ISSN 1009 - 3095 Journal of Zhejiang University SCIENCE V . 4 , N o . 2 , P . 121 - 1 3 0 , M a r . - A p r . , 2003

http.//www, periodicals, com. cn; http://www, zju. edu. cn/English http://www, zjupress, com; http://lib, zju. edu. cn/eindex, htm; jzus @ zju. edu. cn 121

Ethene/norbornene copolymerization by [ Me2Si(3-t tBuCp) ( Nt"rt Bu) ]TiCl2/MAO-catalyst

TRAN Phu-Dennis, KAMINSKY Walter * ( Institute of Technical and Macromolecular Chemistry, University of Hamburg, Germany)

E-mai l : P h u - D e n n i s . Tran @ c h e m i c , u n i - h a m b u r g , de ; kaminsky @ chemic , u n i - h a m b u r g , de

Rece ived Dec . 1 6 , 2 0 0 2 ; revision accepted Jan . 5 , 2 0 0 3

Abstract: Ethene /norbornene copolymerizat ion by the catalyst sys tem [ Me 2 Si ( 3 -~" BuCp) ( N tea Bu) ] TiC12 /

MAO was invest igated in detail at 30~C , 60~C , and 900(2 . A mass flow controller was used in this work to ob-

tain kinetic data and investigate t empera tu re ' s effects on act ivi ty , norbornene incorporat ion, copolymerization

paramete r , micros t ruc ture , g lass t ransi t ion t empera tu re , and molar masses were desc r ibed . High copolymer-

ization va lues r E and high al ternat ion are de te rmined . The n u m b e r of isotactic a l ternat ing s equences is much

higher than that of the syndiotactic a l ternat ing s e q u e n c e s .

K e y w o r d s : Polymerizat ion, E thene /no rbo rnene copolymers , Const ra ined geometry ca ta lys t , Tempera ture

ef fects . Document code : A C L C n u m b e r : 0 6 3 2 . 1 2

INTRODUCTION

For more than 10 years, ethene/norbornene copolymers (COCs) have been of great interest to industry and science, because of their excel- lent optical, mechanical, and electrical proper- ties. With their high transparency, low birefrin- gence and transparency to blue-green laser light, they have potential application to higher-capacity CDs and DVDs (Cherdron et a l . , 1994, Lam- onte et a l . , 2001) . In September, 2000 Ticona started up the wor ld ' s first commercial metallo- cene-based COC (TOPAS) plant in Oberhaus- en, Germany, with capacity of 30 000 t /yr . An- other great manufacturer of COCs is Mitsui Chemical with its product APEL (Brekner et a l . , 1992). Metallocene catalysts to copolymer- ize ethene and norbornene to cyclic olefin copol- ymers without ring opening (Kaminsky et a l . , 1989; 1991; 1993) were first described by us. The microstructure of these copolymers show al- ternating, statistical or blocky sequences de- pending on the metallocene used. Recently, sur- prising results were received for the ethene/nor- bornene copolymerization by Palladium(II) a-di- imine catalysts (Kiesewetter and Kaminsky, 2002; Goodall et al. , 2001) . For copolymeriza-

tions with a molar fraction of norbornene lower than XN = 0. 5 the incorporation rate of nor-

bornene of these catalysts is higher than that of ethene. With low norbornene content in the co- polymer short chain branches are observed in the

13C NMR spectra. Alternating COCs are pro- duced by two new catalyst systems, [ 2- (PhNCH) C4H3 N]zTiC12 (Yoshida et al. , 2002)

and ( "05-C2B9H11 ) Zr ( NEtz )2 ( NHEt2 )-AliBu3

(Ahamura et a l . , 2001 ) , whereas the latter produced crystalline alternating sequences. Con- strained geometry catalysts are also able to copo- lymerize ethene with norbornene (Ruchatz and Fink, 1998; McKnight and Waymouth, 1999). COCs derived from these catalysts mainly have alternating microstrncture. Moreover, [ MezSi

