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The polymerization of acrylamide on poly(ethylene glycol) template
Eur. Pol~m. J. Vo1.24, No.5, pp.501-503, 1988 Printed in Great Britain
THE POLYMERIZATION
OF ACRYLAMIDE
0014-3057/88 $3.00+0.00 Pergamon Press plc
ON POLY(ETHYLENE
GLYCOL)
TEMPLATE a
by A.V.PANTAR~ R.V.BAHULEKAR,
S.PONRATHNAM c and N.R.AYYANGAR
National Chemical
Pune 411 008, India.
Laboratory,
a - NCL Communication no. 4282 b - present address: Indian Petrochemicals Corpn. Vadodara 391 346, India c - author for correspondence
Ltd.,
(Received 11 December 1987; in Revised form 11 December 1987) ABSTRACT The polymerization of acrylamide has been investigated in the presence of poly(ethylene glycol) in methanol/water using redox initiation. The resulting polymer is a hydrogen-bonded polycomplex of poly(ethylene glycol) and polyacrylamide. The poly(ethylene glycol) influences the rate of polymerization, acting as a template. INTRODUCTION Template
(matrix)
polymerizations
are well documented
merizing system may interact with the monomer, stereostructure ogen bonding
of the resulting
in a polycomplex
of acrylamide
forces
(AAM) in the presence of poly(ethylene
(7). The composition
matrix,
the polymerization
rate and the (4), hydr-
(6) have been studied. glycol)(PEG)
of the complex depends on reaction variables
the polarity of the solvent and the dilution oligomeric
influencing
polymer. Effects due to Van der Waal interactions
(5) and electrostatic
The polymerization
(1,2). Inert polymer present in a poly-
(8). In this communication,
PEG 200, on the rate of polymerization
of acrylamide
results
such as
the effect of an is considered.
EXPERIMENTAL AAM was recrystallized from benzene. PEG 200 was dried over phosphorus pentoxide. Ammonium persulphate and NNN'N'-tetramethyl ethylene diamine (TEMED) were of analytical reagent grade. Deionized water and distilled methanol were used as solvents. Polymerizations were performed at 35 ~ 0.1°C. Appropriate quantities of AAM and PEG 200 were dissolved in methanol. The reactions were initiated with aq. solutions of TEMED and the persulphate. Samples of the reaction mixture were precipitated with excess cold methanol, filtered and dried to constant weight. Intrinsic viscosities of the polymers were determined in water at 30.0 ~ 0.1°C using an Ubbelohde viscometer. IR spectra of the polymers were recorded with a Perkin Elmer 621 spectrometer using films formed from aq. solution. NMR spectra of polymers in D20 solution (10% w/v) were recorded with a Perkin Elmer 90 MHz instrument~ tetramethylsilane was taken as external reference and the probe temperature was 40°C. RESULTS AND DISCUSSION Three sets of experiments
were performed to evaluate
the time dependence of the polymerization
of AAM, the template effect of PEG 200 and the effect of solvent polarity system PEG-AAM in methanol/water are soluble but the polymer
is a typical precipitative
(polyacrylamide,
hours was noted during which no precipitation methanol.
After 18 hours,
PAAM)
polymerization.
precipitates.
(see Table 1). The AAM and PEG 200
An induction period of 18
occurred when the reactants were poured into
turbidity was observed in the reaction vessels and polymer was ob-
tained on pouring into excess methanol. the absence of any interaction
PEG 200 is soluble in methanol but PAAM is not. In
between PEG and PAAM, only PAAM should be precipitated.
