Bulk polymerization of certain allyl and acrylic monomers

BULK POLYMERIZATION OF CERTAIN ALLYL AND ACRYLIC MONOMERS* M. G. KORCHEVEI, V. V. KORSHAK and S. V. VINOGRADOVA Institute of Heteroorganic Compounds of the U.S.S.R. Academy of Sciences (Received 26 March 1964)

A REPORT was published in 1963 on the synthesis and properties of unsaturated polyarylates containing allyl groups [lJ wMeh are capable o f giving crosslinked polymers, particularly by copolymerization with monomers. Up to now there has been no detailed information in the literature on copolymerization with any monomeric unsaturated polyesters containing allyl groups. Therefore, considering the properties of polymerization ofallyl monomers in general, prior to studying the copolymerization of unsaturated polyarylates containing allyl groups with certain monomers, it was advisable to investigate the homopolymerization of these monomers in order to determine the main :features of polymerization and evaluate comparative reactivities. We used the following monomers i~ the investigation: methyl methacrylate, styrene, ethylene glycol dimethaerylate, 2,2-di-(4-oxyphenyl)propyl(diane) diacrylate, diane dimethaerylate, diallyl phthalate, diallyl isophthalate and diallyl terephthalate (Table 1). Many detailed investigations are reported in the literature on bulk polymeriza. ¢ion of styrene and methyl methacrylate. Therefore, similar experiments with these monomers were only made to obtain the required data for comparison with other monomers which have been less investigated. Numerous papers have been published in recent years which are devoted ¢o polymerization producing crosslinked polymers. Some of these papers have important theoretical aspects since their object was the quantitative elucidation of gel formation, gel effect, eyclization, effect of diffusion, etc. [2-12]. However, these problems have not so far been completely elucidated and there are varying views on the mechanism and laws of three-dimensional polymerization. Of the tetra-functional monomers the glycol dimethacrylates and diacrylates [6, 10, 12-15] and diallyl phthalate [7, 11, 16-19, 21-23] have been studied in most detail. Polymerization of diallyl isophthalate and diallyl terephthalate ,[11, 16, 20], has been studied to a comparatively small extent and the polymers of bisphenol dimethacrylates and diaerylates are only described in patent literat u r e [24]. *Vysokomol. soyed. 7: No. I, 150-155, 1965. 164

Diane diacrylate Diane dimethacrylate Diallyl phthalato Diallyl isophthalato Diallyl terephthalate

Styrene Methyl methacrylato Ethylene glycol dimethacrylate

Monomer

1~6/1 155/1.5

148-149/1

82/1

146/760 101/760

found

150/1 [26]

146/760 100--101/760 83/2 [14] 101-103/2 [12]

literature data

B.p.,°C/mm

86 65-5

m

found

1.5198 1.5248 1.5254

N

1.5470 1.4153 1.4553

--33 --48

84-5-86 [24] 65.5-66.5 [24]

foun4

literature data

M.p., °C

TABLE 1. PHYSICALCONSTANTSOF THE MONOMERSSTUDIED

1.5194 [1l, 26] 1.5248 [11] 1.5244 [ l l ]

1.5462 1.415 1.4558

lit~raturo data

O

O

O

O

M. G. KORCHEYEIet al.

166

F r o m t h e i n f o r m a t i o n a v a i l a b l e in t h e l i t e r a t u r e it is impossible t o o b t a i n c o m p a r a b l e d a t a on t h e r e a c t i v i t y of these m o n o m e r s since t h e i r p o l y m e r i z a t i o n was n o t s t u d i e d u n d e r identical conditions a n d for s o m e (bisphenol d i m e t h acrylic a n d diacrylic esters) t h e r e are no kinetic d a t a a v a i l a b l e a t all. EXPERIMENTAL

