Macromolecules 1992,25, 6395-6399
6396
Radical Polymerization Behavior of 7,8-Bis(ethylthio)-and 7,8-Bis(phenylthio)-7,8-dicyanoquinodimethanes Shouji Iwatsuki,' Takahito Itoh, Naoko Kusaka, and Hajime Maeno Department of Chemistry for Materials, Faculty of Engineering, Mie University, Kamihama-cho, Tsu 514, Japan Received March 20, 1992; Revised Manuscript Received July 24, 1992
ABSTRACT Radical polymerizations of 7,8-bis(ethylthio)-7,8-dicyanoquinodimethane(ESCQ) and 7,8bis(phenylthio)-7,8-dicyanoquinodimethane(PSCQ) were studied in chloroform with 2,2'-azobis(isobutyronitrile). ESCQ and PSCQ were found to undergo a typical equilibrium polymerization, which allowed one to obtain their values for equilibrium monomer concentration, ceiling temperature of polymerization, and enthalpy and entropy changesof polymerization. When reacted abovethe equilibrium monomer concentration, ESCQ and PSCQ were copolymerized in a random fashion with styrene (St) in chloroform to afford the monomer reactivity ratios rl(ESCQ) = 72.2 f 7.5 and rz(St) = 0.005 f 0.01 at 50 "C for the ESCQ-St system and rl(PSCQ) = 40.4 f 5.0 and r*(St) = 0.006 f 0.01 at 50 "C for the PSCQ-St system. Then Alfrey-Price's Q and e values were calculated as Q = 89.2 and e = +0.21 for ESCQ and Q = 64.3 and e = +0.39 for PSCQ. It was found that ESCQ and PSCQ were extremely conjugative and were close to neutral in polarity, probably due to the captodative substitution. When reacted below the equilibrium monomer concentration, ESCQ and PSCQ were not copolymerized with St and served as inhibitors of polymerization.
Introduction Previously we reported that an interesting group of quinodimethanescarryingtwo different electron-accepting substituents such as cyano and acyl or alkoxycarbonyl groups at the 7 and 8 positions was obtainable as crystals and was homopolymerizable with radical and ionic initiator~.l-~ Recently another group of quinodimethanes with captodative substitution, Le., an electron-accepting cyano group and an electron-donatingalkylthiogroup such as ethylthio, phenylthio, or tert-butylthio group, was prepared as isolable crystals and was polymerizable with a very wide range of initiator^.^ From the viewpoint of polarity, it was conceivable that the former quinodimethanes were very strongly electron-accepting but the latter were allowed by captodative substitution to be much close to neutral. It should be interesting, therefore, for a polymerization chemistry of quinodimethanes that the polymerizations of the captodatively substituted quinodimethanesas highly conjugated,neutral monomers are compared in detail with those of the former electronaccepting quinodimethanes. In this work detailed kinetics of radical homopolymerizations of captodatively substituted quinodimethanes such as 7,gbis(ethylthio)-7,8dicyanoquinodimetha (ESCQ)and 7,8-bis(phenylthio)-7,8-dicyanoquinodimethane
Styrene (St) was washed with a 2% aqueous sodium hydroxide solution and water, dried over anhydrous magnesium sulfate, stirred with calcium hydride at room temperature for 24 h, and then distilled under reduced pressure. 2,2-Azobis(isobutyronitrile) (AIBN)was recrystallized from methanol. Chloroformwas refluxed over calcium hydride for 24 h and then distilled. Homopolymerization Kinetics of ESCQ and PSCQ. Given amounts of ESCQ or PSCQ as a monomer, chloroform as a solvent, and AIBN as an initiator were placed in an ampule, which was degassed completely by the freeze-thaw method (repeated three times) and sealed. The ampule was set in a bath thermostated at temperatures of 40,50,60,65,70,75, or 80 "C for the time of polymerization and then opened. A fixed volume of an aliquot of the polymerization mixture was taken out of the ampule and added into a given volume of chloroform. The resulting solution was measured spectrophotometricallyto obtain the concentration of unreacted monomers, ESCQ or PSCQ, by using an absorbance band of 470 nm (e = 6.90 X 10') characteristic of ESCQ and that of 472 nm (e = 5.85 X lo4) characteristic of PSCQ. The polymerization rate, R,, was calculated on the basis of the monomer amounts reacted for various times of polymerization. Copolymerization. Given amounts of ESCQ or PSCQ as a monomer, St or BCQ as a comonomer, AIBN as an initiator, and chloroform as a solvent were placed in an ampule. By adjusting an amount of chloroform, the monomer concentration of ESCQ or PSCQ was maintained at a fixed value. The ampule was degassed by the freeze-thaw method (repeated three times) and sealed. It was set in a bath thermostated at 50 "C for the time of polymerization and unsealed. The reaction mixture wm poured into an excess of hexane to deposit a polymeric product which was dissolved in a small amount of dichloromethane. The resulting solution was poured again into an excess of hexane to deposit a polymeric product. The dissolution-precipitation process was repeated more than three times for purification. The purified product was dried under reduced pressure until a constant weight. Characterization. The copolymer composition was established by elemental analysis. The number-average molecular of the polymer was determined by gel permeation weight (Mn) chromatography (GPC) with a series of four columns, Tosoh G4000H, G3000H, G2500H, and G2000H,using tetrahydrofuran (THF) as eluent and standard polystyrenes as reference, without further correction.
