Synthesis of pentafluorophenyl(meth)acrylate polymers: New ...

Abstract
Synthesis of pentafluorophenyl(meth)acrylate polymers:
New precursor polymers for the synthesis of
multifunctional materials
Marc Eberhardt, Ralf Mruk, Rudolf Zentel, Patrick Théato *
Institute of Organic Chemistry, University of Mainz, Duesbergweg 10-14, D-55099 Mainz, Germany
Received 10 October 2004; received in revised form 19 January 2005; accepted 26 January 2005
Available online 25 February 2005
Pentafluorophenyl acrylate and -methacrylate were polymerized using AIBN as a thermal initiator. The obtained
polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers.
The reactivity of poly(pentafluorophenylacrylate) and poly(pentafluorophenylmethacrylate) towards primary and secondary
amines, as well as alcohols was investigated in a quantitative way. Both poly(active esters) reacted satisfactorily
with aliphatic primary and secondary amines but only low conversion was found in the case of aromatic amines. Conversions
of only 30% were reached when poly(pentafluorophenylacrylate) was treated with one equivalent of alcohol
under base catalysis. In time resolved FT-IR studies the rate constants of the polymer analogous reactions were
determined.
Ó 2005 Elsevier Ltd. All rights reserved.
Keywords: Active ester monomers; Multifunctional polymers; Reactivity; Polymer analogous reaction; Poly(acrylamide); Poly(pentafluorophenylacrylate)
1. Introduction
European Polymer Journal 41 (2005) 1569–1575
The appearance of active esters and of coupling
agents brought an unforeseen richness to the synthesis
of peptides in organic chemistry [1]. Many different active
esters have been presented: thiophenylesters were
suggested by Wieland, activated methyl esters by Schwyzer
and nitrothiophenyl esters by Farrington et al. [2–4].
New active esters, O-acyl derivatives of hydroxylamines
*
Corresponding author. Tel.: +49 6131 3926256; fax: +49
6131 3924778.
E-mail address: theato@uni-mainz.de (P. Théato).
0014-3057/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.eurpolymj.2005.01.025
EUROPEAN
POLYMER
JOURNAL
www.elsevier.com/locate/europolj
such as N-hydroxysuccinimide esters and numerous
aryl esters with electron withdrawing substituents in
the aromatic ring, were investigated afterwards. Of
these esters the pentachlorophenyl esters introduced by
Kupryszewski excel a high reactivity, but suffer from
the steric effect of the bulky activating groups [5]. Hence,
these esters are less potent to be used in solid-phase peptide
synthesis. A logical remedy for this shortcoming was
the replacement of the five chlorine atoms by fluorine
resulting in a very powerful active ester with less steric
hindrance that retains its reactivity even in the matrix
used for solid-phase peptide synthesis [6].
Functional polymers are usually prepared by polymerization
of the respective functional monomers.

1570 M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575
However, the preparation of the corresponding monomers
and/or their polymerization to high molecular
weight polymers is often difficult or even impossible,
especially when complex structures are desired. In many
cases these problems can be evaded if prepolymers with
reactive chemical functions in the side chain are utilized.
As described above active esters are an ideal starting
point in this kind of concept because these reactive
groups can be transformed into amide groups by polymer
analogous reaction with primary or secondary amines in
a quantative and simple way, as outlined in Scheme 1.
The fact that active ester polymers react fast and
quantitatively with primary or secondary amines to
form the corresponding poly(acrylamide) derivatives
provides an opportunity to obtain macromolecules with
specialized functionalities [7]. Furthermore, amines with
a suitable structure are generally easier to synthesize
than the corresponding monomeric derivatives.
The motivation of this work was to provide alternative
monomers for the synthetic scheme mentioned
(Scheme 1), as part of the research of synthesizing
multifunctional polymers. These materials can be used,
for example, in pharmaceutical or biomedical applications
[8,9].
Acryloylchloride and methacryloylchloride seemed
not to be suitable monomers to be used as active esters
as already shown by Schulz et al. [10,11]. They are
aggressive chemicals, exhibiting a tremendous sensitivity
towards nucleophiles and thus cannot be copolymerized
with many other functional monomers. Additionally,
they often yield cyclic or cross-linked products during
the reaction with amines. As polymerizable active esters
the acryl- and methacryl esters of N-hydroxysuccinimide
(NHS) are used almost exclusively [12–15]. They have
been used successfully for the preparation of multifunctional
poly(acrylamides) [16,17]. However, poly(NHS
acrylates) are poorly soluble which lead to the synthesis
of novel active ester polymers that provide a better solubility.
