Supporting information for:
Allyl sulfides and α-substituted acrylates as addition-fragmentation chain
transfer agents for methacrylate polymer networks
Samuel Clark Ligon,1, 2 Konstanze Seidler,1, 2 Christian Gorsche,1, 2 Markus Griesser,1, 2
Norbert Moszner,2,3 Robert Liska*,1, 2
1
Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163/MC, A1060 Vienna, Austria
2
Christian Doppler Laboratory for Digital and Restorative Dentistry, Getreidemarkt 9, A-1060 Vienna,
Austria
3
Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
Correspondence to: R. Liska (E-mail: robert.liska@tuwien.ac.at)
1
Table of Contents
Synthesis of 2-(allylthio)ethanol (1)1 ............................................................................................. 3
Synthesis of 5-dodecylthio-1,3-pentadiene (2) ............................................................................. 3
Synthesis of α-(n-dodecylthiomethyl)styrene (3) ......................................................................... 3
Synthesis of ethyl 2-((n-dodecylthio)methyl)acrylate (4) ............................................................. 4
Synthesis of ethyl-2-((phenylsulfonyl)methyl)acrylate (5) ........................................................... 4
Synthesis of ethyl 2-((diethoxyphosphinyl)methyl)acrylate (6) ................................................... 5
Synthesis of diethyl 2.2’-(thiobis(methylene))diacrylate (7) ........................................................ 5
Figure S 1. Photo-DSC for BMA neat and with 0.20 double bond equivalents of CTA. .................. 6
Figure S 2. Photo-DSC results for the polymerization of UDMA:D3MA neat and with 0.20 double
bond equivalents of different α-acrylate CTAs. Units of the vertical axis are dependent on the
measurement: J/g for heat of polymerization (ΔHp) and seconds (s) for the time to reach 95%
completion (t95%). ............................................................................................................................ 6
Table S 1. Initial rate of polymerization of UDMA:D3MA alone and with 0.20 double bond
equivalents of different CTAs. Values determined from the average slope for the first five
seconds recorded by RTIR (see Figures 5 and 8). ........................................................................... 7
Figure S 3. Monitoring loss modulus (G’’) with change in monomer conversion for the
polymerization of UDMA:D3MA neat and with 0.20 double bond equivalents of CTA. ................ 7
Figure S 4. Monitoring loss factor (tan δ) with change in monomer conversion for the
polymerization of UDMA:D3MA neat and with 0.20 double bond equivalents of CTA. ................ 8
Figure S 5. Monitoring of glass transition by DMTA of UDMA:D3MA polymerized neat and with
0.20 double bond equivalents of CTA additive. .............................................................................. 9
SUPPORTING INFORMATION REFERENCES ................................................................................... 9
2
Synthesis of 2-(allylthio)ethanol (1)1
2-Mercaptoethanol (52.88 g, 677.8 mmol) was added to the solution of sodium (62.26 g, 551.5
