U.S. patent application number 08/913654 was filed with the patent office on 2002-08-01 for polymer electrolytes and process for their production.
Invention is credited to CLAUB, JOACHIM, DECKERS, GREGOR, SCHNELLER, ARNOLD, WITTELER, HELMUT.
Application Number | 20020103327 08/913654 |
Document ID | / |
Family ID | 26013531 |
Filed Date | 2002-08-01 |
United States Patent
Application |
20020103327 |
Kind Code |
A1 |
CLAUB, JOACHIM ; et
al. |
August 1, 2002 |
POLYMER ELECTROLYTES AND PROCESS FOR THEIR PRODUCTION
Abstract
Polymer electrolytes and process for their preparation A
sulfonated aromatic polyether ketone of the formula (II)
[Ar--O--Ar'--CO--Ar'--O--Ar--CO--Ar"--CO--] (II) in which from 1%
to 100% of the O-phenylene-CO units are substituted with an
SO.sub.3M group and sulfonated and unsulfonated O-phenylene-CO
units can be in any desired sequence with respect to one another,
the radicals Ar, Ar' and Ar" independently of one another are
substituted or unsubstituted 1,2-, 1,3- or 1,4-phenylene rings, and
M, taking into account the ionic valencies, comprises one or more
elements selected from the following group: H, NR.sub.4.sup.+,
where R is H or C.sub.1-C.sub.4-alkyl, or an alkali metal or
alkaline earth metal or a metal from subgroup 8, and is preferably
H, NR.sub.4.sup.+, Li, Na, K, Ca, Mg, Fe or Pt.
Inventors: |
CLAUB, JOACHIM; (FRANKFURT,
DE) ; DECKERS, GREGOR; (FRANKFURT, DE) ;
SCHNELLER, ARNOLD; (MESSEL, DE) ; WITTELER,
HELMUT; (FRANKFURT, DE) |
Correspondence
Address: |
FROMMER LAWRENCE & HAUG
745 FIFTH AVENUE- 10TH FL.
NEW YORK
NY
10151
US
|
Family ID: |
26013531 |
Appl. No.: |
08/913654 |
Filed: |
September 18, 1997 |
PCT Filed: |
March 5, 1996 |
PCT NO: |
PCT/EP96/00925 |
Current U.S.
Class: |
528/125 ; 521/27;
521/28; 525/328.5; 525/471; 525/535; 528/128; 528/175; 528/226;
528/229; 528/28; 528/373; 528/391 |
Current CPC
Class: |
C08G 61/12 20130101;
C08G 65/48 20130101; Y02E 60/10 20130101; H01M 8/1067 20130101;
H01M 8/1081 20130101; H01M 8/1072 20130101; B01D 71/52 20130101;
C08G 61/127 20130101; Y02E 60/50 20130101; H01M 8/1025 20130101;
Y02P 70/50 20151101 |
Class at
Publication: |
528/125 ;
528/128; 528/175; 528/226; 528/229; 528/373; 528/391; 525/328.5;
525/471; 525/535; 521/27; 528/28; 521/28 |
International
Class: |
C08J 005/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 20, 1995 |
DE |
19510027.1 |
Dec 7, 1995 |
DE |
19545643.2 |
Claims
1. A sulfonated aromatic polyether ketone of the formula (II)
[Ar--O--Ar'--CO--Ar'--O--Ar--CO--Ar"--CO--] (II) in which from 1%
to 100% of the O-phenylene-CO units are substituted with an
SO.sub.3M group and sulfonated and unsulfonated O-phenylene-CO
units can be in any desired sequence with respect to one another,
the radicals Ar, Ar' and Ar" independently of one another are
substituted or unsubstituted 1,2-, 1,3- or 1,4-phenylene rings, and
M, taking into account the ionic valencies, comprises one or more
elements selected from the following group: H, NR.sub.4.sup.+,
where R is H or C.sub.1-C.sub.4-alkyl, or an alkali metal or
alkaline earth metal or a metal from subgroup 8, and is preferably
H, NR.sub.4.sup.+, Li, Na, K, Ca, Mg, Fe or Pt.