Ringsdorf and coworkers has designed further
active ester monomers using trichlorophenol or N-hydroxy
benzotriazol; all of them resulting in active ester
polymers [18]. However, trichlorophenol suffers from
the fact to be very toxic, while as active esters based
on N-hydroxy benzotriazol are easily hydrolyzed, affecting
the long time stability of these polymers. Therefore,
n
O
R
X
Initiator
active ester monomer poly (active ester)
O
R
X
n
k
R 2
N
H
R 1
O
R 2
N
the survey for alternative active ester monomers and
their resulting polymers is still challenging. Pentafluorophenyl
esters proved to be very effective in peptide chemistry.
Surprisingly, acrylates of pentafluorophenol were
not considered in polymer chemistry as active ester polymers.
To the best of our knowledge, there is only one
paper describing the synthesis of pentafluorophenylacrylate
and the efforts to polymerize it in bulk [19]. However,
the obtained polymeric material was insoluble
and consequently no size exclusion chromatography or
any other detailed characterization could be presented.
In this paper we describe the successful polymerization
of pentafluorophenylacrylate and -methacrylate yielding
soluble polymeric active esters. Furthermore model
polymer analogous reactions converting them into
poly(acrylamides) will be discussed.
2. Experimental
2.1. Materials
All chemicals were commercially available and used
as received unless otherwise stated. Benzene was distilled
over CaH 2. THF was distilled over potassium. Azodiisobutyronitrile
(AIBN) was recrystallized from diethylether.
2.2. Monomer synthesis
Pentafluorophenylacrylate M1: Pentaflourophenol
(5.4 g, 29.3 mmol) and 3.5 ml 2.6-lutidine (30.0 mmol)
were dissolved in 50 ml dichloromethane. Under cooling
acryloyl chloride (2.6 ml, 31.9 mmol) was added and the
whole mixture stirred for 3 h at 0 °C. After removing the
ice bath the reaction mixture was kept at room temperature
overnight. After filtration of the solution to remove
the precipitated 2.6-lutidine hydrochloride the
filtrate was washed twice with 30 ml water and dried
over MgSO4. The solvent was removed and the remaining
liquid distilled under reduced pressure yielding a colorless
product (4.9 g, 70%) with a boiling point of 27 °C
at 0.05 mbar. A small amount of di-tert-butyl-p-cresol
was added to avoid polymerization during the
distillation.
R R
k m
O
R 1
X
m
R 3
N
H
R 4
O
R
R 2
N
R 1
O
R 3
R
k m
N
statistical copolymer
Scheme 1. Poly(active ester) as starting material for the preparation of multifunctional materials.
R 4

1 H NMR (CDCl3): d/ppm: 6.70 (1H, dd, JHH = 17.1
and 1.5 Hz), 6.36 (1H, dd, J HH = 10.3 and 16.6 Hz),
6.16 (1H, dd, JHH = 10.2 and 1.5 Hz);
19 F NMR (CDCl3): d/ppm: 162.77 (2F, dd,
J FF = 12 and 18 Hz), 158.39 (1F, t, J FF = 15 Hz),
153.02 (2F, d, JFF = 15 Hz);
¼ 1:4318.
n 25
D
Pentafluorophenylmethacrylate M2: M2 was synthesized
as described for M1, starting from 3.0 ml methacryloyl
chloride (32.7 mmol) and the same quantities of
pentafluorophenol, 2,6-lutidine and dichloromethane
gave 4.6 g of a colorless liquid (62%) with a boiling point
of 30 °C at 0.03 mbar).
1 H NMR (CDCl3): d/ppm: 6.43 (1H, t, JHH = 2 Hz),
5.89 (1H, t, JHH = 1.5 Hz), 2.06 (3H, t, JHH =
1.5 Hz);
19 F NMR (CDCl3): d/ppm: 162.90 (2F, dd, JFF =
12 and 18 Hz), 158.63 (1F, t, JFF = 15 Hz),
153.17 (2F, d, JFF = 15 Hz);
¼ 1:4397.
n 25
D
The monomers M3 and M4 were prepared as described
in the literature [21].
