Acid-catalyzed oligomerization of aromatic ethers (Rolivsans) with terminal styrene and methacrylate groups

Article abstract of DOI:10.1134/S1070427207040210

Cationic mechanism of transformation of unsaturated aromatic monomers contained in Rolivsans into thermosetting aromatic oligoethers with increased molecular weight was analyzed. The composition and chemical structure of Rolivsans as influenced by catalytic systems with various donor-acceptor properties were studied.

Full text of DOI:10.1134/S1070427207040210

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 4, pp. 623 628.
Pleiades Publishing, Ltd., 2007.
Original Russian Text
pp. 637 642.
B.A. Zaitsev, G.I. Khromova, I.D. Shvabskaya, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 4,
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Acid-Catalyzed Oligomerization of Aromatic Ethers (Rolivsans)
with Terminal Styrene and Methacrylate Groups
B. A. Zaitsev, G. I. Khromova, and I. D. Shvabskaya
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received December 14, 2006
Abstract Cationic mechanism of transformation of unsaturated aromatic monomers contained in Rolivsans
into thermosetting aromatic oligoethers with increased molecular weight was analyzed. The composition and
chemical structure of Rolivsans as influenced by catalytic systems with various donor-acceptor properties
were studied.
DOI: 10.1134/S1070427207040210
Rolivsans are low-viscosity thermosetting resins of
new type, formed by reactions of secondary aromatic
diols, such as di-[4-(1-hydroxyethyl)phenyl] ether (I)
These formulations yield thermosetting polymers with
controlled network density and can be used to prepare
heat-resistant coatings and binders [11 12].
H3C
OH
EXPERIMENTAL
,
O
HO
CH3
The IR spectra were recorded on a Specord 75-IR
device (thin films or CHCl3 solutions). The exclu-
sion liquid chromatography (ELC) of Rolivsans was
performed on a GPC Waters chromatograph equipped
with Ultrastyrogel (500 ) columns at 20 C, using
toluene as eluent. The number-average molecular
weights of oligomers Mn were determined with a Hi-
tachi Perkin Elmer 115 vapor osmometer. The sam-
ple unsaturation was studied on a ADS-4 ozonizer at
0 C (CCl4 solvent). The viscosity and viscoelastic
properties of Rolivsan MV-1 and of the products of
its oligomerization were studied on a PIRSP-1 rheo-
goniometer with a cone-plate working unit (cone di-
ameter 2 cm, cone angle 1 ). The velocity gradients
with methacrylic acid catalyzed by strong acids [1 5].
Their thermal treatment yields heat-resistant glassy
network polymers [6 10] which are used in (micro)-
electronics and electrical engineering.
It has been found previously that Rolivsans contain
the following monomer aromatic ethers: 4,4 CH2=
CH PhOPh CH=CH2 (M1), 4,4 CH2=CH PhOPh
CH(CH3)OCO C(CH3)=CH2 (M2), 4,4 CH2=C(CH3)
COO(CH3)CH PhOPh CH(CH3)OCO C(CH3)=CH2
(M3), and oligoethers (OL) with terminal styrene-like
and methacrylate groups.
The monomer-oligomer composition and properties
of Rolivsans can be varied in a wide range depending
on the synthesis conditions [3 5]. Low-viscosity com-
2
1
were varied from 2 10 to 4 102 s , and circular
2
1
frequencies, from 2 10 to 10 s .
1
positions (500 1500 mPa s ) containing no solvents
Samples of Rolivsan MV-1 (series I and II) were
prepared in accordance with TU (Technical Specifica-
tions) 6-36-57-0 91 by condensation of di-[4-(1-hy-
droxyethyl)phenyl] ether (I) with methacrylic acid in
the presence of p-toluenesulfonic acid monohydrate
(TSA-M) [3 5]; their compositions and properties
are listed in Table 1.
and predominantly consisting of monomers M1, M2,
and M3 and small amounts (15 30%) of low-molec-
ular-weight unsaturated oligomers (dimers and tri-
mers) can be used as heat-resistant insulating cast-
ing and impregnating compounds.
