GB2169304A - Polymers from carbon disulphide and epoxides - Google Patents

Abstract

Polymers of formula <IMAGE> wherein R is a group selected from a C2 or higher alkyl, a haloalkyl, an alkenyl, a haloalkenyl, an aryl, an alkaryl and an epoxy or halogen substituted epoxy group are made by contacting carbon disulphide with an epoxide of the formula: <IMAGE> in the presence of a catalyst system comprising an organometallic compound and an electron donor at temperatures from about 0 DEG C to 100 DEG C, in an atmosphere inert under the reaction conditions.

Description

SPECIFICATION Novel carbon disulphide copolymers The present invention relates to novel carbon disulphide copolymers.

Organic polymeric materials of many different types have been used for countless technological applications. However, there is continual commercial need for low cost, high performance polymers for both existing and new applications. The production of polymers by the copolymerisation of inexpensive, readily available small molecules such as CO2, CO, SO2 with suitable monomers offers the possibility of a wide range of new, potentially inexpensive copolymers and has recently received much attention.

Little work has been conducted on similar copolymerisations with carbon disulphide in spite of the structural similarlity between carbon dioxide and carbon disulphide. This may be due to the fact that the preparation of carbon disulphide copolymers cannot always be predicted from that of the corresponding carbon dioxide copolymers. For example, zinc catechol-0,0-diacetate catalyses the copolymerisation of carbon dioxide and propylene oxide. However the same catalyst does not copolymerise carbon disulphide and propylene oxide under the same conditions.

The copolymerisation of carbon disulphide and propylene oxide has been reported by Coskun et al, Chem. Abs.83, 193775b (1975) in the presence of O-isopropyl zinc xanthate. Adachi et al, J. Polymer Science, Polymer Chem., 15, 937 (1977) teach the copolymerisation of carbon disulphide and propylene oxide in the presence of a catalyst system comprising an electron donor such as hexamethyl phophoric triamide and an organozinc compound to produce polymers.

It has now been found that novel copolymers can be prepared from carbon disulphide and selectively substituted epoxide monomers.

According to the present invention, novel copolymers are provided which are represented by the following formula:

wherein R is a group selected from a C2 or higher alkyl, a haloalkyl, an alkenyl, a haloalkenyl, an aryl, an alkaryl and an epoxy or halogen substituted epoxy group.

In another embodiment of the present invention, a process is provided for the preparation of carbon disulphide copolymers, the process comprising contacting carbon disulphide with an epoxide compound having the formula

where R has the same significance as in formula (I) above in the presence of a catalyst system comprising an organometallic compound and an electron donor at temperatures from about 0 C to 100"C, in an atmosphere inert under the reaction conditions.

The substituted epoxide monomers copolymerised with carbon disulphide suitably carry a substituent selected from the group consisting of C2 and higher alkyls, haloalkyls, alkenyls, haloalkenyls, aryl, alkaryl, epoxys and halo-substituted epoxy groups.

The alkyl halide or alkenyl substituents on the epoxide suitably contain from 1-20, preferably from 1-4 carbon atoms in the alkyl halide and from 2-6 carbon atoms in the alkenyl substituent. The aryl substituents typically contain a benzene ring or substituted derivatives thereof. Examples of the alkaryl substituents are toluene and xylene radicals.

It will be understood from the above that when the substituent group on the epoxide is a C1 group the substituent must also carry a halogen function e.g. as in methylene halide.

The carbon disulphide copolymers herein are believed to have highly complex structures.

Gel permeation chromatographic analyses of the copolymers indicate that these polymers have molecular weights of the order of 1000 with a wide distribution.

Elemental analyses of these copolymers show significant levels of sulphur in the copolymers examined although in most cases the copolymers contained slightly more units derived from epoxide than from carbon disulphide. The copolymers examined contained from 64 to 91 per cent of the calculated amount of sulpur for a 1:1 copolymer of carbon disulphide and epoxide.

Infrared spectroscopic examination showed the presence of both carbonyl and hydroxyl groups in these copolymers.

The Raman spectra of some of the copolymers studied indicated the presence of disulphide links.

Dynamic mechanical analyses, which measure the change in tensile loss modulus (a measure of a material's ability to convert mechanical energy into heat which is related to the movement of molecular segments in a polymer chain) with temperature were performed on five of the copolymers studies. From this, the glass transition temperature (Tg) was determined and these results are shown in Table Ill (see untreated sample).

