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Alkali salts of (ω-sulphoxyalkyl)-acrylates and -methacrylates: Radical polymerization and copolymerization
European Polymer Journal, Vol. 14, pp. 977 to 980 © Pergamon Press Ltd 1978. Printed in Great Britain
0014-3057/78/1201-0977502.00/0
ALKALI SALTS OF (og-SULPHOXYALKYL)-ACRYLATES A N D -METHACRYLATES: RADICAL POLYMERIZATION A N D COPOLYMERIZATION M . ~ORM a n d
S. NE~PUREK
Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6, Czechoslovakia
(Received 3 April 1978; in final form 7 June 1978) Abstract--A new preparation of alkali salts of (og-sulphoxyalkyl}-acrylates and -methacrylates, by reaction of alkali salts of acrylic and methacrylic acids with cyclic sulphates, is described; spectral characterization of the products is described. The kinetics of the radical polymerization of sodium (2-sulphoxyethyl)methacrylate (SSEM) were studied; monomer reactivity ratios for copolymerization with methacrylic acid were: r t = 1.1 ___0.15 and r 2 = 0.73 + 0.05. Dark electrical surface conductivity of some homopolymers and copolymers with methacrylic acid was found to be 104-10 tt f~-t, depending on relative humidity.
late (21.6g, 0.2mole) and of hydroquinone (0.1g) in 210cm 3 of absolute ethanol. Sodium methacrylate dissolved gradually during the reaction, and towards the end a white crystalline product precipitated. After 1 hr stirring at the reaction temperature, the reaction mixture was cooled to - 5 °. The crystalline product was filtered off, washed with ethanol and recrystallized from ethanol. Sodium salt (44.1 g, 95% theor.) in the form of white crystalline powder was obtained after vacuum drying (13 Pa) over phosphorus pentoxide; m.p. 162-165 °. Similarly potassium (2-sulphoxyethyl)methacrylate (yield, 96~ theor.; m.p. 169-172 °) and sodium (2-sulphoxyethyl)acrylate (yield, 80~o theor.; m.p. 163-165 r~) were prepared by the reaction of ethylene sulphate with potassium methacrylate and ethylene sulphate with sodium acrylate, respectively.
INTRODUCTION
In connection with the preparation of new hydrophilic systems suitable for obtaining some biologically active substances, alkali salts (~o-sulphoxyalkyl)-acrylates and -methacrylates have been synthesized. Water-soluble polymers behaving as strong anionactive polyelectrolytes have been prepared by radical polymerization and copolymerization with ~,fl-unsaturated acids. The properties of these products have not been published. Use of substances of this type in connection with the preparation of various silver-halide photographic emulsions has been mentioned in the patent literature [1-3]. Bowman [4] reported briefly the preparation of pyridinium (2-sulphoxyethyl)methacrylate by reaction of (2hydroxyethyl)methacrylate with complex Py.SO3. Stecker [5] described the preparation of a m m o n i u m and alkali salts of (2-sulphoxyethyl)-acrylate and -methacrylate by sulphonation of (2-hydroxyethyl)acrylate and -methacrylate respectively with sulphonic acid, using organic amides as catalysts. For preparation of the above alkali salts, we used reaction of cyclic sulphates with alkali salts of acrylic and methacrylic acids. The kinetics of radical polymerization of SSEM are now described, together with the copolymerization parameters of SSEM with methacrylic acid. EXPERIMENTAL [6] Sodium methacrylate was prepared by neutralization of aethacrylic acid with sodium hydroxide and isolated by evaporation. Lithium and potassium salts were prepared similarly. The cyclic ethylene sulphate was prepared [7] by reaction of the cycfic ethylene sulphite with sulphuric acid and thionyl chloride and purified by vacuum distillation (13Pa); m.p. 97-98 ° (lit. m.p. 99°)[8]. The cyclic 1,3-butanediol sulphate [9] was prepared by reaction of 1,3-butanediol with 50% fuming sulphuric acid; m.p. 44-45 ° (lit. m.p. 44-46°)[10].