2.3. Preparation of the polymers
In a typical polymerization a mixture of 5.0 g monomer,
25 g dry benzene and 32.5 mg (0.27 mmol) azodiisobutyronitrile
(AIBN) was placed into a Schlenk-flask
and freeze-thawn three times. The flask was sealed, immersed
in a preheated oil bath of 80 °C and kept there
for 6 h. After removing most of the benzene the polymer
was isolated by precipitation in methanol. The crude
polymer was dissolved in benzene, precipitated again
in methanol, centrifuged and finally dried in a vacuum
oven at 40 °C. Usually between 4.0 and 4.25 g (80–
85%) of a white powder is collected which is characterized
by NMR and elemental analysis. The molecular
weight distribution is obtained by gel permeation chromatography
(GPC) in THF.
Poly(pentafluorophenylacrylate) PM1:
1
H NMR (CDCl3): d/ppm: 3.07 (1H, br s), 2.09 (2H,
br s);
19
F NMR (CDCl3): d/ppm: 162.59 (2F, br s),
157.15 (1F, br s), 153.56 (2F, br s);
IR: 1782.0 cm 1 (C@O).
Elemental analysis:
M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575 1571
PM1: C: calc. 45.39%, found: 45.38%; H: calc. 1.26%,
found: 1.32%;
GPC data:
M n = 24,050 g/mol;
M w = 37,010 g/mol;
PDI = 1.5.
Poly(pentafluorophenylmethacrylate) PM2:
1
H NMR (CDCl3): d/ppm: 2.41 (2H, br s), 1.38 (3H,
br s);
19
F NMR (CDCl3): d/ppm: 161.33 (2F, br s),
156.2 (1F, br s), 151.77 (2F, br s);
IR: 1780.2 cm 1 (C@O).
Elemental analysis:
PM2: C: calc. 47.64%, found: 47.94%; H: calc. 2.00%,
found: 2.19%;
GPC data:
M n = 26,680 g/mol;
Mw = 48,830 g/mol;
PDI = 1.6.
The polymers PM3 and PM4 were prepared according
to the literature [21].
2.4. Polymer analogous reactions
A general procedure was performed as follows: 0.15 g
of poly(reactive ester) were dissolved in 15 ml dry DMF.
One equivalent of amine or alcohol and base was added
using syringes. The mixture was stirred over a period of
24 h at 50 °C under a nitrogen atmosphere. After evaporating
the solution to dryness in vacuum the remaining
crude product was redissolved in THF and precipitated
in n-hexanes. In the case of secondary poly(acrylamides)
the polymer was cleaned by dialysis in THF. The isolated
product was finally dried in a vacuum oven at
40 °C.
2.5. Kinetic FT-IR measurements
A general procedure to follow the polymer analogous
reactions by FT-IR was performed as follows: the polymers
were dissolved in dry THF at a concentration of
0.02 mol/L. Then the respective nucleophile was added
in one equivalent and the solution was placed in a
50 °C tempered FT-IR transmission liquid cell. FT-IR
spectra were then recorded in time intervals of 1 min
for the primary amines and 10 min for the secondary
amines, respectively. Time resolved conversion was calculated
by the decrease of the area of the activated

1572 M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575
carbonyl peak in the spectrum. The integral of the peak
at 0 min was defined as 0% conversion.
3. Results and discussion
3.1. Monomers
Pentafluorophenylacrylate and -methacrylate, M1
and M2, were prepared in a slightly modified way as described
in the literature [20]. Briefly, pentafluorophenol
was allowed to react with acryloyl chloride in the presence
of an auxiliary base, as shown in Scheme 2. Purification
by vacuum distillation yielded the monomers M1
and M2. They were soluble in many solvents such as
dioxane, diethylether, chloroform, benzene, methanol,
n-hexane. Further they were stable, not air sensitive
and relatively robust against hydrolysis in air. Preparation
in a large scale was possible and even after storage
at 10 °C under nitrogen over several weeks no signs of
decomposition could be detected.
The 19 F NMR spectra of M1 and M2 showed the expected
signals of the five fluorine atoms attached to the
aromatic ring. Fig. 1a exemplarily shows the 19 F NMR
spectrum of M1. Integration of the peaks gave a 2:1:2
ratio, as expected. The fluorine peaks of the monomer M1
are found at 162.8 ppm, 158.4 ppm, and 153.0 ppm,
respectively. Pentafluorophenol itself showed signals at
163.9 ppm, 164.2 ppm and 168.7, which are not
present in the 19 F-spectrum of M1 thus supporting the
purity of the monomer. An analogous 19 F NMR spectrum
was measured for M2.