NCe::mB
mBuOOC
ESCO, R = Et PSCQ. R = Ph
BCO
(PSCQ)were studied to observe their equilibrium polymerization behavior and to obtain the thermodynamic parameters for their polymerization, and their copolymerizations were carried out with styrene (St) and 7,8bis(butoxycarbonyl)-7,&dicyanoquinodimethane (BCQ) to evaluate their monomer reactivity. Experimental Section Materials. 7,~Bia(ethylthio)-7,gdicyanoquinodimethane (ESCQ): 7,&bis(phenylthio)-7,8-dicyanoquinodimethane (PSCQ),' and 7.8-bi~(b~toxvcarbonvlb7.&dicvanwuinodimethane ( _ . .-B- C W were prepared aicording tk the m e t h d s reported previously.
Results and Discussion Kinetics of Radical Homopolymerization. The Dolvmerization rates in the presence of AIBN were measured at temperatures of 46,50,60,70, and 75 O C for
0024-929719212225-6395$03.00/00 1992 American Chemical Society
6396 Iwatauki et al.
Macromolecules, Vol. 25, No. 24, 1992
- 6.0 l01
=
70 "C
/,
1
60 "C
I
60°C
j
0
-8.01 0
0
5
10
15
,
- 1.8
-1 9
Time, hr
Figure 1. Time-conversioncurves for polymerizations of ESCQ in chloroform at 40, 50, 60,70,and 75 "C, with a [ESCQ] of 0.014 25 mol/L and a [AIBN] of 8.53 X mol/L.
,
.
,
.
,
- 1.7 i o g c ~ l ,m o i i ~
j
- 1.6
Figure 4. log-log plots of R vs [MI in chloroform at 60"C, with a [AIBN] of 8.53 X lo-" moP/L for ESCQ ( 0 )and of 8.89 X 10-4 mol/L for PSCQ (0).
0
E
3 0
5 Time, h r
Temp.
10
Figure 2. Time-conversion curvesfor polymerizations of PSCQ at 40,50,60, and 70 "C in chloroform, with a [PSCQ] of 0.014 36 mol/L and a [AIBN] of 8.89 X lo4 mol/L.
- 6.5 -
60 "C
ul
-
-1 \
0
E - 7.0P
a
-
0 0
- 8.0
- 4.0
- 3.5 log I A i
- 3.0
- 2.5
B N 1.mol/L
Figure 3. log-log plots of R vs [AIBN] in chloroform at 60 "C, witha [ESCQ]of0.020 26moP/LforESCQ(O)andwitha[PSCQ] of 0.022 25 mol/L for PSCQ (0). ESCQ and of 40,50,60, and 65 "C for PSCQ. Examples of time-conversion curves for ESCQ and PSCQ are shown in Figures 1 and 2, respectively. In both cases the conversion was found to increase linearly with the time of polymerization as to form the straight line, the slope of which allowed one to obtain the polymerization rate, R,. log-log plots of R, versus initiator concentration, [AIBN], for the polymerizations of ESCQ and PSCQ at 60 "C displayed good straight lines with a slope of 0.51 f 0.05 for ESCQ and with one of 0.52 f 0.04 for PSCQ, as shown in Figure 3, indicating that the polymerizations obeyed a square-root rule of initiator concentration and were compatible with a conventional radical polymerization mechanism.
