Telechelic polyphosphazenes: Reaction of living poly(dichlorophosphazene) chains with alkoxy and aryloxy phosphoranimines

Article abstract of DOI:10.1021/ma030554x

A modification of the method for synthesis of well-defined mono- and ditelechelic polyphosphazenes via the living, cationic polymerization of phosphoranimines has been developed. This process provides access to phosphazene block, comb, and graft copolymer

Full text of DOI:10.1021/ma030554x

Macromolecules 2004, 37, 3635-3641
3635
Telechelic Polyphosphazenes: Reaction of Living
Poly(dichlorophosphazene) Chains with Alkoxy and Aryloxy
Phosphoranimines
†
Ha r r y R. Allcock ,* Er ic S. P ow ell, An d r ew E. Ma h er , Robbyn L. P r a n ge, a n d
Ch r istin e R. d e Den u s‡
Department of Chemistry, The Pennsylvania State University, 152 Davey Laboratory,
University Park, Pennsylvania 16802
Received November 10, 2003; Revised Manuscript Received March 1, 2004
ABSTRACT: A modification of the method for synthesis of well-defined mono- and ditelechelic polyphos-
phazenes via the living, cationic polymerization of phosphoranimines has been developed. This process
provides access to phosphazene block, comb, and graft copolymers that contain organic or organosilicon
macromolecules. Several alkoxy and aryloxy phosphoranimines, RO(CF PdNSiMe
3
CH
2
O)
2
3
(R ) Ph,
MeOPh, C10 , BOC-NH-CH CH , t-BuMe SiO(CH , C 11, and CH dCH-C H ), were synthesized
H
7
2
2
2
2
)
5
8
H
2
6 4
via the reaction between a bromophosphoranimine and the appropriate sodium alkoxide or aryl oxide.
These species are potential initiators or terminators, useful for the synthesis of telechelic polyphosphazenes
with etheric linkages rather than the amino linkages used previously. Ditelechelic polymers, RO[(CF
CH O) PdN] CF OR, were prepared by terminating living poly(dichlorophosphazene) chains,
Cl PdN-(Cl
3
-
2
2
n
-P(OCH
PdN) -PCl
2
3 3
)
+
-
[
3
2
n
3
] [PCl
6
] , with these alkoxy or aryloxy phosphoranimines. Alternatively,
CH Pd
with the appropriate alkoxy or aryloxy phosphoranimines. In all cases,
monotelechelic polyphosphazenes were produced through the termination of the polymer [(CF
N-(Cl
3
2 2 3
O )
+
-
2
PdN)
n
-PCl
3
] [PCl
6
]
hydrolytically stable telechelic polymers with controlled molecular weights and low polydispersities were
obtained in good yield after macromolecular replacement of labile chlorine atoms with sodium trifluo-
roethoxide.
In tr od u ction
polymer. If X contains a functional group, such as a
vinyl, allyl, or protected hydroxyl or amino group, then
the resultant telechelic polyphosphazene may be sub-
jected to further reactions to generate block copolymers
using reactive end groups as linkages or graft copoly-
mers by addition polymerization through unsaturated
end groups.
Earlier work focused on initiating and terminating
species in which a functional group was linked to the
end of the polyphosphazene chain through amino units.4
It was considered useful for future work to study etheric
linkages as well as amine linkages. This would increase
the number of functional groups available for the
synthesis of telechelic polyphosphazenes and reduce the
possibility that the linkages between the polymer
backbone and the telechelic group could be cleaved in
acidic media. Thus, here we describe the synthesis of
several oxygen-linked phosphoranimine species and
demonstrate their usefulness as terminators for the
synthesis of mono- and ditelechelic polyphosphazenes
via the living, cationic polymerization of phosphoran-
imines.
The synthesis of hybrid macromolecules that combine
polyphosphazenes with organic polymers is an essential
component in the development of polymeric systems
1
,27
that contain the attributes of both types of systems.
One method that allows such hybrid systems to be
produced utilizes the living, cationic polymerization of
phosphoranimines, shown in its simplest form in reac-
tion 1.2,3 Poly(dichlorophosphazene) produced in this
manner can be converted to a wide variety of poly-
(
organophosphazenes) by macromolecular replacement
of the chlorine atoms by organic or organometallic
nucleophiles.
The utilization of this pathway for the production of
hybrid organic-inorganic block, comb, or graft copoly-
mers requires the use of specific phosphoranimine
Resu lts a n d Discu ssion
initiators and terminators.4
-10
These organophospho-
Syn th esis of Fu n ction al P h osph or an im in es R-O-
CF3CH2O)2P dNSiMe3 (2a-g). Phosphoranimines such
ranimines have a general formula of X-P(R)(R′)d
NSiMe3, where R and R′ represent unreactive organic
groups, and X can be either an organic linker that bears
a functional group or a polymeric chain. If X is an
organic polymer, then termination by or initiation from
this species will directly give a hybrid organic-inorganic
(
as Br(CF3CH2O)2PdNSiMe3 (1) are known to undergo
bromine replacement reactions with various metal
alkoxides to produce R-O(CF3CH2O)2PdNSiMe3 spe-
1
0,11
cies.
