxide polymer 
composition will generally have at least one alkyl group on each phenylene 
ring. The alkyl group can vary in size and may have from 1 to 3 carbon 
atoms or more. In most cases there will be two alkyl groups on each 
phenylene ring with both alkyl groups being in an ortho position with 
respect to the oxygen of the phenylene oxide. When there are more than one 
carbon atoms in the alkyl group attached to the phenylene ring the akly 
groups are preferably halogenated at the benzylic carbon atom which is 
that carbon atom of the alkyl group which is attached to the phenylene 
ring. The preferred halogens are chlorine and bromine. The preferred alkyl 
group attached to the phenylene ring is the methyl group. The most 
preferred alkyl halogenated phenylene oxide polymer is a brominated 
polymer of 2,6-dimethyl-1,4-phenylene oxide. 
In order for cross-linking reaction to occur between the alkyl halogenated 
phenylene oxide polymer and a primary monoamine it is not necessary that 
an active halogen atom be attached to each alkyl group of any polymer. In 
this regard it is often adequate for formation of the cross-linked 
phenylene oxide polymer composition that there be sufficient bromine atoms 
per phenylene oxide unit such that the cross-linking reaction can occur. 
In this regard haloalkyl substituted phenylene oxide polymer is useful in 
the cross-linking reaction when there are from 0.01 to 2.0 benzylic 
halogen atoms per phenylene oxide unit. Cross-linking reactions also 
readily occur when there are more than 2.0 benzylic halogen atoms per 
phenylene oxide unit. Preferably the alkyl halogenated phenylene oxide 
polymer will comprise from 0.01 to 2.0 benzylic bromine atoms per 
phenylene oxide unit of poly(2,6-dimethyl-1,4-phenylene oxide). More 
preferably there will be from about 0.2 to about 1.2 benzylic bromine 
atoms per phenylene oxide unit. 
The primary monoamines which are useful in forming the compound of this 
invention are non-sterically hindered such that they readily react in the 
cross-linking reaction. It is often desired that the primary monoamines 
have small hydrocarbon groups, such as lower alkyls having 6 or less 
carbon atoms or single aryl groups. Preferred monoamines having a lower 
alkyl group include methylamine, ethylamine, propylamines such as 
n-propylamine, and butylamines such as n-butylamine. A preferred monoamine 
having a single aryl group is aniline. Such monoamines may, of course, be 
substituted with non-reactive groups. 
The cross-linked phenylene oxide polymer compositions of this invention 
will have cross-linkage between phenylene groups represented by the 
structural formula --CHR'NRCHR'--, where R is a lower alkyl group selected 
from the group consisting of methyl, ethyl, propyl such as n-propyl, butyl 
such as n-butyl or a single aryl group such as phenyl, and where R' is 
hydrogen or a lower alkyl of less than 4 carbons. When the polymer 
composition of this invention is a cross-linked substituted polymer of 
2,6-dimethyl-1,4-phenylene oxide the cross-linkage between phenylene 
groups is represented by the structural formula --CH.sub.2 NRCH.sub.2 --. 
The cross-linked phenylene oxide polymer compositions of this invention are 
useful wherever it is desirable to utilize a polyphenylene oxide having 
resistance to organic solvents and improved physical properties. A 
preferred use for such cross-linked polyphenylene oxide polymer 
composition is as a membrane, for instance a selectively permeable gas 
separation membrane. Such membranes can be provided in either film or 
hollow fiber form. 
FORMATION OF HALOGENATED POLYPHENYLENE OXIDE 
A preferred method of forming the polyphenylene oxide precursor having 
halogenated alkyl groups substituents is to halogenated an alkylated 
polyphenylene oxide. Such alkylated polyphenylene oxides can comprise a 
poly(2,6-dialkyl-1,4-phenylene oxide), such as a 
poly(2,6-dimethyl-1,4-phenylene oxide). Halogenation of the alkyl group 
occurs generally at the benzylic carbon. 
