New cleavable photoinitiator architecture with huge molar extinction coefficients for polymerization in the 340-450 nm range.

Article abstract of DOI:10.1021/ma3024359

A new Type I photoinitiator Tr-DMPA is described. It consists in three 2,2′-dimethoxy 2-phenyl acetophenone (DMPA) units grafted onto a truxene (Tr) scaffold. Compared to DMPA itself, the lowest electronic transition exhibits a ππ* character and the corre

Full text of DOI:10.1021/ma3024359

Article
pubs.acs.org/Macromolecules
New Cleavable Photoinitiator Architecture with Huge Molar
Extinction Coefficients for Polymerization in the 340−450 nm Range.
Mohamad-Ali Tehfe,† Frederic Dumur,‡ Bernadette Graff,† Jean-Louis Clement,‡ Didier Gigmes,*,‡
́
́
́
Fabrice Morlet-Savary,† Jean-Pierre Fouassier,§ and Jacques Lalevee*,†
́
†Institut de Science des Mater
́
iaux de Mulhouse IS2M, LRC CNRS 7228, UHA, 15, rue Jean Starcky, 68057 Mulhouse Cedex, France
‡CNRS, Institut de Chimie Radicalaire, Aix-Marseille Universite,
́
UMR 7273, F-13397 Marseille, France
§UHA-ENSCMu, 3 rue Alfred Werner 68093 Mulhouse, France
S
* Supporting Information
ABSTRACT: A new Type I photoinitiator Tr_DMPA is
described. It consists in three 2,2′-dimethoxy 2-phenyl
acetophenone (DMPA) units grafted onto a truxene (Tr)
scaffold. Compared to DMPA itself, the lowest electronic
transition exhibits a ππ* character and the corresponding
molar extinction coefficients ε are increased from about 400
M−1 cm−1 (at about 332 nm for DMPA) to 63 000 M−1 cm−1
(at 338 nm for Tr_DMPA); such huge values are exceptional
in Type I photoinitiators at this wavelength. Tr_DMPA
undergoes a fast cleavage and efficiently initiate an acrylate
polymerization upon a Xe−Hg lamp, a halogen lamp or a laser
diode exposure at 405 nm (upon very low light intensities: 2−
12 mW/cm2) in the 300−450 nm range. The polymerization
of epoxides or divinylethers is also feasible in the presence of an iodonium salt at 405 nm where reference photoinitiators cannot
efficiently operate. The chemical mechanisms analyzed by ESR, fluorescence, steady state photolysis, and laser flash photolysis
experiments are discussed.
classes of highly reactive PIs already allowed (to some extent) a
red-shift of the absorption and/or an increase of the ε. They are
usually realized,1 and, as still exemplified in very recent papers,
through, e.g., (i) the introduction of suitable substituents (e.g., in
triazine,7 thioxanthone,8 coumarin,9 xanthone,10 disulfone,11
benzophenone,12,13 1,4-naphtoquinone,14 pyridinium salt,15,16
ferrocenium salt,17 pyrromethene derivatives,18 in modified
hydrocarbons,19 titanocenes,20 dyes,21−23 metal carbonyls,24
iridium,25 and platinium26 or zinc complexes;27 the older
complete investigation of electronic effects in the series of
hydroxyl alkyl phenyl ketones HAP or morpholinoketones2d
remains a nice example), (ii) the incorporation of substituents or
spacers that can enhance the π electron delocalization (e.g., a
double or triple bond between a phenyl and a carbonyl group,28 a
INTRODUCTION
■
The design of photoinitiator PI of free radical polymerization
FRP, cationic polymerization CP, free radical promoted cationic
photopolymerization FRPCP and to a lesser extent anionic
polymerization, acid and base cross-linking has received a
considerable attention in the last 50 years (see ref 1 (up-to-date
situation) and other books2). Both the amount of light absorbed
I
abs by PI (together with the absorption wavelength range) and
the PI reactivity are obviously the crucial key points for the design
of high performance systems, the quantity Iabs depending on both
the wavelength (λ) and the molar extinction coefficients (ε).
