Process for the production of poly(alkylene oxide)

A process for the production of poly(alkylene oxide) which includes providing a polyhydroxy compound or compounds and an acid resin catalyst or a salt thereof that has been converted to the acid form; and reacting said polyhydroxy compound or compounds in the presence of said acid resin catalyst at a temperature and under conditions to allow polymerization.

This invention relates to a process for the manufacture of poly(alkylene 
oxide) oligomers and co-oligomers, and low molecular weight polymers and 
copolymers. More specifically, the present invention relates to a process 
for the production of such compounds by intermolecular dehydration of 
polyhydroxy compounds in the presence of perfluorinated resin sulfonic 
acid catalysts. 
The term poly(alkylene oxides) is used herein to refer to the reaction 
product produced by the process of the invention described. The scope of 
this term should be considered in light of the spirit of the following 
description and should not be considered limited to the specific examples. 
Poly(alkylene oxides) are important precursors in the preparation of 
copolymers and segmented copolymers such as polyurethane and 
polyurethaneurea elastomers. These poly(alkylene oxides) when incorporated 
into polyurethanes form the "soft segment", and impart many useful 
properties to the polyurethane including elasticity, hydrolytic stability, 
thermal stability, and abrasion resistance. Common poly(alkylene oxides) 
that are produced for such purposes include poly(ethylene oxide), 
poly(propylene ozide) and poly(tetramethyleneoxide). These compounds may 
be prepared by the ring-opening polymerization of the corresponding cyclic 
ethers. This method is most suitable to polymerize cyclic ethers having 
2-4 carbon and 1-3 oxygen atoms in the ring. Larger compounds however may 
also be used. For example, a cyclic ether having more than 4 carbon atoms 
and one hetero atom in a ring that undergoes ring opening polymerization 
is oxacycloheptane. German Patent Specification No. 1,125,386 describes a 
process to prepare poly(hexamethylene oxide) from oxacycloheptane using 
Friedel-Crafts catalysts or Lewis Acids. 
German Patent Specification No. 1,156,709 describes a process for preparing 
poly(alkylene oxides) from alkanediols having 5-12 carbon atoms by heating 
to temperatures in the range from 200.degree. to 400.degree. C. in the 
presence of solid, non-basic catalysts such as oxides of aluminum, 
tungsten and chromium etc. One major disadvantage of this process is the 
need to use such high temperatures. The use of high temperatures may lead 
to the formation of undesirable side products and to discoloration of the 
product. Poly(alkylene oxides) having molecular weights of 450 to 1400 may 
be obtained by this process in yields ranging from 18-55%. 
An article in Journal of the American Chemical Society, Vol. 72, pp 
2216-2219 (1949) by P. J. Flory and M. J. Rhoad, describes a process to 
prepare poly(decamethylene oxide) by sulphuric acid catalysed 
polymerization of 1,10-decanediol at 200.degree. C. However, purification 
of the product to remove the acid catalyst in this process is difficult. 
The acid catalyst is usually removed either by repeated recrystallization 
or by treatment with a base such as calcium hydroxide followed by washing 
the product with water. Often emulsions are formed during the washing step 
making isolation of the product extremely difficult. Incomplete removal of 
the acid catalyst can cause degradation of the poly(alkylene oxide). 
Furthermore, significant charring occurs especially when long reaction 
times are used. 
It is an object of the present invention to overcome, or at least alleviate 
one or more of the difficulties associated with the prior art. 
The present invention provides a process for the production of a 
poly(alkylene oxide) which includes, providing a polyhydroxy compound or 
compounds and an acid resin catalyst or a salt thereof that has been 
converted to the acid form; and 
reacting said polyhydroxy compound or compounds in the presence of said 
acid resin catalyst at a temperature and under conditions to allow 
polymerization. Preferably the catalyst is a sulfonic acid resin 
containing one or more halogen atoms. More preferably, the halogen atoms 
are fluorine. Most preferably, the sulfonic acid resin is a perfluorinated 
sulfonic acid resin. 
