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Synthesis and polymerization of methylolmethacrylamide esters
SYNTHESIS AND POLYMERIZATION OF METHYLOLMETHACRYLAMIDE ESTERS* I. A. ARBI~ZOVAand I. K. MOS~VlOH Institute of High-Molecular Weight Compounds, U.S.S.R. Academy of Sciences (Received 2 Jubj 1965)
THIS paper describes the synthesis, polymerization and properties of polymers of methylolmethacry.lamide esters. Methylomethacrylamide esters have been little investigated. They are of interest as new monomers which, in addition to the reactive double bond, contain a methylolamide ester group capable of chemical conversion. Earlier we described the synthesis and certain properties of monomers and polymers of methylolamide derivatives. Among these are symmetrical unsaturated methylene N,I~-bis-amides [1] and mixed derivatives [2], Mannich bases, methylolamide esters. There are also indications related to synthesis of polymers of methylolamide esters and mixed N,N-bis-amides [3]. According to the data of 1Kiiller and his colleagues, the main difference between polymers containing substituted methylolamide groups and polymethylol-
4O A%
8O
\ 4O
88
FIG. 1
FIG. 2
:FIG. 1. Dependence of the degree of conversion of the acetic ester of M1KAA on time. 0-2% benzoyl peroxide, 45 °. :FIG. 2. Effect of temperature on the stability of acid groups in polymers of the butyric ester of MMAA. Heating time 24 hours. A - content of acid groups in t h e polymer * Vysokomol. soyed. 8: No. 7, 1307-1310, 1966. 1438
Polymerization of methylolmethacrylamide esters
1439
acrylamides is that the substitution of methylol group results in stabilization, consequently the cross-linking reaction typical of methylolamide compounds is reterded. This makes it possible to obtain easily linear polymers which are stable in storage under normal conditions. Linear polymers can be converted into three-dimensional ones by heating or altering the medium pH. Among substituted methylolamide derivatives esters occupy a special position as acids may separate during heat treatment resulting in acceleration and not retardation of condensation.
5
I
I
I
I
3600
2000
IGO0
1200
1
800 1),cm-~
FIG. 3. I R spectra of a butyric ester polymer of MMAA: 1 - - i n i t i a l polymer; 2, 3, 4 - - h e a t e d at 100, 140, 150 °, respectively.
The authors have synthesized acetic, butyric and benzoic esters of methylolmethacrylamide (MMAA). All these monomers polymerized easily with radical type initiators. The kinetic curve of polymerization of the acetic ester of MNIAA was linear in the initial stage of polymerization (up to ~ 50//o conversion) (Fig. 1). Further, a phase of self-acceleration was observed which was completed on reaching ~20% conversion. The polymer obtained under these conditions was insoluble in organic solvents. Polymerization of the butyric ester of MMAA at 50-70 ° resulted in the formation of a polymer soluble in acetone, methylethylketone, dioxane, benzene and having an intrinsic viscosity in methylethylketone of ~0.2. A reduction of polymerization temperature to room temperature enabled polymers to be obtained with higher intrinsic viscosities ( ~ 0.9 in methylethylketone). The elementary composition of the polymer and saponification by an alkaline solution were in full agreement with monomer composition. However, during storage
1440
I.A. AmBUZOVA and I. K. MOSEVrC~
in air a n d p a r t i c u l a r l y a t increased t e m p e r a t u r e t h e p o l y m e r b e c a m e t h r e e dimensional. F i g u r e 2 shows d a t a o n t h e v a r i a t i o n of acid g r o u p c o n t e n t in t h e p o l y m e r on h e a t i n g . T h e s a m e r e l a t i o n s h i p could b e o b s e r v e d in t h e I R s p e c t r a of t h e p o l y m e r in r e l a t i o n t o t h e a b s o r p t i o n b a n d s o f c a r b o n y l g r o u p s w i t h I ~ H - - (1680 c m -x) a n d in t h e a c y l residue (1720 cm-1). F i g u r e 3 shows t h a t w i t h increased t e m p e r a t u r e t h e c o n t e n t o f c a r b o n y l g r o u p s o f t h e acyl residue r a p i d l y decreases, c o m p a