The halogenation can be effected by addition of a halogen to a solution of 
the polyphenylene oxide in a solvent, for instance a halogenated solvent, 
such as chlorobenzene. The preferred halogenating agents include chlorine, 
bromine, chlorine-producing compounds and bromine-producing compounds. The 
halogenating agent is added to the solution of polyphenylene oxide under 
conditions to control halogenation. Halogenation will tend to occur by 
free radical reaction at higher temperatures. Under such free radical 
reaction halogen will be added to the benzylic carbon. Halogenation tends 
to occur by electrophilic substituion at lower temperatures. Under such 
electrophilic substitution the halogen is added to the aromatic ring. For 
instance, in the bromination of a solution of 
poly(2,6-dimethyl-1,4-phenylene oxide) in chlorobenzene by the addition of 
bromine, electrophilic substitution predominates at lower temperatures, 
for instance temperatures lower than about 80.degree. C., and free radical 
substitution predominates at higher temperatures, for instance under 
reflux conditions at temperatures of about 130.degree. C. Halogenation by 
both free radical substitution and electrophilic substitution can occur at 
intermediate temperatures. 
In some instances it may be desired to conduct halogenation under 
conditions under which free radical substitution predominates to produce a 
polyphenylene oxide precursor with halogen primarily on a benzylic carbon. 
In other instances it may be desirable to provide a polyphenylene oxide 
precursor with some halogen directly substituted onto the aromatic ring. 
Such halogen substituted onto the aromatic ring does not freely react in 
subsequent cross-linking operations but may provide desirable properties, 
for instance, for membrane gas separation. 
The halogenated polyphenylene oxide precursor can be recovered by 
precipitation in a non-solvent, for instance such as methanol. Other 
recovery steps include filtration washing with such non-solvent and drying 
for instance at elevated temperatures and reduced pressures. 
CROSSLINKING OF HALOGENATED POLYPHENYLENE OXIDE 
The halogenated polyphenylene oxide can be cross-linked before or after 
forming the halogenated polyphenylene oxide into a useful form. In many 
cases it is desirable to crosslink the preformed article of the 
halogenated polyphenylene oxide. The cross linking reaction can be 
effected with a primary monoamine as the cross-linking agent. The primary 
monoamine can be utilized either in gaseous form such as gaseous 
methylamine or in a liquid form, for instance as a solution such as a 
primary monoamine. Such solutions can be aqueous solutions of a primary 
monoamine or organic solutions of a primary monoamine. 
Cross-linking can be effected by any means of contacting the cross-linking 
agent with active halogen on the halogenated polyphenylene oxide membrane 
under conditions which do not deleteriously effect the preformed structure 
of the polymer. In the case of cross-linking with methylamine gas it is 
generally sufficient to expose the halogenated polyphenylene oxide 
membranes to the methylamine gas, for instance in a confined space. 
Exposure at mild conditions, for instance ambient temperature and 
atmospheric pressure, are often sufficient to effect adequate 
crosslinking. Cross-linking can be effected to a higher degree by 
employing more severe reaction conditions, for instance higher pressure 
and/or higher temperature. 
In the case of cross-linking of halogenated polyphenylene oxide membranes 
with solutions of a primary monoamine, for instance aqueous solutions of 
n-propylamine, effective cross-linking can often be obtained by simply 
soaking the halogenated polyphenylene oxide membrane in the solution for a 
reasonable time. Of course more extensive cross-linking can be effected by 
utilizing more severe reaction conditions, for instance higher 
temperatures.

The invention is further illustrated by, but not limited to, the following 
examples. 
EXAMPLE 1 
This example demonstrates the use of bromine as the brominating agent for a 
polyarylene oxide. 
250 g of poly(2,6-dimethyl-2,4-phenylene oxide) having an intrinsic 
viscosity of 0.508 dl/g, as measured in chloroform at 25.degree. C., was 
dissolved in 3,200 ml of chlorobenzene in a reactor consisting of a 5 
liter 3-neck Morton flask equipped with a mechanical stirrer, addition 
funnel and a condenser having an acid water trap. The solution was heated 
via oil bath to boiling and dried by removing 200 ml of distillate. To the 
boiling solution, 250 g of bromine was added over four hours. The solution 
was allowed to boil for an additional 30 minutes under a nitrogen sweep. 
After cooling, the solution was sprayed into 15 liters of methanol to 
precipitate the halogenated polymer. The halogenated polymer was collected 
on a filter, washed with methanol and dried at 50.degree. C. under reduced 
pressure. The yield was 339.5 grams (90 percent of theoretical). The 
halogenated polymer had a total bromine content of 31.4 percent by weight. 
Calculations from the integral curve of the proton magnetic resonance 
spectra of the halogenated polymer showed that bromine was substituted at 
benzylic carbons at a level of 0.6 bromine per phenylene oxide unit and 
that bromine was substituted into the aromatic ring at the level of 0.08 
bromine per phenylene oxide unit. 