mmol) in 600 mL of anhydrous ethanol. Allyl bromide (87.04 g, 719.5 mmol) was added
dropwise and the mixture was refluxed for 16 h. Afterwards, the precipitated solid was filtered
and washed thoroughly with CH2Cl2 and the mother liquor collected. The solvent was
concentrated to dryness. The organic solution was extracted with HCl (0.1 M, 2 x 50 mL). The
aqueous layer was extracted with CH2Cl2 (2 x 50 mL). The organic layer was dried over Na2SO4,
filtered and concentrated to give the crude product. After addition of 2,6-di-(t-butyl)-4methylphenol (0.123 g, 0.558 mmol) as inhibitor, the product was purified by distillation under
reduced pressure (76-77 °C, 10 mbar) with a yield of 84% 1H NMR (200 MHz, CDCl3, 𝛿, ppm):
2.23 (s, 1H; COH), 2.70-2.63 (t, 2H; SCH2CH2), 3.14-3.18 (dt, 2H; CHCH2S), 3.72-3.66 (t, 2H;
CH2OH), 5.14-5.05 (m, 1H; CH2=CH), 5.87-5.70 (m, 1H; CH2=CH).13C NMR (50.3 MHz, CDCl3, 𝛿,
ppm): 33.5 (CH-CH2-S), 34.1 (S-CH2-CH2), 60.1 (CH2-OH), 117.4 (CH2=CH), 134.0 (CH2=CH). MS
(m/z): calcd.118.20, found: 117.99
Synthesis of 5-dodecylthio-1,3-pentadiene (2)
Synthesis is modified from the procedure of Nair et al.2 Freshly distilled n-dodecylthiol (1.38 g,
6.8 mmol) and triethylamine (0.69 g., 6.8 mmol) were dissolved in ether and stirred under
argon. To this was added dropwise a solution of 5-bromo-1,3-pentadiene (1.00 g., 6.8 mmol) in
8 mL ether. The mixture was stirred at room temperature for 90 min. The white
triethylammonium bromide precipitate was removed by filtration and the remaining product
was washed with water and the organics dried with Na2SO4. Concentration by rotary
evaporator provided the product as a colourless oil in 81% yield. TLC (Rf): 0.44 (PE/CH2Cl2 20:1).
1H NMR (200 MHz, CDCl , δ, ppm): 0.88 (t, J = 6.46 Hz, 3H; -CH -CH ), 1.04-1.75 (m, 20H; -CH 3
2
3
2
(CH2)10-CH3), 2.44 (t, J = 7.23 Hz, 2H; -S-CH2-(CH2)10-), 3.16 (d, J = 7.44 Hz, 2H; =CH-CH2-S-), 5.05
(dd, J = 10.37 Hz, 1H; J = 1.57 Hz, H2C=CH-), 5.17 (dd, J = 16.4 Hz, J = 1.57 Hz, 1H; H2C=CH-), 5.67
(qi, J=7.48 Hz, 1H; =CH-CH=CH-), 6.01-6.20 (m, 1H; -CH=CH-CH2-), 6.22-6.46 (ddd, J = 36.9 Hz, J =
16.8 Hz, J=3.33 Hz, 1H; CH2=CH-CH=).
Synthesis of α-(n-dodecylthiomethyl)styrene (3)
Synthesis is based on the procedure of Mejis et al.3 Potassium carbonate (0.28 g, 2.0 mmol), α(bromomethyl)styrene (0.36 g, 1 mmol), and n-dodecylthiol (0.40 g, 2.01 mmol) were added to
a round bottom flask with methanol and stirred under argon at room temperature. Progress of
the reaction was monitored by TLC. After 24 h, first deionized water was added to dissolve any
salt. The organics were extracted with ether (3x) and dried with Na2SO4 before concentrating
on the rotary evaporator. The product was further purified by MPLC and collected in 53% yield.
TLC (Rf): 0.29 (PE). 1H NMR (200 MHz, CDCl3, δ, ppm): 0.88 (t, J = 6.36 Hz, 3H; -CH2-CH3), 1.091.68 (m, 20H; -CH2-C10H20-CH3), 2.46 (t, J = 7.34 Hz, 2H; -S-CH2-C11H23), 3.59 (d, J = 0.78 Hz, 2H;
3
=C(C6H5)-CH2-S-), 5.17-5.23 (m, 1H; H2C=C(C6H5)-), 5.43 (d, J = 1.78 Hz, 1H; H2C=C(C6H5)-), 7.277.53 (m, 5H; H2C=C(C6H5)-CH2-).