A preferred catalyst used in the process of the invention is a polymer of 
an ethylenically unsaturated monomer containing groups such that the final 
polymer will contain groups of the formula 
##STR1## 
where represents the catalyst polymer chain or a segment thereof; 
A is hydrogen, an aliphatic or aromatic hydrocarbon radical of 1-10 carbon 
atoms, a halogen atom or a segment of the polymer chain; 
X and Y are hydrogen, halogen or an aliphatic or aromatic hydrocarbon 
radical of 1-10 carbon atoms, but at least one is fluorine; 
R is a linear or branched linking group having up to 40 carbon atoms in the 
principal chain; and 
Z is hydrogen, halogen or an aliphatic or aromatic hydrocarbon radical of 
1-10 carbon atoms; or a copolymer of such a monomer with at least one 
other copolymerizable ethylenically unsaturated monomer. 
The linking group defined by R in formula (II) can be a homogeneous one 
such as an alkylene radical, or it can be a heterogeneous one such as an 
alkylene ether radical. In the preferred catalysts, this linking radical 
contains 1-20 carbon atoms in the principal chain. 
In particular, the most preferred sulfonic acid resins for use in the 
present invention are perfluorinated acid resins that consist of a 
backbone of fluoropolymer such as poly(tetrafluoroethylene) with pendant 
side chains of fluorinated or perfluorinated ethers such as vinyl ethers 
which terminate in a sulfonic acid group. It will be appreciated that 
other polymer chains such as bromo substituted chains or substituted 
propylene chains are contemplated for use in the present invention and the 
preferred examples referred to above are merely illustrative of the 
present invention. Most preferably, the pendant side chains are terminated 
with a sulfonic acid, but again, it should be appreciated that this is 
merely illustrative of a preferred embodiment of the invention. 
Commercially available preferred examples of an acid resin are Nafion-H.TM. 
and its salts which are products of E. I. du Pont de Nemours Co., Inc. 
having the following general structure. 
##STR2## 
Generally the catalyst will be used in solid form, for example the Nafion 
resin may be used in both the powder or membrane form. The solid form of 
the catalyst allows for ease of removal through common liquid/solid 
separation techniques from the reaction mixture. Various salts of resins 
such as Nafion-K.sup.+ may also be used once converted to the acid form. 
The amount of catalyst used in the reaction may range from 0.1% to 30% of 
the total weight of monomer present, preferably 2-10%. 
Suitable polyhydroxy compounds that may be used in the process of the 
present invention include any polymerizable compound having an 
availability of at least two hydroxy groups. Such compounds include 
alkanediols preferably having from 2 to 20 carbon atoms in the main chain. 
The compounds may be branched or unbranched, cyclic or linear, substituted 
or unsubstituted or contain one or more hetero atoms in the main chain. 
Suitable substituents include any atom or side chain that does not 
substantially interfere with the polymerization process, such as 
substituted or unsubstituted aliphatic or aromatic hydrocarbons. 
As an illustration, suitable polyhydroxy compounds include 1,6-hexanediol, 
1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 
1,12-dodecanediol, glycerol, trimethylolpropane, 
2-ethyl-2-(hydroxymethyl)-1,3-propanediol, pentaerythritol, 
3,3,4,4,5,5-hexafluoro-1,5-pentanediol, 
2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol and 
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-hexadecafluoro-1,12-dodecanediol, 
1,4-cyclohexanediol and 1,4-cyclohexanedimethanol. 
The process according to the present invention may be used to produce 
poly(alkylene oxides) having a molecular weight of about 150 to 10,000 by 
the condensation polymerization of the polyhydroxy compound(s). The 
process is preferably carried out at a temperature above the melting point 
of the polyhydroxy compound(s) involved. More preferably the reaction 
temperature is from 130.degree. C. to 220.degree. C., most preferably 
about 170.degree. C. It has been found that reaction at these temperatures 
is not sufficient to discolour the resultant reaction product 
significantly, or produce undesired by-products. 
In a preferred embodiment of the invention, the process allows to a certain 
extent, control of the polymerization by removal of the catalyst when the 
desired level of polymerization has been reached. In this sense, the 
molecular weight of the resultant poly(alkylene oxide) may be controlled. 