Therefore, the search of new high performance compounds has
been continuously considered as of prime importance for many
years. Two directions were used:1 (i) search for new structures
and (ii) modification of starting structures. Today, many
chemical families of PI with characteristic λ and ε have been
developed and the discovery of really new structures (exhibiting
novel cleavable bonds, chromophores or electron/hydrogen
atom donors/acceptors...) with improved absorption properties
remains a challenge. Some recent achievements include the
proposal of novel systems, e.g., C−Ge3 or C−Si, Si−Si bond4
containing PIs, graphitic carbon nitride or fullerenes,5 NHC-
boranes.6
triple bond linked to a thioxanthone and a silane group,29
a
thioxanthone-diphenylanthracene,30 modified thioxanthones,31
sulfur containing benzophenones,32 sulfides33), (iii) the syn-
thesis of difunctional derivatives DfcPI (e.g., by coupling two
HAP moieties with a very small spacer),34 (iv) the construction
of bifunctional compounds BfcPI (e.g., benzophenone−sulfonyl
ketone,35 thioxanthone−anthracene,36 thioxanthone−fluorene
Received: November 26, 2012
Revised: December 29, 2012
On the opposite, the modification of starting structures is
more easily accessible. Indeed, structural changes in existing
© XXXX American Chemical Society
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Scheme 1
Scheme 2
or −carbazole,37 thioxanthonemethyl−carboxylate,38 keto oxime
ester−eosin,39 triazine derivative-dye,40 Ir complex−Ru com-
plex,41 Ir complex−coumarin moiety42) or double photochromic
initiator,43 and (v) the coupling of several conjugated units (e.g.,
multifunctional thiophene and related compounds).44,45
In all these examples, (i) the absorption is often red-shifted (up
to 30−40 nm in some cases), (ii) the ε are often higher
(sometimes noticeably), (iii) the practical polymerization
efficiency is usually better (as a consequence of a better light
absorption), and (iv) the photochemical reactivity can be
compared to that of the parent compounds (except in cases
where the novel molecular orbitals arrangement induces a
complete change of the excited state properties).
B
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few drops of DMF were added. The reaction was refluxed until no
evolution of fumes evolves. Excess of thionyl chloride was removed
under reduced pressure and 20 mL (190.4 mmol) of bromobenzene
were added. The solution was diluted with 20 mL of chloroform and
cooled to 0 °C. Then 5 g (37.5 mmol) of AlCl3 was added in one
portion, and the reaction mixture was stirred at room temperature for 1
h. The solution was then heated at 80 °C overnight. The solution was
quenched onto ice, extracted several times with DCM. The residue was
purified by column chromatography using DCM/pentane = 1/3 as the
eluent. A brown oil was isolated in quantitative yield (10 g, 99% yield).
1H and 13C NMR spectral data were consistent with those previously
reported.52 1H NMR (CDCl3) δ (ppm): 4.24 (s, 2H), 7.20−7.34 (m, 5
H), 7.59 (d, 2H, J = 8.4 Hz), 7.85 (d, 2H, J = 8.4 Hz). 13C NMR (CDCl3)
δ (ppm): 45.5, 127.1, 128.2, 128.8, 129.4, 130.2, 132.0, 134.2, 135.3,
196.6; HRMS (ESI MS) m/z: theor, 275.0066; found, 275.0068 ([M +
H]+ detected).
A fascinating question is the following: is it still possible (and
how) to boost the ε and/or the λ red-shift of existing PIs? For
example, let us consider the near UV−visible light (360−430
nm) induced FRP area. In a general way, PIs are based on small
molecular structures (e.g., aromatic ketones) but macro PIs
(oligomeric, polymeric or dendritic PIs) have also been
mentioned. They are usually classified as Type I PIs (cleavable
compounds), Type II PIs (PI/hydrogen donor couples) and
multicomponent PIs (e.g., PI/electron or hydrogen donor/
additive). A very recent account has shown an interesting and
promising achievement using a new trifunctional architecture
TfcPI where the molecular orbitals MOs of the core are coupled
with those of three PI moieties (in macroPIs, the coupling
between the PI units is inexistent). The first examples of such
TfcPIs involved (i) a truxene structure as the core and
benzophenone (Tr_BP) or thioxanthone (Tr_TX)46 as possible
PI units or (ii) a trichloromethyl triazine substituted by three
benzophenone, anthracene or pyrene moieties.47 These TfcPIs
give rise to Type II PIs.