Synthesis of ethyl 2-((n-dodecylthio)methyl)acrylate (4)
Synthesis is based on modification of the procedure from Reddy et al. 4 Ethyl-2bromoethylacrylate (1.52 g, 7.9 mmol), freshly distilled dodecylthiol (1.58 g, 7.8 mmol), and
triethylamine (1.10 g, 10.9 mmol) were added to THF (19 mL) in a round bottom flask fitted
with a reflux condenser. This resulted in a fine white precipitate. The mixture was stirred at
room temperature and based on TLC stopped after 21 h. The reaction mixture was poured into
water and extracted three times with petroleum ether before drying with Na2SO4 and
concentrating via rotary evaporator. The product was collected in sufficient purity as a slightly
yellow oil in 95% yield. TLC (Rf): 0.46 (PE/EtOAc 12:1). 1H NMR (200 MHz, CDCl3, δ, ppm): 0.85
(t, J = 6.46 Hz, 3H; -C10H20-CH3), 1.10-1.65 (m, 20H; -CH2-C10H20-CH3 and -O-CH2-CH3), 2.42 (t, J =
7.24 Hz, 2H; -S-CH2-C11H23), 3.35 (s, 2H; =C(COOC2H5)-CH2-S-), 4.21 (q, J = 7.11 Hz, 2H; -O-CH2CH3), 5.61 (d, J = 1.17 Hz, 1H; H2C=C(COOC2H5)-), 6.17 (d, J = 1.98 Hz, 1H; H2C=C(COOC2H5)-). 13C
NMR (50.3 MHz, CDCl3, δ, ppm): 14.19 (-C11H22-CH3), 14.25 (-CH2-CH3), 22.77 (-CH2-CH2-CH3),
28.99-29.73 (-CH2-C8H16-C3H7), 31.70 (-C9H18-CH2-C2H5), 32.00 (-C(=CH2)-CH2-S-), 32.79 (-S-CH2C11H23), 60.99 (-O-CH2-CH3), 125.46 (H2C=C(COOEt)-), 137.40 (-H2C-C(=CH2)-C(=O)-), 166.29 (C(=CH2)-COOEt). GC-MS (m/z): 73, 99, 114, 145, 201, 314.
Synthesis of ethyl-2-((phenylsulfonyl)methyl)acrylate (5)
Synthesis is based on a modified procedure from Zink et al.5 Ethyl-2-bromoethylacrylate (8.36 g,
43.3 mmol), sodium-p-tosylate (8.48 g, 47.6 mmol), and PEG400 (0.89 g, 0.05 mmol) were
added to THF (70 mL) in a round bottom flask fitted with a reflux condenser. The reaction
mixture was stirred under argon and refluxed while monitoring periodically by TLC (PE/EtOAc
3:1). After 3 h, the reaction was cooled and washed with water. The product was extracted
three times with ether, dried with Na2SO4 and concentrated by rotary evaporator. The product
was initially purified by flash chromatography. Recrystallization was performed in cold ether to
give the product as a colorless solid in 90% yield. Mp: 46.9 °C. TLC (Rf): 0.53 (PE/EtOAc 3:1). 1H
NMR (200 MHz, CDCl3, δ, ppm): 1.17 (t, J = 7.15 Hz, 3H; -CH2-CH3), 2.43 (s, 3H; -Ar-CH3), 4.02 (q,
J = 7.11 Hz, 2H; -O-CH2-CH3), 4.14 (s, 2H; =C(COOC2H5)-CH2-SO2-), 5.89 (s, 1H; H2C=C(COOC2H5)-),
6.50 (s, 1H; H2C=C(COOC2H5)-), 7.32 (d, J = 8.21 Hz, 2H; Ar-H3,5), 7.73 (d, J = 8.21 Hz, 2H; Ar-H2,6).
13C NMR (50.3 MHz, CDCl , δ, ppm): 13.91 (-CH -CH ), 21.53 (-Ar-CH ), 57.48 (-O-CH -CH ), 61.34
3
2
3
3
2
3
Ar
Ar
Ar
(-C(=CH2)-CH2-SO2-), 128.68 (-C -(CH)2 -(CH)2 -), 129.22 (H2C=C(COOEt)-), 129.59 (-(CH)2Ar (CH)2Ar-CAr), 133.07 (-SO2-CAr-(CH)2Ar-), 135.37 (-H2C-C(=CH2)-C(=O)-), 144.83 (-(CH)2Ar-CAr-CH3),
164.73 (-C(=CH2)-COOEt). GC-MS (m/z): 65, 91, 155, 204, 223.