( 3 -tert BuCp) ( 1-adamantyl amido) ] M M e 2 ( M =

Zr or Hf) was reported to produce semicrystalline COCs with high melting points about 250~ (Harrington and Crowther, 1998) . The used catalyst [ Mez Si ( 3 -tert BuCp ) ( N tert Bu ) ] TiC12

(Scheme 1 ) was mentioned to have larger copo- lymerization parameter value r E = 5 , 1 than oth-

er constrained geometry catalysts at 40qC poly- merization temperature, because of the influence of nonbonding interactions between the bulky li-

* Author for correspondence

122 TRAN Phu-Dennis, KAMINSKY Walter

gand ( t " r 'BuCp) and the large norbornene com-

onomer . The a im of this work is to get a closer look at the microst ructure and to invest igate the tempera ture effects on the e thene /norbornene co- polymer iza t ion , especia l ly on the kinet ic prof i le ,

copolymerizat ion pa ramete r , micros t ruc ture , glass transit ion t empera tu re , and molar masses . Scheme 1. [ Me2 Si (3 -te~' BuCp) ( N t~' Bu) ~ TIC12

I1% ~ " ~ S i Ti . . . . CI

\ ~ C l N

RESULTS AND DISCUSSION

To keep the conversion of norbornene below 10 t oo l -% , the polymerizat ion t imes and cata lys t concentra t ions were va r ied . E thene /norbornene copolymerizat ions were carr ied out at 30~C, 60~ , and 90~ and over the whole molar f rac- tion of norbornene X N from 0 to 0 . 9 9 .

For more detai led information about the poly- merizat ion conditions see Table 1.

Table 1 Polymerization conditions

at 30 ~C at 6 0 ~C a t 90 qC

[ C a t a l y s t ] 5 . 0 x l 0 6 - - 2 . 5 x 1 0 - S m o l / L 2 . 2 x 10 -6 - 2 . 1 • 1 0 - S m o l / L 2 . 5 • 10 -7 - 1 . 3 • 1 0 - S m o l / L

MAO a) 5 0 0 r a g 5 0 0 m g 5 0 0 m g

[ E t h e n e ] b) 0 . 2 3 7 m o l / L ( 2 b a r ) 0 . 1 6 4 m o l / L ( 2 b a r ) O. 1 2 8 m o l / L ( 2 b a r )

[ Norbornene~ c) 0 - 1 . 1 3 m o l / L 0 - 0 . 7 8 m o 1 / L 0 - 0 . 6 1 m o l / L

Solven t to luene t o l u e n e t o l u e n e

R e a c t i o n v o l u m e d) 2 0 0 m l 20Oral 2 0 0 m l

Catalyst = [Me2Si(3-tr162 . For copolymerizations with ~> for xN/>0.9 1000 nag MAO were used; b) for XN t>0.9 the pressure was re-

duced to 1 or 0 .5 bar; c) for XN = 0.99 more norbornene were used: 5.87 rnol/L(at 30 ~C ) , 4.05 mol/L (at 60~C ) , and 3.17 mol/L (at 90~C ) , respective-

ly, a) for XN between 0 .2 and 0 .6 , 400 ml solvent was used.

Activities/Deactivations The activit ies of the copolymerizations of

ethene with norbornene at reaction temperatures of 30~C, 60qC, and 90~ are displayed in Fig. 1.

35000- �9 30~C

3 0 0 0 0 - �9 60~ ~ O~ ~, 25000

20000

~,~ 15000

._~ 10000

< 5000

0 , , , '

0.2 0.4 0.6 0.8 t

Mola r f rac t ion norbornene in feed x N

Fig. 1 Activities of the copolymerizations of ethene w i t h n o r b o r n e n e b y [ M e 2 S i ( 3 - ~ t B u C p ) ( N ~a B u )

T i C I 2 / M A O at 30~C, 60~C, and 90~ respectively

As a s s u m e d , the activit ies rise with increas ing

t empera tu re and the differences between the ac -

tivities at different t empera tu res decrease for XN

---~0 and XN---~l . The data showed that the act iv-

ities at 60~ are approximate ly 5 t imes and at

90~ about 15 t imes that at 30ff2 depending on

the norbornene molar fract ion in the feed X N.