An insoluble polymeric catalyst may be removed by conventional 
solid/liquid separation steps such as decantation, filtration and 
centrifugation. Such procedures yield a product that is substantially free 
of catalyst residue. An added benefit is that the catalyst may 
subsequently be regenerated and reused if desired. 
By the combination of two or more polyhydroxy compounds, it is possible to 
obtain the corresponding poly(alkylene oxide) co-oligomer or copolymer. 
Polymerisation of diols or diol mixture will generally yield a linear 
bis-hydroxy terminated poly(alkylene oxide). 
Branched chain poly(alkylene oxides) may be produced by incorporating a 
small amount, for example 1 to 10%, of a tri- or tetrahydroxy compound in 
the polymerization of a diol or mixture of diols. 
By utilising the process according to the present invention, it is possible 
to produce a high yield product of high purity that has a reasonably 
narrow molecular weight distribution after removal of the water. By the 
incorporation of a small quantity of a monoalcohol in the reaction 
mixture, products that do not contain terminal functionality may be 
produced. The poly(alkylene oxides) of the present invention may be 
converted into hydrolysis and oxidation resistant polyurethanes. These 
polyurethanes may have various applications, for example biomedical use, 
or as a coating for fabric to make durable synthetic leather. The 
poly(alkylene oxides) per se may also have use as, or in surfactants. 
The following examples are illustrative of processes according to the 
present invention, the scope of which, should not be considered to be 
limited thereto.

EXAMPLE 1 
1,8-octanediol (100 g) was placed in a 500 ml round bottom flask and heated 
under vacuum (0.1 tort) at 100.degree. C. for 1 hour. The flask was cooled 
to 50.degree. C., and fitted with a nitrogen bleed, Dean-Stark trap and a 
condenser. Perfluorinated resin sulfonic acid resin (Nafion-H.TM., 5.0 g) 
was added, and the reaction mixture was heated at 170.degree. C. under a 
controlled flow (100 ml/min) of dry nitrogen with stirring. The side arm 
of the Dean-Stark trap was kept insulated with cotton wool during the 
reaction. The reaction was monitored by analysing samples at different 
time intervals by size exclusion chromatography (SEC), and continued until 
the desired molecular weight was obtained. Polymers with different 
molecular weights were obtained by varying the interval of the heating 
process as shown by the results in Table 1. In another experiment, after 9 
hours of reaction, the Nafion catalyst was removed by decanting off the 
molten polymerized reaction mixture. The product was further purified by 
recrystallization from absolute ethanol. The solid product isolated by 
filtration was dried in a vacuum oven at 45.degree. C. for 48 h to give 70 
g of pure product. The molecular weight of the purified product, 
poly(octamethylene oxide), was determined by SEC, vapour pressure 
osmometry (VPO) and proton nuclear magnetic resonance spectroscopy (.sup.1 
H-NMR). 
The .sup.1 H-NHR signals at 3.63 (triplet, OCH.sub.2 end group), 3.36 
(triplet, OCH.sub.2 of repeat unit), 1.57 (multiplet, --OCH.sub.2 
CH.sub.2), 1.31 [multiplet, --(CH.sub.2).sub.4 --] and 2.0 PPM (OH end 
group) established the structure of the polymer as HO(CH.sub.2 CH.sub.2 
CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 O).sub.7 --H. 
EXAMPLES 2-3 
The procedure described in Example 1 was followed, except that 
1,10-decanediol (100 g) and 1,6-hexanediol (100 g) were used for Examples 
2 and 3, respectively. The molecular weight results at different time 
intervals are given in Table 1. The molecular weights of the purified 
products, poly(decamethylene oxide) and poly(hexamethylene oxide), 
obtained after 9 and 23 hours, respectively, are given in Table 2. 
TABLE 1 
______________________________________ 
Nafion .TM. Catalysed Polymerization of Alkylenediols 
reaction time 
MW by SEC.sup.a 
at 170.degree. C., hours 
M.sub.n M.sub.w /M.sub.n 
conversion (%).sup.b 
______________________________________ 
1,8-octanediol (Example 1) 
3 420 1.07 40 
6 470 1.15 70 
9 800 1.43 93 
23 2040 1.67 100 
1,10-decanediol (Example 2) 
3 720 1.16 55 
6 1720 1.42 100 
9 2200 1.60 100 
1,6-hexanediol (Example 3) 
3 320 1.09 39 
6 480 1.18 85 
23 1730 2.92 100 
1,8-octanediol (Example 4) 
4.5.sup.c 750 1.62 -- 
6.sup.d 2370 1.57 100 
______________________________________ 
.sup.a molecular weight relative to polystyrene standards 
.sup.b estimated from SEC peak areas 
.sup.c 3 hours under nitrogen flow and 1.5 hours under vacuum (0.1 torr). 