4
Synthesis of ethyl 2-((diethoxyphosphinyl)methyl)acrylate (6)
Synthesis is based on minor modification of the procedure from Mejis et al.3 Ethyl-2bromoethylacrylate (1.51 g, 7.8 mmol) and triethyl phosphite (1.30 g, 7.81 mmol) were placed
in a round bottom flask fitted with a reflux condenser. The reaction mixture was refluxed under
argon for 7 h and then stirred for an additional 12 h at room temperature. The mixture was
transferred to pear-shaped flask and subjected to vacuum (5 mbar) to remove ethyl bromide
(b.p. = 38°C at 1.013 bar). Purification was performed by MPLC using PE/EtOAc (3:2) as solvent
to give the product as a colorless oil in 82% yield. TLC (Rf): 0.13 (PE/EtOAc 3:2). 1H NMR (200
MHz, CDCl3, δ, ppm): 0.92-1.34 (m, 3x, 9H; -CH2-CH3), 2.77 (d, J = 0.78 Hz, 1H; =C(COOEt)-CH2PO(OEt)2), 2.87 (d, J = 0.78 Hz, 1H; =C(COOEt)-CH2-PO(OEt)2), 3.87-4.18 (m,3x, 6H; -O-CH2-CH3),
5.73 (dd, J = 5.46 Hz, J = 0.78 Hz, 1H; H2C=C(COOEt)-), 6.22 (dd, J = 5.66 Hz, J = 0.58 Hz, 1H;
H2C=C(COOEt)-). 13C NMR (50.3 MHz, CDCl3, δ, ppm): 13.92 (-CH2-CH3), 16.03 (-PO(-O-CH2-CH3)O-CH2-CH3), 16.15 (-PO(-O-CH2-CH3)-O-CH2-CH3), 28.23 (d, 1JCP = 139.96 Hz, -C(=CH2)-CH2-PO-),
60.91 (-O-CH2-CH3), 61.73 (-PO(-O-CH2-CH3)-O-CH2-CH3), 61.86 (-PO(-O-CH2-CH3)-O-CH2-CH3),
128.20 (d, 3JCP = 9.84 Hz, H2C=C(COOEt)-), 131.35 (d, 2JCP = 10.03 Hz, -H2C-C(=CH2)-COOEt),
165.76 (-C(=CH2)-COOEt). GC-MS (m/z): 68, 99, 113, 137, 177, 205, 250.
Synthesis of diethyl 2.2’-(thiobis(methylene))diacrylate (7)
Synthesis is modified from the procedure of Tsuda.6 Ethyl-2-bromoethylacrylate (10.01 g, 51.8
mmol) and freshly recrystallized sodium sulfide (5.93 g, 24.7 mmol) were added to deionized
water (10 mL) in a round bottom flask. The mixture was stirred at room temperature for 24 h,
at which point TLC indicated completion. Additional DI water was given to the reaction mixture
and the organic product was extracted three times with PE. This was washed again with brine
and dried with Na2SO4. Purification was performed by flash chromatography with PE/EtOAc
(6:1) to provide the product in 32% yield. TLC (Rf): 0.67 (PE/EtOAc 3:1). 1H NMR (200 MHz,
CDCl3, δ, ppm): 1.30 (t, J = 7.14 Hz, 2x, 3H; -CH2-CH3), 3.33 (d, J = 0.58 Hz, 2x, 2H; =C(COOC2H5)CH2-S-), 4.23 (q, J = 7.10 Hz, 2H; -O-CH2-CH3), 5.66 (d, J = 0.98 Hz, 2x, 1H; H2C=C(COOC2H5)-),
6.22 (d, J = 0.98 Hz, 2x, 1H; H2C=C(COOC2H5)-). 13C NMR (50.3 MHz, CDCl3, δ, ppm): 14.10 (2x CH2-CH3), 31.98 (2x -C(=CH2)-CH2-S-), 60.89 (2x -O-CH2-CH3), 125.90 (2x H2C=C(COOEt)-), 136.96
(2x -H2C-C(=CH2)-C(=O)-), 166.00 (2x -C(=CH2)-COOEt). GC-MS (m/z): 59, 69, 71, 99, 114, 145,
258.