EXAMPLE 2 
This example demonstrates the use of N-bromosuccinimide as the brominating 
agent. 
11.4 g of poly(2,6-dimethyl-1, 4-phenylene oxide), having an intrinsic 
viscosity of 0.50 dl/g, as measured in chloroform at 25.degree. C., was 
dissolved in 410 ml of chlorobenzene in a 500 ml 3-neck round bottom flask 
equipped with a mechanical stirrer, condenser having an acid water trap 
and a nitrogen inlet tube. Using an oil bath, the polymer solution was 
heated to 115.degree. C. 16.9 of N-bromosuccinimide were added. While 
under nitrogen, the reaction mixture was allowed to boil until bromine was 
no longer observed in the vapor phase over the reaction medium. After 
cooling to ambient temperature, the reaction mixture was filtered and the 
product precipitated in methanol. The halogenated polymer was collected, 
washed with methanol and air dried on the filter. The halogenated polymer 
was dissolved in 120 ml chloroform and reprecipitated in methanol. 
Finally, the halogenated polymer was dried four days at 50.degree. C. in a 
vacuum oven. The yield was 12.0 g (63 percent theoretical). The total 
bromine content of the halogenated polymer was 36.8 percent by weight. 
Calculations based on the integral curve of the nuclear magnetic resonance 
spectra showed that the halogenated polymer was substituted with bromine 
at the benzylic carbon at a level of 0.65 bromine per phenylene oxide unit 
and substituted with bromine at the aromatic ring at a level of 0.22 
bromine per phenylene oxide unit. 
EXAMPLE 3 
This example demonstrates a general procedure for introducing bromine at 
both the aryl and benzylic position of PPO a polyarylene oxide. 
30 g of poly(2,6-dimethyl-1,4-phenylene oxide) having an intrinsic 
viscosity of 0.508 dl/g, as measured in chloroform at 25.degree. C., was 
dissolved in 450 ml of chlorobenzene in a reactor consisting of a 1000 ml 
3-neck round bottom flask equipped with an addition funnel, a mechanical 
stirrer and a condenser having an acid water trap and a thermometer. 
Bromine was substituted into the polymer principally at the aromatic ring 
(aryl bromination) by adding 42 g of bromine over 15 minutes while the 
solution was maintained at 66-72.degree. C. The aryl brominated polymer 
solution was heated to reflux, at a temperature of about 130.degree. C. 
Under reflux, a condition favorable to benzylic bromination, 22 g of 
bromine was added over 30 minutes. After reflux for 10 minutes, about 20 
percent of the solvent was distilled from the reaction solution. The 
solution was cooled and the halogenated polymer precipitated in methanol. 
The halogenated polymer was washed with methanol and dried at 55.degree. 
C. for five days in a vacuum oven. The yield was 61.5 g (99 percent of 
theoretical). The halogenated polymer had a total bromine content of 49.3 
percent by weight. Calculations based on nuclear magnetic resonance 
analysis showed that the halogenated polymer was substituted with bromine 
at benzylic carbon at a level of 0.88 bromine per phenylene oxide unit and 
substituted with bromine in the aromatic ring at a level of 0.56 bromine 
per phenylene oxide unit. That is, the benzylic halogen level was 0.88 and 
the aryl halogen level was 0.56. 
EXAMPLE 4 
This example demonstrates an alternate method of preparing an aryl-benzylic 
brominated polyarylene oxide as well as the importance of reaction 
temperature on bromine distribution in the product. 
In this example, 30 g of poly(2,6-dimethyl-1,4-phenylene oxide) having a 
weight average molecular weight, Mw, of 49,000 was dissolved in 450 ml 
chlorobenzene in a reactor consisting of a 1000 ml 3-neck round bottom 
flask equipped as in Example 3. The solution was heated to 115.degree. C. 
40 g of bromine was added over 20 minutes. The solution was kept at 
115.degree. C. for an additional 30 minutes, then cooled to room 
temperature. The halogenated polymer was precipitated in methanol, washed 
with methanol and dried at 50.degree. C. in a vacuum oven. The yield was 
48.7 g (97.4 percent of theoretical). The halogenated polymer had total 
bromine content of 38.98 percent by weight. Nuclear magnetic resonance 
showed that the halogenated polymer had a benzylic halogen level of 0.38 
and an aryl halogen level of 0.6. 
EXAMPLES 5-10 
These examples illustrate the flexibility in introducing bromine at various 
levels at the aryl and benzylic positions of a polyarylene oxide. 