.sup.d 3 hours under nitrogen flow and 3 hours under vacuum (0.1 torr). 
EXAMPLE 4 
1,8-octanediol (100 g) was placed in a 500 ml round bottom flask and heated 
under vacuum (0.1 torr) at 100.degree. C. for 1 hour. The flask was cooled 
to 50.degree. C., and fitted with a nitrogen bleed, Dean-Stark trap and a 
condenser. Perfluorinated resin sulfonic acid (Nafion-H, 5.0 g) was added, 
and the reaction mixture was heated at 170.degree. C. under a controlled 
flow (100 ml/min) of dry nitrogen with stirring. The side arm of the 
Dean-Stark trap was insulated with cotton wool during the reaction. After 
three hours the flask was connected to a vacuum pump and heating at 
170.degree. C. was continued for a further 3 hours (0.1 torr). The results 
are given in Table 1. The product obtained after 9 hours of reaction was 
purified using the procedure in Example 1, and the results are shown in 
Table 2. 
EXAMPLES 5-6 
The procedure described in Example i was followed, except that the 
reactions were carried out at 150.degree. C. and 190.degree. C., 
respectively, for Examples 5 and 6. In Example 5, the molecular weight of 
the purified polymer obtained after 23 hours reaction time was 5020 
(dispersity=1.53) as determined by SEC. In Example 6, a product with a 
molecular weight of 1220 (dispersity=1.34) was obtained after one hour of 
reaction time. 
EXAMPLE 7 
The procedure in Example 1 was followed, except that 100 g of an equimolar 
mixture of 1,6-hexanediol (40.4 g) and 1,10-decanediol (59.6 g) was used 
in place of 1,8-octanediol. After the reaction catalyst was removed by 
filtration to yield 87 g of copolymer. The copolymer was further purified 
by recrystallization from a 50/50 mixture of ethanol and water to yield 65 
g of pure product. The number average molecular weight of the copolymer 
was 1280 (poly-dispersity=1.13) as determined by SEC. 
TABLE 2 
______________________________________ 
Molecular Weights of Purified Poly(alkylene oxides) 
Determined by Various Methods 
molecular weight 
SEC.sup.a yield.sup.b 
Example 
VPO .sup.1 H-NMR 
M.sub.n 
M.sub.w /M.sub.n 
(%) functionality.sup.c 
______________________________________ 
1 860 850 1550 1.20 77 2.0 
2 745 755 1450 1.23 76 2.0 
3 2390 -- 4680 1.25 30 -- 
4 1580 1600 3090 1.25 75 2.0 
______________________________________ 
.sup.a SEC calibration was relative to polystyrene standards 
.sup.b % of theoretical yield as purified product 
.sup.c number of hydroxyl groups/molecule calculated from VPO and NMR 
results 
EXAMPLE 8 
The procedure in Example 1 was followed, except that 73 g of 
1,7-heptanediol and 3.7 g of Nafion-H were used in place of the reactants 
in Example 1. The reaction was carried out for 12 h at 170.degree. C., and 
Nafion-H was removed by decanting off the molten polymerized reaction 
mixture to yield 53 g of polymer. The number average molecular weight of 
the polymer was 820, as estimated by areas of .sup.1 H-NMR signals at 3.62 
(triplet, end group OCH.sub.2), and 3.37 PPM (triplet, repeat unit 
OCH.sub.2). 
