Ultra-High-Molecular-Weight Polymers Produced by the Immortal Phosphine-Based Catalyst System

Article abstract of DOI:10.1002/anie.201811946

A strong organophosphorus superbase, N-(diphenylphosphanyl)-1,3-diisopropyl-4,5-dimethyl-1,3-dihydro-2H-imidazol-2-imine (IAP3) was combined with a sterically encumbered but modestly acidic Lewis acid (LA), (4-Me-2,6-^tBu₂-C₆

Full text of DOI:10.1002/anie.201811946

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Ultra-High-Molecular-Weight Polymers Produced by the
“Immortal” Phosphine-Based Catalyst System
Authors: Yun Bai, Jianghua He, and Yuetao Zhang
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201811946
Angew. Chem. 10.1002/ange.201811946
Link to VoR: http://dx.doi.org/10.1002/anie.201811946
http://dx.doi.org/10.1002/ange.201811946

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
Ultra-High-Molecular-Weight Polymers Produced by the
“Immortal” Phosphine-Based Catalyst System
Yun Bai, Jianghua He, and Yuetao Zhang*
Abstract:
A
strong
organophosphorus
superbase,
N-
such as alkylphosphines and N-heterocyclic carbenes,[15]
organophosphorus(III) superbase, imidazolin-2-ylidenamino
substituted phosphines (IAPs) are capable of capturing CO2 and
SO2 molecules to form stable phosphine-based adducts[16-18] and
activating extremely inert greenhouse gas sulfur hexafluoride.[19]
Although strong donor ability and easily adapted steric
hindrance of IAPs should enpower them to be a very promising
LB candidate for FLP system, no report on the employment of
IAPs for LPP yet. Herein five sterically hindered IAPs with the
same imidazolin framework but varied substituents on the N
atom (N-diisopropylphosphanyl, IAP1; N-di-tert-butylphosphanyl,
IAP2; N-diphenylphosphanyl, IAP3; N-dimesitylphosphanyl,
(diphenylphosphanyl)-1,3-diisopropyl-4,5-dimethyl-1,3-dihydro-2H-
imidazol-2-imine (IAP3) was combined with a sterically encumbered
but modestly acidic Lewis acid (LA), (4-Me-2,6-tBu2-C6H2O)AliBu2
((BHT)AliBu2), to synergistically promote the frustrated Lewis pair
(FLP)-catalyzed living polymerization of methyl methacrylate (MMA),
achieving ultrahigh molecular weight (UHMW) poly(methyl
methacrylate) (PMMA) with Mn up to 1927 kg/mol and narrow
molecular weight distribution (MWD) at room temperature (RT). This
FLP catalyst system exhibits exceptionally long lifetime
polymerization performance even in the absence of free MMA, which
could reinitiate the desired living polymerization after the resulting
system was held at RT for 24 h.
IAP4;
N-(bis(6,6,6,6,6-pentafluoro-6λ8-hexa-1,3,4-triyn-1-
yl))phosphanyl, IAP5, Scheme 1) were synthesized and
employed to combine with a series of organoaluminum LAs to
achieve an “immortal” FLP catalyst system for living
polymerization of MMA at RT, producing PMMA with medium to
UHMW (up to 1927 kg/mol), narrow MWD (Ð as low as 1.06)
and high to quantitative initiation efficiencies. To the best of our
knowledge, this is for the first time UHMW PMMA with Mn >106
g/mol and narrow MWD was achieved in polymer synthesis
under mild conditions so far.
There have been continuing efforts in the development of living
polymerization systems to produce polymers with controlled
molecular weight (MW) and narrow MWD since properties of
polymeric materials are closely related to their MW and MWD.[1-
4]
However, it remains as a challenging task to synthesize
UHMW polymers,[5] especially PMMA with Mn >106 g/mol, only a
handful of examples have been achieved under harsh reaction
conditions so far, such as PMMA with Mn up to 3.6 × 106 g/mol
prepared through free radical polymerization under high
pressure of 500 MPa and ~ 60 ºC.[6-7] On the other hand, the
synthesis of UHMW PMMA by anionic polymerization was
restricted by difficulty in obtaining ultra-purified MMA and
solvents and the requirement of low temperature.[8-9] There is no
report on the production of UHMW PMMA with Mn >106 g/mol
and narrow MWD under mild condition up to date. Therefore, it
is a great impetus to research efforts to develop new catalyst
system to overcome these limitations.