In this
work, conversions exceeded the expected yield~ (see Table 1B). Additionally, elemental analysis, IR and NMR studies showed the presence of PEG in the precipitate (8). The nitrogen
502
Short Communications
contents of the polymers were lower than that for pure PAAM (9). In the IR spectra, strong absorption at 1102 cm -I characteristic of PEG (10) was noted for all the polymers. The polycomplex compositions were estimated quantitatively from the N~R data (8). The molar ratios of the ethylene oxide residue to the AAM in the complexes were estimated from the relative areas at 3 . 6 5 ~ and 1.7 and 2.2~ respectively. The data are presented in Tables 1A and IB and used to calculate conversions (PAAM formed). The polymer formed initially has the highest ratio
of PEG in the complex. The PEG content in
the complex increases as the solvent polarity decreases (see Tables IA and 1C) and is independent of the PEG to AAM ratio in the reaction mixture (see Tables IA and IB). With increasing conversion, the PEG content decreases in all three systems. The initial polymerization can be visualized as occurring in the vicinity of PEG 200, generating the polycomplex. This polycomplex induces a plurimolecular aggregation of AAM (11). The polymer subsequently formed is adsorbed on the polycomplex thereby increasing the PAAM mole fraction with increasing conversion. The polymerization rate of AAM increases with increase in the relative concentration of PEG 200 from 0.2 to 0.4 (see Tables IA and 1B) with other parameters remaining unchanged. PEG indeed provides an orientation effect for AAM. The concentration of AAM in the vicinity of PEG increases, resulting in enhanced rate. Thus PEG 200 acts as a template even though it is essentially a mixture of tetramer and pentamer. Table I. Results for acr~lamide/poly(ethylene qlycol) systems.
System
Reaction % conversion time (min) CAAM) 1120 1325 1665 2120 4665
5.94 8.11 15.36 20.91 59.44
~395 1890 2145 2885 4665 1980 2400 2580 2700 3960 (NH4)2S208 = 0.005 gl
(dl/g) in ~ o m p l e x 0.10 0.10 0.08 0.04 0.04
1.11 1.50 1.54 1.88 1.61
14.70 44.52 52.51 60.86 100.00
0.09 0.04 0.07 0.03 0.03
0.95 1.31 1.62 1.08 0.82
25.35 28.83 34.85 32.76 71.93
0.30 0.22 0.13 0.09 0.03
0.88 1.39 1.84 2.50 2.00
:.
TEMED = 0.1150 gÁ temp. ~ 35 -+ 0.1°C.
solvent = CH3OH/H20 ~EG]/[AAM]:-
A and C, 0.2: B, 0.4
CH3OH/H20 (v/v) :- A and B, 25/4| C, 20/1.
The intrinsic viscosities of the isolated polymers do not follow a regular trend. PEG 200 does not act as a limiting template for which a one-to-one correlation between the template polymer and daughter polymer would be observed (12). The reaction medium acts as a precipitant for the PAAM formed. The variation in the intrinsic viscosity is due to the precipitation and the growth of the polymer radicals in the precipitated phase. As the polarity of
Short Communications
503
the reaction medium is decreased, the intrinsic viscosity of the formed polymer increases. Polymerization proceeds in the precipitated phase. Repeated dissolution and reprecipitation of the polycomplex in water/methanol affects its composition~ PEG is removed. Co-operative hydrogen-bonding between PEG and PAAM in the complex is weak and the individual polymers do not lose their specific solubility characteristics.
REFERENCES (1). C.H.Bamford, in "Developments in Polymerisation - 2", ed. R.N.Haward, Applied Science Publishers, London, 1981. (2). V.A.Kabanov, Makromol. Chem.!
suppl., ~,
41 (1979).
(3). R.Buter, Y.Y.Tan and G.Challa, J. Pol[m. Sci.; Part A-l, I~0, 1031 (%972). (4). J.Gons, E.J.Vorenkarmp and G.Challa, J. Pol[m. Sci. T Pol~m. Chem. Ed., 13, 1699 (1975). (5). J.Ferguson and S.A.O.Shah, Eur. Pol~m. J., ~, 343 (1968). (6). A.Blumstein, S.R.Kakivaya and K.R.Shah, J. Pol[m. Sci. T Pol[m. Symp., 4~, 75 (1974). (7). A.V.Pantar, M.Atreiyi and M.V.R.Rao, Angew. Makromol. Chem., 129, 163 (1985). (8). A.V.Pantar, Eur. Pol~m. J., 2A~2, 939 (1986). (9). A.V.Pantar, unpublished results. (10). K.J.Liu and J.L.Parsons, Macromolecules, 2, 529 (%969). (11). A.Chapiro, Eur. Polym. J., ~9, 417 (1973). (12). S.R.Kakivaya and A.Blumstein, J. Chem. Soc. I Chem. Commun., 459 (1974).
