GB2090843A

GB2090843A - Substituted Polyarylethersulphone Copolymers

Info

Publication number: GB2090843A
Application number: GB8137183A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1981-01-08
Filing date: 1981-12-09
Publication date: 1982-07-21
Also published as: GB2090843B

Abstract

A polyarylethersulphone copolymer having nuclear substituent groups of formula -SO2X where X is halogen (preferably chlorine) or -NHR where R is H, aryl (preferably phenyl) or halogen (preferably chlorine), which copolymer has 1 to 99 mole % of repeat units based on the repeat unit which without nuclear substitution has the formula <IMAGE> where substantially all of said repeat units are nuclear substituted by -SO2X groups, the substitution present being in the sub-units <IMAGE> with monosubstitution thereof in the case of the ether linkages being ortho or para disposed and disubstitution thereof in the case of the ether linkages being meta disposed; and correspondingly 99 to 1 mole % of substantially unsubstituted repeat units of formula <IMAGE> or the alkali metal or onium salt thereof where formable.

Description

SPECIFICATION Substituted Polyarylethersulphone Copolymers The present invention relates to certain nuclear substituted polyarylethersu Iphone copolymers.

In European Patent Publication 0 008 894 there is described certain hydrophilic sulphonated copolymers derived by controllably sulphonating, using a sulphonating agent such as conc.

sulphuric acid, a copolymer having the repeat unit of formula

together with the repeat unit of formula

substantially all the units A being sulphonated after sulphonation and substantially all the units B remaining unsulphonated after sulphonation.

The formation of these sulphonated copolymers is a consequence of the discovery that, when using a suitable sulphonating agent (such as conc. sulphuric acid), the units A can be rapidly sulphonated by the substitution of SO2OH groups in substantially all the aromatic rings in the sub-units

with monosulphonation occurring in the case of ortho or para disposed ether linkages and disulphonation occurring in the case of meta disposed ether linkages, while the units B remain substantially unsulphonated. Consequently polyarylethersulphone copolymers containing repeat units A and B may be controllably sulphonated to give hydrophilic sulphonated copolymers by varying the proportions of the repeat unit B in the copolymer.

As described in European Patent Publication 0 008 894 these sulphonated copolymers, or their corresponding alkali metal or onium salts, are potentially useful as membrane materials, e.g. for microfiltration technologies such as reverse osmosis and ultra filtration, since they are not only hydrophilic in nature but retain considerable strength even when containing a considerable quantity of water.

I have now discovered certain novel and surprisingly useful polyarylethersulphone copolymers which can be derived from the above described sulphonated copolymers.

According to the present invention there is provided a polyarylethersulphone copolymer having nuclear substituent groups of formula -S02X where X is halogen (preferably chlorine) or -NHR where R is H, aryl (preferably phenyl) or halogen (preferably chlorine), which copolymer has 1 to 99 mole % of repeat units based on the repeat unit which without nuclear substitution has the formula

wherein substantially all of said repeat units are nuclear substituted by --SO,X groups, the substitution present being in the sub-units

with monosubstitution thereof in the case of the ether linkages being ortho or para disposed and disubstitution thereof in the case of the ether linkages being meta disposed; and correspondingly 99 to 1 mole % of substantially unsubstituted repeat units of formula

or the alkali metal or onium salt thereof where formable.

The substituted polyarylethersulphone copolymer of the invention preferably has 5 to 80 mole % of the substituted repeat units based on the repeat unit A and correspondingly 95 to 20 mole % of repeat units B.

Of particular interest in the present invention are those nuclear substituted polyarylethersulphone copolymers in which the ether linkages in the subunits

are para disposed. Since these "para" copolymers are monosubstituted in the sub-units their nuclear substituted repeat units (based on A) must in fact have the formula

with substitution at any position in the sub-unit being chemically equivalent.

Accordingly the preferred copolymers of the invention have the repeat units of formula

and

The -SO2X-substituted copolymers of the present invention where X is halogen (preferably chlorine) find their prime utility as intermediates in the preparation of the~SO2X-substituted copolymers where X is -NHR. They may be conveniently prepared by reacting the alkali metal (preferably sodium) salt of the corresponding sulphonated copolymer (i.e. X=OH), these sulphonated copolymers being described and claimed in European Patent Publication 0 008 894 as explained above, with thionyl halide (e.g. thionyl chloride when the -SO2Cl- substituted copolymer is being made), using a suitable solvent (e.g. pyridine or dimethyl formamide) as or if appropriate.

The SO2X-substituted copolymers of the present invention where X is -NHR (R is H, aryl ~preferably phenyl, or halogen - preferably chlorine), or their alkali metal or onium salts if formable, like the corresponding prior art sulphonated copolymers with X=OH (or their alkali metal or onium salts), exhibit hydrophilicity and so are likewise suitable for the production of membranes valuable for membrane separation technologies such as reverse osmosis and ultra filtration. This utility is surprising since it might have been expected that the hydrophilicity of the prior art sulphonated copolymers would be lost by conversion of the sulphonic acid or sulphonate substituents thereof to ones not capable of yielding -502O-ions as in the present invention.

