Temperature and Dilution Effects in Polymerization Induced by

31 Temperature and Dilution Effects in Polymerization Induced by Peroxides Undergoing Rapid Decomposition (t ^ΧΑ)""* Downloaded by CORNELL UNIV on August 17, 2016 | http://pubs.acs.org Publication Date: April 19, 1983 | doi: 10.1021/bk-1983-0212.ch031

R - m + _____ tDMF

The s o l u t i o n polymerization of ΜΑΗ i s s u b j e c t t o a d i l u t i o n e f f e c t , i . e . the y i e l d of poly-ΜΑΗ i s d r a m a t i c a l l y reduced when the s o l v e n t c o n c e n t r a t i o n i s a t l e v e l s which are completely s a t i s f a c t o r y f o r the polymerization of r e a c t i v e monomers. T h i s may be a t t r i b u t e d t o the s h o r t h a l f l i f e of the ΜΑΗ excimer and/or com p l e x o r the i n t e r a c t i o n of the e x c i t e d species with the s o l v e n t . Table I . Homopolymerization o f Maleic A n h y d r i d e

Temp, °C 60 80 100 80

t

tBPP ,min

1 / 2

345 30 2.5 30

Solvent

-acetone benzophenone benzene xylene

ml

_ _

1 1 5 5 50

a

PMAH Yield,% 30 40 62 57 62 5 16 8 + 45

b

a

i m m o l e t - b u t y l peroxypivalate (tBPP) added i n 4 p o r t i o n s over 20 min t o 4.9g (50 mmoles) ΜΑΗ; t o t a l r e a c t i o n time k 60 min Waxy s o l i d ; i n f r a r e d spectra i n d i c a t e presence of aromatic structures

Bailey et al.; Initiation of Polymerization ACS Symposium Series; American Chemical Society: Washington, DC, 1983.

31.

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Temperature and Dilution Effects

453

Polymerization o f Norbornene

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Analogous t o the s i t u a t i o n with ΜΑΗ, the polymerization of norbornene shows a strong dependence on the c a t a l y s t h a l f l i f e , i . e . bulk polymerization does not occur unless the c a t a l y s t h a l f l i f e i s l e s s than 2 h r s a t the r e a c t i o n temperature. F u r t h e r , even when the c a t a l y s t h a l f l i f e i s 30 min, the higher the temper ature the higher the y i e l d o f polynorbornene, probably r e f l e c t i n g a strong dependence of the c o n c e n t r a t i o n o f polymerizable species and/or the propagation r a t e on the temperature (_5). NMR s p e c t r a of the polymer i n d i c a t e t h a t a rearrangement o f the s t r u c t u r e occurs during propagation.

The s o l u t i o n polymerization o f norbornene occurs only when low concentrations o f s o l v e n t s are present (6). Table I I . Homopolymerization o f Norbornene b Catalyst DsBPDC tBPP tBPA DsBPDC AIBN

V 2 min 30 30 30 90 60

Temp,°C 70 80 130 50 70

Solvent _

_

acetone

0.3

benzene dioxane

tBPA

75

120

ml

benzene

2.0 0.05 1.85 10.0 0.045

Polymer Yield,% 12 12 58 2 0 11 3 0 20

1 mmole c a t a l y s t added i n 4 p o r t i o n s over 20 min t o 1.84g (20 mmoles) norbornene; t o t a l r e a c t i o n time 60 min DsBPDC = d i - s e c - b u t y l peroxydicarbonate; tBPA = t - b u t y l peroxyacetate; AIBN = a z o b i s i s o b u t y r o n i t r i l e Polymerization o f S u b s t i t u t e d Norbornenes The D i e l s - A l d e r adducts o f eye1opentadiene (CPD) with ΜΑΗ and with N-phenylmaleimide (NPMI) c o n t a i n the norbornene moiety and undergo polymerization under the same c o n d i t i o n s as ΜΑΗ and nor bornene, i . e . i n the presence o f r a d i c a l c a t a l y s t s undergoing r a p i d decomposition a t the r e a c t i o n temperature and s u b j e c t t o a s i g n i f i c a n t d i l u t i o n e f f e c t (7_, 8) .


454

INITIATION OF

Table I I I . Homopolymerization

Adduct endo

b Catalyst BPO° tBPP tBPA tBHP-70


exo

tBPA tBHP-70

o Temp, C

POLYMERIZATION

o f CPD-MAH Adduct

Solvent^

ml

80 80 120 147 170 240

dioxane dioxane CB xylene

5 20 2 0.3

-

-

120 147 240

CB xylene

-

Polymer Yield,% 0 0 50 50 47 80 72 65 35

2 0.3

-

" 1 . 2 5 mmoles c a t a l y s t added i n 4 p o r t i o n s over 20 min t o 2g k (12 mmoles) adduct; t o t a l r e a c t i o n time 60 min BPO = benzoyl peroxide; tBHP-70 = 70% t - b u t y l hydroperoxide with 20% d i - t - b u t y l peroxide ^ Reaction time 5 h r s CB = chlorobenzene a Table IV. Homopolymerization

Adduct endo

b Catalyst C

BP0 tBPP tBPA tBPB tBHP-70

exo

tBPP tBPA tBHP-90

ο Temp, C

of CPD-NPMI Adduct

Solvent^

ml

80 80 85 120 150 150 210

CB dioxane DCE CB CB

20 20 10 3 2

-

-

85 120 155 260

DCE CB CB

16 3 3 _

-

Polymer Yield,% 0 0 9 60 53 0 20 0 0 60 30

1.25 mmoles c a t a l y s t added i n 4 p o r t i o n s over 20 min t o 2g (8.4 mmoles) adduct; t o t a l r e a c t i o n time 60 min tBPB = t - b u t y l perbenzoate; tBHP-90 - 90% t - b u t y l hydroperoxide Reaction time 5 h r s DCE = 1,2-dichloroethane The d i l u t i o n e f f e c t i s very s i g n i f i c a n t i n some conjugated diene-MAH copolymerizations which a l s o r e q u i r e the use of c a t a l y s t s a t temperatures where they have a s h o r t h a l f l i f e . Thus,