The max imum of activit ies lies be tween XN =

0 . 5 and X N = 0 . 6 . That max imum of act ivi ty is

known in the l i terature as the posit ive comono-

mer effect (o r second comonomer e f f ec t ) .

For compar ing act iv i t ies , it is important to

know about the kinet ic profile or l ifetime of the

invest igated cata lys ts . The activity does not show

if the catalyst polymerizes fast and deact iva tes or

if it has a higher stabil i ty but lower activity max-

i m u m . Therefore , a kinet ic profile of a cata lys t

is needed to choose the right polymerizat ion con- di t ions .

As can be seen in Fig . 2 showing the typical

consumpt ion of e thene dur ing the copolymeriza-

[ Me2 Si (3-tert BuCp) ( N tert Bu ) ] TiCl2 / MAO- catalyst 123

25

.~ 20'

15.

~ 10

~ 5

~ o

Fig . 2

. . . . at 30~C,x~-0.9 ~ - - at 60~2, x~=0.9

at 90~ x 0 95 , x = .

5 10 15 20 25 30 35 Time (min)

Ethene consumption during the ethene/nor- bornene copolymerizations versus reaction time at dif- f e ren t polymerization temperatures: 30~ 60~C, and 90~ respectively

-t ion at different t empera tu res , the t ime of incu- bation decreased as the react ion t empera tu re in- c reased . The constra ined geometry catalysts are well known for their high t empera tu re s tabi l i ty , but in this case the activity dec reased after five minutes at a polymerizat ion t empera tu re of 90qC, whereas copolymerizat ions at 30~ and 60~ showed nearly no deact iva t ion . It has to be

ment ioned that the e thene consumpt ion line recorded for the copolymerizat ion at 90~ ( s e e F i g . 2 ) has a higher norbornene feed XN = 0 . 9 5

than that for the copolymerizat ions at 30qC and 60~ (xN = 0 . 9 0 ) , because of the high e thene

consumpt ion for the copolymerizat ion at 90 ~

and xN = 0 . 9 .

Norbornene incorporation and copolymerization pa- rameters

Genera l ly , cycloolefine copolymers ( C O C s )

with a norbornene content of above 15 m o l - % are amorphous , but some highly al ternat ing COCs show crystal l ine a r ea s , if the norbornene

incorporat ion lies be tween 38 - 50 m o l - % ( Cherdron et a l . , 1994; Harr ington and Crowther , 1 9 9 8 ) . T h u s , the norbornene incor-

porat ion has great inf luence on the po lymer prop- er t ies . The best method to de te rmine the nor-

bornene content is t3C NMR spec t roscopy . In

genera l , 13C NMR signals are subdivided into

four areas ( s e e F i g . 3 and 4 ) , which belong to

A

....... 1:! i ' , ' " l ' l ' , l l , , , l , l l l ,"l

55 50

F ig .3

t

i + , i ,

45

1 i_ . . M.k._. ' i " ' " " " ~'"

4O

C

' ' ' 1 ' ' '

35 r l ! , " , , ' i ' " ' I ~ " J ' '~ . . . . I . . . . I ' ' ' ' I . . . . I . . . . I

30 25 20 15

Separation of 13C N M R spectrum of an ethene/norbornene copolymer into the peak regions A to D

\ a /

1 4

6 5

Fig . 4 Denomination of a 2, 3-cis-exo orientated norbornene unit and the neighboring methylene car- bons in an ethene/norbornene copolymer chain

different signal groups: A ) 56 - 4 4 . 8 • 10 -6

( C 2 , C 3 ) , B) 4 4 . 8 - 3 6 . 8 x 1 0 - 6 ( C 1 , C 4 ) ,

C) 3 6 . 8 - 3 2 . 8 x 1 0 - 6 ( C 7 ) , D) 3 2 . 8 -

2 7 . 8 x 1 0 - 6 ( C 5 , C 6 , C a , C ~ , C T , C ~ ) .

The norbornene content can be ca lcula ted by the equat ion 1 ( A r n d t - R o s e n a u and Beul ich ,

1 9 9 9 ) .