Sodium (2-sulphoxyethyl)methacrylate Ethylene sulphate (24.8 g, 0.2mole) was added at 65 ° within 30 min to a stirred suspension of sodium methacry-
Sodium (3-sulphoxy butyl)methacrflate 1,3-Butanediol sulphate (1.52g~ 0.01 mole) and hydroquinone (0.1 g) were added all at once to a suspension of sodium methacrylate (l.08g, 0.01 mole) in 20cm 3 of absolute ethanol at 65 °. The reaction mixture was stirred for 3 hr at this temperature until all sulphate was dissolved. Ethanol was then distilled off in vacuum and the oily product was washed with pentane; the final powdery product was crystallized at - 7 0 ° from ethanol-ether. After drying, 1.4g (54~o theor.), white product was obtained; m.p. 130-135 °.
Polymerization Alkali salts of (~o-sulphoxyalkylhacrylates and -methacrylates were polymerized in polar solvents (water, ethanol, DMSO, DMFA) at temperatures from 50 ° to 60 ° initiating with ammonium persulphate or ABIN in nitrogen. The polymers were precipitated in excess ethanol or ethanol ether mixture. For polymerization in ethanol, the polymer preci pitat ed. The radical polymerization of sodium (2-sulphoxyethyl)methaerylate in DMSO was studied kinetically in lensshaped dilatometers at (60 + 0.2°). At the required conversion (10~o), the reaction was stopped by cooling in liquid nitrogen. After 5-8~o conversion in copolymerizations of SSEM with methacrylic acid, dilatometers were cooled in liquid nitrogen and the copolymers were precipitated as described previously. The copolymer compositions were determined from NMR spectra from the intensities of the chemical shifts o f - - C H 2 - - C H 2 - - and ~ C H 2 ~ C ( C H j ) - - groups.
977 I:.P.J. 14/12 A
978
M. ,~ORMand S. NF_~PI~REK
Reaction of potassium poly(methacrylate) with ethylene sulphate Potassium polymethacrylate (2.48g, 0.2 mole) in 20 cma of water was mixed with ethylene sulphate (2.48 g, 0.2 mole) and stirred for l hr at room temperature. The temperature increased spontaneously to 30°. The yield of the precipitated polymer was 4.0 g (82.5%). Potassium (3-sulphoxybutyl)methacrylate was prepared similarly by reaction of potassium polymethacrylate with 1,3-butanedioi sulphate; the reaction time was 6 hr and the yield was 80% theor. RESULTS AND DISCUSSION
Kaiser et al. [11] studied the solvolysis of ethylene-, trimethylene- and dimethylsulphates; for the pH range 2-9, the reactions were first-order with relative rates 12:1:6. The predominant first reaction step consists of the cleavage of the C---O bond and the formation of monoesters of sulphuric acid. In a strongly alkaline medium, the prevailing reaction is saponification with cleavage of the S---O bond. Brimacombe [12] came to similar conclusions for the acidobasic hydrolysis of other cyclic sulphates. Preliminary experiments have shown that alkali salts of the carboxylic acids, exhibiting the properties of weak organic bases, react with cyclic sulphates similarly to weak inorganic bases, with formation of the respective monoesters of co-hydroxyalkyl sub phuric acid with organic acids. Acrylic and methacrylic acids were chosen as organic acids. The reaction was carried out in absolute ethanol at 60-70 °. The reaction of sodium methacrylate with ethylene sulphate can be described thus CH2---O CH2 = C(CH3)COO Na +
system. The corresponding reaction of 1,3-butanediol sulphate was much slower than that of ethylene sulphate. Here the finely ground sulphate was added all at once to the suspension of an alkali salt of the organic acid and the reaction mixture was stirred until the whole sulphate reacted (usually for some hours). Alkali salts of (co-sulphoxyalkyl)-acrylates and -methacrylates [13] are white crystalline compounds, rather stable if kept in the cold. At their melting points, they polymerize. They are freely soluble in polar solvents, e.g. alcohols, water, DMFA and DMSO. Both neutral and alkaline solutions of the salts are stable. In acidic solutions, they decompose slowly to sulphuric acid and to the corresponding ta-hydroxyalkyl esters of methacrylic or acrylic acids.
Polymerization The reaction order with respect to initiator (ABIN) was 0.34 + 0.01 and that with respect to monomer was 0.87 + 0.05. The compositions of the initial reaction mixtures and the measured polymerization rates are given in Table 1. The dependences of the molecular weights of SSEM on the concentrations of initiator and monomer were also determined. The course of the radical polymerization of SSEM is "non-idear'. This kinetic behaviour may result from one or more of the following causes [14,15"1: invalid basic assumptions, degradation transfer, diffusion control of termination, formation of donor-acceptor complexes, and others. We have not studied these effects in detail, but the results indicate that variations in the diffusion
\ /
SO2-~CH2 = C(CH3)COOCH2CH2OSO3Na
CH2--.O The reaction is exothermic and the rate of addition of the solid sulphate was regulated so that the temperature did not change (without external heating). The product usually precipitated toward the end of the reaction. For lithium salts and 1,3-butanediol sulphate, the products remained dissolved; they were isolated by evaporation of the solvent and purified by successive crystallization from a suitable solvent
controlled termination constants, usually attributable to viscosity factors, significantly influence this polymerization.