In this study, we examined the formation of mono-
mer oligomer formulations with molecular weight of
components increased due to higher content of aro-
matic oligoethers with terminal unsaturated groups.
Oligomer no. 1 was isolated from the initial reac-
tion mixture (Rolivsan VM-1, series I) after its dilu-
tion with chloroform and subsequent precipitation
623

624
ZAITSEV et al.
Table 1. Properties of Rolivsan MV-1*
Composition, wt %
Series
d20
,
g cm
25
>C=C<,
,
Mn
n2D0
140, h
1
1
3
mol g
mPa s
M1
M2
M3
OL
I
II
13
13
31
26
23
18
33
43
0.0058
0.0056
400
420
1.585
1.590
1500
1800
1.09
1.09
1.5
2.5
*
>C=C< is the degree of unsaturation of oligomer, mole of double bonds per gram of product; M , number-average molecular
n
140
weight; and
, time of gelation at 140 C.
with ethanol. The efficiency of oligomer isolation was
monitored chromatographically (ELC) by the absence
of peaks belonging to monomers M1, M2, and M3
in the product isolated. After a fourfold reprecipita-
tion, the oligomer contained insignificant amounts (2
4%) of the initial monomers; the monomer-free prod-
uct was obtained only after an eightfold reprecipita-
tion. The properties of oligomer no. 1 were as fol-
lows: mp 80 C, Mn 1650, content of dimers with
Mn 500 (ELC data) 2 4%; found (%): C 79.6, H 6.5.
soluble in acetone and chloroform, Mn 1000. Oligo-
mer no. 3 isolated by the similar procedure contained
(wt %): 1 M1, 2 M2, 4 M3, and 93 OL; Mn 1220.
To prepare oligomer nos. 4 and 5, CS B (0.80 g)
was added with stirring to Rolivsan MV-1, series I
(99.20 g), and then one portion (50 g) of the homo-
genized composition was heated at 80 C for 2 h
10 min, and another portion (50 g) was stored at 20 C
for 21 days. The compositions of the resulting prod-
ucts were analyzed as described above. The composi-
tion of the sample containing OL no. 4 before isola-
tion was as follows, wt %: 3 M1, 6 M2, 4 M3, and
87 OL. No monomers were found in OL no. 4 after
an eightfold reprecipitation; mp 90 110 C; found (%):
C 79.60, H 6.70; 0.0030 mol of double bonds per gram
of product, Mn 3375. The composition of the sample
containing OL no. 5 before isolation was as follows,
wt %: 2 M1, 5 M2, 3 M3, and 90 OL (no. 5). After
precipitation and drying, we obtained oligomer no. 5 as
a light brown resin with mp 95 115 C. After reprecip-
itation in the presence of hydroquinone (1%), the melt-
ing point of OL no. 5 increased to 125 135 C; found
(%): C 81.20, H 6.70; 0.0037 mol of double bonds per
gram of product, Mn 2700.
The degree of unsaturation of oligomer no. 1 was
0.37 mole of double bonds per 100 g of the product.
Two catalytic systems (CS A and CS B) were tested
in oligomerization of Rolivsans catalyzed by TSA-M.
Catalytic system A [solution of TSA-M (19.80 wt %)
in polyphenyl ether (PPE, m-C30H22O4, analytically
pure grade, 5F 4E brand, mp 28 C] was prepared
by through trituration of TSA-M (8.7841 g, 99%
main compound) with liquid PPE (35.1365 g). Cat-
alytic system B is a glycerol-like solution of TSA-M
(23.63 wt %) in Cellosolve.
The acid-catalyzed oligomerization was performed
by thorough mixing of Rolivsan with CS and storage
of the homogenized composition at room tempera-
ture or at elevated temperature for a given time; then
the composition and properties of the resulting com-
pound were analyzed (Table 2).
