Loading…
Bis(formylpyrrolyl) cobalt complexes as mediators in the reversible-deactivation radical polymerization of styrene and methyl methacrylateElectronic supplementary information (ESI) available. CCDC 1574383-1574385. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8nj00350e
The combination of [Co (II) {κ 2 N,O-NC 4 H 3 -C(H)&z.dbd;O} 2 (PMe 3 ) 2 ] ( 1 ) and tert -butyl-α-bromoisobutyrate ( t BiB-Br) is a suitable initiation system for controlling the radical polymerization of styrene, by an atom transfer radical polymerization (ATRP) mechanism, below 70 °C and of...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The combination of [Co
(II)
{κ
2
N,O-NC
4
H
3
-C(H)&z.dbd;O}
2
(PMe
3
)
2
] (
1
) and
tert
-butyl-α-bromoisobutyrate (
t
BiB-Br) is a suitable initiation system for controlling the radical polymerization of styrene, by an atom transfer radical polymerization (ATRP) mechanism, below 70 °C and of methyl methacrylate, by an organometallic mediated radical polymerization (OMRP)/catalytic chain transfer (CCT) interplay mechanism, below 50 °C. The pure ATRP nature of styrene polymerization allowed the synthesis of the polystyrene-
b
-poly(methyl methacrylate) block copolymer, as confirmed by GPC/SEC and DOSY NMR studies. Attempts to isolate a Co(
iii
) species containing a Br atom (
Co(
iii
)-Br
), supposedly a key ATRP deactivator, by reacting
1
and
t
BiB-Br quantitatively afforded the cationic Co(
iii
) complex [Co
(III)
{κ
2
N,O-NC
4
H
3
-C(H)&z.dbd;O}
2
(PMe
3
)
2
]Br (
2
). Metathetic exchange reactions of complex
2
with TlX gave rise to analogues of the type [Co
(III)
{κ
2
N,O-NC
4
H
3
-C(H)&z.dbd;O}
2
(PMe
3
)
2
]X (
3a
, X = BF
4
−
;
3b
, X = BPh
4
−
), containing non-coordinating anions. In the absence of a radical initiator, complex
2
mediated the formation of polystyrene and poly(methyl methacrylate), with poor control, likely
via
a generation of activators by a monomer addition (GAMA) mechanism. Complexes
3a
and
3b
, however, have been shown to be completely inactive. Addition of 0.5 equivalents of AIBN to
2
drastically improved the molecular weight control in the polymerization of styrene, at 70 °C, through a reverse-ATRP mechanism.
Bis(formylpyrrolyl) cobalt complexes mediate the reversible-deactivation radical polymerization of styrene and methyl methacrylate. |
|---|---|
| ISSN: | 1144-0546 1369-9261 |
| DOI: | 10.1039/c8nj00350e |