1/5" I - I (C2 , C3) + I ( C 1 , C4) + I ( C 7 ) XN = 1 / 2 " [ I ( C 5 , C 6 ) + I ( C ~ , C ~ , C r , C ~ ) J -

124 TRAN Phu-Dennis, KAMINSKY Walter

= I ( A ) + I ( B ) + I ( C ) (1 ) 2 . 5 - I ( D )

Fig. 5 shows the ineorporation of norbornene depending on the molar fraction of norbornene in the feed and the eopolymerization parameters at reaction temperature of 30qC . The copolymeriza- tion parameters for Markov 1 order were deter- mined on the basis of the copolymerization equation which correlates the feed composition with the polymer composition (Arnd t and Beuli-

ch , 1 9 9 8 ) .

E M O e~

e -

<3 r

O

Fig.5

0.8-

0.6-

- -Markovl .order �9 observed

0.4- r~=15.1 , i

0.2- y

O " r i

0 012 0.4 016 018 Molar fraction norbornene in feed x~

Copolymerization diagram and copolymeriza- tion parameters of [ Me2 Si ( 3- ~rt BuCp ) ( N t*rt Bu ) ] TiCI2/MAO at 30~

The copolymerization diagrams of [ Me2Si

(3-tertBuCp) ( N ' ~ ] TiC12/MAO at 60~ and

90~ are similar to those of the copolymerization at 30~ ( F i g . 5 ) . Therefore , the values of the copolymerization parameters are in similar di-

mensions : at 60~ r E = 1 6 . 6 r N ~ 0

and at 90~ r E = 1 4 . 6 r N ~ 0 .

In agreement with previous works ( B e u l i c h , 1999 ; T ran , 1999) the temperature has nearly no effect on the incorporation of norbornene , ex- cept the copolymerizations with a very high molar

fraction of norbornene in the feed X N = 0 . 99 ,

where with increasing temperature the nor- bornene rates r i se . It can be explained by the fact that with sufficient norbornene in the feed , in this case XN = 0 . 9 9 , norbornene homopoly-

merization occurs . Therefore , with increasing temperature the ethene rate is negl ib le ; but the

norbornene increases , so a little more nor- bornene diads could be accrue and the nor- bornene content increases . Finnish researchers also found an increase in norbornene incorpora- tion with increasing tempera ture (Laserov et a l . ,

1998) using meta l locenes . All copolymerization parameters r E at differ-

ent polymerization tempera tures , have values of around 15. This is three times that repor ted (McKnigh t and Waymouth , 1 9 9 9 ) . The dis- c repancy might be at tr ibuted to the different ways of calculat ing the e thene concentrat ion in tolu- ene . The copolymerization parameters r N are

nearly zero, so that the product of the two copo- lymerization parameters is nearly zero, which signifies alternating s t ructures . Again, no tem- perature effects were observed in the copolymer- ization parameters .

Microstructure

As mentioned before , the homo- and copoly- merizations of norbornene are a vinyl polymeriza- tions where the norbornene unit is inserted through a 2 , 3 - c i s - ex o -ad d i t i o n . Considering the fact that the C2- and C3-atoms of the norbornene unit in an e thene /norbornene copolymer are ter- tiary carbons , the copolymers are erythrodi tac- t ic . Therefore , the microstructures of COCs are more manifold than those of most other copoly- mers like e thene /propene copolymers . Possible norbornene unit sequences in an e thene /nor - bornene copolymer are displayed in F i g . 6 .

The best way to descr ibe the microstructure

of COCs is by means of 23 C-NMR spectroscopy (Tr i t to et a l . , 2000 ; Arndt -Rosenau and Beuli- ch 1 9 9 9 ) , although the spectra are quite compli- cated considering all the possible norbornene se- q u en ces . Metallocenes are able to produce COCs with different kinds of norbornene unit sequences in the copolymer . COCs with norbornene block sequences are synthesized by metal locenes such as [ Me2 Si ( C p ) 2 ] ZrC12 with a great coordination