As shown previously, cleavage of esters (such as
methacrylates) [1 5] and cationic addition polymer-
ization of divinyl aromatic monomers with proton
transfer [13 18] are of particular importance in cat-
alyzed reactions of aromatic ethers containing sec-
ondary alcohol groups with carboxylic acids, such as
methacrylic acid (MAA). The cleavage of dimethac-
rylate of aromatic diol (I), which is the main compo-
nent of Rolivsan M3, and subsequent dimerization of
the resulting vinyl aromatic monomer M2 are typical
examples of such transformations [19]:
To prepare oligomer nos. 2 and 3, CS A (1.05 g)
was added with stirring to Rolivsan MV-1, series I
(98.95 g), the homogenized composition was heated
at 80 c for 1 h 35 min, and a sample was taken for
isolation of OL no. 2. The process was continued for
2 h 40 min, and OL no. 3 was isolated from the re-
action mixture. The product compositions were stud-
ied by ELC and IR spectroscopy. The composition of
the sample containing OL no. 2 before isolation was
as follows, wt %: 9 M1, 18 M2, 17 M3, and 56 OL.
The sample was diluted with chloroform; the oligomer
was precipitated with ethanol and dried at 20 C at
reduced pressure. The precipitated product contained
(wt %): 3 M1, 4 M2, 6 M3, and 87 OL no. 2, it is
H3C O H3C
CH3 O CH3
H2C C C O HCPhOPhCH O C C CH2
M3
H3C
O CH3
H+
H2C HC PhOPhCH O C C CH2,
M2
MAA
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007

ACID-CATALYZED OLIGOMERIZATION OF AROMATIC ETHERS
H3C O CH3 H3C O H3C CH3 O CH3
625
H3C
H+
H2C HC PhOPhCH O C C CH2
M2
H2C C C O HCPhOPhCH CH CH PhOPhCHO C C CH2
Unsaturated dimer
These data suggest that the intensified cleavage
of methacrylates (M2, M3, and related compounds:
dimers, trimers, etc.) and cationic addition polymer-
ization of vinyl and divinyl aromatic compounds can
yield linear unsaturated oligomers of the following
type:
H3C O
CH3
CH3
CH3
CH3 O CH3
H2C C CO HCPhOPh CH (CH CH PhOPh CH)n CH CH PhOPh CH OC C CH2
Oligomerization was studied using two series of
Rolivsans with different compositions and properties
(Table 1). It should be noted that homogenization
(dissolution) of TSA-M powder by direct stirring with
a resin was rather difficult, because a high local con-
centration of the catalyst sharply accelerates oligo-
merization in situ and causes encapsulation of the
TSA-M particles with the oligomer formed. To im-
prove the homogenization conditions, we suggested
two catalytic systems (CS A and CS B) based on PPE
and Cellosolve solvents with different donor-acceptor
properties.
urated structures (e.g., 1-methyl-3-phenylindan), along
with the main structure of 1,3-diphenyl-1-butene
(trans) type, in the course of acid-catalyzed dimeri-
zation of styrene. We also cannot rule out the side
The conditions of the acid-catalyzed process and
the composition and characteristics of the oligomer-
ized compositions and oligomers are listed in Table 2.
The oligomers were isolated by dilution of the com-
positions with chloroform and subsequent precipitation
with ethanol. Changes in the monomer-oligomer com-
position under different conditions of oligomerization
of Rolivsans were studied by ELC (Fig. 1), IR spec-
troscopy (Figs. 2, 3), and rheokinetics (Fig. 4).
Fig. 1. Gel chromatograms of the (1) monomer oligomer
composition Rolivsan MV-1 (series I), (2) composition
oligomerized by heating at 80 C for 1 h 35 min in the pres-
ence of CS A (content of TSA-M 1.19 10 M), and
(3) oligomer no. 1 reprecipitated eight times to remove
2
monomers. (M ) Molecular weight of oligomers.
n
Gel chromatograms (Fig. 1) show that the content
of the monomers decreases with time, with a simul-
taneous increase in the content of oligomers (espe-
cially, dimers and trimers) with number-average mo-
lecular weights of 500 800. Oligomerization was per-
formed at a fixed content of catalysts both at 20 2 C
and at elevated temperatures. With the temperature
increasing from 60 to 80 C, the process rate grows
by more than a factor of 4, which corresponds to
the known empirical van’t Hoff rule.