With this in mind, stoichiometric amounts of
different sodium alkoxides and aryloxides, RONa, were
allowed to react with 1 in THF at -78 °C to produce
the corresponding alkoxy or aryloxy phosphoranimines,
R-O(CF3CH2O)2PdNSiMe3 (R ) Ph (2a ), MeOPh (2b),
C10H7 (2c), BOC-NH-CH2CH2 (2d ), t-BuMe2SiO(CH2)5
†
Present address: The Dow Chemical Corporation, 2301 Bra-
zosport Rd., B. 1608, Freeport, TX 77541.
‡
Present address: Department of Chemistry, Hobart and
William Smith Colleges, Geneva, NY 14456.
1
0.1021/ma030554x CCC: $27.50 © 2004 American Chemical Society
Published on Web 04/22/2004

3
636 Allcock et al.
Macromolecules, Vol. 37, No. 10, 2004
Sch em e 1
Ta ble 1. Molecu la r Weigh t Da ta for Ditelech elic
P olym er s 5a -f
Mn × 10-
4
polymer
M:I
calculateda
foundb
PDI
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
a
a
a
a
b
b
b
b
c
c
c
c
d
d
d
d
e
e
e
e
f
10:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
0.55
1.04
2.01
2.98
0.56
1.05
2.02
2.99
0.56
1.05
2.02
2.99
0.57
1.05
2.02
3.00
0.58
1.06
2.04
3.01
0.56
1.05
2.02
2.99
0.99
2.10
2.79
3.29
1.05
1.67
5.67
5.10
1.68
2.03
4.82
4.62
0.92
1.59
3.36
4.91
0.90
1.75
3.07
4.15
1.03
1.27
4.73
5.47
1.26
1.10
1.14
1.17
1.18
1.24
1.05
1.06
1.13
1.18
1.08
1.07
1.08
1.14
1.11
1.16
1.08
1.17
1.11
1.19
1.18
1.24
1.07
1.47
Sch em e 2
(
2e), C8H11 (2f), and CH2dCH-C6H4 (2g)) (Scheme 1),
5f
5f
5
in good yields. These phosphoranimines were used as
terminators in subsequent phosphazene polymerization
reactions. The objective of this was to utilize these
phosphoranimines as alternatives to the aminophos-
phoranimines used in earlier work.
f
a
Calculated from initial ratio of monomer to PCl5 initiator at
100% conversion. b Obtained by GPC vs polystyrene standards.
The functional groups present on these phosphoran-
imines enable them to be used either in organic trans-
formations or directly in polymerization reactions. For
instance, amino-terminated polyphosphazenes should be
accessible through nitration and subsequent reduction
of a phenoxy end group or by deprotection of BOC-
terminated species. In addition, the 1-naphthoxy end
group opens the possibility of Scholl-type polymeriza-
tions, while the 5-norbornene-2-methoxy end group is
suitable for ring-opening metathesis polymerization
polymers were isolated in good yield after replacement
of the chlorine atoms by sodium trifluoroethoxide. The
final polymers ranged in physical properties from
viscous liquids to solids, depending on their molecular
weight.
The polymers were characterized using multinuclear
NMR spectroscopy and gel permeation chromatography
1
13
31
(GPC). H, C, and P NMR spectroscopy were utilized
to detect the presence of the new end groups introduced
via the alkoxy and aryloxy phosphoranimines. The
molecular weights of these polymers, as determined by
gel permeation chromatography against polystyrene
(
ROMP) reactions. It has already been demonstrated
that 4-vinylanilino-substituted phosphoranimines (-NH-
linked species) can be used to synthesize polyphos-
phazenes with a reactive styryl end group, which allows
4
4
standards, ranged from 0.90 × 10 to 8.38 × 10 (Table
1). In all cases, the polymers were obtained with low
polydispersities. The low polydispersities are attributed
to the living nature of the polymerization process, while
the discrepancy between the calculated and GPC mo-
lecular weights is probably due to an overestimation of
1
2
their subsequent incorporation into graft copolymers.
The 4-vinylphenoxy derivative discussed here
-O-linked species) should undergo the same types of
(
reactions. Finally, deprotection of a TBDMS end group
should allow the preparation of a hydroxyl-terminated
polyphosphazene. All of these materials are important
for future investigations into block, comb, and graft
copolymer formation.
1
3
molecular weight by GPC. It was also found that the
molecular weights of the polymers increased as the
monomer-to-initiator ratio was increased, as illustrated
in Table 1.
Syn th esis of Ditelech elic P olyph osph azen es (5a-
f). A recent report from our laboratory has shown that
the addition of 2 equiv of a phosphoranimine with an
amino-linked functional group to a living chain of poly-
Syn th esis of Mon otelech elic P olyp h osp h a zen es
(9a -g). Monotelechelic materials are important for the
production of diblock copolymers with a high degree of
architectural control. Monotelechelic materials are also
useful as preformed building blocks in graft or comb
copolymer syntheses and would eliminate possible cross-
linking that might arise from bifunctional species. Thus,
we investigated the preparation of such polymers by the
process outlined in Scheme 3.