SyntheSis and purification of monomers. Styrene, methyl methacrylate a n d ethylene

glycol dimethacrylate were purified by alkaline washing, drying over anhydrous sodium sulphate and vacuum distillation in a current of nitrogen. Diallyl phthalate was synthesized by the methods described in the literature [25] by esterification of phthalie anhydride with aUyl alcohol. Diallyl isophthalate and diallyl terephthalato were synthesized from acid chlorides of phthalic acids and allyl alcohol. In contrast with the method described by Simpson and Holt [11] for synthesis of acid chlorides of phthalic acids directly during the synthesis of diallyl isophthalate and diallyl terephthalate, we separately synthesized 100

2

4

I

0

I

100

I

200 300 Time, rain

FIG. 1. Bulk polymerization at 80°C in the presence of 0.2% benzoyl peroxide. The kinetic curves were determined gravimetricaUy. 1 - Ethylene glycol dimethacrylate; 2--methyl methacrylate; 3--diane dimethacrylate; d--styrene. TABLE 2. GEL FORMATION DURING POLYMERIZATION OF CERTAIN MONOMERS

Monomer

Ethylene glycol dimethacrylate Diallyl phthalate DiaUyl isophthalate Diallyl terephthalate

Time of gel formation at 137 ° (tert. butyl peroxide as initiator), min

0.5-0.7 15 14 14

Soluble polymer yield in gel formation, ~o

1.5-2.0 20.0 18.5 18.6

Polymerization of allyl and acrylic monomers

167

t h e acid,chlorides of t h e phthalic a~ids a n d introduced t h e m into the reaction with allyl alcohol only after careful purification. The diallyl esters of the phthalic acids obtained were purified b y v a c u u m distillation in a current of purified nitrogen. A description is given in the p a t e n t literature of the synthesis of dimethacrylic and diacrylie esters of 2,2-di-(4-oxyphenyl) propane (diane) [24] b y the reaction of the sodium salt of diane with acid chlorides of methacrylic a n d acrylic acids in an organic solvent. W e carried out this synthesis without organic solvent b y dropwise addition of t h e pure acid chloride to the aqueous solution of the sodium salt of diane a t room temperature, while stirring vigorously. The yields of acrylic diane derivatives obtained were 76~o of the theoretical calculated on diane in the case of diane diacry]ate a n d 82~o of t h e theoretical in t h e case of diane dhnethacrylate. PoZy~nerization. Bulk polymerization kinetics of the abovo monomers were studied a t 80-}-0.1 ° with benzoyl peroxide (in amounts of 0"2~o b y weight for vinyl derivatives a n d 2 % b y weight for diallyl phthalates) a n d a t 1374-0.2 ° with t e r t i a r y b u t y l peroxide (in amounts of 0.14~o b y ~ t . for vinyl derivatives and 1.4% b y wt. for allyl monomers). Polymerization was studied in parallel with gravimetric a n d cl~latometric observations. Before polymerization the ampoules and dilatometers were freed from air b y three s u c cessive evacuations in a v a c u u m of 0.5 × 10-2 m m (the contents being frozen b y means of d r y ice) followed b y 6]llng with pure nitrogen a t room temperature.

100

I00 L

a 1 2

a

.~5o

2

0

i

I

lO0

200 T/me, m/n

FIG. 2.

0

ZOO • 200 77me, rain

F I a . 3.

FIG. 2. Bulk polymerization at 137 ° in the presence of 0.14% tert. b u t y l peroxide (gravimetric m e t h o d ) . / - - E t h y l e n e glycol dimethacrylatc; 2 - - s t y r e n e ; 3 - - d i a n e diacrylate. FIG. 3. Thermal bulk polymerization a t 138 ° (gravimetric method). / - - E t h y l e n e glycol dimethacrylate; 2 - - diane diacrylate; 3 -- diane dimethacrylate.

After a certain time interval, the contents of the ampoules were e x t r a c t e d with acetone. Th e p a r t of the polymer soluble in acetone was precipitated with methanol. The insoluble (trimer) a n d soluble p a r t s of t h e polymer together form t h e t o t a l polymer yield. Figures 1-5 present t h e kinetic curves obtained. Table 2 shows d a t a of gel formation during polymerization of certain monomers studied b y t h e authors. Residual unsaturation of trimers obtained b y polymerization of diallyl esters of phthalic acids (Table 3) was determined b y IR-spectroseopy using t h e methods described.