Aryl brominated poly(2,6-dimethyl-1,4-phenylene oxide) was produced as in 
Example 3. Benzylic halogenation was also carried out as in Example 3 
except that the amount of bromine added to the aryl brominated polymer 
solution at reflux was varied. The variations in benzylic halogenation are 
illustrated in Table I. 
TABLE I 
__________________________________________________________________________ 
Bromine 
Grams of Br.sub.2 Added to Distribution/ 
Aryl Brominated Polymer 
Yield Bromine 
Arylene Unit 
Example 
Solution at Reflux 
(g) 
(% theoretical) 
(Wt %) 
Aryl 
Benzylic 
__________________________________________________________________________ 
5 4.0 53 
100 42.6 0.92 
0.19 
6 10.0 54 
96 44.7 0.90 
0.30 
7 16.0 56 
95 46.7 0.89 
0.41 
8 34.0 67 
99 52.9 0.91 
0.75 
9 42.0 72 
100 55.4 0.90 
0.94 
10 54.5 77 
98 58.3 0.89 
1.18 
__________________________________________________________________________ 
EXAMPLE 11 
This example illustrates a procedure for forming hollow fiber membranes of 
brominated polyarylene oxide. 
Brominated polyarylene oxide was prepared from 
poly(2,6-dimethyl-1,4-phenylene oxide). The brominated polyarylene oxide 
had a bromine content of 31.1 percent by weight and had a benzylic bromine 
level of 0.58 and an aryl bromine level of 0.10. The brominated polymer 
had a weight average molecular weight of about 86,000 and a number average 
molecular weight of about 43,000. A spinning solution was prepared and 
consisted of about 37 percent by weight of the brominated polymer and 63 
percent by weight of a liquid carrier consisting of 95 percent by weight 
of N-formylpiperidine, 2 percent by weight acetic acid and 3 percent by 
weight acetic anhydride. The spinning solution was prepared by mixing for 
four hours to completely dissolve the brominated polymer. The brominated 
polymer solution was allowed to deaerate at room temperature for about 18 
hours. 
The deaerated brominated polymer solution was heated to about 
46.degree.-48.degree. C. and pumped to a tube-in-orifice-type spinnerette 
having an orifice diameter of 508 microns, an injection tube outside 
diameter of 229 microns and an injection tube inside diameter of 152 
microns. The spinnerette was maintained at a temperature of approximately 
47.degree. C. by the use of an external electrical heating jacket. 
Deionized water at ambient temperatures was fed to the injection tube at a 
rate sufficient to maintain the hollow fiber shape, about 1.7 milliliters 
per minute. The nascent hollow fiber was extruded at a rate of about 36.6 
meters per minute through an air gap of about 10.2 centimeters into a 
coagulation bath containing running tap water. The coagulation bath was 
maintained at a temperature of about 9.degree. C. The nascent hollow fiber 
passed vertically downward into the coagulation bath for a distance of 
about 17 centimeters, around a roller to a slightly upwardly slanted path 
through the coagulation bath and then exited from the coagulation bath. 
The distance of immersion in the coagulation bath was about 1 meter. 
The hollow fiber from the coagulation bath was then washed with running tap 
water in three sequential baths having Godet rolls. In each bath, the 
hollow fiber was immersed for a distance of about 10 to 13 meters. The 
first bath was maintained at a temperature of about 8.degree. C., while 
the second and third baths were at 26.degree. C. The wet hollow fiber had 
an outside diameter of about 680 microns and an inner diameter of about 
280 microns. 
The hollow fiber, while being maintained wet with water, was wound on a 
bobbin using a Leesona winder. The bobbin was stored in a vessel 
containing running tap water for about 24 hours and then stored in tap 
water at about ambient temperature for about 4 to 5 days. The hollow 
fiber, while being maintained wet, was wound on a skeiner to form hanks of 
hollow fibers. The hanks of hollow fiber were hung vertically and are 
allowed to air dry at ambient temperature for about five days. The dried 
hollow fiber had an outside diameter of about 620 microns and an inner 
diameter of about 255 microns. 
A test bundle of 6 to 8 hollow fiber membranes each of about 12 centimeters 
in length, was prepared. At one end, the test bundle was embedded in epoxy 
to form a cylindrical tube sheet through which the bores of the hollow 
fibers communicate. The other end was plugged with epoxy. 