2. A process for the preparation of a polyether ketone of the
formula (II) in which Ar, Ar' and Ar" are as defined in claim 1 by
dissolving the corresponding unsulfonated polyether ketone of the
formula (II) in from 94 to 97% strength by weight sulfuric acid,
adding a sulfonating agent to the solution thus obtained, at an
appropriate temperature, and working up the reaction mixture as
soon as the desired degree of sulfonation has been reached, and, if
desired, converting the sulfonic acid groups into their salt
form.
3. The process as claimed in claim 2, wherein the dissolution
temperature is in the range from 10 to 80.degree. C.
4. The process as claimed in claim 2, wherein the sulfonation
temperature is in the range from 10 to 100.degree. C.
5. The process as claimed in claim 2, wherein following addition of
the sulfonating agent the temperature of the solution is at least
30.degree. C.
6. The process as claimed in claim 2, wherein the sulfonating agent
used is sulfuric acid, fuming sulfuric acid, oleum, chlorosulfonic
acid, sulfur trioxide or a mixture of these compounds.
7. The process as claimed in claim 2, wherein oleum is added to the
polyether ketone, dissolved in sulfuric acid, until the
concentration of sulfuric acid is from 98 to 100% by weight or the
concentration of oleum is from 0.01 to 15% by weight of
SO.sub.3.
8. The process as claimed in claim 2, wherein a polyether ketone of
the formula (I) is dissolved in from 95 to 97% strength by weight
sulfuric acid at not more than 80.degree. C. and is sulfonated at
temperatures of from 50 to 100.degree. C.
9. A process for the preparation of a sulfonated polyether ketone
by dissolving the polyether ketone in from 94 to 97% strength by
weight sulfuric acid, sulfonating the polyether ketone in sulfuric
acid, fuming sulfuric acid, oleum, chlorosulfonic acid or a mixture
thereof and working up the reaction mixture as soon as the desired
degree of sulfonation has been reached, wherein from 1 to 100% of
the O-phenylene-CO units are substituted with an SO.sub.3M
group.
10. A polymer electrolyte solution comprising a sulfonated aromatic
polyether ketone of formula (II).
11. The polymer electrolyte solution as claimed in claim 10, which
comprises at least 1% by weight of sulfonated polyether ketones of
the formula (II).
12. The polymer electrolyte solution as claimed in claim 10, whose
principal constituent is an aprotic dipolar solvent, for example
N-methylpyrrolidone or dimethyl sulfoxide.
13. The polymer electrolyte solution as claimed in claim 10, which
comprises a further, sulfonated or unsulfonated polymer and, if
desired, small quantities of auxiliaries.
14. The use of a polymer electrolyte solution as claimed in claims
10 to 13 for preparing asymmetric membranes, for example for nano-,
ultra- or microfiltration.
15. The use of a polymer electrolyte solution as claimed in claims
10 to 13 for preparing cohesive films.
16. The use of a polymer electrolyte solution as claimed in claims
10 to 13 for establishing particularly intensive contact between
two polymer electrolyte surfaces.
17. The use of a polymer electrolyte solution as claimed in claims
10 to 13 for achieving a porous or rough surface after contacting
the solution with a precipitating agent.
18. The use of a polymer as claimed in claim 1 for preparing a
polymer electrolyte solution and/or for preparing a polymer
film.
19. The use of a polymer as claimed in claim 1 and/or 18 in
electrochemical cells.
20. The use as claimed in claim 19, wherein the electrochemical
cell is a fuel cell or an electrolyzer.
21. A film having a thickness of from 5 .mu.m to 1 mm, which
comprises a polyether ketone as claimed in claim 1.
Description
[0001] The invention relates to polymer electrolytes which consist
of a sulfonated aromatic polyether ketone, to a process for their
preparation, to the use of these polymer electrolytes, and to
solutions of these polymer electrolytes and the use thereof.
[0002] Sulfonated polyether ketones constitute cationic ion
exchangers. They are useful as membrane materials, for example for
ultrafiltration, for desalination and for the removal of
microorganisms, since in many cases they are mechanically stable
even in the presence of water. Sulfonated polyether ketones are
proton- and cation-conducting materials which are useful for
electrodialysis or as a component of electrochemical cells.