(
dichlorophosphazene) (4) allows the controlled intro-
duction of two functional terminal units onto the
polymer chain. This arises because the cationic termi-
4
nus of a living cationic polymerization can be delocalized
to both ends of the macromolecule. Thus, for compari-
son, ditelechelic polymers 5a -f were prepared as out-
lined in Scheme 2, using alkoxy or aryloxy phosphor-
animines to terminate living poly(dichlorophosphazene)
at both ends. For these materials, the length of the poly-
Two molar equivalents of PCl5 was allowed to react
with the initiating phosphoranimine (CF3CH2O)3Pd
NSiMe3 at 25 °C in CH2Cl2 to generate the initiating
+
-
species [(CF3CH2O)3PdN-PCl3] [PCl6] (7). This en-
sured that only one end of the living poly(dichlorophos-
phazene) chain remained reactive. The formation of this
initiator was confirmed in situ by the presence of two
(
dichlorophosphazene) chain was controlled by the molar
ratio of Cl3PdNSiMe3 to PCl5 in the initial step of the
reaction, and the terminator was then introduced in the
appropriate molar ratio. In all instances, the resultant
3
1
+
doublets in the P NMR spectrum for the N-PCl3 and

Macromolecules, Vol. 37, No. 10, 2004
Telechelic Polyphosphazenes 3637
Sch em e 3
Ta ble 2. Molecu la r Weigh t Da ta for Mon otelech elic
polymers 9a -g. All polymers were characterized by the
spectroscopic and analytical methods mentioned previ-
ously. The molecular weights, obtained from GPC vs
P olym er s 9a -g
Mn × 10-
4
4
calculateda
foundb
polystyrene standards, ranged from 0.94 × 10 to 4.14
polymer
M:I
PDI
4
×
10 (Table 2). Although phosphoranimines 2a -g
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
a
a
b
b
c
d
d
d
e
e
e
e
f
10:1
20:1
5:1
0.52
1.01
0.26
0.53
1.01
1.01
1.98
2.96
0.53
1.02
1.99
2.96
0.53
0.65
1.02
1.02
1.15
1.59
0.49
1.29
1.55
1.70
2.64
4.14
0.94
1.46
2.52
3.73
1.25
1.46
1.87
1.67
1.10
1.22
1.10
1.08
1.19
1.10
1.12
1.14
1.28
1.31
1.08
1.04
1.19
1.14
1.17
1.13
performed well as terminators for the living, cationic
polymerization of Cl3PdNSiMe3, attempts to initiate
polymerization from them gave inconsistent chain
lengths, decreased molecular weight control, and broad
polydispersities. Thus, monotelechelic polyphosphazenes
could not be obtained by the growth of a polyphos-
phazene from these phosphoranimines.
10:1
20:1
20:1
40:1
60:1
10:1
20:1
40:1
60:1
10:1
12:1
20:1
20:1
Ch ar acter ization of Mon o- an d Ditelech elic P oly-
3
1
p h osp h a zen es. The P NMR spectra in Figures 1 and
illustrate the changes that occur during the synthesis
of a monotelechelic polyphosphazene. Figure 1 shows a
2
f
f
g
3
1
typical P NMR spectrum for the initiating species 7,
with doublets at 22.78 and -9.91 ppm. Figure 2a shows
3
1
the P NMR spectra for polymer 8, obtained after the
phosphoranimine 3 has been polymerized from the
initiating species 7. The peaks in Figure 2a are assigned
a
Calculated from initial ratio of monomer to PCl5 initiator at
00% conversion. b Obtained by GPC vs polystyrene standards.
1
+
as follows: +8 ppm (d, terminal PCl3 ), -12 ppm (d,
(
CF3CH2O)3PdN units. Subsequent addition of given
amounts of Cl3PdNSiMe3 (3) to the reaction mixture
containing 7 resulted in the formation of living poly-
dichlorophosphazene) (8) with controlled chain lengths.
The progress of each reaction was monitored by
NMR spectroscopy, and it was found that all polymer-
izations were complete within 24 h at 25 °C. Mono-
telechelic materials were then obtained by termination
of these living poly(dichlorophosphazene) chains, by the
addition of 1.1 equiv of a functional phosphoranimine
terminator (2a -g) to the reaction mixture that con-
tained 8. Macromolecular replacement of the chlorine
atoms with sodium trifluoroethoxide or sodium phen-
oxide then yielded the hydrolytically stable derivative
(
(
[
CF3CH2O)3P), -14 ppm (t, -PCl2dN-PCl3), -15 ppm
t, -Cl2PdN-Cl2PdN-PCl3), and -17 ppm (br s,
Cl2PdN]n). The living poly(dichlorophosphazene) chain
(
3
1
was terminated by the addition of phosphoranimine 2f,
P
as indicated by the disappearance of the resonance for
+
the PCl3 unit and the appearance of a new resonance
for the 5-norbornene-2-methoxy-P at -7 ppm (Figure
2
b).
MALDI mass spectrometry was carried out on rep-
resentative samples of these new materials.28 The
MALDI spectra of a di- and monotelechelic polymer, 5e
and 9b, are shown in Figure 3. Figure 3a (polymer 5e)
shows a series of signals that are representative of the
F igu r e 1. 31P NMR spectrum of the initiating species [(CF ]+[PCl ]- (7).
CH O) PdNPCl
3 2 3 3 6

3
638 Allcock et al.
Macromolecules, Vol. 37, No. 10, 2004
F igu r e 2. 31P NMR spectrum of (a) a living poly(dichlorophosphazene) chain initiated from 7 and (b) a slight excess of alkoxy
phosphoranimine 2f added to quench the polymerization process.