The --SO,NHR-substituted copolymers additionally possess an advantage over the prior art sulphonated copolymers (X=#OH) in that they are not ion exchange resins so that the characteristics of membranes prepared therefrom will not change significantly with change in the pH of the environment in which the membranes operate. It is also likely that the substituted copolymers with R=Halogen (particularly chlorine) will be fabricatable into membranes having useful antiseptic properties.

The -SO2NHR-substituted copolymers of the invention are readily soluble in organic solvents such as tetrahydrofuran, dimethyl sulphoxide and dimethyl formamide (or mixtures thereof) and may therefore readily be fabricated into membranes by solvent casting.

The SO2~NH2-substituted copolymers of the invention may conveniently be prepared by reacting the~SO2CI-substituted copolymers discussed above with aqueous ammonia using a suitable solvent (e.g. dimethyl formamide). The -SO2NHR-substituted copolymers where R is aryl may conveniently be prepared by reacting the -SO2Cl-substituted copolymers with a primary aromatic amine (e.g. aniline where R is phenyl) using a suitable solvent (e.g. pyridine or dimethyl formamide). The -SO2NHR substituted copolymers where R is halogen may conveniently be prepared by reacting the -SO2NH2- substituted copolymers with aqueous sodium hypohalite (e.g. sodium hypochlorite where R is chlorine); this reaction could conceivably be carried out in situ by e.g. treating a membrane made from a -S02NH2-substituted copolymer with sodium hypochlorite solution.

The sulphonic acid-substituted prior art copolymers of European Patent Publication 0 008 894 (from which, after neutralization to the alkali metal salt, the --SO,CI-substituted copolymers of the present invention can be made may conveniently be prepared (as described in 0 008 894) by dissolution and consequent reaction of the unsubstituted copolymers having the repeat units A and B in conc. sulphuric acid.

The unsubstituted copolymers having the repeat units A and B may themselves be conveniently prepared by condensation of the appropriate dihydroxy phenol (e.g. hydroquinone, catechol or resorcinol), 4,4'-dihydroxy-diphenylsu phone and 4,4'-dichloro-diphenyl sulphone, and an alkali metal carbonate or bicarnonate in the presence of a sulphone or sulphoxide solvent using the method of preparing polyarylene polyethers described in Canadian Patent 847 963.

The present invention is now illustrated by the following examples.

Example 1 A copolymer (1 kg) of repeat units A (para disposed ether linkages) and B containing 40 mole % A and 60 mole % B was dissolved in 98% w/w conc. sulphuric acid (6 litres) and the solution stirred at ambient temperature for 48 hours. The solution was poured into distilled water to yield a white polymeric lace which was comminuted into granules and washed with water until the washings were neutral to litmus.

The product was monosubstituted with -SO2OH groups on substantially all the sub-units

in the polymer chain but was unsubstituted in the repeat units B (this being determined by 220 MHZ spectroscopy).

500 g of the sulphonated copolymer were placed in NaOH solution (5-fold excess) and the mixture heated at 60-700C for 48 hours with stirring to produce the sodium salt of the polymeric sulphonic acid. The mixture was filtered and washed with water until the washings were neutral to litmus paper. The product was then oven-dried.

40 g of the --SO,ONa-substituted copolymer were placed in a 1 litre flask fitted with a stirrer, reflux condenser, drying tube and addition funnel.

200 ml of thionyl chloride were added quickly into the stirred mixture. The mixture was heated until the thionyl chloride begin to reflux freely; the presence of the salt as a thick sludge made stirring difficult. 5 ml of pyridine dissolved in 40 ml thionyl chloride were added to the stirred refluxing mixture and the salt began to dissolve with SO2 gas being evolved; after about 2 hours refluxing the salt had almost completely dissolved although SO2 gas evolution continued. After 4 hours heating, SO, evolution was much slower and after 5.5 hours had virtually ceased. After 5.45 hours heating the reflux condenser was replaced by a still head and 175 ml thionyl chloride distilled out of the reaction mixture.The resulting thick almost clear liquid was poured portionwise into about 2 litres of iced water in a Waring blender to give a precipitate which was filtered off, washed with 2 litres of iced water in the filter, treated twice with 2 litre portions of iced water (with water washing on the filter between each treatment) and then dried in a vacuum oven overnight at 600 C. The product obtained (an almost white powder) was the -SO2Cl- substituted copolymer having 40 mole % of repeat units C where X is Ci and 60 mole % of repeat units B. The yield obtained was 35 g (88% of theoretical).

The above preparation was repeated on a larger scale, using 120 g of the -SO2ONa- substituted copolymer, 550 ml of initially added thionyl chloride, and 15 ml of pyridine dissolved in 50 ml thionyl chloride added after the start of refluxing. The yield of -SO2Cl-substituted polymer obtained was 91.6 g (77% of theoretical).

Example 2 5 g of the -SO2CI-substituted copolymer prepared in Example 1 were dissolved in 50 ml of hot dimethyl formamide. 10 ml of 0.880 ammonia solution were added and the slightly opalescent copolymer solution heated with stirring to about 700C over 2 hours. The solution, which after this treatment exhibited greater opalescence, was poured into 400 ml methanol containing 20 ml of conc. HCI to yield a white precipitate. The precipitate was filtered off, washed on the filter with about 400 ml methanol, and dried in a vacuum oven at 700C.