r e d w i t h t h e c o n t e n t of carbon y l g r o u p s a t t h e N H - g r o u p . I n p r o p o r t i o n to t h e s e p a r a t i o n of acid groups, t h e p o l y m e r b e c a m e insoluble. W e also o b t a i n e d c o p o l y m e r s of M M A A esters w i t h m e t h y l m e t h a c r y l a t e a n d studied some of their properties. The copolymerization constants determined for M M A A b u t y r i c e s t e r - m e t h y l m e t h a c r y l a t e were 0-50 a n d 1.65 r e s p e c t i v e l y a n d i n d i c a t e d t h e high a c t i v i t y of t h e esters in c o p o l y m e r i z a t i o n . T h e m e t h y l m e t h a c r y l a t e - M M _ A A e s t e r c o p o l y m e r s h a d high intrinsic viscosities in d i o x a n e ( ~ 2.0), were soluble in acetone~ benzene, m e t h y l e t h y l k e t o n e a n d dioxane. EXPERIMENTAL The acetic ester of M M A A was synthesized according to the method described by Miiller et al. [3] by reaction of methacrylamide with paraformaldehyde in toluene at 50-55 ° with
subsequent addition of acetic anhydride to the reaction mixture cooled to 40 ° . The yield of the pure product of b.p. 88-89°/2.5 × 10 -s m m was 60~o of the stoichiometric. Found, %: C~HxlNO3. Calculated, %:
C 53.64; C 53.49;
H 7.31; I-I 7.05;
Found %: CTHllO3NBr2. Calculated, ~o:
N 9.01; 1~ 8.91;
l~lCtD 39"62. MR D 39.32
Br: 50.41. Br 50.34.
Synthesis of the butyric ester of M M A A was carried out by the reaction of 1 mole methacrylamide with 1 mole paraformaldehyde, 1.2 g sodium methylato and 0.5 g phenothiazine in 200 ml toluene at 50-55°; in 20-30 minutes the reaction of methylolation was complete, the bath temperature was reduced to 40 ° and 170 g butyric anhydride was added drop by drop. After three hours heating of the mixture at 100-110 ° in vacuo excess toluene and butyric anhydride were eliminated and the residue distilled. The yield of butyric ester of methylolmethacrylamide of b.p. 91-92°/4)< 10 -2 ram, d~° 1.0536, n~ 1.4643 was 50-60% of the theoretical.
Found, %: C~H15NOs. Calculated, ~o,
C 58.38; C 58.36;
H 8.24; N 7.77; H 8"16; N 7.59;
Found, %: CgH15NOaBr2. Calculated, ~o:
MR~ 48.51. MR D 48.56.
Br 46.32. Br 46.19.
The benzoic ester of M M A A was obtained by the Feuer and Lynch [4] method by the reaction of methylolmethacrylamide with benzoyl chloride in pyridine. The yield of pure ester of m.p. 87 ° was ~ 80~o of theory.
Found, %: C12HlaOsN. Calculated, ~o:
C 66.30; C 66.13;
H 6.11. H 5.97.
Polymerization of methylohnethacrylamide esters
1441
Polymerization of M M A A esters. 1) 11 g butyric ester of MMAA, 55 g dry benzene, 0.022 g benzoyl peroxide were heated in a three-necked flask in an argon flow at 70 ° while stirring. After 8 hours the viscous solution was decanted into ether. The polymer was reprecipitated twice from an acetone solution into ether. The yield was 35~o; acid group content was 99.65°/o; intrinsic viscosity in m e th y l e t h y l k et o n e was 0"16; 2) 3-35 g b u t y r i c ester of MMAA, 16.75 g dioxane, 0.0067 g eyelohexyl ester of percarbonic acid (CPA) were sealed in an ampoule from which air was displaced b y argon and polymerized at 20 ° until a noticeable viscosity increase developed. The yield of polymer re-precipitated twice from dioxane into ether was 13"7~o; intrinsic viscosity in dioxane was 0.84. Polymerization of the benzoic ester of M M A A in argon was carried out in dioxane solution in a sealed ampoule with a solvent : m o n o m e r ratio of 5 : 1 in the presence of 0.2% CPA. 2.26 g benzoic ester of MMAA, 11 g dioxane, 0.0045 g CPA were kept at 20 ° until m a r k e d viscosity increase was observed. Intrinsic viscosity of the polymer in dioxane was 1.64. Copolymerization of M M A A esters with methyl methacrylate was carried out in d i o x an e solution with a ratio of monomer m ix tu r e : solvent of 1 : 5. Methyl methacrylate and the benzoic ester of MMAA in the ratio of 85 : 15, 0.2% CPA and dioxane were placed in an ampoule from which air was displaced b y argon and sealed. The ampoule was kept at room te mpe r at u re until a noticeable viscosity increase