As a newly emerging polymerization technique, Lewis pair
polymerization (LPP) has demonstrated extraordinary activity
towards various monomers and exhibits very promising prospect
in the polymer synthesis in recent years,[10] since the well-
established application of FLP in small-molecule chemistry.[11]
Despite the development of a wide range of effective LP
systems, the application of LPP was still hampered by both low
initiation efficiencies and chain-termination side reactions.[12-13]
Until recently, by choosing appropriate combination of Lewis
base (LB) and LA with matching acidity and steric hindrance,[14]
the first example of authentic FLP catalyst system has been
developed to successfully remove these restriction barriers and
achieve living (co)polymerization of MMA and benzyl
methacrylate, producing PMMA with Mn up to 351 kg/mol.
Scheme 1. Structures of Lewis acids, Lewis bases, monomers, and resulting
(co)polymers investigated in this study.
When combined with a strong acidic Al(C6F5)3, IAP-based LPs
exhibited extraordinary highly effective catalytic activity for
polymerization in an 800:1:2 MMA/IAP/Al(C6F5)3 ratio, achieving
quantitative monomer conversion by IAP1 to IAP4-based LPs in
30 s (runs 1-4) but only 41% MMA conversion by IAP5- based
LP in 24 h (run 5) probably due to the lower nucleophilicity of
IAP5 resulting from the presence of electron-withdrawing
pentafluorophenyl substituent. Since IAP3 exhibited the highest
initiation efficiency I*% of 92 among the investigated IAPs, it was
employed for the following polymerization. MALDI-TOF MS
spectrum indicated the exclusive presence of a cyclic chain end
derived from backbiting cyclization side reactions in the low-MW
As a strong nucleophile superior than many organobases
Yun Bai, Jianghua He, and Yuetao Zhang*
State Key Laboratory of Supramolecular Structure and Materials,
College of Chemistry, Jilin University, Changchun, Jilin, 130012,
China
E-mail: ytzhang2009@jlu.edu.cn
PMMA
produced
by
IAP3/Al(C6F5)3
LP
Supporting information containing experimental details, NMR
spectra and further tabular data (PDF, 41 pages) is available on the
WWW under http://
This article is protected by copyright. All rights reserved.

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
Table 1. Results of polymerization by IAP-based LPs[a]
[c]
Run
LB
LA
M
M/LB/LA
Time
Conv.[b]
(%)
100
100
100
100
41
100
100
100
100
100
100
100
100
100
89
Mn
MWD[c]
I*[d]
(%)
80
52
92
81
8
91
112
75
(kg/mol)
100
154
1
2
3
4
5
6
7
8
IAP1
IAP2
IAP3
IAP4
IAP5
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
IAP3
Al(C6F5)3
Al(C6F5)3
Al(C6F5)3
Al(C6F5)3
Al(C6F5)3
(BHT)2AlMe
(BHT)2AliBu
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
MMA
EMA
MMBL
DMAA
800:1:2
800:1:2
800:1:2
800:1:2
800:1:2
800:1:2
800:1:2
400:1:2
800:1:2
1600:1:2
3200:1:2
6400:1:2
10000:1:2
15000:1:2
20000:1:2
400:1:2
800:1:2
800:1:2
30 s
30 s
30 s
30 s
1.17
1.21
1.11
1.14
1.35
1.19
1.13
1.06
1.10
1.06
1.07
1.09
1.08
1.08
1.10
1.16
1.12
1.64
1.39
n.d
86.9
99.2
392
88.3
72.0
54.0
92.8
153
24 h
10 min
340 min
40 s
2 min
10 min
30 min
135 min
11 h
21 h
48 h
2 min
340 min
5 min
(BHT)AliBu2 MMA
.
.
9
(BHT)AliBu2 MMA
86
.
10
11
12
13
14
15
16
17[e]
18
(BHT)AliBu2 MMA
105
108
98
97
96
92
90
105
(BHT)AliBu2 MMA
297
656
.
(BHT)AliBu2 MMA
.
(BHT)AliBu2 MMA
1029
1568
1927
49.7
85.6
833
.
(BHT)AliBu2 MMA
.
(BHT)AliBu2 MMA
.
