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Carbon black as an initiator of cationic polymerization of isobutyl vinyl ether
000%6223/80/04Ol-0163802.00,/0
Carbon Vol. I& p. 163 0 Pergamon Press Ltd., 1980 Printed in Great Bntain
LETTER
TO THE EDITOR
Carbon black as an initiator of cationic polymerization isobutyl vinyl ether (Received
20 Sepfember
The cationic polymerization of N-vinylcarbazole (NVC) initiated by carbon black surface has been reported by us[I]. Furthermore, Ohkita et al. have described that phenolic hydroxyl groups on the surface of carbon black have an ability to initiate the polymerization of NVC [2]. We have observed that channel blacks such as Carbolac 1 and Neospectra II can induce the conventional cationic polymerization of isobutyl vinyl ether (IBVE) at below room temperature. In this paper, the polymerization of IBVE initiated by carbon black surface is reported. Furnace blacks Philbla~k 0 (HAF, Specific surface area; 79.6 m’/g) and Vulcan SC (SCF, 194.4 m’/g) were dried at 80°C in uacuo after Soxhlet extraction with benzene to remove the resinous substances present on the surface. Channel blacks Carbolac 1 (HCC, 839.2m2/g), FW-200 (HCC, 460m’/g) and Neospectra II (HCC) were dried in u(1c210 without extraction. Guaranteed reagent grade IBVE from Tokyo Kasei Kogyo Co. Ltd. was purified and distilled by a general method. The polymerization was carried out in carbon tetrachloride in a lOO-ml tear-drop type flask. The reaction mixture was stirred at constant rate with a magnetic stirrer. The polymer containing carbon black was precipitated by methanol [3] and conversions were determined by the method reported previously [43. When the polymerization of IBVE was carried out in the absence of carbon black, no polymer could be obtained. In the presence of Carbolac 1, however, the polymerization proceeded as shown in Fig. 1, in which the effect of Carbolac 1 as an initiator is clearly shown. Arrhenius plots gave a straight line with an apparent activation energy of polymerization of 15 kcal/mol. More-
of
1979)
Table 1. Polymerization of IBVE in the presence of various carbon blacks
BO-
Carbon black -
(g)
Temp. Time i’c) (h)
Conversion i”<,)+
Carbolac 1 (HCC) FW-200 (HCC) Neospectra II (HCC)
0.1 0.1 0.1
20 20 20
2 2 2
44.0 84.0 29.1
Philblack 0 (HAFl Vulcan SC (SCF)
1.0 0.5
50 50
24 24
0 1.7
TIBVE; 7.6 x 10e2 mol. carbon tetrachloride;
10ml.
over, the carbon black obtained by the reaction with IBVE gave a stable colloidal dispersion in good solvents for poly(isobutylvinylether) such as benzene. The effect of various carbon blacks on the polymerization of IBVE is given in Table 1. The results shown in Table 1 indicate that channel blacks initiate the polymerization of IBVE at relatively low temperature. However, for furnace blacks such as Philblack 0 and Vulcan SC polymerization could be scarcely detected at 50°C even after 24 hr. From these results, it may be suggested that the mitiation mechanism of the polymerization of IBVE is different from that of NVC, since the polymerization of NV<‘ was initiated even by Philblack 0. The polymerization of IBVE is totally inhibited by pyridine and N,N-dimethylformamide which indicate the cationic nature of the reaction. In addition. daylight or oxygen did not affect the rate of polymerizatinn. To clarify the reaction mechanism and the initiation site for the ~lymerization of IBVE on the carbon black SUFface, a detailed kinetic study is in progress. Acknowkdgemenr --The authors thank Professor K. Ohkita for many discussions.
NORIOTSUBCKAWA NACKI
TAKEDA
KIN’FTSL’KIJM~H REFERENCES O
1
3
2
Time
4
5
, hr
Fig. 1. Polymerization of IBVE initiated by Carbolac 1 in carbon tetrachloride: IBVE (7.6 x lo-’ mol) was polymerized in the presence of Carbolac 1 (0.10 g) in 10 ml of carbon tetrachloride.
163
K. Ohkita, N. Tsubokawa, M. Noda and M. Uchiyama, Curbon IS, 194 (1977). K. Ohkita, M. Uchiyama and H. Nishioka. Carbon 16, 19s (1978). D. D. Eley and A. W. Richards. Trans. Ynrudu~ Sot. 45, 425 (I 949). K. Ohkita, N. Tsubokawa, E. Saitoh. M. Noda and N. Takashina. Carbon 13,443 (19751.