Sch em e 4
that trail the major signals in Figure 3b are indicative
of multiple sodium ion additions to the polymer back-
bone and do not support the existence of multiple chain
structures. In both spectra the series of signals are
representative of polymer chains with the repeating unit
[
(CF3CH2O)2PdN]n, where the distance between the
peaks is calculated to be that of the repeating unit’s
mass, 243 g/mol. These findings support that the
polymer chains are telechelic in nature, were synthe-
sized without any structural changes to the backbone,
and contain functional groups only at the terminus of
the polymer chains.
Differential scanning calorimetry was used to exam-
ine the effect of the various telechelic end groups on the
glass transition temperatures of the synthesized poly-
mers. Ditelechelic polymers 5a -f and monotelechelic
polymers 9a -g all showed a Tg of -66 °C, characteristic
of poly[bis(trifluoroethoxy)phosphazene] homopolymer.
This demonstrates that the presence of the functional
end groups on the polymers in this study did not affect
the Tg values. This allows for the synthesis of hybrid
copolymers via telechelic polyphosphazenes without
unwanted alteration of thermal properties of the phos-
phazene block.
Rea ctivity In vestiga tion s. Polymer 9f, with various
chain lengths, undergoes ROMP reactions with Grubbs’
catalyst in THF (Scheme 4), in a manner similar to that
described for other phosphazene-functionalized nor-
bornenes. The synthesis and characterization of these
F igu r e 3. MALDI mass spectra of (a) ditelechelic polymer
e and (b) monotelechelic polymer 9b.
5
average repeat unit [(CF3CH2O)2PdN]20 (mass 4860),
the P-(OCH2CF3)3 transition group (mass 328), the two
end groups, t-BuMe2SiO(CH2)5-O (mass 434), and a
sodium ion for a total mass of approximately 5645.
Figure 3b (polymer 9b) has a similar signal pattern with
the average mass signal of approximately 3463 arising
from the average repeat unit [(CF3CH2O)2PdN]12 (mass
1
4,15
types of polymers are reported elsewhere.
It has also
been found that polymer 9g copolymerizes with styrene
and methyl methacrylate, in the same manner as the
vinylanilino-terminated polyphosphazene previously re-
ported, to yield a polystyrene- or poly(methyl methacry-
1
2,26
late)-graft-polyphosphazene copolymer.
Polymers 9f
2
3
916), the -P-(OCH2CF3)3 transition groups (mass
and 9g demonstrate the reactivity and utility of tele-
chelic polyphosphazenes. However, initial studies into
the Scholl polymerization behavior of the ditelechelic
28), and the two end groups, -OC6H4-O-CH3 and
CF3CH2O- (mass 223). The smaller secondary peaks

Macromolecules, Vol. 37, No. 10, 2004
-naphthoxy polymers (5c) have shown that these
Telechelic Polyphosphazenes 3639
1
acetone bath. A quantitative amount of the desired sodium
salt (prepared via reaction of the appropriate alcohol with
sodium hydride in 50 mL of THF) was added to this solution
over a period of 20 min. The reaction mixture was allowed to
warm slowly to room temperature and was stirred overnight.
materials resist polymerization under the reaction
conditions described in the literature.1
6-18
Polymer 5e
has been deprotected to its free hydroxyl derivative.
1
Both IR and H NMR spectroscopy have confirmed that
3
1
P NMR spectroscopy was used to verify complete conversion
reagents for cleavage of the TBDMS group, such as
tetrabutylammonium fluoride, boron trifluoride, HCl,
pyridinium p-toluenesulfonate, and a Pd catalyst give
of 1 to the corresponding functional phosphoranimine. Salts
were removed by filtration under an inert atmosphere, and
all volatiles were removed under reduced pressure. The
resultant oils were purified by distillation under high vacuum
to yield the alkoxy/aryloxy phosphoranimines 2a -g in good
yields.
1
9-24
the terminal hydroxyl unit in moderate yields.
Con clu sion s
For 2a : Distillation under reduced pressure (114 °C, 10
1
mmHg) gave a 72% yield. H NMR (CDCl
3
): δ ) 7.34 (t, 2H),
The preparation of mono- and ditelechelic polyphos-
phazenes using alkoxy or aryloxy phosphoranimines and
an ambient temperature polymerization process have
been carried out. These alkoxy and aryloxy derivatives
are shown to work best as terminators for the cationic
polymerization process rather than as initiators. The
length of the polymer backbone and nature of its end
groups were controlled to produce polymers with narrow
polydispersities, predetermined molecular weights, and
well-defined structures with functional groups only at
the termini of the polymer chains. In addition, mono-
telechelic polymers 9f and 9g have been polymerized
via their end groups using ROMP methods or under free
radical conditions to yield graft copolymers. These
examples illustrate that use of alkoxy or aryloxy phos-
phoranimines is a viable alternative to the use of amino-
linked phosphoranimines and provides a more stable
linkage for the synthesis of block and graft copolymers.
31
7
(
1
.13-7.21 (m, 3H), 4.30-4.39 (m, 4H), 0.00 (s, 9H). P NMR
13
CDCl
3
): δ ) -16.55 (s). C NMR (CDCl
3
): δ ) 150.69, 122.9,
29.72, 125.41, 120.54, 120.49, 63.72, 2.45. MS (CI): m/z )
409 (MH+, 100%), 397 (M-C H , 83%), in good agreement
6
5
with isotopic abundance calculations.
For 2b: Distillation under reduced pressure (70 °C, 20
1
mmHg) gave a 52% yield. H NMR (CDCl
3
): δ ) 7.05 (d, 2H),
3
1
6
.86 (d, 2H), 4.27-4.38 (m, 4H), 3.80 (s, 3H), 0.00 (s, 9H).