(BHT)AliBu2 EMA
100
100
100
.
(BHT)2AliBu
(BHT)AliBu2
44.4
n.d
19
IAP3
(BHT)AliBu2
MS
400:1:2
24 h
16
n.d
[a] Conditions: carried out at RT in toluene using procedure A; for a 800MMA/1LB/2LA ratio, [M] = [MMA]0 = 0.936 M and [LA]0 = 2[LB]0 = 2.34 mM. n.d. = not
determine. [b] Monomer conversions measured by 1H NMR. [c] Mn and Ð determined by GPC relative to PMMA standards in DMF. [d] Initiator efficiency (I*)% =
Mn(calcd)/Mn(exptl) × 100, where Mn(calcd) = [MW(MMA)]([MMA]0/[I]0) (conversion) +MW of chain-end groups.[e] performed in CH2Cl2.
(Figure S36 and S37), which revealed that polymerization
catalyzed by IAP3/Al(C6F5)3 LP is not a living process.
Previously, we have demonstrated that both the acidity and
steric hindrance of LA play significantly important role in the
performed with the sequential addtion of three batches
(1000/1000/1000 equiv) of MMA (Figure 2b, Table S5) and the
synthesis of well-defined diblock copolymer PMMA-b-PEMA and
triblock copolymer PMMA-b-PEMA-b-PMMA (runs 2 and 3,
Table S6; Figure 2c) by using EMA as co-monomer. Next, we
investigated the effectiveness of IAP3-based LPs for
polymerization of the other monomers and found that it also
exhibited well control on polymerization of both EMA (run 16)
and renewable monomer, -methyl-α-methylene--butyrolactone
(MMBL) (run 17). Polymerization of N,N-dimethylacrylamide
(DMAA) produced polymers with a bimodal MWD, indicating the
coexistence of different active species (run 18) whereas only
16% monomer conversion was obtained for polymerization of
methyl sorbate (MS) in 24 h (run 19).
reactivity of polymerization. Therefore,
a
series of
organoaluminum LAs with descending acidity (Al(C6F5)3 (100%)
> (BHT)2AlMe (86%) ≈ (BHT)2AliBu (85%) > (BHT)AliBu2 (74%),
Table S1) on a relative scale[20] were examined for MMA
polymerization in an 800:1:2 MMA/IAP3/LA ratio. It turned out
that LP composed of bulky (BHT)2AlMe with lower acidity
relative to Al(C6F5)3 fully converted MMA to PMMA with Mn =
88.3 kg/mol, Ð = 1.19 and I*% = 91 in 10 min (run 6). However,
MALDI-TOF MS spectrum indicated that the final product still
contained a cyclic chain end (Figure S38 and S39). Using
(BHT)2AliBu with similar acidity but larger steric hindrance to that
of (BHT)2AlMe, we could successfully suppress backbiting
cyclization (Figure S40 and S41) at the expense of
To gain further insight into the above-described
polymerization behavior, we systematically investigated
polymerization by IAP3/(BHT)AliBu2 LP system. It is generally
accepted that a catalyst system should meet the following
polymerization activity (run 7). Excitingly, switching to
a
(BHT)AliBu2·MMA adduct with lower acidity but reduced steric
hindrance led to the significantly enhanced polymerization
activity, producing PMMA with Mn = 92.8 kg/mol, Ð = 1.10, thus
furnishing I*% = 86 (run 9). Moreover, chain-end analyses
revealed that the produced polymer is a linear, living chain,
capped with IAP3/H chain ends, and showed no evidence for
the formation of cyclic backbiting chain end (Figure 1). These
results further highlight the importance of considering both
electronic and steric factors when matching LA with LB for
generating a suitable LP that can promote living polymerization.