'C
Figure 5. Relationship of R, vs polymerization temperature in chloroform, with a [ESCQl of 0.014 25 mol/L and a [AIBN] of 8.53 X lo-' mol/L for ESCQ ( 0 )and a [PSCQ] of 0.014 36 mol/L and a [AIBN] of 8.89 X 104 mol/L for PSCQ (0). log-log plots of R, versus monomer concentration for the polymerization of ESCQ and PSCQ at 60 "C displayed straight lines with a slope of unity in the monomer concentration range of ESCQ and PSCQ above 0.018 mol/ L, as shown in Figure 4, indicating that the Rpe were directly proportional to monomer concentration in the region of the high monomer concentration in a manner similar to a conventional radical polymerization, whereas, in the region of monomer concentration below 0.018 mol/L, ita slope deviated such that the less the monomer concentration, the slower the R,. The dependence of the Rpe on polymerization temperature was measured for the polymerizations of ESCQ and PSCQ with the monomer concentration of 0.0143 mol/L, at which the R, greatly deviated from the linear relationship with monomer concentration, as shown in Figure 5. The R,,s increased with Polymerization temperature in the region of temperature below 70 OC for ESCQ and below 60 OC for PSCQ, whereas they decreased sharply with polymerization temperature in the region of temperature above 70 "C for ESCQ and above 60 "C for PSCQ. Extrapolation of the R , versus temperature plot to the rate of zero gave about 80 "C for ESCQ and about 70 "C for PSCQ, above which the polymerization did not take place at all. This temperature was regarded as the ceiling temperature of polymerization, To,for ESCQ and PSCQ. The value waa in good agreement with 2 ' 8 of ESCQ (79 OC) and PSCQ (67 "C) determined according to the method described later. So-called Arrhenius plots of In R, versus the reciprocal of the absolute polymerization temperature, 1/T, for their polymerizations with a monomer concentration of 0.0143 mol/L, are shown in Figure 6. It was found in the polymerization temperature range below 60 "C that the plota each fell into good straight lines, from slopes of which values for an apparent overall activation energy of the polymerization amounted to 54.4 kJ/mol for ESCQ and 40.2 kJ/mol for PSCQ. On the other hand, in the
Macromolecules, Vol. 25, No. 24, 1992
-
.
1
Radical Polymerization Behavior of ESCQ and PSCQ 6397
6
1
ESCQ
I3 CPSCQI, mollL
Figure 8. Relationship of polymerization rate (R,)vs monomer concentration in chloroform for PSCQ at 40 (O), 50 (a),and 60 "C (O),with a [AIBNI of 8.89 X lo4 mol/L.
70'C 4
L
Table I Equilibrium Monomer Concentrations, [MI,,of ESCQ, PSCQ, AcCQ, BzCQ, and BCQ at 40,50,60, and 70 OC
/ 0.02 CESCQI , m o l l L 0.01
0.03
- 6.O
Figure 7. Relationship of polymerization rate (R,) vs monomer and 70 concentration in chloroform for ESCQ at 50 (a),60 (01, "C (A),with a [AIBNI of 8.53 X lo4 mol/L.
range of polymerization temperature above 60 "C they deviated greatly from straight lines. From the two dependences of the R , on monomer concentration and on polymerization temperature, it was concluded that ESCQ and PSCQ underwenta typicalequilibrium polymerization with considerableparticipation of depolymerization. Rates of polymerization,R,, at three different temperatures were plotted against monomer concentrationas shown in Figure 7for ESCQ and in Figure 8for PSCQ to give straight lines, the extrapolation of which to the rate of zero allowed one to obtain an equilibrium monomer concentration, [MI,. The values of [MI,at some polymerization temperatures are summarizedin Table I, together with the corresponding ones for the polymerization of 7,8-diacetyl-7,8-dicyanoquinodimethane (Ad=&)?7,8-dibenzoyl-7,8-dicyanoquinodimethane (BzCQ)? and BCQ2for comparison. The loglog plots of the effective monomer concentration, ([MI [MI,), versus R , gave straight lines with a slope of 0.99 f 0.03 for ESCQ and that of 0.98 f 0.08 for PSCQ in the whole range of monomer concentration,as shown in Figure 9, different from the profiles in Figure 4. In other words, the rates of polymerization of ESCQ and PSCQ were able to be expressed by the equations
R , = k[AIBN]0*510.06([ESCQ] - [ESCQ]e)0.99i0.03(1) R , = k[AIBN1°.52* 0.04([PSCQ] - [PSCQle)0.98i0.08(2)
--L?E. - 7 . 0 2
P
a
-0 -8.0.