[0003] The starting material is the aromatic polyether ketone
indicated in formula (I). The polymer is available commercially
under the name Ultrapek. 1
[0004] Polyether ketones are readily accessible. They can be built
up in principle by electrophilic Friedel-Crafts polycondensation,
in which a corresponding aromatic bis-acid dihalide is reacted with
an aromatic ether. This possibility is set out, for example, in
U.S. Pat. No. 3,065,205, GB-971 227, U.S. Pat. No. 3,441,538, GB-1
387 303 and WO 84-03 891 and in the paper by Iwakura, Y., Uno, K.
and Tahiguchi, T. J., Polym. Sci., Pat. A-1, 6, 3345 (1968). In
addition, the ether ketones can be obtained by nucleophilic
aromatic substitution. For this purpose an appropriate aromatic
bisdiol is reacted with an aromatic bishalo ketone, as described
for example in: R. A. Clendinning, A. G. Farnham, W. F. Hall, R. N.
Johnson and C. N. Merriam, J. Polym. Sci. A1, 5, 2375, (1967), GB-1
177 183, GB-1 141 421, EP-0 001 879, U.S. Pat. Nos. 4,108,837,
4,175,175, T. E. Attwood, A. B. Newton, J. B. Rose, Br. Polym.
Journ., 4, 391, (1972); T. E. Attwood, P. C. Dawson, J. L.
Freemann, L. R. J. Hoy, J. B. Rose, P. A. Staniland, Polymer, 22,
1096, (1981).
[0005] The preparation of sulfonated polyether ketones from some of
these polyether ketones is described in EP-A-008 895, EP-A-041 780
and EP-A-575 807.
[0006] According to EP-A-008 895, the polymer to be sulfonated is
suspended at room temperature in 98% strength by weight sulfuric
acid. The dissolution process and the sulfonation proceed
simultaneously to give, gradually, a highly viscous solution. This
solution is either left as it is or diluted at the same temperature
with sulfuric acid of the same concentration. The reaction takes
place very slowly. Not until 10 weeks had elapsed were about 90% of
the sulfonatable phenylene units in fact sulfonated. In the ether
ketones employed, the numerical ratio of ether bridges to CO
bridges was approximately 2:1. According to the authors, under
these conditions only O-phenylene-O units are sulfonated.
[0007] According to the process of EP-A-041 780, aromatic polyether
ketones which are copolymers are sulfonated at elevated
temperatures. Only some of the monomer units (A) are accessible to
sulfonation, while monomer units (B) are not sulfonated. Thus the
degree of sulfonation can be controlled by the ratio A/B. However,
here too the reaction conditions remain unchanged during the
dissolution process and thereafter. Under the conditions indicated,
corresponding homopolymers (A) would be too highly sulfonated and
would therefore lead to water-soluble compounds. Since in this case
sulfonation takes place while the polymer is still in the process
of dissolving, it is difficult to control the degree of sulfonation
and to obtain products with a low degree of sulfonation. According
to the authors, under these conditions only O-phenylene-O units are
sulfonated.
[0008] In the case of the process disclosed in EP-A-575 807, the
polymer to be sulfonated is suspended at room temperature in from
94 to 97% strength by weight sulfuric acid. The dissolution process
and a partial sulfonation of the polymer proceeds simultaneously to
give, gradually, a viscous solution. A sulfonating agent is added
to the solution until the concentration of sulfuric acid is from 98
to 99.9% by weight. The solution is left until the desired degree
of sulfonation has been reached, and is then worked up. Under these
conditions only O-phenylene-O units are sulfonated, while
O-phenylene-CO units are not attacked. This is also confirmed by
Daoust et al. (Polymer, vol. 35 (25), 5491-5497 (1994)), where the
sulfonation process is restricted to one sulfonic acid group per
repeating unit and to one of the four equivalent positions of the
phenylene ring surrounded by two ether units. According to Daoust,
the other two phenylene rings are so highly deactivated by the
adjacent ketone unit that no sulfonation takes place here.