developed. The copelymer was purified by double re-precipitation from dioxane solution into ether. The yield was 17.7% , intrinsic viscosity in dioxane 1"83. Copolymerization of the acetic ester of M M A A with methyl methacrylate was carried out in dioxane solution with a m o n o m e r m i x t u r e : solvent ratio of 1 : 4 (the ratio of acetic ester of MMAA : m e t h y l methacrylate was 15 : 85) in the presence of 0.2% CPA. The yield o f copolymer twice re-precipitated from dioxane by ether was 15"8~o, intrinsic viscosity in dioxane 2.23. The stability of ester groups of the M M A A butyric ester was determined by heating the polymer at 80-150 ° . The heated specimen was washed with acetone to remove the butyric acid separated, dried to constant weight and the acid residue determined by heating in 50 ml of 0.1 ~ sodium hydroxide solution, followed by back titration. The copolymerization constants of m e t h y l methacrylate (M1) and the butyric ester of MMAA (M2) were determined by the Mayo and Lewis method [5] using a differential equation. Copolymerization was carried out in a homogeneous solution at 70 ° with a 3-6~Zo conversien. The copolymers were purified by threefold re-precipitation from acetone solution by ether. Copolymer composition was determined from nitrogen content. The following constants were obtained: rl ~ 1-65 ± 0.13, r ~--0.50 ± 0.07.
CONCLUSIONS (1) P o l y m e r s
and
copolymers of
methylolmethacrylamide
esters were syn-
thesized and some of their properties studied. (2) O n s t o r a g e or h e a t i n g t h e p o l y m e r s t h e a c i d g r o u p s e a s i l y d i s s o c i a t e a n d the polymers become three-dimensional.
Translated by E. SEMERE REFERENCES 1. I. A. ARBUZOVA and I. K. MOSEVICH, Zh. obshch, khimii 31: 3023, 1961 2. I. A. ARBUZOVA, E. N. ROSTOVSKII, A. L. LIS and A. G. YELISEYEVA, Zh. obshch. khimii 29: 3943, 1959 3. E. MULLER, K. DINGES and W . GRAULICH, Makromelek. Chem. 57: 2751, 1962 4. H. FETTER and U. LYNCH, J. Amer. Chem. See. 75: 5027, 1953 5. F. R. MAYO and F. M. LEWIS, J. Amer. Chem. Soc. 66: 1574, 1944
THIS paper describes the synthesis, polymerization and properties of polymers of methylolmethacry.lamide esters. Methylomethacrylamide esters have been little investigated. They are of interest as new monomers which, in addition to the reactive double bond, contain a methylolamide ester group capable of chemical conversion. Earlier we described the synthesis and certain properties of monomers and polymers of methylolamide derivatives. Among these are symmetrical unsaturated methylene N,I~-bis-amides [1] and mixed derivatives [2], Mannich bases, methylolamide esters. There are also indications related to synthesis of polymers of methylolamide esters and mixed N,N-bis-amides [3]. According to the data of 1Kiiller and his colleagues, the main difference between polymers containing substituted methylolamide groups and polymethylol-
4O A%
8O
\ 4O
88
FIG. 1
FIG. 2
:FIG. 1. Dependence of the degree of conversion of the acetic ester of M1KAA on time. 0-2% benzoyl peroxide, 45 °. :FIG. 2. Effect of temperature on the stability of acid groups in polymers of the butyric ester of MMAA. Heating time 24 hours. A - content of acid groups in t h e polymer * Vysokomol. soyed. 8: No. 7, 1307-1310, 1966. 1438
Polymerization of methylolmethacrylamide esters
1439
acrylamides is that the substitution of methylol group results in stabilization, consequently the cross-linking reaction typical of methylolamide compounds is reterded. This makes it possible to obtain easily linear polymers which are stable in storage under normal conditions. Linear polymers can be converted into three-dimensional ones by heating or altering the medium pH. Among substituted methylolamide derivatives esters occupy a special position as acids may separate during heat treatment resulting in acceleration and not retardation of condensation.
5
I
I
I
I
3600
2000
IGO0
1200
1
800 1),cm-~
FIG. 3. I R spectra of a butyric ester polymer of MMAA: 1 - - i n i t i a l polymer; 2, 3, 4 - - h e a t e d at 100, 140, 150 °, respectively.