The yield of the copolymeric product, which was the -SO2NH2-substituted copolymer having 40 mole % of repeat units C where X is NH2 and 60 mole % of repeat units B, was 4.2 g (85% of theoretical). The copolymer was readily soluble in dimethyl formamide and dimethyl sulphoxide.

Example 3 23.6 g of the -SO2Cl-substituted copolymer prepared in Example 1 were shaken with 100 ml pyridine in a conical flask until it had almost completely dissolved. 9.1 ml aniline were added and the solution became orange-red in colour.

The flask contents were heated on a steam bath for 5 hours (with a loosely fitting stopper in the neck of the flask); after 0.5 hours heating the copolymer had completely dissolved and the solution became progressively darker. The solution was poured into methanol to yield a soft white lump which hardened on standing overnight. The product was comminuted in methanol using a Waring blender and dried overnight in a vacuum oven at 800C.

The copolymer thus obtained (yield not recorded) was the

substituted polymer having 40 mole % of repeat units C, where X is NHR and R is phenyl, and 60 mole % of repeat units B.

Example 4 A copolymer (100 g) of repeat units A (para disposed ether linkages) and B containing 80 mole % A and 20 mole % B was dissolved in 98% w/w conc. sulphuric acid (600 ml) and the solution stirred at ambient temperature for 48 hours. The solution was poured into distilled water and the precipitate worked up as in Example 1 to yield the sulphonated copolymer having one -SO2OH substituent on substantially all the sub-units

and no substituents in the repeat units B.

All of the sulphonated copolymer was neutralized with NaOH (as in Example 1) to yield the sodium salt.

To 60 g of the -SO2ONa-substituted copolymer were added 250 ml of thionyl chloride (using the same equipment as in Example 1) and the mixture heated to reflux with stirring under nitrogen. 3 ml of pyridine in 12 ml thionyl chloride were added when rapid evolution of SO2 started and the salt began to dissolve. The mixture was heated under reflux overnight when all the salt dissolved to give a clear solution. Excess thionyl chloride was distilled off to yield a very viscous gold-coloured liquid. This was poured rapidly into iced water in a Waring blender (much of the liquid remained in the flask however because of its high viscosity). The coarse solid so obtained was filtered off, washed twice in the blender with 2 litre portions of iced water (filtering each time) and finally washed with cold water on the filter.

The solid was dried for several days in a vacuum oven at 8O0C.

The product obtained was the --SO,CI- substituted copolymer having 80 mole % of repeat units C where X is Cl and 20 mole % of repeat units B. The yield was only 34 g because much of the product was lost when the liquid from distillation could not be poured completely out of the flask. The copolymer was readily soluble in dimethyl formamide.

Example 5 4.4 g of the -SO2Cl-substituted copolymer prepared in Example 4 where dissolved in 20 ml of dimethyl formamide and 10 ml of 0.880 ammonia solution added. Some warming and precipitation occurred. Afurther 30 ml dimethyl formamide was added and the precipitate dissolved. The solution was heated on a steam bath for 2 hours and then left to stand overnight, when slight precipitation occurred. The reaction mixture was poured into 500 ml methanol in a blender to yield a white powder. This was filtered off, washed twice with 200 ml of methanol and vacuum dried overnight at 700C.

The yield of the copolymeric product, which was the -SO2NH2-substituted copolymer having 80 mole % of repeat units C where X is NH2 and 20 mole % of repeat units B was 3.4 g. The copolymer was readily soluble in dimethyl formamide and dimethyl sulphoxide.

Example 6 The water absorption of the -SO2NH2- substituted copolymers of Examples 1 and 5 where measured after steeping initially dry films of the copolymers (cast from solution in dimethyl formamide) in water for 24 hours and 72 hours at ambient temperature. The results were as follows: Molar ratio -SO2NK2-substituted Water A bsorpdon C/B (wt%) in copolymer of copolymer 24 hours 72 hours 40/60 4.5 4.6 80/20 8.0 9.4

Claims

1. A polyarylethersulphone copolymer having nuclear substituent groups of formula -SO2X where X is halogen or -NHR where R is H, aryl or halogen, which copolymer has 1 to 99 mole % of repeat units based on the repeat unit which without nuclear substitution has the formula

wherein substantially all of said repeat units are nuclear substituted by -SO2X groups, the substitution present being in the sub-units

or the alkali metal or onium salt thereof where formable.

2. A polyarylethersulphone copolymer according to claim 1 having 5 to 80 mole % of the substituted repeat units based on the repeat unit A and correspondingly 95 to 20 mole % of repeat units B.

3. A polyarylethersulphone copolymer according to either claim 1 or claim2 wherein X is chlorine.

4. A polyarylethersulphone copolymer according to either claim 1 or claim 2 wherein X is -NHR and R is H, phenyl or chlorine.

5. A polyarylethersulphone copolymer according to any one of the preceding claims wherein the substituted repeat units based on the repeat unit A have the formula