C opol ymerization The results of copolymerizations of SSEM with methacrylic acid in DMSO at 60 ° are shown in
Table 1. Dependence of the polymerization rate and molecular weight of sodium (2-sulphoxyethyl)methacrylate on the composition of the initial mixture in DMSO at 60° Composition of the starting mixture (mole/L) Sample No.
SSEM
SI $2 $3 $4 $5 $6 $7 $8 $9 S10 SI1
1.417 1.410 1.421 1.422 1.415 0.496 0.763 0.896 1.374 1.426 1.627
ABIN 7.51 x 1.15 × 1.51 x 2.31 x 3.45 x 2.89 x 2.89 x 2.89 x 3.24 x 2.92 x 2.21 x
10-s 10-4 10-4 10-4 10-'* 10-4 10-'* 10-4 l0 -4 10-4 10-4
DMSO 13.33 13.31 13.32 13.32 13.35 26.32 21.75 23.11 14.84 14.88 13.25
Rp. l04 (mole/I.sec) Mw x l0 -6 2.188 2.570 2.857 3.182 3.792 1.300 1.857 2.059 3.172 3.375 3.582
5-10 5-10 5-10 5-10 5-10 2.5 4.2 -8.0 8.0 8.3
Alkali salt of (to-sulphoxyalkyl)-acrylates and -methacrylates
979
Table 2. Copolymerization of sodium (2-sulphoxyethyl)methacrylate (l) with methacrylic acid (2) in DMSO at 60°; ABIN = 1.3 x 10-4 mole/l Monomer composition, f~ mole %
R*
Polymer composition, Ft mole ~o
90.0 80.0 65.0 60.0 50.0 30,0 20.0 20.0
1.36 1.44 1.82 2.06 2,27 3.85 4.96 5.01
91.4 85.5 67.8 61.5 54.7 34.2 25.0 25.1
*R--ratio of the intensities of chemical shifts ~CHz---C(CH3)--- and --CH2--qCH2-- groups (NMR).
of
proton
of
Table 2. The copolymerization parameters of the SSEM(I) + MAA(2) system, as determined after Fineman and Ross, are: r I = l.l _+ 0.15 and r 2 = 0.73 + 0.05. Copolymers with various ratios of - - C O O - and - - C O O - - C H 2 - - C H 2 - - O S O ~- groups can be obtained also by reacting an alkali salt of polyacrylic and poly-methacrylic acid with a less than equimolar amount of a cyclic sulphate.
IO II
E
I0 lO
Electrical conductivity i09'
0
I
I0 ~
io
1 50
I00
humidity,
%
tO
Relotive
I
Fig. 1. Dependence of the surface electrical resistance of the homopolymer on ambient humidity: (l) M, = 8.3 x 106; (2) M~ = 4.2 x 106.
The surface electrical conductivity, about one order higher than those of all anionic polyelectrolytes known so far and comparable with that of cationic polyelectrolytes, is an interesting feature of these new polymers. The electrical conductivity depends strongly on the humidity of the environment and water content of the polymer, but remains high at relative low humidities (Fig. l). It decreases slightly with increasing molecular weight of the polymers. The polymers can be described as "water-holding electrolytes", conducting via migration of ions rather than by transport of electrons. The time dependence of the surface resistance is thus influenced by the kinetics of water adsorption (Fig. 2). The polymeric film was dried in vacuum then kept over phosphorus pentox-
il
.
IO 9
~
107
w
I
///
/
106
,o'- i / I , /I 860 / I00
}01
102
Time,
I05
104 IO0
I0 ~
I02
min
Fig. 2. Time-dependence of the surface electrical resistance: (1) polymer S 1l; (2) polymer with 25% of COOK and 75~o of OSOaNa.