The living feature of the polymerization could be confirmed by
the linearly (R2 = 0.9996, Figure S35) increased Mn values of
PMMA with an increase in [MMA]0/[IAP3]0/[(BHT)AliBu2·MMA]0
ratio from 400:1:2 to 20000:1:2 (runs 8-15), while Đ values
remained narrow (from 1.06 to 1.10) (Figure 2a). Worth noting
that UHMW PMMA with Mn up to 1927 kg/mol were achieved by
FLP for the first time (runs 13-15). The livingness and
robustness also enable successful chain-extension experiments
requirements
to
synthesize
UHMW
polymers: First,
extraordinarily effective polymerization activity. Second,
exclusive active species to initiate polymerization. Third, long
lifetime polymerization performance and no interference with
other side reactions such as chain-termination. As an
organophosphorus superbase, the combination of IAP3 with
(BHT)AliBu2 could achieve high to quantitative monomer
conversion for polymerization with [MMA]0/[IAP3]0/[(BHT)AliBu2]0
ratio ranging from 400:1:2 to 20000:1:2. Different from NHO
alone could initiate polymerization of MMA,[14] IAP3 itself is
completely ineffective whereas (BHT)AliBu2 only exhibits
negligible effect for polymerization in up to 24 h (Table S2). We
performed a series of stoichiometric reactions at RT and
observed the formation of classic Lewis adduct for reaction of
IAP3 and Al(C6F5)3 (Figure S16-S18) and the exclusive
generation of noninteracting, true FLP for reaction of IAP3 with
(BHT)2AlMe, (BHT)2AliBu or (BHT)AliBu2, respectively (Figure
S19-S24). As revealed by 1H and 31P NMR spectroscopy,
This article is protected by copyright. All rights reserved.

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
reaction of IAP3 and (BHT)AliBu2·MMA immediately and
polymerization of MMA at RT. Systematic investigation revealed
that the combination of extraordinarily effective polymerization
activity, exclusive zwitterionic active species and immortal
polymerization process without observance of side reaction or
chain termination enabled IAP3/(BHT)AliBu2 FLP system to
accurately control over polymerization of MMA and achieve
UHMW PMMA in the end. These findings not only provide
significantly important foundation to synthesis of UHMW polymer
in the future, but also enable us to synthesize advanced
polymers such as thermoplastic elastomer or self-assembling
polymers by this highly effective and “immortal” catalyst system.
Relevant research work is in progress.
exclusively yielded
a
clean zwitterionic species IAP3-
CH2C(Me)=C(OMe)OAl(BHT)iBu2, which possessed analogous
structure with that of IAP2-CH2C(Me)=C(OMe)OAl(C6F5)3
(Figure 3) generated from the reaction of IAP2 and
Al(C6F5)3·MMA adduct (Scheme S1, Figure S30-S33). Above
results indicated that such zwitterionic species is the exclusive
active species for polymerization and there is no unwanted
reaction resulting from the other active species. Comparative
studies performed with different activation procedures (check
supporting information for details of procedures A and B)
afforded the exactly same PMMA as revealed by their
completely overlapped GPC traces (Figure 4, Table S3), which
further confirmed the uniqueness of zwitterionic species. In
addition to meet the requirement of no occurrence of side
reaction (vide supra), IAP3/[(BHT)AliBu2 FLP system exhibited
exceptionally longlife catalytic performance, which is significantly
important for synthesis of UHMW polymer. The living
polymerization system is “immortal” and could reinitiate the
desired living polymerization after 400 equiv of MMA was fully
consumed and the resulting system was held in the absence of
free MMA at RT for 24 h by the sequential addition of another
batch (400 equiv) of MMA, producing PMMA with Mn = 96.1
kg/mol, Ð = 1.18 (run 2, Table S4), which is similar with that (Mn
= 92.8 kg/mol, Ð = 1.10, run 8) obained for polymerization in an
800:1:2 [MMA]0/[IAP3]0/[(BHT)AliBu2·MMA]0 ratio (Figure S34).
As discussed above, IAP3/(BHT)AliBu2 FLP system meets all
requirements for synthesis of UHMW polymers and thus
accomplishing the goal.
Figure 1. MALDI-TOF MS spectrum of the low-MW PMMA sample produced
by IAP3/(BHT)AliBu2 LP in toluene at RT. Inset: Plot of m/z values vs the
number of MMA repeat units (n).
In summary, the first example of UHMW PMMA with Mn
=
1927 kg/mol and small Ð = 1.10 was produced from the
noninteracting, authentic IAP3/(BHT)AliBu2 FLP-promoted living
Figure 2. GPC traces of (a) PMMA produced by IAP3/(BHT)AliBu2 LP at various [MMA]0/[IAP3]0/[(BHT)AliBu2]0 ratio at RT. Conditions:
[MMA]0/[IAP3]0/[(BHT)AliBu2]0 = 400:1:2, 800:1:2, 1600:1:2, 3200:1:2, 6400:1:2, 10000:1:2, 15000:1:2, 20000:1:2, [MMA]0 = 0.936 M and (b) PMMA samples
obtained from chain extension experiments in toluene at RT, [MMA]0 = 0.47 M and (c) homopolymer, diblock and triblock copolymer produced from the sequential
block copolymerization of MMA and EMA by IAP3/(BHT)AliBu2 in toluene at RT: polymerizing MMA first, [MMA]0 = 0.936 M.