NMR (CDCl ): δ ) 157.20,
): δ ) -15.87 (s). 13C NMR (CDCl
44.28, 122.96, 121.47, 121.42, 114.67, 63.74, 55.48, 2.59. MS
, 100%), in good
P
3
3
1
(
FAB+): m/z ) 440 (MH+, 77%), 424 (M-CH
3
agreement with isotopic abundance calculations.
For 2c: Distillation under reduced pressure (115 °C, 10
1
mmHg) gave a 68% yield. H NMR (CDCl
3
): δ ) 8.20 (d, 1H),
7.91 (d, 1H), 7.75 (d, 2H), 7.39-7.65 (m, 1H), 4.41-4.54 (m,
4H), 0.03 (s, 9H). 31P NMR (CDCl
(CDCl ): δ ) 146.63, 146.54, 135.08, 128.06, 126.74, 126.49,
25.27, 121.63, 115.41, 115.37, 124.28-127.46, 63.76, 2.43. MS
, 73%), in good
): δ ) -16.78 (s). C NMR
13
3
3
1
(
CI): m/z ) 459 (MH+, 89%), 332 (M-C10H
7
agreement with isotopic abundance calculations.
For 2d : Distillation under reduced pressure (93 °C, 10
1
Exp er im en ta l Section
mmHg) gave a 65% yield. H NMR (CDCl
3
): δ ) 4.22 (m, 4H),
3
1
1
.75 (t, 2H), 1.45 (s, 9H), 1.24 (t, 2H), 0.13 (d, 9H). P NMR
(CDCl ): δ ) 124.6, 63.5, 65.5,
): δ ) -16.3. 13C NMR (CDCl
32.2, 30.1, 28.2, 2.1. MS (FAB+): m/z ) 403 (MH+ -SiMe
90%), 387 (MH+ -SiMe -Me, 63%) in good agreement with
isotopic abundance calculations.
Ma ter ia ls. Lithium bis(trimethylsilyl)amide, phenol, p-
methoxyphenol, 5-(tert-butyldimethylsilyloxy)-1-pentanol, N-
3
3
3
,
(tert-butoxycarbonyl)ethanolamine, 5-norbornene-2-methanol,
3
and 95% sodium hydride were obtained from Aldrich and were
used without further purification. Phosphorus pentachloride
For 2e: Distillation under reduced pressure (84 °C, 10
1
(Aldrich) was purified by sublimation under vacuum prior to
mmHg) gave a 64% yield. H NMR (CDCl ): δ ) 4.17 (m, 4H),
3
use. 1-Naphthol was recrystallized from a deionized water/
ethanol mixture before use. 2,2,2-Trifluoroethanol was dried
3.56 (q, 4H), 1.48-1.54 (m, 4H), 1.34-1.36 (m, 2H), 0.84 (s,
3
1
9H), 0.02 (s, 6H), 0.00 (s, 9H). P NMR (CDCl ): δ ) -8.91
3
(s). 13C NMR (CDCl ): δ ) 121.65, 62.0, 64.1, 28.7, 45.2, 41.3,
over calcium hydride (CaH
NSiMe , Br(CF CH O) PdNSiMe
-vinylphenol were synthesized and purified by literature
2
) and distilled before use. Cl
3
Pd
3
3
3
2
2
3
, (CF CH O) PdNSiMe , and
3
2
3
3
30.8, 24.2, 1.4. MS: (FAB+) m/z ) 533 (MH+, 25%), 518 (M+
-CH , 35%), 434 (M+ -CH -OCH CF , 21%) in good agree-
4
3
3
2
3
1
1,25
procedures.
Aldrich) were distilled into the reaction flask from sodium
benzophenone ketyl under an atmosphere of dry argon.
Dichloromethane (CH Cl ) (Aldrich) was dried over CaSO and
distilled from CaH into the reaction flask.
Tetrahydrofuran (THF), toluene, and hexanes
ment with isotopic abundance calculations.
(
For 2f: Distillation under reduced pressure (110 °C, 5
1
mmHg) gave a 77% yield. H NMR (CDCl ): δ ) 6.16-6.19
3
2
2
4
(m, 1H), 6.10 (br s, 1H), 5.93-5.96 (m, 1H), 4.19-4.28 (m, 4H),
3.72-3.76 (m, 2H), 3.52-3.60 (m, 2H), 2.92, 2.83, 2.76 (3 br s,
4H), 2.37-2.45 (m, 1H), 1.75-1.86 (m, 2H), 1.44-1.49 (m, 1H),
1.23-1.30 (m, 1H), 1.02-1.16 (m 1H), 0.49-0.55 (m, 1H), 0.06
2
All glassware was dried overnight in an oven at 125 °C or
flame-dried under vacuum before use. Reactions were carried
out using standard Schlenk techniques or an inert atmosphere
glovebox (Vacuum Atmospheres or MBraun) under an atmo-
sphere of dry argon or nitrogen.
3
1
13
(br s, 9H). P NMR (CDCl
3
): δ ) -8.18 (s). C NMR
): δ ) 138.33, 137.73, 136.92, 133.04, 124.24, 72.37,
(CDCl
3
71.72, 63.31-64.53, 49.89, 45.42, 44.40, 44.05, 42.98, 42.35,
40.27, 40.00, 29.69, 29.08, 3.16. MS (FAB+): m/z ) 439 (MH+,
Equ ip m en t. H, C, and 31P spectra were obtained using
1
13
a Bruker AMX-360 NMR spectrometer, operated at 360 and
8
21%), 316 (M-C H11O, 35%), in good agreement with isotopic
1
13
1
46 MHz. H and C NMR spectra are referenced to solvent
abundance calculations.
