The borane groups incorporated in PE were quantitatively converted to the
corresponding hydroxy groups by reacting with NaOH/H 2 O 2 reagents at 40
C for
1 h. Despite the heterogeneous reaction conditions in forming the PE–OH
polymers, the interconversion reaction was very effective due to the high surface
area of borane groups in the semicrystalline microstructure of the PE copolymers.
The borane groups in the flexible side chains should be located in amorphous phases
where the chemical reagents can be easily reached. It is very interesting to note that
the resulting PE–OH, containing a hydroxy group located at the end of the flexible
side chain, is structurally similar to that of LLDPE, with expected OH groups
located at the end of each side chain. Figure 1 shows the gel permeation chromatography (GPC) curves for PE–OH polymers containing 0.5 and 1.2 mol% OH
groups. The copolymers were prepared using the Et(Ind)2ZrCl2/MAO catalyst with
ethylene/5-hexenyl-9-BBN comonomers. Overall, the copolymers have high
molecular weight and narrow molecular weight distribution (M w /M n < 3). There
is no indication of any negative influence of the borane group on the metallocene
polymerization.
Scheme 3 Functionalization of polyolefin using “reactive” borane comonomer
Table 1 Copolymerization reactions between ethylene (M 1 ) and 5-hexenyl-9-BBN (M 2 ) using
various catalysts, including [(η
5
-C 5 Me 4 )SiMe 2 -(η
1
-NCMe 3 )]TiCl 2 /MAO (I), Et(Ind) 2 ZrCl 2 /MAO
(II), Cp 2 ZrCl 2 /MAO (III), and TiCl 3 AA/Et 2 AlCl (IV)
Run no. Catalyst
Comonomers
M 1 /M 2 (psi/g)
Reaction temperature/
time (
C/min)
Catalyst activity
(kg/mol∙h)
Borane in PE
(mol%)
I-I-1
I
450/0
150/5
2,100
0
I-I-2
I
450/2
150/5
2,000
1.46
I-I-3
I
450/4
150/5
2,200
2.75
I-I-4
I
450/8
150/5
2,800
4.65
I-II-1
II
40/0
30/70
350
0
I-II-2
II
45/0.22
30/30
480
1.25
I-II-3
II
45/0.61
30/30
660
2.15
I-II-4
II
45/0.82
30/30
850
2.30
I-III-1
III
45/0
30/70
110
0
I-III-2
III
45/5
30/70
210
1.22
I-IV-1
IV
80/10
60/110
1.3
0
Functional Polyolefins: Synthesis and Energy Storage Applications
239
corresponding hydroxy groups by reacting with NaOH/H 2 O 2 reagents at 40
C for
1 h. Despite the heterogeneous reaction conditions in forming the PE–OH
polymers, the interconversion reaction was very effective due to the high surface
area of borane groups in the semicrystalline microstructure of the PE copolymers.
The borane groups in the flexible side chains should be located in amorphous phases
where the chemical reagents can be easily reached. It is very interesting to note that
the resulting PE–OH, containing a hydroxy group located at the end of the flexible
side chain, is structurally similar to that of LLDPE, with expected OH groups
located at the end of each side chain. Figure 1 shows the gel permeation chromatography (GPC) curves for PE–OH polymers containing 0.5 and 1.2 mol% OH
groups. The copolymers were prepared using the Et(Ind)2ZrCl2/MAO catalyst with
ethylene/5-hexenyl-9-BBN comonomers. Overall, the copolymers have high
molecular weight and narrow molecular weight distribution (M w /M n < 3). There
is no indication of any negative influence of the borane group on the metallocene
polymerization.
Scheme 3 Functionalization of polyolefin using “reactive” borane comonomer
Table 1 Copolymerization reactions between ethylene (M 1 ) and 5-hexenyl-9-BBN (M 2 ) using
various catalysts, including [(η
5
-C 5 Me 4 )SiMe 2 -(η
1
-NCMe 3 )]TiCl 2 /MAO (I), Et(Ind) 2 ZrCl 2 /MAO
(II), Cp 2 ZrCl 2 /MAO (III), and TiCl 3 AA/Et 2 AlCl (IV)
Run no. Catalyst
Comonomers
M 1 /M 2 (psi/g)
Reaction temperature/
time (
C/min)
Catalyst activity
(kg/mol∙h)
Borane in PE
(mol%)
I-I-1
I
450/0
150/5
2,100
0
I-I-2
I
450/2
150/5
2,000
1.46
I-I-3
I
450/4
150/5
2,200
2.75
I-I-4
I
450/8
150/5
2,800
4.65
I-II-1
II
40/0
30/70
350
0
I-II-2
II
45/0.22
30/30
480
1.25
I-II-3
II
45/0.61
30/30
660
2.15
I-II-4
II
45/0.82
30/30
850
2.30
I-III-1
III
45/0
30/70
110
0
I-III-2
III
45/5
30/70
210
1.22
I-IV-1
IV
80/10
60/110
1.3
0
Functional Polyolefins: Synthesis and Energy Storage Applications
239