gap aperture angle This achirale catalyst also produces nearly equal amounts of rac- and meso- connec ted diads. On the cont rary , the C l - s y m - metric [ P h z C ( C p ) ( I n d ) ]ZrC12 produces NN di-

ads that are mostly meso-connec ted ( T r a n ,

1 9 9 9 ) . Alternating COCs can be produced by

[ Me2 C ( 3 -tert S u C p ) ( F l u ) ] ZrC12 or [ Me2 C ( 3 -is~

[ Me2 Si (3-t~'t BuCp) ( N tert BU ) ] TiCI: / MAO-catalyst 125

PrCp) Flu ] ZrC12 with isotactic alternating se-

quences. Constrained geometry catalysts were reported to produce atactic alternating COCs (Ruchatz and Fink , 1998; McKnight and Way- mouth 1999; Tritto et a l . , 2 0 0 0 ) . Moreover,

[ Me2 Si (3 -~" BuCp ) ( 1-adamantyl amido ) ] MMe2

(M = Zr or Hf) was reported to produce alter- nating semicrystalline COCs with high melting points of about 250~ ( Harrington and Crowther, 1998) .

(l) Isolated norbornene unit

\ /

(IIl) Norbornene triads

(a) meso, meso (IV)Alternating Sequences

(II) Norbornene diads

(a) meso (b) rac m

�9 (b) rac (c) meso

�9

F i g . 6

(a) isotactic (meso) (b) syndiotactic (rac)

Overv iew of possible norbornene unit sequences in an e thene /norbornene-copo lymer

Looking at Fig. 7 , it is evident that the used catalyst produces much more isotactic alternating sequences than syndiotactic alternating sequenc-

es. [2 - (PhNCH)C4H3N]2TiC12, (-o5-CzB9Hll)

Zr(NEtz )2 (NHEt2)-AliBu3 and constrained ge-

ometry catalysts reportedly produce atactic alter- nating COCs with nearly equal amounts of isotac- tic and syndiotactic structure. An exception is [ MezSi ( 3 -tea BuCp ) ( 1-adamantyl amido ) ]

ZrC12 , which produces more isotactic alternating

sequences than syndiotactic alternating sequenc- es like the used catalyst . Thus , they seem to have the same steric hindrance effect , although the N-adamantyl group is much bigger than the N -t~rt Bu group.

The temperature has no influence on the ste- reoselectivity of the monomer insertion. For all

temperatures more isotactic alternating sequences are produced than syndiotactic sequences ( s ee Fig. 8 ) .

The catalyst described in this paper was as- sumed to synthesize highly alternating copoly- mers, but the resulting copolymers did not show any crystalline areas (McKnight et a l . , 1999) . The prepared COCs also did not show any crys- talline sequences , but the alternation could be calculated from the experimental triad distribut- ions. This calculation was performed according to an earlier publication ( We n d t et a l . , 1999) . The alternation is shown in Fig. 9 for different temperatures and different norbornene contents .

The alternation of COCs produced at high temperature and low norbornene content is lower than that of COCs produced at lower temperature

126 TRAN Phu-Dennis, KAMINSKY Walter

A

isotactic alternating /

B C ~ D o

isotactic isotactic alternating altemati l~ NEENE

syndiotactic isotactic altematin alternating + isolated syndiotactic alternating F meso-diads

meso-diad / ~ ~ ', = 9 == ~ ~ i ~ ~ /

50 45 40 35 30

Fig.7 13C NMR Speetrmn of an ethene/norbornene eopolymer produced by EMe2Si(3-tmBuCp) (Nt~aBu)] TiCI2/MAO at 90~ and x N = 0 . 9 9

C B

A

I ' ' ' ' t , , , , I . . . . i , , , , I . . . . i , , , , i ' ' ' ' i . . . . I ' ' ' ' i , , , , I . . . . i . . . . I