3
1
signals while P NMR chemical shifts are relative to 85%
phosphoric acid as an external reference, with positive shift
values downfield from the reference. All chemical shifts are
reported in ppm. Molecular weights were estimated using a
Hewlett-Packard HP 1090 gel permeation chromatograph
equipped with an HP-1047A refractive index detector and
American Polymer Standards AM gel 10 mm and AM gel 10
mm 104 Å analytical columns and calibrated against polysty-
rene standards (Polysciences). The samples were eluted at 40
For 2g: Distillation under reduced pressure (95 °C, 10
1
mmHg) gave a 67% yield. H NMR (CDCl
3
): δ ) 7.39 (d, 2H),
7.10 (d, 2H), 6.69 (m, 1H), 5.71 (d, 1H), 5.25 (d, 1H), 4.35 (m,
4H), 0.06 (d, 9H). 31P NMR (CDCl
(CDCl
): δ ) -17.15 (s). C NMR
13
3
3
): δ ) 150.75, 143.29, 137.45, 122.54, 130.05, 125.42,
120.53, 61.25, 2.40. MS (CI): m/z ) 436 (MH+, 65%), in good
agreement with isotopic abundance calculations.
Typ ica l Syn th esis of Ditelech elic P olyp h osp h a zen es
5a -f. Phosphorus pentachloride (100 mg, 0.48 mmol, 2 equiv)
°C with a 0.1 wt % solution of tetra-n-butylammonium nitrate
was dissolved in 10 mL of CH
2
Cl
2
under an argon atmosphere
(Aldrich) in THF (OmniSolv).
for 1 h. Once the PCl
5
had dissolved completely, 540 mg (2.4
Syn th esis of Alk oxy a n d Ar yloxy P h osp h or a n im in es
mmol, 10 equiv) of 3 was added. The reaction was monitored
by 31P NMR spectroscopy until complete conversion of 3 to
polymer had occurred. To this solution was added 210 mg (5.0
2
a -g. A solution of Br(CF
3 2 2 3
CH O) PdNSiMe (1) (5.0 g, 12.59
mmol) in THF (200 mL) was cooled to -78 °C in a dry ice/

3
640 Allcock et al.
Macromolecules, Vol. 37, No. 10, 2004
For 9b: 1H NMR (acetone-d
): δ ) 7.18 (d, 2H), 6.91 (d,
31
mmol, 2.1 equiv) of compound 2a , and the solution was stirred
at 25 °C for 6-24 h. After confirmation of complete termination
of polymerization by P NMR spectroscopy (as determined by
the disappearance of the resonance at +8 ppm), all volatiles
were removed under reduced pressure, and the end-capped
poly(dichlorophosphazene) was subsequently redissolved in 10
mL of THF. To this solution was added 3 mL of a 2.0 M
6
2H), 4.22-4.56 (m), 3.77 (s, 6H). P NMR (acetone-d
6
): δ )
-6.39 (br s), -4.61 (br s), -1.73 (d). C NMR (acetone-d ):
158.11, 145.25, 145.36, 123.79, 122.33, 115.25, 64.03, 55.71.
For 9c: 1H NMR (acetone-d
): δ ) 8.26-8.27 (m, 2H), 7.94
(br s, 2H), 7.80 (d, 2H), 7.41-7.65 (m, 8H), 4.26-4.93 (m,
3
1
13
6
6
3
1
13
OCH
2
CF
3
). P NMR (acetone-d
6
): δ ) -6.32 (s, -1.62 (d). C
solution of NaOCH
2
CF
3
in THF. The resultant mixture was
NMR (acetone-d
6
): 150.83, 135.88, 128.81, 128.62, 127.78,
stirred for 24 h at room temperature, after which the complete
replacement of all chlorine atoms was confirmed by 31P NMR
spectroscopy. The derivatized polymer 5a was recovered and
purified via precipitation from THF into deionized water (3×)
127.45, 126.27, 124.03, 116.56, 64.18.
1
For 9d : H NMR (CDCl ): δ ) 4.24 (q, 2H), 1.75 (t, 2H),
3
3
1
13
1.50 (s, 9H), 1.26 (t, 2H). P NMR (CDCl ): δ ) -16.1 (s).
3
C
NMR (CDCl ): δ ) 123.4, 63.1, 64.9, 32.0, 30.5, 28.7, 10.8.
3
1
and hexanes (2×).
For 9e: H NMR (CDCl ): δ ) 4.18 (m, 4H), 3.55 (q, 4H),
3
1
For 5a : H NMR (acetone-d
6
): δ ) 7.40 (t, 6H), 7.26 (d, 4H),
). P NMR (acetone-d ): δ ) -6.48
): 130.65, 121.68, 121.62,
1.43-1.55 (m, 4H), 1.33-1.36 (m, 2H), 0.86 (s, 9H), 0.06 (s,
6H). P NMR (CDCl
3
1
31
13
4
(
1
.28-4.66 (m, OCH
2
CF
3
6
3
): δ ) -8.83. C NMR (CDCl ): δ )
3
1
3
s), -1.84 (d). C NMR (acetone-d
6
124.3, 63.6, 60.4, 28.4, 44.2, 40.8, 31.2, 25.3.