3.2. Polymerization
According to Blazejewski and coworkers M1 seemed
to cross-link during polymerization in bulk [19], asa
consequence we investigated the solution polymerization
of M1 and M2, respectively. The polymerization could
Cl
R
O
+
F
F
OH
F
F
F
+ 2,6-Lutidin
_
2,6-LutidinHCl
F
F
Fig. 1. (a) 19 F NMR spectrum of monomer M1 and (b) 19 F
NMR spectrum of PM1.
be accomplished at 80 °C using benzene or dioxane as
solvents and azodiisobutyronitrile (AIBN) as a thermal
initiator. After the typical polymerization time of 6 h
the polymers remained in solution and did not precipitate
in contrast to the polymerization of NHS-acrylates
or NHS-methacrylates [21]. The polymers were then isolated
by precipitation into methanol. After reprecipitation
from benzene into methanol the isolated polymers
PM1 and PM2 were characterized by NMR and elemental
analysis. Fig. 1b depicts exemplary the 19 F NMR
spectrum of PM1. The 19 F NMR spectrum of poly(pentafluorophenylacrylate)
PM1 showed three broad peaks
O
F
R
O
F
F
AIBN
benzene, heat
M1: R=H PM1: R=H
M2: R=CH 3
F
F
O
F
R
O
F
F
PM2: R=CH 3
Scheme 2. Preparation of M1, M2 and their thermal polymerization to PM1 and PM2 using AIBN in benzene.
n

at 162.6 ppm, 157.2 ppm, and 153.6 ppm with a
2:1:2 integral ratio. No monomeric peaks could be detected,
as the polymeric peaks were slightly shifted from
those of the monomers. A similar 19 F NMR spectrum
was measured for poly(pentafluorophenylmethacrylate)
PM2.
Mw values are measured by a light scattering detector
and are therefore absolute values. The polydispersity
index (PDI = M w/M n) showed a smaller distribution
than the expected distribution (PDI = 2) for a free radical
polymerization. However, one has to keep in mind
that the polymeric material was isolated by precipitation
and therefore the measured PDI is not exactly the one
for the solution polymerization. Additionally, Mw values
were determined by light scattering, a method, which
tends to underestimates low molecular weights.
The obtained polymers, PM1 and PM2 were highly
soluble in organic solvents such as toluene, chloroform,
tetrahydrofurane, dimethylformamide, acetone,
dimethylsulfoxide or dioxane but completely insoluble
in n-hexane or methanol. Compared to poly(N-acryloxysuccinimide)
and poly(N-methacryloxysuccinimide) which
are only soluble in dimethylformamide and dimethylsulfoxide,
PM1 and PM2 are already superior for any following
polymer analogous reaction from a solvent
point of view.
3.3. Polymer analogous reactions
M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575 1573
3.3.1. NMR studies
In order to be able to compare the novel active ester
polymers PM1 and PM2 with established polymers
poly(N-acryloxysuccinimide) PM3 and poly(N-methacryloxysuccinimide)
PM4 were prepared according to the
literature [21]. However, they suffer, as mentioned earlier,
from their poor solubility. Therefore, for a quantitative
comparison of their reactivity all four types of poly(active
esters), PM1–PM4, had to be dissolved in dry dimethylformamide
(DMF) and the amount of amine or alcohol
and base was added as specified in Table 1. After 24 h
at 50 °C the polymers were isolated, 1 H NMR and
19 F NMR spectra were recorded and the conversion
calculated thereof. In the case of 19 F NMR measurements
1,1,2-tri-chloro-1,2,2-tri-fluoroethane, CCl2FCF2Cl, was
used as internal reference substance. Hence the amount of
internal standard was known and by comparing the polymer
peak area with the peaks of the internal standard, the
mass of unreacted pentafluorophenyl groups could be calculated.
As the overall amount of polymer which was
placed inside the NMR-tube was known the percentage
of conversion could be determined. The results are summarized
in Table 1.
As expected all four poly(active ester) reacted with
primary and secondary amines to form the corresponding
poly(acrylamides) and poly(methacrylamides). Usually
reactivity describes a kinetic term. According to
the reaction procedure in the following analysis the term
‘‘reactivity’’ refers to the thermodynamic term, as we
compare conversions. Though the FT-IR experiments
described later will give a detailed kinetic analysis of
the ‘‘reactivity’’ of poly(active ester).