980
M. gORM and S. NEgPOREK
ide and finally for some days at a relative humidity 15%. Afger transfer to R.H. 86%, the surface electrical resistance was measured. The reverse procedure consisted in the transfer of the film to 15% humidity after equilibration with a relative humidity of 86?/0. Copolymerization with MAA substantially raises the surface electrical conductivity. The electrical conductivity at low relative humidity decreases with increasing content of the ---OSO3Na groups in the copolymer. On the contrary, at higher R.H., the conductivity increases. It seems that at low relative humidities the electrical conductivity is caused by the dissociation of the C O O H groups. REFERENCES
1. K. R. Hollister and E. J. Perry, US pat. 3,679,425 (1972). 2. D. A. Smith, US pat. 3,658,878 0972). 3. J. M. Babbitt, R. W. Spayd and N. F. Irani, F. Demande 2, 178, 157 0973). 4. W. A. Bowman, US pat. 3,748,143 (1973). 5. R. Steckler, US pat. 3,839,393 (1974). 6. Spectral characterization of products was carried o u t
7. 8. 9. 10. 11. 12. 13.
14. 15.
on the following instrumentation: i.r., Perkin-Elmer Model 457 spectrometer; NMR, Jeol PS 100 spectrometer using hexamethyldisiloxane as internal standard. Molecular weights were determined by light scattering using Photogoniodifusomerer Sofica with aqueous KC1 or NaCI. Surface electrical conductivity was measured with a Siemens terraohmeter using thin films on glass supports cast from aqueous solutions. W. W. Carlson and L. H. Cretcher, J. Am. chem. Soc. 69, 1952 (1947). W. Baker, J. chem. Soc. 86 (1932). J. Lichtenberger and R. Lichtenberger, Bull. Soc. Chim. France 1007 (1948). J. J. Miller, J. org. Chem. 27, 2680 (1962). E. T. Kaiser, M. Panar and F. H. Westheimer, J. Am. chem. Soc. 85, 602 (1963). J. S. Brimacombe, A. B. Foster, E. B. Hancock, W. G. Overend and M. Stacey, J. chem. Soc. 201 (1960). The results of elemental analysis and the i.r. and NMR spectra are in accord with the structure of the prepared alkali salts of (~o-sulphoxyalkyl)-acrylate and -methacrylate. D. G. Smith, J. appl. Chem. 17, 339 (1967). G. E. Scott and E. Senogles, J. Macromolek. Sci.-Revs. Macromol. Chem. C9(1), 49 (1973).
0014-3057/78/1201-0977502.00/0
ALKALI SALTS OF (og-SULPHOXYALKYL)-ACRYLATES A N D -METHACRYLATES: RADICAL POLYMERIZATION A N D COPOLYMERIZATION M . ~ORM a n d
S. NE~PUREK
Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6, Czechoslovakia
(Received 3 April 1978; in final form 7 June 1978) Abstract--A new preparation of alkali salts of (og-sulphoxyalkyl}-acrylates and -methacrylates, by reaction of alkali salts of acrylic and methacrylic acids with cyclic sulphates, is described; spectral characterization of the products is described. The kinetics of the radical polymerization of sodium (2-sulphoxyethyl)methacrylate (SSEM) were studied; monomer reactivity ratios for copolymerization with methacrylic acid were: r t = 1.1 ___0.15 and r 2 = 0.73 + 0.05. Dark electrical surface conductivity of some homopolymers and copolymers with methacrylic acid was found to be 104-10 tt f~-t, depending on relative humidity.
late (21.6g, 0.2mole) and of hydroquinone (0.1g) in 210cm 3 of absolute ethanol. Sodium methacrylate dissolved gradually during the reaction, and towards the end a white crystalline product precipitated. After 1 hr stirring at the reaction temperature, the reaction mixture was cooled to - 5 °. The crystalline product was filtered off, washed with ethanol and recrystallized from ethanol. Sodium salt (44.1 g, 95% theor.) in the form of white crystalline powder was obtained after vacuum drying (13 Pa) over phosphorus pentoxide; m.p. 162-165 °. Similarly potassium (2-sulphoxyethyl)methacrylate (yield, 96~ theor.; m.p. 169-172 °) and sodium (2-sulphoxyethyl)acrylate (yield, 80~o theor.; m.p. 163-165 r~) were prepared by the reaction of ethylene sulphate with potassium methacrylate and ethylene sulphate with sodium acrylate, respectively.