This article is protected by copyright. All rights reserved.

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
[3]
a) O. W. Webster, W. R. Hertler, D. Y. Sogah, W. B. Farnham, T. V.
Rajanbabu, J. Am. Chem. Soc. 1983, 105, 5706-5708; b) O. W.
Webster, J. Polym. Sci. Part A: Polym. Chem. 2000, 38, 2855-2860; c)
M.R. Kalourkoti, O. W. Webster, C. S. Patrikios, Group Transfer
Polymerization Encyclopedia of Polymer Science and Technology;
John Wiley
&
Sons, Inc., 2013, Vol. 99, pp 1-17. DOI:
10.1002/0471440264.pst603.
[4]
[5]
a) K. Matyjaszewski, eds. Controlled/Living Radical Polymerization:
Progress in ATRP, ACS Symposium Series; American Chemical
Society: Washington, DC, 2009; b) A. Anastasaki, V. Nikolaou, G.
Nurumbetov, P. Wilson, K. Kempe, J. F. Quinn, T. P. Davis, M. R.
Whittaker, D. M. Haddleton, Chem. Rev. 2016, 116, 835-877; c) M.
Ouchi, M. Sawamoto, Macromolecules 2017, 50, 2603-2614.
a) V. Percec, T. Guliashvili, J. S. Ladislaw, A. Wistrand, A. Stjerndahl,
M. J. Sienkowska, M. J. Monteiro, S. Sahoo, J. Am. Chem. Soc, 2006,
128, 14156-14165; b) B. Mao, L. Gan, Y. Gan, Polymer 2006, 47,
3017-3020; c) R. W. Simms, M. F. Cunningham, Macromolecules
2007, 40, 860-866; d) L. Mueller, W. Jakubowski, K. Matyjaszewski, J.
Pietraskik, P. Kwiatkowski, W. Chaladaj, J. Jurczak, Eur. Polym. J.
2011, 47, 730-734; e) E. Read, A. Guinaudeau, D. J. Wilson, A. Cadix,
F. Violleau, M. Destarac, Polym. Chem. 2014, 5, 2202-2207; f) N. P.
Truong, M. V. Dussert, M. R. Whittaker, J. F. Quinn, T. P. Davis,
Polym. Chem. 2015, 6, 3865-3874; g) Z, Huang, J. Chen, L. Z. Zhang,
Z. Cheng, X. Zhu, Polymer 2016, 8, 59; h) Z. Liu, Y. Lv, Z. An, Angew.
Chem. Int. Ed. 2017, 56, 13852-13856; i) R. N. Carmean, T. E. Becker,
M. B. Sims, B. S. Sumerlin, Chem 2017, 2, 93-101.
Figure 3. X-ray crystal structure of IAP2-CH2C(Me)=C(OMe)OAl(C6F5)3.
Hydrogen and Fluorine atoms are omitted for clarity and ellipsoids drawn at
50% probability.
[6]
[7]
[8]
[9]
J. Rzayev, J. Penelle, Angew. Chem. Int. Ed. 2004, 43, 1691-1694;
Angew. Chem. 2004, 116, 1723-1726.
T. Arita, Y. Kayama, K. Ohno, Y. Tsujii, T. Fukuda, Polymer 2008, 49,
2426-2429.
S. K. Varshney, J. P. Hautekeer, R. Fayt, R. Jérôme, Ph. Teyssié,
Macromolecules 1990, 23, 2618-2622.
J.P. Hautekeer, S. K. Varshney, R. Fayt, C. Jacobs, R. Jérôme, Ph.
Teyssié, Macromolecules 1990, 23, 3893-3898
[10] a) E. Y.-X. Chen, Top. Curr. Chem. 2013, 334, 239-260; b) E. Piedra-
Arroni, A. Amgoune, D. Bourissou, Dalton Trans. 2013, 42, 9024-
9029; c) Y. Zhang, G. M. Miyake, E. Y.-X. Chen, Angew. Chem. Int.