55 50 45 40 35 30 25

Fig.8 13C NMR spectra of COCs by [Me2Si(3-~' tBuCp)(NtmBu)]TiCI2/MAO

A) at 30~C ( X N ---~ 0 . 2 6 ) , B) at 60~C ( x ~ = 0 . 2 6 ) and C) at 90~ ( X N ---~ 0 . 2 8 )

r Me2 Si ( 3-tert BuCp) ( N to" Bu ) ] TiCI 2 / MAO-catalyst 127

at the same norbornene conten t . With fur ther in-

crease of the t empera tu re and norbornene content in the polymer the al ternat ion equa l , unti l the

norbornene content is greater than 35 m o l - % . For XN /> 0 . 35 , the al ternat ion of COCs pro-

duced at 30~ nearly reaches its m a x i m u m . For COCs produced at 60~ , the a l ternat ion increas- es further and COCs produced at 90~ have the highest a l ternat ion A = 0 . 7 7 . Consequen t ly , the amount of a l ternat ing sequences in the copol- ymer increases with increasing t em pe ra t u r e s , if

sufficient norbornene is p resen t .

1.0

0.8

e "

o 0.6

.= = 0.4 <

0.2

0.0

e a t 3 0 ~ i a t 6 0 ~ �9 at 90 ~

l i i~ ~

qPA

Ao o~

ib

n ,A

0.0 0.1 0.2 0.3 0.4 0.5

Molar fraction norbornene in polymer x~

F i g . 9 Alternat ion versus molar fract ion norbornene

in the copolymer for COCs by [ Me2 Si ( 3- ~a BuCp) (NtmBu) ] TiCI2/MAO at 30~C, 60~C, and 90~C, re-

spect ively

G l a s s t r a n s i t i o n t e m p e r a t u r e s

The glass transit ion tempera ture Tg is an im-

portant pa rame te r of po lymers , because it de-

scr ibes the thermal processibi l i ty of the po lymer .

The technical re levant T s for COCs lies be tween

100~C and 250~ ( C h e r d r o n et a l . , 1 9 9 8 ) . Genera l ly , there is a l inear re la t ionship between

the T s and the norbornene incorporat ion (Arnd t

and Beul ich , 1998; Rische et a l . , 1 9 9 8 ) .

However , it was la tely reported that the T s de-

pends also on the microst ructure and not only on

the n o r b o m e n e content (Forsy th et a l . , 2 0 0 1 ) .

That publ ica t ion based on earl ier resu l t s , in

which the researchers found that COCs with the

same norbornene incorporat ion but synthesized

with different a luminoxanes as cocata lys t had dif-

ferent T s s ( Wang et a l . , 1 9 9 7 ) .

They ascr ibed that finding to di f ferences in the microst ructures of the copo lymers . Some t ime

later Exxon researchers showed that s tereoregular

a l ternat ing COCs have lower Tgs than that of co-

polymers with random microstructurc with the

same norbornene content ( Harr ington and Crowther , 1 9 9 8 ) . Norbornene blocks were also

supposed to increase the glass transition t emper - ature due to an increased stiffness in the copoly- mer backbone (Bergstrt~m et a l . 1997) . This conforms with the observat ion that the COC pro- duced at 90~ and x N = 0 . 9 9 , where more NN

sequences exist than in other COCs , have higher T s than expec ted from the norbornene content .

In this s tudy , the polymerizat ion tempera ture had almost no influence on the Tgs ( F i g . 10)

and thus on the microstructure of the COCs de-

rived from [ Me2Si ( 3 -tert BuCp) ( N tert Bu) ~ TIC12/

MAO. The l inear re la t ionship between the Tg

and the norbornene content is well i l lustrated by

this ca ta lys t . Although the T s might be influ-

enced by the microst rncture of the copolymers , the l inear re la t ionship between Tg and nor-

bornene content is still a good method to quantify the norbornene incorporat ion for insoluble E /N copo lymers . Never the less every catalyst has its par t icular l inear relat ionship be tween the T~ and

the norbornene conten t , hence to quantify the norbornene content for insoluble E /N copoly- m e r s , some soluble E /N copolymers produced by the same catalyst have to be measured to evalu- ate the l inear equat ion .