1-(4-Bromophenyl)-2-phenylethane-1,2-dione. A 3 g (10.9 mmol)
sample of 1-(4-bromophenyl)-2-phenylethanone was dissolved in 20
In the present paper, we look for a possible Type I PI (i) being
able to absorb in the near UV−visible range (typically 340−450
nm range) where particular LEDs, halogen lamps or laser diodes
operate, (ii) exhibiting huge ε values, and (iii) potentially keeping
a high photochemical reactivity (e.g., efficient cleavage process).
We propose to modify the well-known PI referred as DMPA
(2,2′-dimethoxy-2-phenyl acetophenone) which undergoes a fast
α-cleavage (within 100−200 ps)48 and behaves as a very efficient
PI in acrylate photopolymerization.2d This will be realized
through a grafting of three DMPA units onto a truxene scaffold
(Tr_DMPA in Scheme 1; as seen below in Scheme 2, this
compound rather consists in a mixture of four regioisomers). The
ability of Tr_DMPA as photoinitiator/photosensitizer for the
FRP of acrylates and the cationic polymerization of epoxides and
vinylethers under very soft irradiation conditions (Xe−Hg lamp,
halogen lamp, laser diode, LED) as well as the associated excited
state processes will be investigated by steady state photolysis,
laser flash photolysis, fluorescence and ESR experiments.
mL of DMSO, 10 mL of water, and 20 mL of HBr in acetic acid. The
solution was heated at 90 °C overnight. After cooling, the solution was
poured onto ice. The solution was extracted with ether several time, the
organic phases were combined, washed with water, dried over
magnesium sulfate and the solvent removed under reduced pressure
providing black oil. The residue was purified by column chromatography
(SiO2) using CH2Cl2:pentane = 1:3 as the eluent and yielded light
1
brown oil (2.58 g, 82% yield). H and 13C NMR spectral data were
consistent with those previously reported.53 1H NMR (CDCl3) δ
(ppm): 7.52 (t, 2H, J = 7.9 Hz), 7.65−7.68 (m, 3H), 7.85 (d, 2H, J = 8.6
Hz), 7.96 (d, 2H, J = 7.1 Hz). 13C NMR (CDCl3) δ (ppm): 129.0, 129.8,
130.3, 131.1, 131.6, 132.3, 132.6, 134.9, 193.1, 193.7. HRMS (ESI MS)
m/z: theor, 288.9859; found, 288.9855 ([M + H]+ detected).
2-(4-Bromophenyl)-2,2-dimethoxy-1-phenylethanone and 1-(4-
Bromophenyl)-2,2-dimethoxy-2-phenylethanone. A 3 g (10.4 mmol)
EXPERIMENTAL SECTION
■
i. Synthesis of Tr_DMPA. All reagents and solvents were purchased
from Aldrich or Alfa Aesar and used as received without further
purification. Mass spectroscopy was performed by the Spectropole of
Aix-Marseille University. ESI mass spectral analyses were recorded with
a 3200 QTRAP (Applied Biosystems SCIEX) mass spectrometer. The
HRMS mass spectral analysis was performed with a QStar Elite (Applied
Biosystems SCIEX) mass spectrometer. 1H and 13C NMR spectra were
determined at room temperature in 5 mm o.d. tubes on a Bruker Avance
sample of 1-(4-bromophenyl)-2-phenylethane-1,2-dione was dissolved
in 1.5 mL (2.47 g, 2 equiv) of thionyl chloride and the solution was
cooled to 0 °C. Then 1.68 mL (1.33 g, 4 equiv) was added over 2 h. After
addition, the solution was allowed to warm to room temperature and the
solution was stirred at 50 °C for 1h30. The solution was diluted with 4
mL of 2-propanol and 0.26 g (1.88 mmol) of potassium carbonate and
0.1 mL of trimethylphosphite were added. The reaction was stirred at
room temperature overnight. All volatiles were removed under reduced
pressure and the residue was diluted with water, extracted with ether
several times. The organic phases were combined, dried over
magnesium sulfate and the solvent removed under reduced pressure.