INTRODUCTION
In connection with the preparation of new hydrophilic systems suitable for obtaining some biologically active substances, alkali salts (~o-sulphoxyalkyl)-acrylates and -methacrylates have been synthesized. Water-soluble polymers behaving as strong anionactive polyelectrolytes have been prepared by radical polymerization and copolymerization with ~,fl-unsaturated acids. The properties of these products have not been published. Use of substances of this type in connection with the preparation of various silver-halide photographic emulsions has been mentioned in the patent literature [1-3]. Bowman [4] reported briefly the preparation of pyridinium (2-sulphoxyethyl)methacrylate by reaction of (2hydroxyethyl)methacrylate with complex Py.SO3. Stecker [5] described the preparation of a m m o n i u m and alkali salts of (2-sulphoxyethyl)-acrylate and -methacrylate by sulphonation of (2-hydroxyethyl)acrylate and -methacrylate respectively with sulphonic acid, using organic amides as catalysts. For preparation of the above alkali salts, we used reaction of cyclic sulphates with alkali salts of acrylic and methacrylic acids. The kinetics of radical polymerization of SSEM are now described, together with the copolymerization parameters of SSEM with methacrylic acid. EXPERIMENTAL [6] Sodium methacrylate was prepared by neutralization of aethacrylic acid with sodium hydroxide and isolated by evaporation. Lithium and potassium salts were prepared similarly. The cyclic ethylene sulphate was prepared [7] by reaction of the cycfic ethylene sulphite with sulphuric acid and thionyl chloride and purified by vacuum distillation (13Pa); m.p. 97-98 ° (lit. m.p. 99°)[8]. The cyclic 1,3-butanediol sulphate [9] was prepared by reaction of 1,3-butanediol with 50% fuming sulphuric acid; m.p. 44-45 ° (lit. m.p. 44-46°)[10].
Sodium (2-sulphoxyethyl)methacrylate Ethylene sulphate (24.8 g, 0.2mole) was added at 65 ° within 30 min to a stirred suspension of sodium methacry-
Sodium (3-sulphoxy butyl)methacrflate 1,3-Butanediol sulphate (1.52g~ 0.01 mole) and hydroquinone (0.1 g) were added all at once to a suspension of sodium methacrylate (l.08g, 0.01 mole) in 20cm 3 of absolute ethanol at 65 °. The reaction mixture was stirred for 3 hr at this temperature until all sulphate was dissolved. Ethanol was then distilled off in vacuum and the oily product was washed with pentane; the final powdery product was crystallized at - 7 0 ° from ethanol-ether. After drying, 1.4g (54~o theor.), white product was obtained; m.p. 130-135 °.
Polymerization Alkali salts of (~o-sulphoxyalkylhacrylates and -methacrylates were polymerized in polar solvents (water, ethanol, DMSO, DMFA) at temperatures from 50 ° to 60 ° initiating with ammonium persulphate or ABIN in nitrogen. The polymers were precipitated in excess ethanol or ethanol ether mixture. For polymerization in ethanol, the polymer preci pitat ed. The radical polymerization of sodium (2-sulphoxyethyl)methaerylate in DMSO was studied kinetically in lensshaped dilatometers at (60 + 0.2°). At the required conversion (10~o), the reaction was stopped by cooling in liquid nitrogen. After 5-8~o conversion in copolymerizations of SSEM with methacrylic acid, dilatometers were cooled in liquid nitrogen and the copolymers were precipitated as described previously. The copolymer compositions were determined from NMR spectra from the intensities of the chemical shifts o f - - C H 2 - - C H 2 - - and ~ C H 2 ~ C ( C H j ) - - groups.