The reactivity towards primary and secondary
aliphatic amines was higher in the case of the poly(acrylates)
PM1 and PM3 compared to the poly(methacrylates)
PM2 and PM4. These results are in agreement
with the common observation that poly(methacrylates)
are less reactive than the corresponding poly(acrylates).
Only a low conversion of 14% was observed during the
reaction of PM1 with aniline. In comparison PM2, PM3
and PM4 did not react at all with aniline under these
conditions. This is rather interesting because it demonstrates
the higher reactivity of the novel poly(active
ester) PM1 compared to the known poly(active ester)
PM3.
Similar results were obtained during the reaction of
all four polymers with one equivalent of alcohol and
one equivalent of base. Under these reaction conditions
only PM1 reacted with a conversion of 30%. Experiments
to increase the conversion by increasing the
amount of auxiliary base were successful. The conversion
could be increased by using a large excess of alcohol
and base (7 equivalents each). Under these conditions
PM1 reacted with 60%. However, under the same conditions
PM3 showed a conversion of 40%. For the polymers
PM2 and PM4 no conversion was observed
under the same conditions. Furthermore, PM4 precipitated
upon the addition of alcohol and base, thus
excluding any polymer analogous reaction. Higher conversions
of the alcoholysis can be reached by increasing
the amount of auxiliary base as well as increasing the
Table 1
Results of the polymer analogous reaction at 50 °C in DMF for 24 h (NMR-analysis)
Amount of amine or alcohol and base PM1 (%) PM2 (%) PM3 (%) PM4 (%)
Hexylamine 1 equivalent 99 65 99 70
N-hexylmethylamine 1 equivalent 80 65 90 90
Aniline 1.5 equivalents 14 0 0 0
1-Hexanol, triethylamine 1 equivalent each 30 0 0 0
1-Hexanol, triethylamine 7 equivalents each 60 0 40 0

1574 M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575
temperature dramatically. However, both possibilities
lead to rather harsh reaction conditions, thus making
the reaction unattractive.
3.3.2. FT-IR studies
Considering the results of the NMR analysis, listed in
Table 1, the poly(acrylates) PM1 and PM3 seemed to be
the more active species, providing a higher synthetic potential.
For this reason their reactivity was analyzed in
detail. In a typical experiment the polymer sample was
dissolved in dry THF. As mentioned earlier, PM3 suffers
from a poor solubility but it can be dissolved in THF at
the very low concentrations used in the present study.
Then the reactant (1 equivalent) was added and the
whole mixture placed in a tempered FT-IR-liquid cell
at 50 °C. FT-IR-spectra were recorded in time intervals
of 1 min for the primary amines and 10 min for the secondary
amines, respectively.
The activated carbonyl group of the poly(active ester)
shows its peak in the range of 1730–1830 cm 1 . In comparison
the peak of the amide carbonyl group occurs at
lower wave numbers, usually around 1690 cm 1 . During
the polymer analogous reaction the intensity of the activated
carbonyl peak decreases while the peak of the
amide carbonyl peak increases. Time resolved conversion
was calculated by the decrease of the area of the
activated carbonyl peak in the spectrum. The integral
of the peak at 0 min was defined as 0% conversion.
The time-dependent behavior of the conversion for the
polymer analogous reactions of PM1 is shown in Fig.
2. In case of the reaction with primary amines the carbonyl
peak of the active ester vanishes completely after
1 h, i.e. 100% conversion. Investigating the polymer
analogous reaction using secondary amines reveals a different
result. According to the conversion determined by
19 F NMR, the reaction with N-hexylmethylamine as a
conversion [%]
100
90
80
70
60
50
40
30
20
10
0
prim. amine
sec. amine
prim. alcohol
0 200 400 600 800 1000
time [min]
Fig. 2. Conversion-time-plot for the polymer analogous reaction
of PM1 with primary amines (squares), secondary amines
(circles) and primary alcohols using an auxiliary base (stars).
secondary amine stopped at 80% conversion. This is in
agreement with the FT-IR analysis, showing that no
change of the carbonyl peak could be detected after
6 h. The conversion calculated thereof was 84%.
In the case of alcoholysis of PM1 under basic conditions,
conversion into the corresponding hexylester was
slow and reached only 35% after one day, determined
by FT-IR. Noteworthy, the conversion determined by
IR was as in the case of N-hexylmethylamine slightly
higher than the conversion determined by 19 F NMR.