5
BMA
CTA1
CTA2
CTA3
CTA4
CTA5
CTA6
CTA7
CTA8
3.0
Heat / W g-1
2.5
2.0
1.5
1.0
0.5
0.0
0
50
100
150
200
250
300
Time / s
Figure S 1. Photo-DSC for BMA neat and with 0.20 double bond equivalents of CTA.
250
250
200
200
150
150
100
100
50
50
t95% / s
Hp / J g-1
Hp / J g-1
t95% / s
0
0
UDMA:D3MA CTA4
CTA5
CTA6
CTA7
CTA8
Figure S 2. Photo-DSC results for the polymerization of UDMA:D3MA neat and with 0.20 double bond
equivalents of different α-acrylate CTAs. Units of the vertical axis are dependent on the measurement:
J/g for heat of polymerization (ΔHp) and seconds (s) for the time to reach 95% completion (t95%).
6
Table S 1. Initial rate of polymerization
of UDMA:D3MA alone and with 0.20
double bond equivalents of different
CTAs. Values determined from the
average slope for the first five seconds
recorded by RTIR (see Figures 5 and 8).
CTA
Initial rate (mol g-1 s-1)
none
2.7 x 10-4
CTA 4
5.5 x 10-5
CTA 5
9.8 x 10-5
CTA 6
8.2 x 10-6
CTA 7
2.8 x 10-4
CTA 8
7.3 x 10-5
106
105
G'' / Pa
104
103
102
UDMA:D3MA
CTA4
CTA5
CTA6
CTA7
CTA8
1
10
100
10-1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Monomer Conversion
Figure S 3. Monitoring loss modulus (G’’) with change in monomer conversion for the polymerization of
UDMA:D3MA neat and with 0.20 double bond equivalents of CTA.
7
102
UDMA:D3MA
CTA4
CTA5
CTA6
CTA7
CTA8
tan 
101
100
10-1
10-2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Monomer conversion
Figure S 4. Monitoring loss factor (tan δ) with change in monomer conversion for the polymerization of
UDMA:D3MA neat and with 0.20 double bond equivalents of CTA.
8
1.2
1.0
tan 
0.8
UDMA:D3MA
CTA4
CTA5
CTA6
CTA7
CTA8
0.6
0.4
0.2
0.0
-100
-50
0
50
100
150
200
T / °C
Figure S 5. Monitoring of glass transition by DMTA of UDMA:D3MA polymerized neat and with 0.20
double bond equivalents of CTA additive.
SUPPORTING INFORMATION REFERENCES
1. J. C. Milano, J. M. Robert, J. L. Vernet, B. Gallot, Macromol. Chem. Phys. 1999, 200, 15801586.
2. C. P. Reghunadhan Nair, P. Chaumont, D. Charmot, J. Polym. Sci., Part A: Polym. Chem.
1995, 33, 2773-2783.
3. G. F. Meijs, E. Rizzardo, S. H. Thang, Polym. Bull. 1990, 24, 501-505.
4. K. C. Reddy, H.-S. Byun, R. Bittman, Tetrahedron Lett. 1994, 35, 2679-2682.
5. M.-O. Zink, D. Colombani, P. Chaumont, Eur. Polym. J. 1997, 33, 1433-1440.
6. T. Tsuda, R. D. Thompson, L. J. Mathias, J. Macromol. Sci., Pure Appl. Chem. 1994, A31,
1867-1879.
9