A feature of the copolymers of the present invention is that upon heat treatment, e.g. at 1600C for 1 hour in nitrogen, the glass transition temperature thereof either remains unaffected or improves when compared with that of the untreated copolymer.

The carbon disulphide copolymers of the present invention are prepared by contacting the carbon disulphide and the substituted epoxide monomers in the presence of a catalyst system comprising an organometallic compound and an electron donor. The mole ratio of organometallic compound to the electron donor in the catalyst may suitably vary from 0.5:1 to 1.0:0.5, but is preferably in equimolar proportions. The mole ratio of the catalyst system to the monomers is suitably from 1:100 to 1:10, preferably from 1:30 to 1:15. The copolymerisation is suitably carried out in solution. Thus the catalyst system is prepared by dissolving the electron donor and the organometaliic compound in a suitable organic solvent such as toluene under an inert atmosphere such as nitrogen.The organometallic compound can be any alkyl substituted transition metal, preferably any C2-C4 alkyl substituted metal from Group IIB of the Periodic Table (e.g. Zn, Cd and Hg), capable of opening the epoxy ring to effect polymerisation. The most preferred organometallic compounds are dialkylzinc compounds such as diethylzinc.

The electron donor can be any material known in the art capable of donating an electron for the initiation of the polymerisation reaction. Examples of such electron donors include tert-amines and tert-phosphines. The preferred electron donors are triethylamine, quinuclidine and hexamethylphosphoric triamide.

After the solution containing the catalyst system i.e. the organometallic compound and the electron donor is thoroughly stirred (e.g. about 1 hour) at ambient temperatures, the carbon disulphide and epoxide monomers are added to the solution and the mixture is continuously stirred while maintaining ambient temperatures in an inert atmosphere. The polymerisation may be terminated after the desired duration e.g. anything from 1 to about 200 hours by adding excess methanol to the resultant mixture and the copolymer precipitates from the solution.

The copolymers of the present invention may be used as rubbers, thermoplastics, insulators and as liquid polymers for thermosetting systems such as resins, foams, fillers and adhesives.

The process for producing copolymers containing carbon disulphide as well as the characteristics of the copolymers so produced are further illustrated with reference to the following Examples. The scope of this invention includes equivalent embodiments, variations and modifications.

General preparation of carbon disulphide copolymers The catalyst system was prepared by adding triethylamine to an equimolar quantity of diethylzinc in toluene and stirred for about75 min. at room temperature in an atmosphere of dry nitrogen. To this mixture was added an equimolar mixture of carbon disulphide and a substituted epoxide comonomer as shown in Table I and stirring was continued at room temperature under nitrogen for varying durations and under various reaction conditions depending upon the reactants as shown in Table I below. The molar ratio of catalyst (diethylzinc/triethylamine) to monomer was about 1:30. As the reaction proceeded the reaction mixture became progressively more viscous. Upon completion, the reaction mixture was poured slowly into a large excess of well stirred methanol containing hydrochloric acid. The precipitated copolymer was recovered, washed well with methanol and held under reduced pressure to remove any excess solvent.

Six copolymers (Examples 1-6) were prepared in accordance with the present invention using the procedure described above. As a Comparative Test (Test A, not according to the invention) carbon disulphide and propylene oxide were copolymerised using the same procedure described above. The products from Examples 1-6 and Test A were subjected to various heat treatments to observe physical changes. Table II shows the results of the heat treatments.

Dynamic mechanical analyses were preformed on the products from Examples 1-3, 5 and Comparative Test A to measure the changes in tensile loss modulus with temperature. From this, the glass transition temperatures were calculated and are shown in Table Ill.