60 *C
../"-;
Macromolecules, Vol. 25, No. 24, 1992
6398 Iwatsuki et al. L
-4 0
'i
ESCQ * \ 28
wO
29
30
31
32
100
50
I
I
m o l % in f e e d
33
PSCQ
~ / T X103, ~1
Figure 10. Plot of In [MI,vs 1/T, with a [AIBN] of 8.53 X mol/L for ESCQ ( 0 )and that of 8.89 x lo4 mol/L for PSCQ (0).
Figure 11. Copolymerizationcomposition curves of ESCQ ( 0 ) and PSCQ (0) with St in chloroform at 50 "C, with a [EsCQl of 84 mmol/L and with a [PSCQ] of 30 mmol/L.
"C with a given monomer concentration of 84 mmol/L above the equilibrium monomer concentration of ESCQ ([ESCQ], = 6.8 mmol/L at 50 "C) and with a given monomer concentrationof 30mmol/L abovethat of PSCQ monomer [M]/mol/L TJ°C -AH/ (kJ/mol) -AS/( J/K-mol) ([PSCQ], = 9.2 mmol/L at 50 "C). These results are summarized in Table 111, and their copolymerization 79 23.4 2.6 31.0 f 8.0 ESCQ 0.01426 422 1.0 composition diagrams are shown in Figure 11. The 67 23.5 2.5 33.8 7.8 PSCQ 0.01436 copolymers obtained in any monomer feed were found to 1.0 481 be composed of a large amount of the PSCQ or PSCQ unit 87 25.4 36.9 AcCQ 0.0177 and a small amount of the St unit. Thus, the copoly415 1.0 merizations were able to be regarded as the copolymer88 21.4 37.5 BzCQ 0.069 ization of a conjugative monomer with a nonconjugative 301.5 1.0 0.0141 93 26.4 36.8 monomer like that of St with vinyl acetatee and that of St BCQ 1.0 442 with vinyl ~hloride.~ In those copolymerizations, it is obvious that ESCQ and PSCQ are much higher in determined to be AH = -23.4 f 2.6 kJ/mol and AS = -31.0 conjugation (general)reactivitythan St and St has toserve f 8.0J/K.mol for ESCQ and AH = -23.5 f 2.5 kJ/mol and just as a nonconjugative monomer, even though St is AS = -33.8f 7.8J/K-molfor PSCQ. The values of entropy generally recognized as a conjugative (reactive)monomer. change for polymerizationfor ESCQ and PSCQ were found The results of the copolymerizations were analyzed with to be similar in magnitude to each other and also similar the intersection8 and Kelen-TOdiisg methods to obtain to those for the homopolymerizable q~inodimethanes~ monomer ratios rl(ESCQ) = 72.2 f 7.5 and r2(St) = 0.005 carrying different electron-accepting substituents, such f 0.01 at 50 OC for the ESCQ-St system and rl(PSCQ) = as AcCQ, BzCQ, and BCQ as summarized in Table 11, 40.4f 5.0 and r2(St) = 0.006f 0.01 at 50 OC for the PSCQindicating that quinodimethane monomers exhibited a St system. Comparison with the reciprocal, l/r2, of the given value of entropy change of polymerization indemonomer reactivity ratio allowed a relative reactivity of pendent of the nature of the substituents to fall into a ESCQ, PSCQ, and St toward the polymeric radical, with family of monomers different from conventional vinyl the St terminal unit being ESCQ (200)> PSCQ (167)>> monomers. St (1). Alfrey-Price's Q and e values for ESCQ and PSCQ were calculated from the monomer reactivity ratios to be Copolymerization. The copolymerizations of ESCQ Q = 89.2 and e = +0.21 for ESCQ and Q = 64.3 and e = and PSCQ with St were carried out in chloroform at 50 Table I1 Ceiling Temperature, To, Enthalpy Change, AH, and Entropy Change, AS, for Polymerization for ESCQ, PSCQ, AcCQ. BzCQ, and BCQ
*
Table 111 Copolymerizations of ESCQ and PSCQ with St in Chloroform at SO OC copolymer monomer feed elem anal.
runno.