[0009] In the sulfonation of polyether ketones using chlorosulfonic
acid or an SO.sub.3/triethyl phosphate complex, a high degree of
crosslinking and decomposition of the polymer main chain are
observed (Marvel et al., Journal of Polymer Science, Polymer Chem.
Edition, vol. 23, 2205-2223, (1985) and Bishop et al.,
Macromolecules, vol. 18, 86-93 (1985)).
[0010] In the case of the processes known from the prior art, it is
always only the O-phenylene-O units of the polyether ketones
employed which are sulfonated, whereas O-phenylene-CO units and
CO-phenylene-CO units remain unsulfonated or are sulfonated only to
a minuscule extent, or, if more drastic conditions are employed,
destruction of the polymer main chain occurs.
[0011] Polymers which do not have O-phenylene-O units, for example
those of the formula (I), cannot be sulfonated, or not to any
significant extent. The products obtained when relatively stringent
reaction conditions are employed are insoluble in the customary
solvents and can therefore not be processed further via a solution,
or only with very great difficulty.
[0012] According to the process known from the prior art,
therefore, it was not to be expected that polymers which possessed
no O-phenylene-O units but only O-phenylene-CO units and
CO-phenylene-CO units can be sulfonated. Likewise, from the prior
art it was not to be expected that the sulfonated products obtained
would dissolve in customary solvents.
[0013] The object of the present invention, therefore, is to
provide a gentle and controllable process for the sulfonation of
polyether ketones which can be used to sulfonate O-phenylene-CO
units as well, and in this way to obtain novel sulfonated polyether
ketones. A further object is to prepare solutions of these
polymers.
[0014] Surprisingly it has now been found that, in contrast to the
doctrine prevailing in the literature, it is possible to sulfonate
polymers well and controllably, even at O-phenylene-CO units, with
the products obtained even being soluble above a certain degree of
sulfonation.
[0015] The present invention therefore provides a sulfonated
aromatic polyether ketone of the formula (II)
[Ar--O--Ar'--CO--Ar'--O--Ar--CO--Ar"--CO--] (II)
[0016] in which from 1% to 100% of the O-phenylene-CO units are
substituted with an SO.sub.3M group and sulfonated and unsulfonated
O-phenylene-CO units can be in any desired sequence with respect to
one another.
[0017] The radicals Ar, Ar' and Ar" independently of one another
are substituted or unsubstituted 1,2-, 1,3- or 1,4-phenylene
rings.
[0018] M, taking into account the ionic valencies, comprises one or
more elements selected from the following group: H, NR.sub.4.sup.+,
where R is H or C.sub.1-C.sub.4-alkyl, or an alkali metal or
alkaline earth metal or a metal from subgroup 8, and is preferably
H, NR.sub.4.sup.+, Li, Na, K, Ca, Mg, Fe or Pt.
[0019] The present invention likewise provides a process for the
preparation of these sulfonated polyether ketones, polymer
electrolyte solutions comprising polymers of the formula (II), and
the use of such polymer electrolyte solutions.
[0020] With the aid of the process according to the invention it is
possible to sulfonate aromatic polyether ketones, including in
particular those which possess no O-phenylene-O units, even at the
O-phenylene-CO units.
[0021] The process comprises dissolving an appropriate unsulfonated
aromatic polyether ketone of the formula (II) in from 94 to 98%
strength by weight sulfuric acid, in particular from 94 to 97% by
weight, adding a sulfonating agent to the solution obtained until
the concentration of sulfuric acid is from 98 to 100% by weight or
until the concentration of oleum is from 0.01 to 15% by weight of
SO.sub.3, and working up the reaction mixture as soon as the
desired degree of sulfonation has been reached.
[0022] The aromatic polyether ketone is preferably dissolved in
sulfuric acid under mild conditions, i.e. under conditions in which
sulfonation is largely suppressed or in which sulfonation does not
yet occur. The concentration of the sulfuric acid used for the
dissolution is preferably from 94 to 97% by weight. The temperature
of dissolution is chosen to be as low as possible, in order largely
to avoid a commencement of the sulfonation reaction at this stage.