The authors have synthesized acetic, butyric and benzoic esters of methylolmethacrylamide (MMAA). All these monomers polymerized easily with radical type initiators. The kinetic curve of polymerization of the acetic ester of MNIAA was linear in the initial stage of polymerization (up to ~ 50//o conversion) (Fig. 1). Further, a phase of self-acceleration was observed which was completed on reaching ~20% conversion. The polymer obtained under these conditions was insoluble in organic solvents. Polymerization of the butyric ester of MMAA at 50-70 ° resulted in the formation of a polymer soluble in acetone, methylethylketone, dioxane, benzene and having an intrinsic viscosity in methylethylketone of ~0.2. A reduction of polymerization temperature to room temperature enabled polymers to be obtained with higher intrinsic viscosities ( ~ 0.9 in methylethylketone). The elementary composition of the polymer and saponification by an alkaline solution were in full agreement with monomer composition. However, during storage
1440
I.A. AmBUZOVA and I. K. MOSEVrC~
in air a n d p a r t i c u l a r l y a t increased t e m p e r a t u r e t h e p o l y m e r b e c a m e t h r e e dimensional. F i g u r e 2 shows d a t a o n t h e v a r i a t i o n of acid g r o u p c o n t e n t in t h e p o l y m e r on h e a t i n g . T h e s a m e r e l a t i o n s h i p could b e o b s e r v e d in t h e I R s p e c t r a of t h e p o l y m e r in r e l a t i o n t o t h e a b s o r p t i o n b a n d s o f c a r b o n y l g r o u p s w i t h I ~ H - - (1680 c m -x) a n d in t h e a c y l residue (1720 cm-1). F i g u r e 3 shows t h a t w i t h increased t e m p e r a t u r e t h e c o n t e n t o f c a r b o n y l g r o u p s o f t h e acyl residue r a p i d l y decreases, c o m p a r e d w i t h t h e c o n t e n t of carbon y l g r o u p s a t t h e N H - g r o u p . I n p r o p o r t i o n to t h e s e p a r a t i o n of acid groups, t h e p o l y m e r b e c a m e insoluble. W e also o b t a i n e d c o p o l y m e r s of M M A A esters w i t h m e t h y l m e t h a c r y l a t e a n d studied some of their properties. The copolymerization constants determined for M M A A b u t y r i c e s t e r - m e t h y l m e t h a c r y l a t e were 0-50 a n d 1.65 r e s p e c t i v e l y a n d i n d i c a t e d t h e high a c t i v i t y of t h e esters in c o p o l y m e r i z a t i o n . T h e m e t h y l m e t h a c r y l a t e - M M _ A A e s t e r c o p o l y m e r s h a d high intrinsic viscosities in d i o x a n e ( ~ 2.0), were soluble in acetone~ benzene, m e t h y l e t h y l k e t o n e a n d dioxane. EXPERIMENTAL The acetic ester of M M A A was synthesized according to the method described by Miiller et al. [3] by reaction of methacrylamide with paraformaldehyde in toluene at 50-55 ° with
subsequent addition of acetic anhydride to the reaction mixture cooled to 40 ° . The yield of the pure product of b.p. 88-89°/2.5 × 10 -s m m was 60~o of the stoichiometric. Found, %: C~HxlNO3. Calculated, %:
C 53.64; C 53.49;
H 7.31; I-I 7.05;
Found %: CTHllO3NBr2. Calculated, ~o:
N 9.01; 1~ 8.91;
l~lCtD 39"62. MR D 39.32
Br: 50.41. Br 50.34.
Synthesis of the butyric ester of M M A A was carried out by the reaction of 1 mole methacrylamide with 1 mole paraformaldehyde, 1.2 g sodium methylato and 0.5 g phenothiazine in 200 ml toluene at 50-55°; in 20-30 minutes the reaction of methylolation was complete, the bath temperature was reduced to 40 ° and 170 g butyric anhydride was added drop by drop. After three hours heating of the mixture at 100-110 ° in vacuo excess toluene and butyric anhydride were eliminated and the residue distilled. The yield of butyric ester of methylolmethacrylamide of b.p. 91-92°/4)< 10 -2 ram, d~° 1.0536, n~ 1.4643 was 50-60% of the theoretical.
Found, %: C~H15NOs. Calculated, ~o,
C 58.38; C 58.36;
H 8.24; N 7.77; H 8"16; N 7.59;
Found, %: CgH15NOaBr2. Calculated, ~o:
MR~ 48.51. MR D 48.56.
Br 46.32. Br 46.19.