977 I:.P.J. 14/12 A
978
M. ,~ORMand S. NF_~PI~REK
Reaction of potassium poly(methacrylate) with ethylene sulphate Potassium polymethacrylate (2.48g, 0.2 mole) in 20 cma of water was mixed with ethylene sulphate (2.48 g, 0.2 mole) and stirred for l hr at room temperature. The temperature increased spontaneously to 30°. The yield of the precipitated polymer was 4.0 g (82.5%). Potassium (3-sulphoxybutyl)methacrylate was prepared similarly by reaction of potassium polymethacrylate with 1,3-butanedioi sulphate; the reaction time was 6 hr and the yield was 80% theor. RESULTS AND DISCUSSION
Kaiser et al. [11] studied the solvolysis of ethylene-, trimethylene- and dimethylsulphates; for the pH range 2-9, the reactions were first-order with relative rates 12:1:6. The predominant first reaction step consists of the cleavage of the C---O bond and the formation of monoesters of sulphuric acid. In a strongly alkaline medium, the prevailing reaction is saponification with cleavage of the S---O bond. Brimacombe [12] came to similar conclusions for the acidobasic hydrolysis of other cyclic sulphates. Preliminary experiments have shown that alkali salts of the carboxylic acids, exhibiting the properties of weak organic bases, react with cyclic sulphates similarly to weak inorganic bases, with formation of the respective monoesters of co-hydroxyalkyl sub phuric acid with organic acids. Acrylic and methacrylic acids were chosen as organic acids. The reaction was carried out in absolute ethanol at 60-70 °. The reaction of sodium methacrylate with ethylene sulphate can be described thus CH2---O CH2 = C(CH3)COO Na +
system. The corresponding reaction of 1,3-butanediol sulphate was much slower than that of ethylene sulphate. Here the finely ground sulphate was added all at once to the suspension of an alkali salt of the organic acid and the reaction mixture was stirred until the whole sulphate reacted (usually for some hours). Alkali salts of (co-sulphoxyalkyl)-acrylates and -methacrylates [13] are white crystalline compounds, rather stable if kept in the cold. At their melting points, they polymerize. They are freely soluble in polar solvents, e.g. alcohols, water, DMFA and DMSO. Both neutral and alkaline solutions of the salts are stable. In acidic solutions, they decompose slowly to sulphuric acid and to the corresponding ta-hydroxyalkyl esters of methacrylic or acrylic acids.
Polymerization The reaction order with respect to initiator (ABIN) was 0.34 + 0.01 and that with respect to monomer was 0.87 + 0.05. The compositions of the initial reaction mixtures and the measured polymerization rates are given in Table 1. The dependences of the molecular weights of SSEM on the concentrations of initiator and monomer were also determined. The course of the radical polymerization of SSEM is "non-idear'. This kinetic behaviour may result from one or more of the following causes [14,15"1: invalid basic assumptions, degradation transfer, diffusion control of termination, formation of donor-acceptor complexes, and others. We have not studied these effects in detail, but the results indicate that variations in the diffusion
\ /
SO2-~CH2 = C(CH3)COOCH2CH2OSO3Na
CH2--.O The reaction is exothermic and the rate of addition of the solid sulphate was regulated so that the temperature did not change (without external heating). The product usually precipitated toward the end of the reaction. For lithium salts and 1,3-butanediol sulphate, the products remained dissolved; they were isolated by evaporation of the solvent and purified by successive crystallization from a suitable solvent
controlled termination constants, usually attributable to viscosity factors, significantly influence this polymerization.
C opol ymerization The results of copolymerizations of SSEM with methacrylic acid in DMSO at 60 ° are shown in
Table 1. Dependence of the polymerization rate and molecular weight of sodium (2-sulphoxyethyl)methacrylate on the composition of the initial mixture in DMSO at 60° Composition of the starting mixture (mole/L) Sample No.
SSEM
SI $2 $3 $4 $5 $6 $7 $8 $9 S10 SI1
1.417 1.410 1.421 1.422 1.415 0.496 0.763 0.896 1.374 1.426 1.627
ABIN 7.51 x 1.15 × 1.51 x 2.31 x 3.45 x 2.89 x 2.89 x 2.89 x 3.24 x 2.92 x 2.21 x
10-s 10-4 10-4 10-4 10-'* 10-4 10-'* 10-4 l0 -4 10-4 10-4
DMSO 13.33 13.31 13.32 13.32 13.35 26.32 21.75 23.11 14.84 14.88 13.25
Rp. l04 (mole/I.sec) Mw x l0 -6 2.188 2.570 2.857 3.182 3.792 1.300 1.857 2.059 3.172 3.375 3.582
5-10 5-10 5-10 5-10 5-10 2.5 4.2 -8.0 8.0 8.3
Alkali salt of (to-sulphoxyalkyl)-acrylates and -methacrylates
979
Table 2. Copolymerization of sodium (2-sulphoxyethyl)methacrylate (l) with methacrylic acid (2) in DMSO at 60°; ABIN = 1.3 x 10-4 mole/l Monomer composition, f~ mole %
R*
Polymer composition, Ft mole ~o
90.0 80.0 65.0 60.0 50.0 30,0 20.0 20.0
1.36 1.44 1.82 2.06 2,27 3.85 4.96 5.01
91.4 85.5 67.8 61.5 54.7 34.2 25.0 25.1
*R--ratio of the intensities of chemical shifts ~CHz---C(CH3)--- and --CH2--qCH2-- groups (NMR).
of
proton
of
Table 2. The copolymerization parameters of the SSEM(I) + MAA(2) system, as determined after Fineman and Ross, are: r I = l.l _+ 0.15 and r 2 = 0.73 + 0.05. Copolymers with various ratios of - - C O O - and - - C O O - - C H 2 - - C H 2 - - O S O ~- groups can be obtained also by reacting an alkali salt of polyacrylic and poly-methacrylic acid with a less than equimolar amount of a cyclic sulphate.