TABLE I Copolymerisation of carbon disulphide with various comonomers Diethylzinc Carbon Comonomer Poly- Weight % Reduction % Sulphur Triethylamine 15% w/w in Disulphide 0.15 mol merisation of in weight in final Example Comonomer 5 mmol Toluene 0.15 mol unless Time Product on final product or Test unless stated 5 mmole unless stated hours g drying unless stated stated 1 Styrne oxide 0.505 g 4.57 ml 11.4 g 18.0 g 92 15.2 22 25.4 2 1,2-Epoxybutane 0.505 g 4.57 ml 11.4 g 10.8 g 50 5.0 15 39.1 A Propylene oxide 0.505 g 4.57 ml 11.4 g 8.7 g 65 4.6 37 34.8 3 Epibromohydrin 0.505 g 4.57 ml 5.7 g 10.27 g 48 8.8 24 19.2 (0.075 mol) (0.075 mol) 4 Butadiene 0.25 g 2.29 ml 5.7 g 5.25 g 96 4.7 5 38.6 monoxide (2.5 mmol) (2.5 mmol) (0.075 mol) (0.075 mol) 5 1,4-Butanediol 0.505 g 4.57 ml 11.4 g 15.15 g 48 28.4 - 23.1 diglycidyl ether 6 1,3-Butadiene 0.505 g 4.57 ml 11.4 g 6.45 g 72 19.3 - 5.6 diepoxide (0.075 mol) TABLE II Heat treatment of carbon disulphide copolymers* Examples Example2 TestA Example 3 Example 4 Untreated Viscous Very viscous Very viscous Viscous Tacky very appearance liquid. liquid. liquid. On liquid. viscous Red/Brown. Orange. standing Dark brown liquid.

became solid. Orange/brown.

Orange.

Heating for Became No change Became harder. Became hard No change.

3 hours at solid. No Colour and brittle.

100 C in air. colour darkened. Blackened.

change.

Heating for Became No change 6 hours at solid. No 100 C in air colour change.

Heating for Became Still very Became harder. Became hard Still very 1 hour at solid. viscous Colour and brittle. viscous 160"C in N2 Darkened liquid. darkened. Blackened. liquid.

slightly. Darkened Darkened slightly. slightly.

Example 5 Example 6 Rubbery gel. Hard brittle On standing solid.

became very Yellow viscous liquid.

Yellow/orange.

Became solid. No change.

Darkened slightly.

Became a Became dark rubbery solid. organge.

Pale yellow.

*Copolymers used were those produced in the corresponding Examples and Test A in Table TABLE Ill Glass transition temperatures (Ts) of carbon disulphide copolymers* Example 1 Example2 TestA Example3 Example 5 Untreated sample 28.9"C -16.4 C -3.6 C -5.7 C -18.1 C After heating for 52.9 C -16.3 C -9.7 C 85.8 C 20.6 C 1 hour at 160 C in nitrogen *Copolymers used were those produced in the corresponding Examples and Test A in Table

Claims (10)

1. Copolymers obtainable by copolymerising carbon disulphide with a substituted epoxide said copolymer being represented by the following formula:

wherein R is a group selected from a C2 or higher alkyl, a haloalkyl, an alkenyl, a haloalkenyl, an aryl, an alkaryl and an epoxy or halogen substituted epoxy group.

2. A copolymer according to claim 1 said copolymer having a molecular weight of around 1000.

3. A copolymer according to claim 1 or 2 wherein said copolymer has a sulphur content from 64 to 91% of the calculated amount of sulphur for a 1:1 copolymer of carbon disulphide and the epoxide.

4. A copolymer according to any one of the preceding claims wherein said copolymer contains carbonyl groups, hydroxyl groups and disulphide links.

5. A copolymer according to any one of the preceding claims wherein said copolymer upon heat treatment at 1600C for 1 hour in a nitrogen atmosphere exhibits a glass transition temperature which is the same as or greater then that of the coploymer prior to heat treatment.

6. A copolymer according to any one of the preceding claims wherein said copolymer is obtainable by the copolymerisation of carbon disulphide with an epoxy comonomer selected from 1,2 epoxy butane, butadiene monoxide, styrene oxide, epibromohydrin, 1,4-butanediol diglycidyi ether and 1,3-butadiene diepoxide.

7. A process for the production of copolymers of carbon disulphide and a substituted epoxide, said process comprising contacting carbon disulphide with an epoxide of the formula:

where R has the same significance as in formula (I) in claim 1 above in the presence of a catalyst system comprising an organometallic compound and an electron donor at temperatures from about 0 C to 100"C, in an atmosphere inert under the reaction conditions.

8. A process according to claim 7 wherein the organometallic compound is an alkyl substituted transition metal.

9. A process according to claim 7 or 8 wherein the electron donor is selected from tertiary amines and tertiary phosphines.

10. A process according to any one of claims 7 to 9 wherein the copolymerisation is carried out in solution.