THE POLYMERIZATION
OF ACRYLAMIDE
0014-3057/88 $3.00+0.00 Pergamon Press plc
ON POLY(ETHYLENE
GLYCOL)
TEMPLATE a
by A.V.PANTAR~ R.V.BAHULEKAR,
S.PONRATHNAM c and N.R.AYYANGAR
National Chemical
Pune 411 008, India.
Laboratory,
a - NCL Communication no. 4282 b - present address: Indian Petrochemicals Corpn. Vadodara 391 346, India c - author for correspondence
Ltd.,
(Received 11 December 1987; in Revised form 11 December 1987) ABSTRACT The polymerization of acrylamide has been investigated in the presence of poly(ethylene glycol) in methanol/water using redox initiation. The resulting polymer is a hydrogen-bonded polycomplex of poly(ethylene glycol) and polyacrylamide. The poly(ethylene glycol) influences the rate of polymerization, acting as a template. INTRODUCTION Template
(matrix)
polymerizations
are well documented
merizing system may interact with the monomer, stereostructure ogen bonding
of the resulting
in a polycomplex
of acrylamide
forces
(AAM) in the presence of poly(ethylene
(7). The composition
matrix,
the polymerization
rate and the (4), hydr-
(6) have been studied. glycol)(PEG)
of the complex depends on reaction variables
the polarity of the solvent and the dilution oligomeric
influencing
polymer. Effects due to Van der Waal interactions
(5) and electrostatic
The polymerization
(1,2). Inert polymer present in a poly-
(8). In this communication,
PEG 200, on the rate of polymerization
of acrylamide
results
such as
the effect of an is considered.
EXPERIMENTAL AAM was recrystallized from benzene. PEG 200 was dried over phosphorus pentoxide. Ammonium persulphate and NNN'N'-tetramethyl ethylene diamine (TEMED) were of analytical reagent grade. Deionized water and distilled methanol were used as solvents. Polymerizations were performed at 35 ~ 0.1°C. Appropriate quantities of AAM and PEG 200 were dissolved in methanol. The reactions were initiated with aq. solutions of TEMED and the persulphate. Samples of the reaction mixture were precipitated with excess cold methanol, filtered and dried to constant weight. Intrinsic viscosities of the polymers were determined in water at 30.0 ~ 0.1°C using an Ubbelohde viscometer. IR spectra of the polymers were recorded with a Perkin Elmer 621 spectrometer using films formed from aq. solution. NMR spectra of polymers in D20 solution (10% w/v) were recorded with a Perkin Elmer 90 MHz instrument~ tetramethylsilane was taken as external reference and the probe temperature was 40°C. RESULTS AND DISCUSSION Three sets of experiments
were performed to evaluate
the time dependence of the polymerization
of AAM, the template effect of PEG 200 and the effect of solvent polarity system PEG-AAM in methanol/water are soluble but the polymer
is a typical precipitative
(polyacrylamide,
hours was noted during which no precipitation methanol.
After 18 hours,
PAAM)
polymerization.
precipitates.
(see Table 1). The AAM and PEG 200
An induction period of 18
occurred when the reactants were poured into
turbidity was observed in the reaction vessels and polymer was ob-
tained on pouring into excess methanol. the absence of any interaction
PEG 200 is soluble in methanol but PAAM is not. In
between PEG and PAAM, only PAAM should be precipitated.