Analogous results were obtained for the polymer
analogous reactions of PM3, investigated by kinetic
FT-IR analysis: the reaction with primary amines was
fast and quantitative, i.e. 100% conversion after 1 h,
whereas the reaction with N-hexylmethylamine was
slower and stopped at 90% conversion after 15 h.
Out of the kinetic FT-IR experiments, carried out at
the same low concentration in THF solution, the rate
constants of the reactions were calculated according to
the standard procedure [22]. In Fig. 3 the plots of
ln([M]0/[M]t]) versus time t, with [M]0 being the integral
value of the poly(active ester) peak in the IR spectrum
at t = 0 s and [M]t being the integral value of the poly-
(active ester) peak at time t, are shown. A straight line
is obtained when ln([M] 0/[M] t]) is plotted against t.
The slope gives directly the rate constant k for the polymer
analogous reaction, which can be converted into the
half-life, s 1/2. It is the time for the concentration of a
reactant to reach half of its initial value. The half-life
s1/2 is in case of a first-order reaction defined by s1/2 =
ln2/k. Results for the values of k and s1/2 are given in
Table 2.
All reactions follow a first-order kinetic in their start
phase. The measured values showed that the polymer
analogous reaction of PM1 was faster compared to
ln([M] 0 /[M] t )
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
PM1 - prim. amine
PM1 - sec. amine
PM3 - prim. amine
PM3 - sec. amine
0.0
0 1000 2000 3000 4000
time [sec]
Fig. 3. Determination of the rate constant for the reaction of
PM1 with primary amines (closed squares), PM1 with secondary
amines (open squares), PM3 with primary amines (closed
triangle) and PM3 with secondary amines (open triangles).

Table 2
Kinetic data for the polymer analogous reactions of PM1 and PM2 at 50 °C in THF
Amount added PM1 PM3
PM3. Therefore PM1 seemed to be a more active polymer
than the commonly used PM3. It is interesting to
note that the obtained initial rate constant of the alcoholysis
of PM1 is close to that of the reaction of PM3
with the secondary amine, although the alcoholysis of
PM1 stopped at 30% conversion, while the reaction of
PM3 with the secondary amines proceeded until a conversion
of 90% was reached.
4. Conclusions
M. Eberhardt et al. / European Polymer Journal 41 (2005) 1569–1575 1575
We could demonstrate the successful polymerization
of the new active ester monomers pentafluorophenylacrylate
M1 and pentafluorophenylmethacrylate M2 into
the respective active ester polymers PM1 and PM2
which were soluble in most organic solvents. The good
solubility offered a superior synthetic value compared
to the commonly used N-hydroxysuccinimide based active
esters. The prepared poly(active esters) were allowed
to react with aliphatic amines and aromatic amines.
Under comparable reaction conditions primary amines
reacted with 100% conversion with PM1 and with 65%
conversion with PM2, while for secondary amines
PM1 could only be converted by 80%. Polymer analogous
reaction with aromatic amines could only be
achieved for PM1 in low conversions of 14%. When
poly(pentafluorophenylacrylate) was treated with one
equivalent of alcohol and base it reacts to 30%. The conversion
could be increased by a large excess of alcohol
and base. Under these conditions both poly(acrylates)
reacted: poly(pentafluorophenylacrylate) to 60% and
poly(N-acryloxysuccinimide) to 40% conversion. In contrast,
the poly(methacrylates) did not react at all under
the same conditions. A detailed study of the reactivity
was performed using time-resolved FT-IR measurements,
revealing that both polymers PM1 and PM2 followed
a first-order reaction kinetics. The rate constants
and half-life of poly(pentafluorophenylacrylate) showed
that PM1 was a more active species than the commonly
used poly(N-acryloxysuccinimide). Hence, poly(penta-
k/s 1
Hexylamine 1 equivalent 1.85 · 10 3
N-hexylmethylamine 1 equivalent 4.67 · 10 4
1-Hexanol, triethylamine 1 equivalent each 2.5 · 10 5
fluorophenylacrylates) and poly(pentafluorophenylmethacrylates)
may be valuable precursor polymers for
the synthesis of multifunctional polymers. Both materials
possess better solubility in organic solvents than
the corresponding poly(N-acryloxysuccinimide) esters
and they provide better reactivities.
References
s1/2/min k/s 1
s1/2/min
6 1.2 · 10 3
10
25 2.67 · 10 5
433
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