Ml/mg
St/mg
Ml/(mol %)
1 2 3 4 5 6 7
24.1 35.3 60.9 69.0 80.0 95.1 109.0
167.4 117.5 90.0 77.0 69.7 54.3 38.3
5.19 10.26 20.44 25.35 30.39 39.98 51.90
8 9
26.7 46.8 75.4 75.4 102.0 122.2 135.9
139.2 110.4 85.8 84.6 58.9 34.6 30.1
5.1 10.6 19.8 20.0 32.7 49.9 55.9
10 11
12 13 14
hfna/lW
time/h conv/% % H MI: [ESCQ] = 84 mmollLb 1.1 1 6.3 5.19 1.5 0.5 12.5 5.11 2.6 0.4 11.5 5.00 3.0 0.25 7.3 5.11 3.5 0.25 17.2 5.02 4.1 0.2 13.9 5.09 4.7 0.15 9.1 5.17
%C
%N
M1unit/(mol%)
63.43 63.74 63.41 63.18 63.22 63.19 62.93
9.58 9.89 9.98 10.02 10.06 10.08 10.13
85.2 92.2 94.3 95.3 96.2 98.0
1.5 1.4 1.2 0.79 0.60 0.79 1.6
MI: [PSCQI = 30 mmol/LC 11.0 7.7 3.74 6.0 6.9 3.65 4.5 7.2 3.35 5.0 7.8 3.61 4.0 6.1 3.61 3.0 7.8 4.56 2.5 5.9 3.73
71.48 70.85 70.16 71.53 71.52 71.59 71.92
7.07 7.22 7.34 7.38 7.44 7.53 7.52
80.2 85.6 90.3 92.0 94.5 98.5 98.1
0.3 0.4 0.7 1.5 1.0 1.2 1.3
solvent/mL
2.2 4.0 6.6 6.6 8.0 10.8 12.0
96.7
@Determinedby GPC using THF as eluent and standard polystyrenes as reference. * AIBN, 0.1 mg. AIBN, 0.55 mg.
Macromolecules, Vol. 25, No. 24, 1992
Radical Polymerization Behavior of ESCQ and PSCQ 6399
Table IV Copolymerizations of ESCQ and PSCQ with BCQ in Chloroform at 50 OC run no.
Mdmg
monomer feed BCQ/mg Md(mo1 %)
solvent/mL
4.7 16.7 25.8 34.9 43.0
36.0 84.6 76.0 65.5 56.9
14.36 20.33 30.52 40.71 49.37
0.9 3.0 4.7 6.4 7.8
10.5 20.6 31.2 50.2
89.6 79.7 69.8 48.2
9.96 19.93 29.89 49.82
1.4 2.8 4.2 6.8
a Detern--ied by GPC using THF as eluent an- stand='mmol/L; AIBN, 0.1 mg.
.r
1
/
I /
-0
/
50
time/min
conv/%
elem anal.: S %
copolymer MI unit/(mol %)
fi,,a/lOr
Mi: ESCQb 15 50.9 5.81 29.94 1.5 25 47.0 7.17 36.37 0.28 40 57.7 8.55 42.70 1.2 30 41.2 9.29 46.01 0.57 60 57.0 10.48 51.22 2.1 Mi: PSCgC 30 40.5 0.56 3.10 19.5 30 35.4 1.15 6.37 7.5 60 28.3 1.46 8-09 4.0 60 23.4 1.96 10.88 2.5 polystyrenes as reference. [ESCQ] = 20 mmol/L; AIBN, 0.5 pg. c [PSCQ] = 20
I I
I
100
E%a m o l % in f e e d PSCQ
Figure 12. Copolymerizationcomposition curves of ESCQ ( 0 ) and PSCQ (0) with BCQ in chloroform at 50 "C, with a [ESCQ] of 20 mmol/L and with a [PSCQ] of 20 mmol/L.