IO II
E
I0 lO
Electrical conductivity i09'
0
I
I0 ~
io
1 50
I00
humidity,
%
tO
Relotive
I
Fig. 1. Dependence of the surface electrical resistance of the homopolymer on ambient humidity: (l) M, = 8.3 x 106; (2) M~ = 4.2 x 106.
The surface electrical conductivity, about one order higher than those of all anionic polyelectrolytes known so far and comparable with that of cationic polyelectrolytes, is an interesting feature of these new polymers. The electrical conductivity depends strongly on the humidity of the environment and water content of the polymer, but remains high at relative low humidities (Fig. l). It decreases slightly with increasing molecular weight of the polymers. The polymers can be described as "water-holding electrolytes", conducting via migration of ions rather than by transport of electrons. The time dependence of the surface resistance is thus influenced by the kinetics of water adsorption (Fig. 2). The polymeric film was dried in vacuum then kept over phosphorus pentox-
il
.
IO 9
~
107
w
I
///
/
106
,o'- i / I , /I 860 / I00
}01
102
Time,
I05
104 IO0
I0 ~
I02
min
Fig. 2. Time-dependence of the surface electrical resistance: (1) polymer S 1l; (2) polymer with 25% of COOK and 75~o of OSOaNa.
980
M. gORM and S. NEgPOREK
ide and finally for some days at a relative humidity 15%. Afger transfer to R.H. 86%, the surface electrical resistance was measured. The reverse procedure consisted in the transfer of the film to 15% humidity after equilibration with a relative humidity of 86?/0. Copolymerization with MAA substantially raises the surface electrical conductivity. The electrical conductivity at low relative humidity decreases with increasing content of the ---OSO3Na groups in the copolymer. On the contrary, at higher R.H., the conductivity increases. It seems that at low relative humidities the electrical conductivity is caused by the dissociation of the C O O H groups. REFERENCES
1. K. R. Hollister and E. J. Perry, US pat. 3,679,425 (1972). 2. D. A. Smith, US pat. 3,658,878 0972). 3. J. M. Babbitt, R. W. Spayd and N. F. Irani, F. Demande 2, 178, 157 0973). 4. W. A. Bowman, US pat. 3,748,143 (1973). 5. R. Steckler, US pat. 3,839,393 (1974). 6. Spectral characterization of products was carried o u t
7. 8. 9. 10. 11. 12. 13.
14. 15.
on the following instrumentation: i.r., Perkin-Elmer Model 457 spectrometer; NMR, Jeol PS 100 spectrometer using hexamethyldisiloxane as internal standard. Molecular weights were determined by light scattering using Photogoniodifusomerer Sofica with aqueous KC1 or NaCI. Surface electrical conductivity was measured with a Siemens terraohmeter using thin films on glass supports cast from aqueous solutions. W. W. Carlson and L. H. Cretcher, J. Am. chem. Soc. 69, 1952 (1947). W. Baker, J. chem. Soc. 86 (1932). J. Lichtenberger and R. Lichtenberger, Bull. Soc. Chim. France 1007 (1948). J. J. Miller, J. org. Chem. 27, 2680 (1962). E. T. Kaiser, M. Panar and F. H. Westheimer, J. Am. chem. Soc. 85, 602 (1963). J. S. Brimacombe, A. B. Foster, E. B. Hancock, W. G. Overend and M. Stacey, J. chem. Soc. 201 (1960). The results of elemental analysis and the i.r. and NMR spectra are in accord with the structure of the prepared alkali salts of (~o-sulphoxyalkyl)-acrylate and -methacrylate. D. G. Smith, J. appl. Chem. 17, 339 (1967). G. E. Scott and E. Senogles, J. Macromolek. Sci.-Revs. Macromol. Chem. C9(1), 49 (1973).