It should be noted that the characteristics of unsat-
1
uration, content of carbon (Table 2), and H NMR
spectra are not fully consistent with the chemical
structure of the oligomers, given above. The calcu-
lated degrees of unsaturation and carbon content are
slightly higher than the experimental values. This is
probably due to formation of small amounts of sat-
Fig. 2. IR spectra of the (1) monomer oligomer compo-
sition Rolivsan MV-1 (series I) and (2) oligomer no. 3.
(T) Transmission and ( ) wavenumber; the same for Fig. 3.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007

626
ZAITSEV et al.
Table 2. Composition and properties of the reaction mixtures before and after oligomerization of Rolivsan MV-1 (series I)
Sam-
ple
no.
Composition, wt %
M1 M2 M3 OL
Found, %
cTSA M
102, M
Composition
(oligomer)
>C=C<,
mol g
T,
C
CS
Mn
, h
mp, C
1
C
H
1
2
3
4
5
6
7
8
9
Initial
13 31 23
33 0.0058 79.1 6.5
91
100 0.0037 79.6 6.5 1650
420
Oligomer no. 1*
Oligomer no. 1**
Oligomerized
The same
1
0
4
4
9
3
1
4
4
3
2
0
6
0
80
(A)
(A)
(A)
(A)
(A)
(B)
(B)
(B)
2.26
2.26
1.19
1.19
1.19
2.02
2.02
1.08
1.08
1.08
20 168
12 12
8
18 17
4
2
8
11
6
72
81
56
87
93
81
76
87
80
80
80
80
80
60
1.2
7
1.6
1.6
2.7
0.45
1.2
Oligomer no. 2
Oligomer no. 3
Oligomerized
6
4
7
9
4
1000
1220
10 The same
11
20 504
20 504
12 Oligomer no. 4** (B)
100 0.0030 79.6 6.7 3400 90 110
90
13 Oligomerized
(B)
80
2.2
2
5
3
14 Oligomer no. 5
(B)
1.08
80
2.2
0.0037 81.2 6.7 2700 125 135
*
**
After fourfold reprecipitation;
After eightfold reprecipitation.
reactions of oxidation on heating of unsaturated com-
pounds in the presence of strong acids and of an addi-
tion of an aromatic solvent (toluene) and an inhib-
itor of the radical polymerization (hydroquinone)
to the internal double bonds of the oligomer of
Ar CH(CH3) CH=CH Ar type [16].
yl and methylene groups at 2960, 2925, 2870, and
1
1
2850 cm , methine group at 2900 cm , and strong
bands of the stretching vibrations of the carbonyl
1
group in methacrylates at 1715 cm and of aromatic
1
ethers at 1240 cm [4]. The IR spectrum of oligomer
no. 3 (Fig. 2 spectrum 2) isolated from the oligomer-
ized composition (Table 2) shows the expected de-
crease in the intensity of the bands of the carbonyl
Similarly to the gel chromatograms, the IR spec-
tra strongly change in the course of oligomerization.
The initial IR spectrum of Rolivsan (Fig. 2, spec-
trum 1) exhibits the absorption bands of the unsatu-
rated and aromatic groups at 3080, 3060, 3030, 2975,
1
groups at 1715 cm and of out-of-plane bending vib-
1
rations H C= at 902 and 940 cm belonging to
the p CH2=CH Ph O Ph and CH2=C(CH3)COO
groups, respectively. Simultaneously, the band of
H C= out-of-plane bending vibrations of the CH=CH
(trans) groups, whose concentration increases in the
course of the stepwise dimerization reactions (cationic
addition polymerization) of vinyl aromatic compounds
[4, 19], grows in intensity.
1
1630, 1600, 1500, 985, 965, 940, and 905 cm , meth-
Oligomerization was also performed at higher tem-
peratures (110 180 C), at which the above reactions
of addition polymerization are accompanied by cross-
linking and cyclization. With heating, the intensity
of the absorption bands of the terminal unsaturated
1
groups at 1630, 940, and 905 cm strongly decreases
(Fig. 3, spectra 2, 3) owing to their consumption in
copolymerization.