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Temperature and Dilution

Effects

455

whereas the copolymerization of butadiene and ΜΑΗ occurs r e a d i l y a t 80 C on the a d d i t i o n of tBPP t o a s o l u t i o n c o n t a i n i n g as much as 90% dioxane, the copolymerization o f CPD and ΜΑΗ i n the pres ence o f tBPP a t 80 C r e q u i r e s t h a t the dioxane c o n c e n t r a t i o n be l e s s than 25% {T). The copolymerization of CPD and NPMI a l s o r e q u i r e s the use of c a t a l y s t s which have s h o r t h a l f l i v e s a t the r e a c t i o n temperature and takes place i n bulk o r i n the presence of low concentrations of s o l v e n t s (8). The copolymerization of butadiene with ΜΑΗ y i e l d s an unsat urated 1:1 a l t e r n a t i n g copolymer while the copolymerizations of CPD with ΜΑΗ and with NPMI y i e l d s a t u r a t e d 1:2 copolymers. The copolymerization of the CPD-MAH adduct with ΜΑΗ and the copoly m e r i z a t i o n of the CPD-NPMI adduct with NPMI y i e l d the same c o polymers as are obtained from CPD and ΜΑΗ and CPD and NPMI, r e s p e c t i v e l y . The CPD copolymerizations may a c t u a l l y proceed through the r a p i d formation of the adducts, followed by t h e i r copolymer i z a t i o n with ΜΑΗ and NPMI, r e s p e c t i v e l y . The homopolymerizations of the CPD-MAH and CPD-NPMI adducts, as w e l l as the copolymerizations of the adducts with ΜΑΗ and NPMI, r e s p e c t i v e l y , a t temperatures above the exo-endo i s o m e r i z a t i o n temperature of the adducts, y i e l d products c o n t a i n i n g both endo and exo s t r u c t u r e s , i n d i c a t i n g t h a t retrograde d i s s o c i a t i o n of the adducts has regenerated the charge t r a n s f e r complex which under the i n f l u e n c e of the r a p i d l y decomposing c a t a l y s t undergoes e x c i t a t i o n and p o l y m e r i z a t i o n . The d i l u t i o n e f f e c t s i n these polymerizations a t temperatures below and above the i s o m e r i z a t i o n temperature, may be a t t r i b u t e d t o the s h o r t h a l f l i f e of the ex c i t e d adducts and the e x c i t e d complexes, r e s p e c t i v e l y .

X = N-0

or 0


456

INITIATION OF POLYMERIZATION

Mechanisms involving rearrangements in the norbornene moiety to yield products with 2,7 linkages, analogous to the rearrangement noted in the homopolymerization of norbornene, have been proposed previously {]_, 8) . However, there is as yet no direct evidence of rearrangement in the products of the adduct homopolymerizations and copolymerizations. A significant temperature effect is noted in the bulk polymerizations of the liquid Diels-Alder adducts of CPD with acrylonitrile (AN) and methyl acrylate (MA) (9).


Table V. Homopolymerization of CPD-AN and CPD-MA Adducts Catalyst

*l/2 mole-% min

Temp Time ~C hr

Q Mp, C

MW (vpo)

10 13 16 27 54

138-150 193-198

425 892

0 0 3 11 32

110-113 139-144

1640 2015

Yield %

CPD-AN Adduct tBPP BPO tBPA tBHP-90

6 5 10 2 10

30 30 3.5 2 2

80 100 150 220 220

1 39 1 2 2

CPD-MA Adduct tBPP tBPO tBPA tBHP-90

10 5 10 2 10

30 30 3.5 2 2

80 100 150 220 220

1 39 1 2 2

Catalyst added over 20 min to 25 mmoles adduct; total reaction time as indicated The yield of homopolymer increases with temperature. The increase in the molecular weight of the polymer with increasing catalyst concentration at the same temperature may be attributed to an increased concentration of polymerizable, i.e. excited species, as the catalyst concentration increases and rapid decomposition occurs. Literature Cited 1. 2. 3. 4.

Dannenberg, E. M.; Jordan, M. E . ; Cole, H. M. J. Polym. Sci. 1958, 11, 253. Gaylord, N. G. Applied Polymer Symposium 1975, 26, 197. Gaylord, N. G.; Maiti, S. J. Polym. Sci., Polym. Lett. Ed. 1973, 11, 253. Gaylord, N. G.; Koo, J. Y. J. Polym. Sci., Polym. Lett. Ed. 1981, 19, 107.


GAYLORD

5.

Gaylord, N. G.; Mandal, B. M.; Martan, M. J. Polym. Sci., Polym. Lett. Ed. 1976, 14, 555. Gaylord, N. G.; Deshpande, A. B.; Mandal, B. M.; Martan, M. J. Macromol. Sci.-Chem. 1977, A11, 1053. Gaylord, N. G. Polymer Preprints 1976, 17, 666. Gaylord, N. G.; Martan, M. Polymer Preprints 1981, 22, 11. Gaylord, N. G.; Schildknecht, E. A.; unpublished results.

6. 7. 8. 9.

10,1983


RECEIVED January

Temperature and Dilution Effects

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Temperature and Dilution Effects in Polymerization Induced by

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