The benzoic ester of M M A A was obtained by the Feuer and Lynch [4] method by the reaction of methylolmethacrylamide with benzoyl chloride in pyridine. The yield of pure ester of m.p. 87 ° was ~ 80~o of theory.
Found, %: C12HlaOsN. Calculated, ~o:
C 66.30; C 66.13;
H 6.11. H 5.97.
Polymerization of methylohnethacrylamide esters
1441
Polymerization of M M A A esters. 1) 11 g butyric ester of MMAA, 55 g dry benzene, 0.022 g benzoyl peroxide were heated in a three-necked flask in an argon flow at 70 ° while stirring. After 8 hours the viscous solution was decanted into ether. The polymer was reprecipitated twice from an acetone solution into ether. The yield was 35~o; acid group content was 99.65°/o; intrinsic viscosity in m e th y l e t h y l k et o n e was 0"16; 2) 3-35 g b u t y r i c ester of MMAA, 16.75 g dioxane, 0.0067 g eyelohexyl ester of percarbonic acid (CPA) were sealed in an ampoule from which air was displaced b y argon and polymerized at 20 ° until a noticeable viscosity increase developed. The yield of polymer re-precipitated twice from dioxane into ether was 13"7~o; intrinsic viscosity in dioxane was 0.84. Polymerization of the benzoic ester of M M A A in argon was carried out in dioxane solution in a sealed ampoule with a solvent : m o n o m e r ratio of 5 : 1 in the presence of 0.2% CPA. 2.26 g benzoic ester of MMAA, 11 g dioxane, 0.0045 g CPA were kept at 20 ° until m a r k e d viscosity increase was observed. Intrinsic viscosity of the polymer in dioxane was 1.64. Copolymerization of M M A A esters with methyl methacrylate was carried out in d i o x an e solution with a ratio of monomer m ix tu r e : solvent of 1 : 5. Methyl methacrylate and the benzoic ester of MMAA in the ratio of 85 : 15, 0.2% CPA and dioxane were placed in an ampoule from which air was displaced b y argon and sealed. The ampoule was kept at room te mpe r at u re until a noticeable viscosity increase developed. The copelymer was purified by double re-precipitation from dioxane solution into ether. The yield was 17.7% , intrinsic viscosity in dioxane 1"83. Copolymerization of the acetic ester of M M A A with methyl methacrylate was carried out in dioxane solution with a m o n o m e r m i x t u r e : solvent ratio of 1 : 4 (the ratio of acetic ester of MMAA : m e t h y l methacrylate was 15 : 85) in the presence of 0.2% CPA. The yield o f copolymer twice re-precipitated from dioxane by ether was 15"8~o, intrinsic viscosity in dioxane 2.23. The stability of ester groups of the M M A A butyric ester was determined by heating the polymer at 80-150 ° . The heated specimen was washed with acetone to remove the butyric acid separated, dried to constant weight and the acid residue determined by heating in 50 ml of 0.1 ~ sodium hydroxide solution, followed by back titration. The copolymerization constants of m e t h y l methacrylate (M1) and the butyric ester of MMAA (M2) were determined by the Mayo and Lewis method [5] using a differential equation. Copolymerization was carried out in a homogeneous solution at 70 ° with a 3-6~Zo conversien. The copolymers were purified by threefold re-precipitation from acetone solution by ether. Copolymer composition was determined from nitrogen content. The following constants were obtained: rl ~ 1-65 ± 0.13, r ~--0.50 ± 0.07.
CONCLUSIONS (1) P o l y m e r s
and
copolymers of
methylolmethacrylamide
esters were syn-
thesized and some of their properties studied. (2) O n s t o r a g e or h e a t i n g t h e p o l y m e r s t h e a c i d g r o u p s e a s i l y d i s s o c i a t e a n d the polymers become three-dimensional.
Translated by E. SEMERE REFERENCES 1. I. A. ARBUZOVA and I. K. MOSEVICH, Zh. obshch, khimii 31: 3023, 1961 2. I. A. ARBUZOVA, E. N. ROSTOVSKII, A. L. LIS and A. G. YELISEYEVA, Zh. obshch. khimii 29: 3943, 1959 3. E. MULLER, K. DINGES and W . GRAULICH, Makromelek. Chem. 57: 2751, 1962 4. H. FETTER and U. LYNCH, J. Amer. Chem. See. 75: 5027, 1953 5. F. R. MAYO and F. M. LEWIS, J. Amer. Chem. Soc. 66: 1574, 1944