170

~" 150

�9 ~ 130

110

~ 90 = 70 o

N 5o e -

~ 3o

= lO

-lO

Fig . 10

�9 at 30 ~C �9 at60 ~C �9 at 90 ~

0.1 0.2 0.3 0.4 0.5

Molar fraction norbornene in polymer A(~

Ethene/norbornene copolymerizations by [ M e : S i ( 3 -~rt B u C p ) ( N ~t B u ) ~ TiCI2/MAO at 30~

60~ and 90~C, respectively. Glass transition temper- ature versus tool fraction norbornene in the polymer

128 TRAN Phu-Dennis, KAMINSKY Walter

M o l a r m a s s e s

The molar masses of all copo]ymers are sum-

marized in Table 2 . The molar masses increase

with increas ing norbornene fract ion in the feed until X N = 0 . 6 . At higher norbornene fractions

the molar masses dec rease . For COCs prepared

at 30~ the molar masses increase from 200 000

to 320 000 then decrease to 76 000 g /mol . In l i terature there are some examples where with in-

creas ing norbornene content the molar masses

dec rease ; al though the opposi te t rend was ob- served ( T r a n , 1999; Ruchatz et a l . , 1998) .

Recen t publ ica t ions even desc r ibed the copoly-

merizat ion of e thene with norbornene to show liv- ing or quas i - l iv ing charac te r ( J a n s e n et a l . ,

2001 ; Thorshaug et a l . , 2002 ; Yoshida et a l . ,

2002) . As an t ic ipa ted , with increas ing t empera - ture the mola r masses d e c r e a s e d , for example

from 230 000 to 85 000 to 48 000 g /mol with XN

= 0 . 4 .

Table 2 Ethene/norbornene copolymerizations by [ Me2 Si(3"~rtBuCp) (N~rtBu) ] TiCI2/MAO

at 30~ 60~ and 90~ respectively. Mo- lar masses determined by viscosimetry and molar fraction norbornene in the feed x N

30~ 60~ 90~ XN M~[ g/moll M~[ g/moll M~[ g/mol~

0 insoluble insoluble insoluble

0.2 200 000 81 000 45 000

0.4 230 000 85 000 48 000

0.6 321 000 95 000 46000

0.8 259 000 62 000 37 000

0.9 100 000 33 000 22 000

0.95 83 000 23 000 20 000

0.99 76 000 28 000 20000

CONCLUSIONS

The cata lys t system [ Me2Si(3- t~"BuCp) ( N tert

Bu) ] TiC12/MAO showed diss imi lar kinet ic pro-

files at different polymerizat ion t empera tu res .

With increas ing tempera ture the t ime of incuba-

tion d e c r e a s e d ; but at 90~ the cata lys t a l ready

deac t iva ted after five minu tes . No deact ivat ion was observed for copolymerizat ions at 30~C and

6 0 ~ Accordingly , it is meaningful to know about the kinetic profiles of the used ca ta lys t s .

The increase of the activit ies with increas ing t empera tu re depends on the molar fract ion of norbornene in the feed; however , they decrease

for X N ~ 0 and xN--~ l . In contrast to other al ter-

na t ing -COC-produced constrained geometry ca ta- lys ts , [ Me2 Si ( 3 -tert BuCp) ( N re" Bu ) ] TiC12/MAO

produces al ternating COCs with mostly isotactic

s t ruc tures , l ike those produced by [ Me2Si (3 -tert

B u C p ) ( 1-adamantyl amido) ] ZrC12 . The al ter-

nat ion is inf luenced by the tempera ture if suffi- c ient norbornene is present in the copolymer iza- t ion. Thus , alternation up to 0 . 7 7 can be ob-

ta ined with X N = 0 . 9 9 and at a polymerizat ion

t empera tu re of 90~ The norbornene incorpora- t ion , copolymerizat ion pa ramete r s , micros t ruc- t u r e s , and glass transition tempera tures are ba re - ly inf luenced by the t empera tu re , except for co- polymerizat ions with very high molar fract ion of norbornene in the feed X N = 0 . 99 , where with

increas ing tempera ture the norbornene incorpora- tion inc reases , more al ternating and NN se- quences are observed and the glass transit ion t empera tu re is higher than expec ted . As as- s u m e d , the tempera ture has great inf luence on the molar masses . Lower tempera tures increase the molar masses intensely.