EXAMPLE 9 
In this example an equimolar mixture of two diols was used to prepare a 
copolymer. 1,10-Decanediol (13.9 g, 0.080 mol), 1,3-propanediol (6.08 g, 
0.080 mol), and Nafion-H (1.0 g) were placed in a 50 ml round bottom flask 
fitted with a nitrogen bleed, Dean-Stark trap and a condenser. The mixture 
was heated at 170.degree. C. under a controlled flow (100 ml/min) of dry 
nitrogen with stirring. The side arm of the Dean-Stark trap was kept 
insulated with cotton wool during the reaction. After nine hours of 
reaction, the Nafion-H catalyst was removed by decanting off the molten 
polymerized reaction mixture. The product was further purified by 
dissolving it in hot isopropanol to make a 10% (w/v) solution and 
precipitating into cold distilled water (2 L). The polymer isolated by 
filtration was dried in a vacuum oven at 45.degree. C. for 48 h to yield 
13.5 g of product. The number average molecular weight and polydispersity 
of the purified polymer was 2050 and 1.45, respectively, as determined by 
SEC. The molecular weight estimated from .sup.1 H-NMR signal areas was 
930. .sup.1 H-NMR spectroscopy also verified that the product contained 
units derived from both 1,10-decanediol and 1,3-propanediol in 1:1 ratio. 
The .sup.1 H-NMR spectrum of the polymer showed signals at 3.77 (triplet, 
OCH.sub.2 end group from propanediol), 3.63 (triplet, OCH.sub.2 end group 
from decanediol), 3.48 (multiplet, OCH.sub.2 of propylene oxide), 3.37 
(triplet, OCH.sub.2 of decamethylene oxide repeat unit), 1.83 (multiplet, 
--CH.sub.2 -- of propylene oxide), 1.56 (multiplet, --OCH.sub.2 CH.sub.2 
of decamethylene oxide), 1.28 (broad singlet, --(CH.sub.2).sub.6) of 
decamethylene oxide) and 1.56 PPM (singlet, OH end group). 
EXAMPLE 10 
In this example a cycloalkane diol was copolymerized with 1,10-decanediol. 
The procedure described in Example 9 was followed, except that the 
reaction was carried out in a 100 ml flask using a mixture of 
1,10-decanediol (37.5 g, 0.216 mol), 1,4-cyclohexanediol (12.5 g, 0.108 
mol) and Nafion-H (2.5 g) in place of the reactants used in Example 9. The 
reaction was carried out for 12 h at 170.degree. C., and Nafion-H catalyst 
was removed by decanting off the molten polymerized reaction mixture. The 
product was further purified by dissolving it in hot absolute ethanol to 
make a 10% (w/v) solution and precipitating into cold distilled water (2 
L). The polymer isolated by filtration was dried in a vacuum oven at 
45.degree. C. for 48h to yield 33 g of pure product. The purified product 
showed a number average molecular weight of 900 and polydispersity of 
1.28, as determined by SEC. 
EXAMPLE 11 
The procedure described in Example 9 was followed, except that the reaction 
was carried out in a 100 ml flask using a mixture of 1,10-decanediol (DD, 
30.8 g, 0.177 mol), 1,4-cyclohexanedimethanol (CHDM, 19.2 g, 0.133 mol) 
and Nafion-H (2.5 g) in place of the reactants used in Example 9. The 
reaction was carried out for 14 h at 170.degree. C., and Nafion-H catalyst 
was removed by decanting off the molten polymerized reaction mixture 
yielding 36 g of polymer. The number average molecular weight and 
polydispersity of the unpurified polymer were 750 and 1.22 respectively, 
as determined by SEC. .sup.1 H-NMR spectroscopy provided evidence for the 
presence of repeat units derived from both DD and CHDM in the copolymer. 
The .sup.1 H-NMR spectrum of the product showed signals at 3.62 (triplet, 
OCH.sub.2 end group of DD), 3.37 (triplet, OCH.sub.2 of DD repeat unit), 
1.53 (multiplet, ring CH.sub.2 of CHDM and --OCH.sub.2 CH.sub.2 of DD 
repeat units), 1.27 (broad singlet, --(CH.sub.2).sub.6 of DD), 0.94 
(multiplet, ring CH.sub.2 of CHDM), 1.82 (multiplet, ring CH of CHDM), 
3.20 (doublet, OCH.sub.2 of CHDM repeat unit) and 3.45 PPM (triplet, 
OCH.sub.2 end group of CHDM).