Carbon Vol. I& p. 163 0 Pergamon Press Ltd., 1980 Printed in Great Bntain
LETTER
TO THE EDITOR
Carbon black as an initiator of cationic polymerization isobutyl vinyl ether (Received
20 Sepfember
The cationic polymerization of N-vinylcarbazole (NVC) initiated by carbon black surface has been reported by us[I]. Furthermore, Ohkita et al. have described that phenolic hydroxyl groups on the surface of carbon black have an ability to initiate the polymerization of NVC [2]. We have observed that channel blacks such as Carbolac 1 and Neospectra II can induce the conventional cationic polymerization of isobutyl vinyl ether (IBVE) at below room temperature. In this paper, the polymerization of IBVE initiated by carbon black surface is reported. Furnace blacks Philbla~k 0 (HAF, Specific surface area; 79.6 m’/g) and Vulcan SC (SCF, 194.4 m’/g) were dried at 80°C in uacuo after Soxhlet extraction with benzene to remove the resinous substances present on the surface. Channel blacks Carbolac 1 (HCC, 839.2m2/g), FW-200 (HCC, 460m’/g) and Neospectra II (HCC) were dried in u(1c210 without extraction. Guaranteed reagent grade IBVE from Tokyo Kasei Kogyo Co. Ltd. was purified and distilled by a general method. The polymerization was carried out in carbon tetrachloride in a lOO-ml tear-drop type flask. The reaction mixture was stirred at constant rate with a magnetic stirrer. The polymer containing carbon black was precipitated by methanol [3] and conversions were determined by the method reported previously [43. When the polymerization of IBVE was carried out in the absence of carbon black, no polymer could be obtained. In the presence of Carbolac 1, however, the polymerization proceeded as shown in Fig. 1, in which the effect of Carbolac 1 as an initiator is clearly shown. Arrhenius plots gave a straight line with an apparent activation energy of polymerization of 15 kcal/mol. More-
of
1979)
Table 1. Polymerization of IBVE in the presence of various carbon blacks
BO-
Carbon black -
(g)
Temp. Time i’c) (h)
Conversion i”<,)+
Carbolac 1 (HCC) FW-200 (HCC) Neospectra II (HCC)
0.1 0.1 0.1
20 20 20
2 2 2
44.0 84.0 29.1
Philblack 0 (HAFl Vulcan SC (SCF)
1.0 0.5
50 50
24 24
0 1.7
TIBVE; 7.6 x 10e2 mol. carbon tetrachloride;
10ml.
over, the carbon black obtained by the reaction with IBVE gave a stable colloidal dispersion in good solvents for poly(isobutylvinylether) such as benzene. The effect of various carbon blacks on the polymerization of IBVE is given in Table 1. The results shown in Table 1 indicate that channel blacks initiate the polymerization of IBVE at relatively low temperature. However, for furnace blacks such as Philblack 0 and Vulcan SC polymerization could be scarcely detected at 50°C even after 24 hr. From these results, it may be suggested that the mitiation mechanism of the polymerization of IBVE is different from that of NVC, since the polymerization of NV<‘ was initiated even by Philblack 0. The polymerization of IBVE is totally inhibited by pyridine and N,N-dimethylformamide which indicate the cationic nature of the reaction. In addition. daylight or oxygen did not affect the rate of polymerizatinn. To clarify the reaction mechanism and the initiation site for the ~lymerization of IBVE on the carbon black SUFface, a detailed kinetic study is in progress. Acknowkdgemenr --The authors thank Professor K. Ohkita for many discussions.
NORIOTSUBCKAWA NACKI
TAKEDA
KIN’FTSL’KIJM~H REFERENCES O
1
3
2
Time
4
5
, hr
Fig. 1. Polymerization of IBVE initiated by Carbolac 1 in carbon tetrachloride: IBVE (7.6 x lo-’ mol) was polymerized in the presence of Carbolac 1 (0.10 g) in 10 ml of carbon tetrachloride.
163
K. Ohkita, N. Tsubokawa, M. Noda and M. Uchiyama, Curbon IS, 194 (1977). K. Ohkita, M. Uchiyama and H. Nishioka. Carbon 16, 19s (1978). D. D. Eley and A. W. Richards. Trans. Ynrudu~ Sot. 45, 425 (I 949). K. Ohkita, N. Tsubokawa, E. Saitoh. M. Noda and N. Takashina. Carbon 13,443 (19751.