EXAMPLE 12 
This example illustrates a procedure for preparing a cross-linked phenylene 
oxide polymer composition comprising the reaction product of a benzyl 
brominated poly(2,6-dimethyl-1,4-phenylene oxide) and methylamine. The 
cross-linked composition was prepared from a preformed hollow fiber 
membrane of the benzyl brominated phenylene oxide polymer. 
A test bundle of hollow fiber membranes prepared in Example 11 was immersed 
for seven days in a 10 percent by volume aqueous solution of methylamine 
at 23.degree. C. The bundle was soaked for 24 hours in deionized water at 
80.degree. C. to remove excess methylamine. The bundle was dried for 22 
hours at 80.degree. C. The bundle of hollow fiber membranes was analyzed 
for permeation properties. 
The utility of the methylamine cross-linked benzylbrominated 
poly(2,6-dimethyl-1,4-phenylene oxide) as a gas separation membrane was 
shown by determination of gas permeabilities and separation factors. These 
permeation properties were determined using gas mixtures in an elongated 
cylindrical chamber of about 150 cc. The gas mixtures were fed to the 
chamber to contact the outer surface of the hollow fiber membranes at 
pressures in a range of 10 to 100 psig. The gas mixtures passed through 
the chamber at a flow rate in the range of one to six liters per minute. 
The bores of the hollow fibers were under vacuum for about 5 to 10 minutes 
until the permeation reached equilibrium. Permeabilities were determined 
by allowing permeate gas to expand into a calibrated volume over a period 
of time. The permeate gas samples were then subjected to analysis. The 
permeability, (P/l), is expressed in units of GPU which is 10.sup.-6 
cm.sup.3 (STP)/cm.sup.2 -sec-cmHg. The hollow fibers exhibited a 
permeability for hydrogen, (P/l)H.sub.2, of 125 GPU and a separation 
factor of hydrogen over methane, .alpha..sub.CH.sbsb.4.sup.H.sbsp.2, of 
5.8 
EXAMPLE 13 
This example illustrates a procedure for preparing a cross-linked phenylene 
oxide polymer composition comprising the reaction product of a benzyl 
brominated poly(2,6-dimethyl-1,4-phenylene oxide) and n-butylamine. The 
cross-linked composition was prepared from a preformed hollow fiber 
membrane of the benzyl brominated phenylene oxide polymer. 
The hollow fiber membranes prepared in Example 11 were soaked for 331/2 
hours in an aqueous solution of 5 percent by volume n-butylamine. The 
solution was maintained at 80.degree. C. The fibers were soaked in water 
at 80.degree. C. for 38 hours to remove excess amine. The fibers were 
dried for 23 hours at 80.degree. C. The cross-linked polymer was not 
soluble in solvents for the precursor brominated phenylene oxide polymer. 
The hollow fiber membranes of the cross-linked polymer were analyzed for 
permeation properties as in Example 12. The membranes exhibited a 
permeability for hydrogen, (P/l)H.sub.2, of 140 GPU and a separation 
factor for hydrogen over methane, .alpha..sub.CH.sbsb.4.sup.H.sbsp.2, of 
21. 
EXAMPLE 14 
This example illustrates a procedure for preparing a cross-linked phenylene 
oxide polymer composition comprising the reaction product of a benzyl 
brominated poly(2,6-dimethyl-1,4-phenylene oxide) and aniline. The 
cross-linked composition was prepared from a preformed hollow fiber 
membrane of the benzyl brominated phenylene oxide polymer. 
The hollow fiber membranes prepared in Example 11 was 331/2 hours in a 
solution of 5 percent by volume aniline in an aqueous mixture of 20 
percent by volume methanol. The solution was maintained at 80.degree. C. 
The fibers were soaked in an aqueous solution of 20 percent by volume 
methanol for 38 hours to remove excess aniline. The fibers were dried at 
80.degree. C. for 23 hours. The cross-linked polymer was not soluble in 
solvents for the precursor brominated phenylene oxide polymer. 
The hollow fiber membranes of the cross-linked polymer were analyzed for 
permeation properties as in Example 12. The membranes exhibited a 
permeability for hydrogen, (P/l)H.sub.2, of 41 GPU and a separation factor 
for hydrogen over methane, of .alpha..sub.CH.sbsb.4.sup.H.sbsp.2, of 50. 
The foregoing description of embodiments of this invention is not intended 
to be a limitation to the scope of this invention. As will be apparent to 
those skilled in the art, many variations and modifications can be made to 
the compositions of this invention as described in the above embodiments 
without departing from the spirit and scope of this invention.