Ed. 2010, 49, 10158-10162; Angew. Chem. 2010, 122, 10356-10360;
d) Y. Zhang, G. M. Miyake, M. G. John, L. Falivene, L. Caporaso, L.
Cavallo, E. Y.-X. Chen, Dalton Trans. 2012, 41, 9119-9134; e) T. Xu,
E. Y.-X. Chen, J. Am. Chem. Soc. 2014, 136, 1774-1777; f) J. He, Y.
Zhang, E. Y.-X. Chen, Synlett. 2014, 25, 1534-1538; g) Y. Jia, W. Ren,
S. Liu, T. Xu, Y. Wang, X. Lu, ACS Macro Lett. 2014, 3, 896-899; h) J.
Chen, E. Y.-X. Chen, Isr. J. Chem. 2015, 55, 216-225; i) P. Xu, X. Xu,
ACS Catal. 2018, 8, 198-202; j) E. Piedra-Arroni, C. Ladaviere, A.
Amgoune, D. Bourissou, J. Am. Chem. Soc. 2013, 135, 13306-13309;
k) J. Zhu, E. Y.-X. Chen, J. Am. Chem. Soc. 2015, 137, 12506-12509;
l) X. Li, B. Wang, H. Ji, Y. Li, Catal. Sci. Technol. 2016, 6, 7763-7772;
m) Q. Wang, W. Zhao, J. He, Y. Zhang, E. Y.-X. Chen,
Macromolecules 2017, 50, 123-136; n) H. Zhang, Y. Nie, X. Zhi, H. Du,
J. Yang, Chem. Commun. 2017, 53, 5155-5158; o) H. Ji, B. Wang, L.
Pan, Y. Li, Green Chem. 2018, 20, 641-648; p) J. Yang, H. Wu, Y. Li,
X. Zhang, D. Darensbourg, Angew. Chem. Int. Ed. 2017, 56, 5774-
5779; Angew. Chem. 2017, 129, 5868-5873; q) C. Zhang, H. Wu, Y. Li,
J. Yang, X. Zhang, Nat. Commun. 2018, 9, 2137; r) M. G. Knaus, M. M.
Giuman, A. Pöthig, B. Rieger, J. Am. Chem. Soc. 2016, 138, 7776-
7781; s) W. Ottou, E. Conde-Mendizabal, A. Pascual, A.-L Wirotius, D.
Bourichon,; J. Vignolle, F. Robert, Y. Landais, J.-M. Sotiropoulos, K.
Miqueu, Macromolecules 2017, 50, 762-774; t) P. Xu, Y. Yao, X. Xu,
Chem. Eur. J. 2017, 23, 1263-1267; u) M. Wang, F. Nudelman, R. R.
Matthes,; M. P. Shaver, J. Am. Chem. Soc. 2017, 139, 14232-14236;
v) Y. Hosoi, A. Takasu, S. Matsuoka, M. Hayashi, J. Am. Chem. Soc.
2017, 139, 15005-15012.
Figure 4. GPC traces of PMMA obtained from the polymerization performed
using different activation procedures
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Grant no. 21422401, 21774042,
21871107, 21374040).
Keywords: frustrated Lewis Pair • living polymerization •
organoaluminum • organophosphorus superbase • ultrahigh
molecular weight polymer
[1]
[2]
a) N. Hadjichristidis, A. Hirao, Anionic Polymerization: Principles,
Practice, Strength, Consequences and Applications, Springer, 2015;
b) D. Baskaran, Prog. Polym. Sci. 2003, 28, 521-581.
a) K. Matyjaszewski, eds. "Cationic Polymerization of Heterocyclics."
Cationic Polymerizations. CRC Press, 1996. 451-568; b) A. Kanazawa,
S. Kanaoka, S. Aoshima, Chem. Lett. 2010, 39, 1232-1237; c) Y.
Kwon, R. Faust, Adv. Polym. Sci. 2004, 167, 107-136.
[11] Selected some reviews and recent examples on activation of small
molecules by FLPs: a) D. W. Stephan, Science 2016, 354, aaf7229; b)
D. W. Stephan, G. Erker, Angew. Chem. Int. Ed. 2015, 54, 6400-6441;
This article is protected by copyright. All rights reserved.