For 9f: 1H NMR (acetone-d ): δ ) 6.11-5.96 (m, 2H), 4.76-
24.02, 64.21.
6
For 5b: 1H NMR (acetone-d
): δ ) 7.06 (d, 4H), 6.79 (d,
6
4.26 (m), 3.67-3.61 (m, 1H), 3.49-3.44 (m, 1H), 2.91 (br s,
1H), 2.82-2.79 (m, 2H), 2.40 (br s, 1H), 1.83-1.76 (m, 1H),
3
1
4
d
1
H), 4.17-4.41 (m, OCH
): δ ) -6.29 (s), -1.67 (d). C NMR (acetone-d
45.34, 145.24, 124.07, 122.53, 115.47, 64.24, 55.82.
2 3
CF ), 3.65 (s, 6H). P NMR (acetone-
1
3
31
6
6
): 158.36,
1.38-1.17 (m, 1H), 0.52-0.48 (br s, 1H). P NMR (acetone-
d
d
6
): δ ) -6.39 (br s), -1.61 (d), -0.98 (d). 13C NMR (acetone-
): δ ) 137.68, 137.31, 136.89, 132.99, 123.82, 49.54, 45.31,
1
For 5c: H NMR (acetone-d ): δ ) 8.26-8.27 (m, 2H), 7.94
6
6
(
br s, 2H), 7.80 (d, 2H), 7.41-7.65 (m, 8H), 4.26-4.93 (m,
44.25, 44.00, 42.87, 43.01, 42.21, 42.18, 40.21, 64.14, 63.01,
62.65.
3
1
OCH
2
CF
3
). P NMR (acetone-d
): 150.83, 135.88, 128.81, 128.62, 127.78,
27.45, 126.27, 124.03, 116.56, 64.18.
6
): δ ) -6.32 (s), -1.62 (d).
1
3
For 9g: 1H NMR (CDCl
): δ ) 7.16 (d, 4H), 6.93 (d, 4H),
3
31
C NMR (acetone-d
6
1
6.58 (m, 1H), 5.58 (d, 2H), 5.11 (d, 2H), 4.18 (m, 4H). P NMR
1
3
1
(CDCl ): δ ) -8.45. C NMR (CDCl ): δ ) 150.23, 136.78,
128.01, 127.21, 126.93, 126.54, 125.12, 123.02, 115.95, 65.31.
For 5d : H NMR (CDCl
3
): δ ) 4.36 (m, OCH
2
CF
): δ ) -6.48
): δ ) 123.4, 63.0, 64.2, 31.8,
3
), 1.83 (t,
3
3
3
1
2
(
3
H), 1.51 (s, 9H), 1.30 (t, 2H). P NMR (CDCl
3
1
3
s), -16.1 (br s). C NMR (CDCl
3
9.7, 28.5, 2.8.
Ack n ow led gm en t. The authors thank the National
Science Foundation for support of this work through
Grant CHE-0211638. C.R.D. also thanks the Natural
Sciences and Engineering Research Council of Canada
(NSERC) for a Postdoctoral Research Fellowship.
For 5e: 1H NMR (CDCl
): δ ) 4.23 (quin, 4H), 3.59 (q, 4H),
3
1
6
1
.50-1.56 (m, 4H), 1.38-1.44 (m, 2H), 0.87 (s, 9H), 0.03 (s,
3
1
1
3
H). P NMR (CDCl
3
): δ ) -9.20 (s). C NMR (CDCl ): δ )
3
21.65, 61.0, 61.3, 26.7, 44.8, 41.9, 30.2, 25.3.
1
For 5f: H NMR (acetone-d
.29 (m, OCH CF ), 3.82-3.46 (m), 2.91, 2.82 (br s), 2.4 (br s),
.91-1.82 (m), 1.45-1.19 (m), 0.52 (br s). P NMR (acetone-
6
): δ ) 6.21-5.98 (m, 4H), 4.55-
4
1
d
1
4
2
3
3
1
Refer en ces a n d Notes
): δ ) -6.27 (s), -1.60 (d). 13C NMR (acetone-d
): δ )
6
6
38.15, 137.53, 137.02, 133.09, 124.03, 49.89, 45.47, 44.50,
4.17, 43.03, 42.99, 42.43, 42.30, 40.23, 64.22, 63.19, 62.80.
(
1) Allcock, H. R.; Lampe, F. W.; Mark, J . E. Contemporary
Polymer Chemistry, 3rd ed.; Pearson Education, Inc.: New
J ersey, 2003.
P r ep a r a t ion of t h e Ca t ion ic In it ia t or [(CF
3 6
P dNP Cl ] [P Cl ]
3
CH
(7). Phosphorus pentachloride (104.0 mg,
Cl over 1 h
at 25 °C. To this solution was added 104.0 mg (0.25 mmol, 1
equiv) of the phosphoranimine (CF CH O) PdNSiMe , and the
2 3
O) -
+ -
(
2) Honeyman, C. H.; Manners, I.; Morrissey, C. T.; Allcock, H.
0
.5 mmol, 2 equiv) was dissolved in 50 mL of CH
2
2
R. J . Am. Chem. Soc. 1995, 117, 7035.
(3) Allcock, H. R.; Crane, C. A.; Morrissey, C. T.; Nelson, J . M.;
Reeves, S. D.; Honeyman, C. H.; Manners, I. Macromolecules
1996, 29, 7740.