I68

~/[. G.

K01~CHEVV,I et

at.

TABLE 3. RESIDUAL UNSATURATI01~ OF POLYMERS OF PHTHALIC ACID DIALLYL ]~STERS

• Analytical frequencies, cm -1 Degree of of groups of groups monomer Residual changing which do not I conversion unsaturation, during I change during % to polymer % polymerization polymerization specimen

Polymer

(o=o

Polydiallyl phthalate Polydiallyl isophthalate Polydiallyl terephthalate

1644 1652 1652

93-7 86.7 84.3

1600 1612

1578

11-12 35-40 33-37

RESULTS I t can be seen in Figs. 4 a n d 5 t h a t t h e di]atometric a n d gravimetric d a t a satisfactorily agree. B y c o m p a r i n g kinetic d a t a it can be d e d u c e d t h a t of t h e m o n o m e r s studied, e t h y l e n e glycol d i m e t h a c r y l a t e is m o s t r e a d i l y po]ymerized. M e t h y l m e t h a c r y l a t e is second in r e a c t i v i t y . These t w o m o n o m e r s show a gel effect which we h a v e n o t o b s e r v e d in t h e o t h e r m o n o m e r s studied.

50 a

1 2

~25-

r

1

I00

I

200

300

b

0

I

100

I

200

I

Time, rain

300

FIG. 4. Bulk polymerization at 80 ° in the presence of 2% benzoyl peroxide: a--grav. imetrie method; 5--dilatometric method. 1--Diallyl isophthalate; 2--diallyl terephthalate; 3--diallyl phthalate.

Polymerization of allyl and~acrylic monomers

109

Diane dimethacrylate and diaerylate are-more readily polymerized than styrene at temperatures of ~ 80 ° (benzoyl peroxide as i n i t i a t o r ) b u t are less so than styrene at higher temperatures (tert.butyl peroxide as initiator). The reactivities of diane diacrylate and dimethacrylate are similar. Diallyl phthalates are the least polymerizable, their reactivities being practically the same (particularly at higher temperatures).

I00 -

0

a

-15~-

1

I

I

25

50

75

T/me, rnin

/ 0

I 25

I " 50

Time, rain

75

FIG. 5. Bulk polymerization at 137°C in the presence of !.4% tort.butyl peroxide; a--gravimetric method; b--dilatometric method. 1--DiaUyl isophthalate; 2--diallyl phthalate; 3--diaUyl terephthalate. Like other research workers [14] we also found that during polymerization of glycol diacrylie and dimethacrylic esters, 7-polymer forms almost immediately. This indicates that the intermediate fl-polymer is erosslinked at a high rate. Diallyl esters of phthalic acids behave in an opposite manner, forming polymers of three-dimensional structure only after considerable fl-polymer yields have been obtained. Differing residual unsaturation of polydiallylphthalates (Table 3) lms also been observed by other authors and is due to intramolecular cyclization during polymerization of an ortho-isomer [20, 22]. CONCLUSIONS

(1) Bulk polymerization kinetics of ethylene glycol dimetlmcrylate, styrene, methyl methacrylate, diane diacrylate and dimethacrylate and diallyl phthalates were studied under comparable conditions. (2) It has been found that in respect of their polymerizability, these monomers can be arranged in thb following sequence: glycol diacrylie esters (most liable to polymerization), methyl methacrylate, diacrylic esters of bisphenols, styrene, diallyl phthalates.

170

M.G. KORCItEVEIet al.

(3) The reactivities of diallyl p h t h a l a t e s do n o t differ in practice. The reactivities o f diane d i a c r y l a t e a n d d i m e t h a c r y l a t e are similar. (4) D u r i n g p o l y m e r i z a t i o n of diacrylie derivatives, y-polymers are f o r m e d a l m o s t i m m e d i a t e l y . I n the case of diallyl derivatives, fl-polymers are f o r m e d with considerable yields as i n t e r m e d i a t e products. Translated by E. SEM]~RE

REFERENCES

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