In general, the dissolution temperature is between 10 and
80.degree. C., in particular between 20 and 70.degree. C. and,
preferably, between 30 and 60.degree. C.
[0023] In our investigations we observed, for the polyether ketone
of formula (I) after the dissolution operation at not more than
80.degree. C. and after 24 h at room temperature in 95 to 97%
strength by weight sulfuric acid, a degree of sulfonation of less
than 12 mol %, based on one repeating unit. The sulfonation
temperature here is preferably in the range from 50 to 100.degree.
C.
[0024] Preferred dissolution conditions are those which lead to a
degree of sulfonation of not more than 35%, based on one repeating
unit. During the dissolution operation, sulfonation of the main
chain is largely suppressed. Our own investigations showed that no
degradation occurred during the dissolution operation.
[0025] As the sulfonating agent, which is used to increase the
concentration of sulfuric acid and for sulfonation, it is preferred
to employ fuming sulfuric acid, oleum, chlorosulfonic acid and
sulfur trioxide.
[0026] After the dissolution operation, the concentration of
sulfuric acid is increased, for example by adding oleum, until it
is from 98 to 100% by weight, or until the concentration of oleum
is from 0.01 to 15% by weight of SO.sub.3, in particular until the
concentration of sulfuric acid is from 99 to 100% by weight or
until the concentration of oleum is from 0.01 to 5% by weight of
SO.sub.3, preferably until the concentration of oleum is from 0.01
to 1% by weight of SO.sub.3.
[0027] During the actual sulfonation the reaction temperature can
be higher or, alternatively, lower than in the dissolution process.
Sulfonation is generally carried out at temperatures in the range
from 10 to 100.degree. C., in particular from 30 to 90.degree. C.,
preferably in the range from 50 to 70.degree. C. Both an increase
in the temperature and an extension to the reaction time bring
about an increase in the degree of sulfonation of the polymer.
Typical reaction times are in the range from 45 minutes to 24
hours, in particular from 1 to 8 hours, preferably in the range
from 1 to 4 hours. Investigations have shown that degradation of
the polymer main chain during the sulfonation reaction occurs only
to a very limited extent.
[0028] As soon as the desired degree of sulfonation has been
reached, the reaction is terminated and the polymer is
precipitated, for example in an aqueous medium, isolated and dried.
The process described gives sulfonation products which above a
certain degree of sulfonation can be dissolved in conventional
solvents, for example NMP or DMSO.
[0029] After sulfonation, the sulfonic acid groups (SO.sub.3H) can
be converted into their salt form (SO.sub.3M) by the known
methods.
[0030] The advantage of the sulfonated O-phenylene-CO units in
comparison to sulfonated O-phenylene-O units in conventional
polymers is, inter alia, the better stability of the SO.sub.3M
groups to hydrolysis. In an aqueous environment and at elevated
temperatures, desulfonation of the sulfonated polyether ketones may
occur. It is known that the extent of hydrolytic desulfonation
depends on the electron richness of the aromatic rings. The general
rule is that, the easier an aromatic unit can be sulfonated, the
easier too it can be desulfonated.
[0031] When sulfonated polymers are employed in an aqueous medium,
it is vital that the properties of the sulfonated polymer remain
constant. In such applications it is therefore advantageous to use
a sulfonated polyether ketone which permits little or no
desulfonation. A polymer whose sulfonic acid groups are located to
a maximum degree at O-phenylene-CO units, consequently, is
particularly suitable in such cases.
[0032] The process described gives sulfonation products which above
a certain degree of sulfonation can be dissolved in conventional
solvents, for example N-methylpyrrolidone (NMP) or dimethyl
sulfoxide (DMSO). The polymer electrolyte solutions prepared in
this way, in a preferred embodiment, contain at least 1% by weight
of polyether ketones of the formula (II) and, as principal constitu
ent, aprotic dipolar solvents, for example NMP or DMSO.
[0033] Depending on the intended subsequent use of the polymer
electrolyte solution, it may if desired comprise a further
unsulfonated polymer or else small quantities of auxiliaries.