EXPERIMENTAL SECTION

Mater ia l s

After pre-drying over K O H , toluene was dried by passing through two co lumns , the first one filled with Cu catalysts ( BASF R3-11 ) and the second one with a 4 /~ molecular s ieve . E thene ( 9 9 . 8 % , Linde) was purif ied by pas- sage through columns containing Cu cata lys t ( B A S F R 3 - 1 1 ) and molecular sieve of 10~,. Norbornene ( A c r o s ) was stirred for 36 hours with t r i i sobutyla luminium at 55 ~ and then dis- t i l l ed . The dry norbornene was dissolved in tolu- ene and the norbornene concentrat ion ( 6 - 7 mol /

1) was analyzed by 1H NMR spec t roscopy . Methyla luminoxan was purchased from Witco ( 1 0 w t - % in to luene) and stored as a solid after removal of all volatiles in vacuum. The cata lys t [ Me2 Si ( 3-tert BuCp) ( N tert S u ) ] TIC12 was synthe-

sized according to a modified l i terature p rocedure

[ Me2 Si (3-'e" BuCp) ( N tert Bu) ] TiCI2 / MAO-catalyst 129

( C a n i c h , J . A . M . , 1 9 9 7 ) .

Ethene/norbornene copolymerizations

For a s tandard copolymer iza t ion , a Biichi 1 1

glass autoclave equ ipped with an addi t ional cool-

ing system were used as the reac tor . The reactor was evacua ted at 95 ~ for 1 . 5 h , f lushed with

argon and cooled down to the polymerizat ion tempera ture . MAO ( 5 0 0 mg or 1000 rag) and

toluenic norbornene solution were loaded into the reac tor , which was then charged with toluene to

a total volume of 200 or 400 ml and with e thene to the desi red feed composi t ion . The polymeriza- tions were ini t iated by an injection of the toluenic catalyst solut ion. During the polymerizat ion the

e thene pressure was kept constant using a pres- sure control ler and e thene consumpt ion was mon-

itored with a mass flow meter ( B r o o k s ) . The po- lymerizat ion was quenched by addit ion of 5 ml of e thanol . The po lymer solution was stirred over-

night with di lute hydrochloric acid followed by separat ion of the organic phase and washing

three times with water . After concentra t ion of the organic phase by evapora t ion , the po lymer was precipi ta ted using 400 ml of e thano l , f i l tered

off, and dried at 60~C in a vacuum oven until the weight r ema ined cons tan t .

Polymer analysis

Incorporat ion rates were de te rmined by 13 C-

NMR spec t roscopy . The NMR samples were pre-

pared by dissolving the polymers ( 2 0 0 - 3 0 0 rag) in a mixture of 3 . 5 ml perch lorobutad iene ( P C B ) and 0 . 5 ml 1 , 1 , 2 , 2 - t e t r a c h l o r o - 1 , 2 - d i -

deuteroe thane ( T C E - d 2 ) and measured at 100~ on a Bruker Avance Ultrashield 400 with 1 0 0 . 6 2

MHz. All chemica l shifts were refer red to the

solvent shift of TC E-d2 at 7 4 . 2 4 • 10 -6 The

molar masses Mv were de te rmined using an Ub-

be lohde v iscos imeter (cap i l l a ry 530 01 0 a , K =

0 . 0 0 5 m m 2 / s 2 ) . The samples were p repa red by

dissolving 50 mg of po lymer in 50 ml of deca - hydronaphtha lene and measured at 135~ As

the Mark -Houwink constants for the e thene /nor -

bornene copolymers are unknown, all molar masses were ca lcu la ted using the values for P E , which were t aken from li terature ( Landoh- Btirnstein 1976) . Differential scanning ca lor ime-

try was per formed on a Met t ler -Toledo DSC 821e . To e l iminate any thermal h is tory , the

samples ( 6 -10 m g ) were hea ted to 250~C,

cooled at -20~ to - 100 ~ and heated to 300~ with a heat ing rate of 2 0 9 C / m i n . The val- ues of the second run are repor ted .

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