Fig. 3. IR spectra (20 C) of the monomer oligomer com-
Another process of the cationic type, namely, cleav-
age of methacrylates to form vinyl aromatic com-
pounds, methacrylic acid, and its copolymers, and also
cationic addition polymerization of divinyl aromatic
compounds occur simultaneously in the course of
position Rolivsan MV-1 (series I) after its heating with
CS B at a TSA-M content of 2.22 10 M. (1) 20 C
(initial composition); (2) heated from 20 to 110 C over
a period of 1 h and kept at 110 C for 2 h; (3) the same plus
heating to 130 C over a period of 2 h.
2
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007

ACID-CATALYZED OLIGOMERIZATION OF AROMATIC ETHERS
627
oligomerization. With heating, the band of the stretch-
ing vibrations of the carbonyl group >C=O of the meth-
Table 3. Gelation time of Rolivsan MV-1 (series I) as
influenced by the conditions of the acid-catalyzed oligo-
merization
1
acrylic ester at 1715 cm splits, and a new band of
1
the MAA carboxy group appears at 1700 1685 cm
(Fig. 3, spectra 2, 3) [19].
C,
wt %
cTSA-M 102,
T,
C
r
g
CS
M
h
Since the viscosity and gelation time (viability) are
the most important process characteristics of the ther-
mosetting plastics, which determine the possibility of
their processing into a polymeric material, we studied
the rheological properties of Rolivsans in the course
of their catalytic oligomerization.
0.00
1.00
2.00
3.30
2.00
0.80
1.15
1.50
1.80
15.0
1.50
0.80
1.50
15.0
0.00
1.14
2.28
3.76
2.28
1.08
1.55
2.02
2.42
20.2
2.02
1.08
2.02
20.2
140
80
80
80
60
80
80
80
80
80
60
60
20
20
1.3
2.5
0.75
0.5
3.0
1.5
3.5
1.0
0.7
>6.0
1.3
0.6
0.45
0.37
0.08
1.5
A
A
A
A
B
B
B
B
B
B
B
B
B
1.0
As can be seen from Fig. 4, each curve can be di-
vided into two portions: that with comparatively slow-
ly increasing viscosity, corresponding to the initial
stage of the process, and that with rapidly increasing
viscosity at the final stage of oligomerization (gela-
tion). The intersection point of the tangents to these
0.45
0.23
0.17
1.4
2.0
>5.0
72
>48
portions characterizes the gelation onset time
.
Table 3 we present the comparative data on
anrd
r
gelation time g, determined visually from the loss
of fluidity.
is higher owing to the lone electron pairs of the ox-
ygen atoms.
The fact that
appreciably exceeds can be ex-
g
plained as follows: The rheokinetic merthod allows
determination of the start of formation of 3D struc-
tures (microgel) from a sharp increase in the viscosity
more precisely than does the visual determination of
the fluidity loss observed at higher microgel concen-
trations.
At a CS A content decreased by a factor of 2,
the rate of viscosity growth can be preserved by rais-
Comparison of curves 2 and 4 (Fig. 4) shows that
the rate of viscosity growth owing to oligomerization
at 60 C is significantly higher in the experiment
with addition of CS B (1.5 wt %), although the con-
2
centration of TSA-M (2.02 10 M) is lower in
this case in this case than that in the experiment with
addition of CS A (2 wt %) and TSA-M concentration
2
of 2.26 10 M. The effect of the donor-acceptor
Fig. 4. Viscosity
time t of oligomerization with addition of (1, 3, 4) CS A
and (2) CS B. (wt %)/c , M: (1, 4) 2/2.26,
(2) 1.5/2.02, and (3) 1/1.14. Temperature, C: (1, 3) 80
and (2, 4) 60.
of Rolivsan MV-1 (series I) vs.
complexes PPE TSA M and Cellosolve TSA M on
the acidity of CS A and CS B and, thus, on their cat-
alytic activity in the course of the Rolivsan oligomer-
ization is illustrated in Fig. 5.
