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Copolymerization of Tetraethyl Vinylidene Phosphonate
(B) with Vinyl Acetate (V)
Degasser; K-5004, Knauer) and used as a mobile phase at
the flow rate of 1.0 mL/min. Samples (concentration of poly-
mers: ꢃ7 mg/mL) were filtered through 0.2 lm pore size
membrane filters. Injection volumes of the sample solutions
were 100 lL. TriSEC software (Viscotek) was used to treat
the data.
Example for [B]0/[V]0 ¼ 1.06/1
1.04 g (3.47 ꢀ 10ꢂ3 mol) of B, 0.28 g (3.26 ꢀ 10ꢂ3 mol) of
V, and 0.026 g (1.6 ꢀ 10ꢂ4 mol) of azoisobutyronitrile
(AIBN) were placed in the glass ampoule and connected to
the vacuum line. The mixture was degassed six times by
freezing and melting under reduced pressure and finally
RESULTS AND DISCUSSIONS
ꢁ
sealed. The reaction mixture was heated at 80 C during the
Monomer Synthesis and Monomer NMR Spectra
Starting monomer: tetraethyl vinylidene phosphonate (B)
was prepared according to the known procedure9 in the fol-
lowing steps, shown in Scheme 1.
desired time. Copolymer was separated from the mixture by
ultrafiltration using membrane cut off 500.
Copolymerization of Tetraethyl Vinylidene Phosphonate
(B) with Acrylic Acid (A)
Monomer—bisphosphonate (B)—prepared according to
Scheme 1 was further purified by fractional distillation at
102 ꢁC/0.2 mmHg. The final purity was established by 1H,
13C, and 31P NMR. We are showing these spectra, as this is
the first time in the polymer literature and could be useful
for other researchers. Besides, particularly the 31P NMR
spectrum, indicate the level of B purity. The corresponding
assignments of peaks are given in the Figures 1–3.
Example for [B]0/[A]0 ¼ 2.28/1
Copolymerization of B with A and separation of the final
product were conducted in the same way as described for
copolymerization of B with V. The following amounts of
reagents were used: B ¼ 1.39 g (4.63 ꢀ 10ꢂ3 mol), A ¼
0.76 g (1.05 ꢀ 10ꢂ2 mol), and AIBN ¼ 0.04 g (2.44 ꢀ 10ꢂ3
mol).
Hydrolysis (dealkylation) of Copolymers
Hydrolyses of Copolymers B-V as well as B-A were Carried
Out in the Same Way
Example: 1.0 g of copolymer B-V was dissolved in 50 mL of
5 M hydrochloric acid. The mixture was refluxed during 5 h.
After that time, the acetic groups of V units were completely
removed and ethyl groups from bisphosphonate units were
hydrolyzed in 98% (according to 1H NMR spectra). Copoly-
mer was purified by ultrafiltration using membrane cut off
500.
The NMR spectra are simple and self-explanatory. It may,
however, be added that four lines from protons (a) at the
double bond in B are due to the geminal AB system. The
nonequivalence comes from cis- and trans-interactions with
P atoms. It is in agreement with a generated spectrum,
according to ACD/HNMR DB program (v. 6.12).
As it follows from the 31P NMR spectrum (Fig. 3), there is
approximately 2.0% of a major impurity with a chemical
shift at 19.5 ppm. Most probably this is the starting com-
pound 1, for which the known chemical shift is equal to 19.0
ppm.10 These values are close enough when difference in
conditions of the 31P NMR measurements are taken into the
account. There are also a few smaller signals; attempts to
remove completely the major and other impurities (at least
to the level of not being seen at the 31P NMR spectrum)
were not successful. The difference in the boiling points of 1
and B is too small and thermal stability of B does not permit
using some other preparative methods. Moreover, handling B
on the high vacuum line was also not possible, due to its
low vapor pressure.
Measurements
NMR Spectra
The 1H (200 MHz), 13C (50ꢁMHz), and 31P (81 MHz) NMR
spectra were recorded at 25 C on a Bruker AC200 spectrom-
eter. Standard acquisition parameters were applied. 13C{1H}
NMR spectra for quantitative estimation of various structures
in the product were recorded with inverse gated proton
decoupling and time delay between pulses equal to 30 s.
MALDI-TOF
Mass spectrometric measurements were performed using a
Voyager-Elite (PerSeptive Biosystems) time-of-flight instru-
ment equipped with a pulsed N2 laser (337 nm, 4-ns pulse
width) and time-delayed extraction ion source. An accelerat-
ing voltage of 20 kV was applied. Mass spectra were
recorded in the linear and reflector mode. The matrix, 2,5-
dihydroxybenzoic acid (DHB), Liþ was used.
Copolymerization of B was conducted with vinyl acetate (V)
and acrylic acid (A). Both in bulk. The choice of comonomers
Molar Mass Determination
SEC chromatography with triple detection was carried out
on the chromatograph Knauer K-501 high performance liquid
chromatography (HPLC) pump with LDC refractive index
(RI) detector and Viscotek T60A dual detector (right angle
laser light scattering, at k ¼ 670 nm and differential viscom-
eter). Three Suprema columns (30 þ 100 þ 3000 Å; 8 ꢀ
300 mm2; Polymer Service Standard) were used in a series.
Aqueous solution of NaN3 (0.1%) was degassed (4-Channel
SCHEME 1 Synthetic route of tetraethyl vinylidene phospho-
nate (B).
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 3030–3038
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