In this
work, conversions exceeded the expected yield~ (see Table 1B). Additionally, elemental analysis, IR and NMR studies showed the presence of PEG in the precipitate (8). The nitrogen
502
Short Communications
contents of the polymers were lower than that for pure PAAM (9). In the IR spectra, strong absorption at 1102 cm -I characteristic of PEG (10) was noted for all the polymers. The polycomplex compositions were estimated quantitatively from the N~R data (8). The molar ratios of the ethylene oxide residue to the AAM in the complexes were estimated from the relative areas at 3 . 6 5 ~ and 1.7 and 2.2~ respectively. The data are presented in Tables 1A and IB and used to calculate conversions (PAAM formed). The polymer formed initially has the highest ratio
of PEG in the complex. The PEG content in
the complex increases as the solvent polarity decreases (see Tables IA and 1C) and is independent of the PEG to AAM ratio in the reaction mixture (see Tables IA and IB). With increasing conversion, the PEG content decreases in all three systems. The initial polymerization can be visualized as occurring in the vicinity of PEG 200, generating the polycomplex. This polycomplex induces a plurimolecular aggregation of AAM (11). The polymer subsequently formed is adsorbed on the polycomplex thereby increasing the PAAM mole fraction with increasing conversion. The polymerization rate of AAM increases with increase in the relative concentration of PEG 200 from 0.2 to 0.4 (see Tables IA and 1B) with other parameters remaining unchanged. PEG indeed provides an orientation effect for AAM. The concentration of AAM in the vicinity of PEG increases, resulting in enhanced rate. Thus PEG 200 acts as a template even though it is essentially a mixture of tetramer and pentamer. Table I. Results for acr~lamide/poly(ethylene qlycol) systems.
System
Reaction % conversion time (min) CAAM) 1120 1325 1665 2120 4665
5.94 8.11 15.36 20.91 59.44
~395 1890 2145 2885 4665 1980 2400 2580 2700 3960 (NH4)2S208 = 0.005 gl
(dl/g) in ~ o m p l e x 0.10 0.10 0.08 0.04 0.04
1.11 1.50 1.54 1.88 1.61
14.70 44.52 52.51 60.86 100.00
0.09 0.04 0.07 0.03 0.03
0.95 1.31 1.62 1.08 0.82
25.35 28.83 34.85 32.76 71.93
0.30 0.22 0.13 0.09 0.03
0.88 1.39 1.84 2.50 2.00
:.
TEMED = 0.1150 gÁ temp. ~ 35 -+ 0.1°C.
solvent = CH3OH/H20 ~EG]/[AAM]:-
A and C, 0.2: B, 0.4
CH3OH/H20 (v/v) :- A and B, 25/4| C, 20/1.
The intrinsic viscosities of the isolated polymers do not follow a regular trend. PEG 200 does not act as a limiting template for which a one-to-one correlation between the template polymer and daughter polymer would be observed (12). The reaction medium acts as a precipitant for the PAAM formed. The variation in the intrinsic viscosity is due to the precipitation and the growth of the polymer radicals in the precipitated phase. As the polarity of
Short Communications
503
the reaction medium is decreased, the intrinsic viscosity of the formed polymer increases. Polymerization proceeds in the precipitated phase. Repeated dissolution and reprecipitation of the polycomplex in water/methanol affects its composition~ PEG is removed. Co-operative hydrogen-bonding between PEG and PAAM in the complex is weak and the individual polymers do not lose their specific solubility characteristics.
REFERENCES (1). C.H.Bamford, in "Developments in Polymerisation - 2", ed. R.N.Haward, Applied Science Publishers, London, 1981. (2). V.A.Kabanov, Makromol. Chem.!
suppl., ~,
41 (1979).
(3). R.Buter, Y.Y.Tan and G.Challa, J. Pol[m. Sci.; Part A-l, I~0, 1031 (%972). (4). J.Gons, E.J.Vorenkarmp and G.Challa, J. Pol[m. Sci. T Pol~m. Chem. Ed., 13, 1699 (1975). (5). J.Ferguson and S.A.O.Shah, Eur. Pol~m. J., ~, 343 (1968). (6). A.Blumstein, S.R.Kakivaya and K.R.Shah, J. Pol[m. Sci. T Pol[m. Symp., 4~, 75 (1974). (7). A.V.Pantar, M.Atreiyi and M.V.R.Rao, Angew. Makromol. Chem., 129, 163 (1985). (8). A.V.Pantar, Eur. Pol~m. J., 2A~2, 939 (1986). (9). A.V.Pantar, unpublished results. (10). K.J.Liu and J.L.Parsons, Macromolecules, 2, 529 (%969). (11). A.Chapiro, Eur. Polym. J., ~9, 417 (1973). (12). S.R.Kakivaya and A.Blumstein, J. Chem. Soc. I Chem. Commun., 459 (1974).