c
CS
TSA-M
As can be seen, CS B containing Cellosolve is more
reactive than CS A, other oligomerization conditions
being equal. This is probably due to the higher basici-
ty of Cellosolve as compared to PPE in which the lone
electron pair of the ether oxygen is delocalized and
interacts with the electron-acceptor phenyl groups,
whereas in Cellosolve it is localized and interacts
with the electron-donor alkyl groups. Thus, the elec-
tron-acceptor properties of PPE and Cellosolve inter-
acting with TSA-M are strongly different. The elec-
tron density on the protonation centers in Cellosolve
Fig. 5. Gelation time
80 C vs. the TSA-M concentration c. Catalytic system:
(1) A and (2) B.
of Rolivsan MV-1 (series I) at
r
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007

628
ZAITSEV et al.
ing temperature from 60 to 80 C (Fig. 3, curves 3, 4)
Zh. Prikl. Khim., 2003, vol. 76, no. 4, pp. 658 662.
which is also consistent with the van’t Hoff rule.
5. Zaitsev, B.A., Polyamides and High-Performance Poly-
mers, STEPI 7 Book, Sillion, B. and Abadie, M.J.M.,
Eds., Montpellier, May 2006, pp. 124 134.
CONCLUSIONS
6. Zaitsev, B.A., Khramova, G.I., and Dantsig, L.L.,
(1) A procedure was developed for altering the
composition and properties of Rolivsans by conver-
sion of the monomer components [4,4 -divinyldiphen-
yl ether, 4-vinyl-4 -(1-methacryloyloxyethyl)diphenyl
ether, and bis[4-(1-methacryloyloxyethyl)phenyl] eth-
er] into linear unsaturated aromatic oligoethers with
the terminal methacrylate groups .
Plast. Massy, 1981, no. 9, pp. 12 13.
7. Zaitsev, B.A., Khramova, G.I., Tsygankova, T.S.,
et al., Mekhn. Kompoz. Mater., 1982, no. 5,
pp. 775 778.
8. Zaitsev, B.A., Khramova, G.I., Tsygankova, T.S.,
et al., Plast. Massy, 2003, no. 10, pp. 23 25.
9. Zaitsev, B.A. and Shvabskaya, I.D., Polyamides and
High Performance Polymers, STEPI 7 Book, Sil-
lion, B. and Abadie, M.J.M., Eds., Montpellier, May
2006, pp. 194 204.
10. Zaitsev, B.A. and Shvabskaya, I.D., Polyamides and
High Performance Polymers, STEPI 7 Book, Sil-
lion, B. and Abadie, M.J.M., Eds., Montpellier, May
2006, pp. 247 253.
(2) Under the conditions of the homogeneous cat-
alytic oligomerization of Rolivsans at moderate tem-
peratures (60 80 C), successive-parallel reactions of
cleavage of methacrylates, formation of (di)vinylar-
omatic compounds, and addition polymerization of
the latter with the proton transfer occur in 1 3 h.
(3) The catalytic systems with different donor-
acceptor properties were developed, allowing varia-
tion of the rate Rolivsan oligomerization in a wide
range.
11. Zaitsev, B.A., Tsygankova, T.S., Garkavi, S.L., et al.,
Mekh. Kompoz. Mater., 1988, no. 4, pp. 579 584.
12. Lukasov, S.V., Zaitsev, B.A., Kenunen, I.V., et al.,
Mekh. Kompoz. Mater., 1988, no. 5, pp. 771 778.
13. Zaitsev, B.A. and Kiseleva, R.F., Vysokomol. Soedin.,
Ser. A, 1981, vol. 23, no. 8, pp. 1783 1790.
14. Zaitsev, B.A. and Kiseleva, R.F., Acta Polym., 1983,
(4) Low-melting oligoethers with the terminal
methacrylate groups containing unsaturated and di-
phenyl oxide groups in the backbone were prepared
and characterized.
vol. 36, no. 10, pp. 527 530.
15. Zaitsev, B.A., Kiseleva, R.F., Denisov, V.M., et al.,
Vysokomol. Soedin., Ser. A, 1984, vol. 26, no. 8,
pp. 1602 1609.
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007