+0.39 for PSCQ. It is obvious that both ESCQ and PSCQ have very large Q values, indicative of extremely conjugative (reactive)monomers, and ESCQ and PSCQ exhibit relatively low positive e values, comparable to that of methyl methacrylate (Q= 0.74, e +0.4),1° suggesting that the captodatively substituted quinodimethanes are close to neutral in polarity and quite different from the quinodimethanes with two different electron-accepting substituents such as BCQ, AcCQ, and BzCQ. When the copolymerizations of ESCQ and PSCQ with St were attempted at 50 "C in chloroform with a monomer concentration below each equilibrium monomer concentration of ESCQ and PSCQ, no copolymerizationtook place at all. It can be pointed out that when polymerized below the equilibrium monomer concentration,ESCQ and PSCQ lose the homopolymerizability and at the same time actually react as an inhibitor of polymerization. Copolymerizationsof ESCQ and PSCQ with BCQ were carried out at 50 "C in chloroform with a given monomer concentration of ESCQ and PSCQ of 20 mmol/L above each equilibrium monomer concentrations and with various monomer concentrations of BCQ from 20 to 180 mmol/L above its equilibrium monomer concentration ([BCQI, = 4.45 mmoVL at 50 "C). The results of the copolymerizationsare summarized in Table IV, and their copolymerization composition diagrams are shown in Figure 12. The results were analyzed according to the integrated copolymer composition equation of Mayo and Lewis8 to obtain monomer reactivity ratios rl(ESCQ) = 0.73 f 0.28 and rZ(BCQ) = 0.66 f 0.23 at 50 "C for the ESCQ-BCQ system and rl(PSCQ) = 0.85 f 0.05 and rz(BCQ) = 1.11 f 0.06 at 50 "C for the PSCQ-BCQ system, respectively. From comparison with the llrz values, the relative reactivity of ESCQ, PSCQ, and BCQ toward the
*
polymeric radical with the BCQ terminal unit was given as ESCQ (1.5)> BCQ (1) > PSCQ (0.91, indicating that ESCQ was more reactive than BCQ toward the polymeric radical with the BCQ terminal unit. The interesting fact that ESCQ with conjugatingelectron-acceptingnitrile and nonconjugating ethylthio groups at each of the 7 and 8 positions is more highly conjugativeand reactive than BCQ with two conjugative electron-acceptinggroups,nitrile and butoxycarbonyl, could be explained in terms of a captodative substituent effect on the radical as proposed by Viehe et al.ll In summary, the radical polymerization kinetics of ESCQ and PSCQ interestingly revealed that they underwent typical equilibrium polymerization. The entropy change for polymerization for them fell into almost a given value including those for homopolymerizable quinodimethanes such as BCQ, AcCQ, and BzCQ. The quinodimethanecompounds may be grouped into a family of monomers different from a conventionalvinyl monomer. From the copolymerizations of ESCQ or PSCQ with St, it was found that ESCQ and PSCQ were extremely conjugative and reactive and were close to neutral in polarity. From the copolymerization of ESCQ with BCQ, ESCQ was found to be more reactive than BCQ, being well explained in terms of the captodative substituent effect of the radical.
References and Notes (1) Iwatauki, S.; Itoh, T.;Iwai,T.;Sawada,H. Macromolecules1985, 18, 2726. (2) Iwatauki, S.; Itoh, T.;Higuchi,T.;Enomoto, K. Macromolecules 1988,21,1571. (3) Iwatsuki, S.;Itoh,T.;Yabunouchi, H.; Kubo, M. Macromolecules 1990,23,3450. (4) Iwatauki, S.; Itoh, T.; Miyaehita, I. Macromolecules 1988,22, 557. (5) Dainton, F. S.; Ivin, K. J. Quart. Reu. 1958, 12, 61. (6) Mayo, F. R.; Walling, C.; Lewis, F. M.; Hulse, W. F. J. Am. Chem. SOC. 1948, 70,1523. (7) Doak, K. W. J. Am. Chem. SOC. 1948, 70,1525. 1944.66, 1594. (8) Mayo, F. €2.; Lewis, F. M. J. Am. Chem. SOC. (9) Kelen, T.; Tad&, F. J. Macromol. Sci., Chem. 1975, A9, 1. (10) Yong, L. J. Tabulation of Q,e values. In Polvmer Handbook. 2nd sd.; Brandroup, J., Immergut, E. H., E&.; Wiley-Inter: science: New York, 1975; p 11-387. (11) Viehe,H.G.:Merenvi,R.:Stella.L.:Janousek.Z.Anpew.Chem.. . . Int. Ed. Engl. 1979, 18,917. I
Registry No. ESCQ, 131457-67-5;PSCQ, 112347-79-2;BCQ, 99214-01-4; St, 100-42-5; (PSCQ)(St) (copolymer), 143969-86-2; (PSCQNBCQ) (copolymer), 143969-88-4; (ESCQ)(St) (copolymer), 143969-89-5; (ESCQ)(BCQ) (copolymer), 143969-87-3.