(4) Allcock, H. R.; Nelson, J . M.; Prange, R.; Crane, C. A.; de
Denus, C. R. Macromolecules 1999, 32, 5736.
(5) Nelson, J . M.; Primrose, A. P.; Hartle, T. J .; Allcock, H. R.
Macromolecules 1998, 31, 947.
3
2
3
3
3
1
mixture was stirred at room temperature for 2-4 h. P NMR
spectroscopy of the reaction mixture indicated the presence
of the desired product as evidenced by two doublets for the
+
terminal PCl
3
and the (CF
3
CH
2
O)
3
P phosphorus atoms.
For 7: 31P NMR (D
9.91 (d, Cl PdN).
Typical Syn th esis of Mon otelech elic P olyph osph azen es
O): δ ) 22.78 ((d, (CF
CH O) PdN),
2
3
2
3
(
(
6) Allcock, H. R.; Prange, R. Macromolecules 2001, 34, 6858.
7) Allcock, H. R.; Crane, C. A.; Morrissey, C. T.; Olshavsky, M.
A. Inorg. Chem. 1999, 38, 280.
-
3
+
-
fr om [(CF
3
CH
2
O)
3
P dNP Cl
3
] [P Cl
6
] (7). A solution of 7 was
(8) Allcock, H. R.; Nelson, J . M.; Reeves, S. D.; Honeyman, C.
prepared as described above. Phosphoranimine 3 (1.12 g, 5
mmol, 20 equiv) was added to the solution, and the mixture
was stirred at 25 °C for 2-24 h. After the conversion of
phosphoranimine 3 to polymer 8 was complete, as indicated
H.; Manners, I. Macromolecules 1997, 30, 50.
(9) Allcock, H. R.; Reeves, S. D.; Nelson, J . M.; Crane, C. A.
Macromolecules 1997, 30, 2213.
10) Nelson, J . M.; Allcock, H. R. Macromolecules 1997, 30, 1854.
(11) Neilson, R. H.; Wisian-Neilson, P. Inorg. Synth. 1989, 25, 69.
(
3
1
by P NMR spectroscopy, 112 mg of compound 2a (0.27 mmol,
.1 equiv) was added to the reaction mixture, which was then
stirred overnight. The reaction was considered complete when
(
12) Prange, R.; Reeves, S. D.; Allcock, H. R. Macromolecules 2000,
1
3
3, 5763.
(
13) The discrepancy between theoretical and experimentally
obtained molecular weights is likely due to differences in
hydrodynamic radii between the polyphosphazenes and the
polystyrene standards.
3
1
P NMR spectroscopy showed the disappearance of the doublet
at +8 ppm. All volatiles were removed from the reaction
mixture under reduced pressure, and the resultant residue was
dissolved in 10 mL of dry THF. Subsequent treatment of the
reaction mixture with 3 mL of a 2.0 M solution of sodium
trifluoroethoxide and purification by precipitation from THF
into deionized water (3×) and hexanes (2×) yielded the
hydrolytically stable monotelechelic polyphosphazene 9a .
(14) Allcock, H. R.; Laredo, W. R.; deDenus, C. R.; Taylor, J . P.
Macromolecules 1999, 32, 7719.
(15) Allcock, H. R.; de Denus, C. R.; Prange, R. L.; Laredo, W. R.
Macromolecules 2001, 34, 2757.
16) Kovacic, P.; J ones, M. B. Chem. Rev. 1987, 87, 357.
(17) Colon, I.; Kelsey, D. R. J . Org. Chem. 1986, 51, 2627.
18) Colon, I.; Kwiatkowski; G. T. J . Polym. Sci.; Part A: Polym.
Chem. 1990, 28, 367.
19) Lipshutz, B. H.; Pollart, D.; Monforte, J .; Kotsuki, H.
Tetrahedron Lett. 1985, 26, 705.
(20) Prakash, C.; Saleh, S.; Blair, I. A. Tetrahedron Lett. 1989,
30, 19.
(
3
1
For 8: P NMR (D
2
O): δ ) 8.2 (d, 1P), -12.46 (d, 1P), -14.5
(
(
t, 2P), -15.5 (t, 2P), -17.6 (br s, 16P).
1
For 9a : H NMR (acetone-d
6
): δ ) 7.39 (t, 3H), 7.25 (d, 2H),
.21-4.56 (m). P NMR (acetone-d ): δ ) -6.40 (s), -4.65
): 150.81, 135.78, 129.01,
28.91, 127.93, 127.64, 126.42, 123.96, 116.06, 64.11.
(
3
1
4
(
1
6
1
3
br s), -1.85 (d). C NMR (acetone-d
6

Macromolecules, Vol. 37, No. 10, 2004
Telechelic Polyphosphazenes 3641
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22) Cunico, R. F.; Bedell, L. J . Org. Chem. 1980, 45, 4797.
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phazenes; J ohn Wiley & Sons: New York, 2003.
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Spectrometry of Polymers; Montaudo, G., Lattimer, R. P.,
Eds.; CRC Press: Boca Raton, FL, 2001; Chapter 10.
(
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190.
24) Kelly, D. R.; Roberts, S. M.; Newton, R. F. Synth. Commun.
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(
(
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MA030554X