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
Angew. Chem. 2015, 127, 6498-6541; c) D. W. Stephan, Acc. Chem.
Res. 2015, 48, 306-316; d) D. W. Stephan, J. Am. Chem. Soc. 2015,
137, 10018-10032; e) W. Meng, X. Feng, H. Du, Acc. Chem. Res.
2018, 51, 191-201; f) C. Tang, Q. Liang, A. R. Jupp, T. C. Johnstone,
R. C. Neu, D. Song, S. Grimme, D. W. Stephan, Angew. Chem. Int. Ed.
2017, 56, 16588-16592; Angew. Chem. 2017, 129,16815-16819; g) A.
Simonneau, R. Turrel, L. Vendier, M. Etienne, Angew. Chem. Int. Ed.
2017, 56, 12268-12272; Angew. Chem. 2017, 129, 12436-12440; h) L.
Liu, L. Cao, Y. Shao, D. W. Stephan, J. Am. Chem. Soc. 2017, 139,
10062-10071; i) Z. Jian, G. Kehr, C. G. Daniliuc, B. Wibbeling, T.
Wiegand, M. Siedow, H. Eckert, M. Bursch, S. Grimme, G. Erker, J.
Am. Chem. Soc. 2017, 139, 6474-6483; j) M. Trunk, J. F. Teichert, A.
Thomas, J. Am. Chem. Soc. 2017, 139, 3615-3618; k) Z. Mo, T.
Szilvasi, Y. Zhou, S. Yao, M. Driess, Angew. Chem. Int. Ed. 2017, 56,
3699-3702; Angew. Chem. 2017, 129, 3753-3756; l) O. J. Metters, S.
J. K. Forrest, H. A. Sparkes, I. Manners, D. F. Wass, J. Am. Chem.
Soc. 2016, 138, 1994-2003.
[12] J. He, Y. Zhang, L. Falivene, L. Caporaso, L. Cavallo, E. Y.-X. Chen,
Macromolecules 2014, 47, 7765-7774.
[13] Y. Jia, Y. Wang, W. Ren, T. Xu, J. Wang, X. Lu, Macromolecules 2014,
47, 1966-1972.
[14] Q. Wang, W. Zhao, S. Zhang, J. He, Y. Zhang, E. Y.-X. Chen, ACS
Catal. 2018, 8, 3571-3578.
[15] M. A. Wünsche, P. Mehlmann, T. Witteler, F. Buß, P. Rathmann, F.
Dielmann, Angew. Chem. Int. Ed. 2015, 54, 11857-11860; Angew.
Chem. 2015, 127, 12024-12027.
[16] F. Buß, P. Mehlmann, C. Mück-Lichtenfeld, K. Bergander, F. Dielmann,
J .Am. Chem. Soc. 2016, 138, 1840-1843.
[17] P. Mehlmann, C. Mück-Lichtenfeld, T. T. Y. Tan, F. Dielmann, Chem.
Eur. J. 2017, 23, 5929-5933.
[18] F. Buß, P. Rotering, C. Mück-Lichtenfeld, F. Dielmann, Dalton Trans.
2018, 47, 10420-10424.
[19] F. Buß, C. Mück-Lichtenfeld, P. Mehlmann, F. Dielmann, Angew.
Chem. Int. Ed .2018, 57, 4951-4955; Angew. Chem. 2018, 130, 5045-
5049.
[20] a) M. A. Breckett, D. S. Brassinton, S. J. Coles, M. B. Hursthouse,
Inorg. Chem. Commun. 2000, 3, 530-533; b) Z. M. Heiden, A. P.
Lathem, Organometallics 2015, 34, 1818-1827.
This article is protected by copyright. All rights reserved.

10.1002/anie.201811946
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
An “immortal“ FLP system
composed of organophosporus
Yun Bai, Jianghua He, Yuetao
Zhang*
superbase
and
Page 1– Page 5
organoaluminum promoted the
living polymerization of methyl
Ultra-High-Molecular-Weight
Polymers Produced by the
“Immortal”
methacrylate,
achieving
polymers with medium to
ultrahigh molecular weight (Mn
up to 1927 kg/mol) and narrow
molecular weight distribution.
Phosphine-
Based Catalyst System
This article is protected by copyright. All rights reserved.