[0034] The polymer electrolyte solutions according to the invention
are particularly suitable for preparing asymmetric membranes, for
example for nano-, ultra- or microfiltration, and for preparing
cohesive films having a thickness in the range from 5 .mu.m to 1
mm.
[0035] The polymer electrolyte solutions according to the invention
have an especially important role in the establishment of
particularly intensive contact between two polymer electrolyte
surfaces. A porous or rough surface can in this way be obtained,
for example, after contacting the solution with a precipitating
agent.
EXAMPLES
[0036] 96% strength concentrated sulfuric acid was placed in a
four-necked stirred apparatus fitted with dropping funnel and oil
bath, and polyether ketone of the formula (I) was dissolved. A
sulfonating mixture with oleum concentrations of from 0.1 to 0.7%
by weight of SO.sub.3 was then established by titration with oleum
(containing 20% SO.sub.3). The mixture was then brought to room
temperature to ensure controlled sulfonation. After the desired
degree of sulfonation had been reached, the reaction was terminated
and the product was isolated. The product was characterized by
viscometry, .sup.13C-NMR spectroscopy and elemental analysis.
[0037] The experiments in Table 1 were carried out with a
homopolymer of the formula (I). The following abbreviations are
used in the table.
1 EN Experiment number PC Polymer concentration in % by weight DT
Dissolution temperature in .degree. C. Dt Dissolution time in min.
RC Reaction concentration of oleum in % by weight of SO.sub.3 RT
Reaction temperature in .degree. C. (sulfonation temperature) Rt
Reaction time in min. DS Degree of sulfonation in mol % based on
one repeating unit IV Intrinsic viscosity in dl/g measured in conc.
H.sub.2SO.sub.4 at 25.degree. C.
[0038]
2TABLE 1 EN PC DT Dt RC RT Rt DS IV 1 6.7 50 60 0.4 60 0 5.8 0.93 2
6.7 50 60 0.4 60 30 22.0 0.90 3 6.7 50 60 0.4 60 60 35.3 0.87 4 6.7
50 60 0.4 60 90 44.1 0.85 5 6.7 50 60 0.4 60 120 51.4 0.84 6 6.7 50
60 0.4 60 150 59.6 0.82 7 6.7 50 60 0.7 50 0 9.0 1.01 8 6.7 50 60
0.7 50 30 18.5 0.96 9 6.7 50 60 0.7 50 60 27.4 0.93 10 6.7 50 60
0.7 50 120 44.6 0.91 11 6.7 50 60 0.7 50 180 56.8 0.89 12 6.7 50 60
0.7 50 240 65.1 0.84 13 6.7 50 60 0.7 50 360 81.0 0.81 14 6.7 50 60
0.7 50 460 96.0 0.76 15 6.7 50 60 0.7 50 525 104.0 0.74 16 6.7 50
60 0.7 70 0 6.6 0.94 17 6.7 50 60 0.7 70 60 99.9 0.79 18 6.7 50 60
0.7 70 120 152.2 0.71 19 6.7 50 60 0.7 70 180 188.2 0.62 20 6.7 50
60 0.7 70 240 213.8 0.58 21 6.7 50 60 0.7 70 320 229.8 0.55 22 6.7
50 60 0.1 50 0 3.0 1.02 23 6.7 50 60 0.1 50 60 5.3 0.97 24 6.7 50
60 0.1 50 120 9.7 0.94 25 6.7 50 60 0.1 50 180 14.1 0.91 26 6.7 50
60 0.1 50 240 17.8 0.89 27 6.7 50 60 0.1 50 300 22.3 0.88 28 6.7 50
60 0.1 50 435 28.2 0.84 29 6.7 50 60 0.1 70 0 6.3 0.91 30 6.7 50 60
0.1 70 30 37.3 0.87 31 6.7 50 60 0.1 70 60 43.8 0.85 32 6.7 50 60
0.1 70 120 52.9 0.82 33 6.7 50 60 0.1 70 180 59.0 0.79 34 6.7 50 60
0.1 70 330 81.8 0.74 35 6.7 50 60 0.1 70 390 86.3 0.70
* * * * *