The residue was purified by column chromatography (SiO2) using a
gradient of solvent from DCM:pentane = 1:1 to DCM:acetone = 1:1.
Monoacetal of diketone was obtained as a mixture of two regioisomers
(2.50 g, 72% yield). 1H NMR (CDCl3) δ (ppm): 3.21 (s, 12H), 7.28−
7.38 (m, 6H), 7.42−7.49 (m, 5H), 7.59 (d, 2H, J = 7.8 Hz), 7.94 (d, 2J, J
= 8.6 Hz), 8.04 (d, 2H, J = 7.5 Hz). 13C NMR (CDCl3) δ (ppm): 50.0,
103.2, 103.4, 123.2, 126.7, 128.08, 128.13, 128.5, 128.6, 129.8, 131.4,
131.5, 131.7, 132.7, 133.0, 133.9, 136.0, 136.4, 194.0, 194.5. HRMS (ESI
MS) m/z: theor, 357.0097; found, 357.0095 ([M + Na]+ detected).
Tr_DMPA. To a mixture of 1-(4-bromophenyl)-2,2-dimethoxy-2-
phenylethanone and 2-(4-bromophenyl)-2,2-dimethoxy-1-phenyletha-
none (1.07 g, 3.2 mmol) and 2,7,12-tris(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)hexahexyltruxene (980 mg, 0.8 mmol) in THF (80
400 spectrometer of the Spectropole: H (400 MHz) and 13C (100
1
1
MHz). The H chemical shifts were referenced to the solvent peak
DMSO-d6 (2.49 ppm) and the 13C chemical shifts were referenced to
the solvent peak DMSO-d6 (39.5 ppm). Monoacetal of aromatic
diketone was synthesized by adapting a literature procedure.49 2,7,12-
Tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexahexyltruxene was
prepared following a procedure previously reported in the literature
without modification and with similar yields.50 The new photoinitiator
was synthesized by adapting a literature procedure.51
1-(4-Bromophenyl)-2-phenylethanone. A 5 g (36.7 mmol) sample
of 2-phenylacetic acid was suspended in 20 mL of thionyl chloride, and a
C
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Scheme 3
mL) were added Pd(PPh3)4 (60 mg) and aqueous KOH solution (5 mL,
2 M). The mixture was refluxed for 48 h under nitrogen. Then the
mixture was poured into water. The aqueous layer was extracted with
CHCl3. The combined organic phase was washed with brine and dried
(MgSO4). The residue was purified by column chromatography (SiO2)
using DCM:acetone = 1:1 as the eluent. During evaporation, a light
brown solid formed. A yield of 1.13 g of photoinitiator was obtained as a
mixture of four regioisomers (88% yield). 1H NMR (CDCl3) δ (ppm):
0.52−0.59 (m, 18H), 0.75−1.10 (m, 48H), 2.12−2.17 (m, 6H), 2.95−
3.01 (m, 6H), 3.22−3.29 (m, 18H), 7.28−8.24 (m, 36H). 13C NMR
(CDCl3) δ (ppm): 13.8, 22.18, 22.28, 22.35, 22.39, 23.8, 29.4, 31.3, 37.0,
50.0, 50.1, 55.8, 103.3, 103.6, 103.7, 120.4, 120.5, 123.3, 124.8, 124.9,
126.9, 126.7, 126.8, 126.9, 126.93, 127.1, 127.2, 127.5, 127.74, 127.80,
127.86, 128.04, 128.08, 128.16, 128.2, 128.48, 128.54, 128.7, 128.87,
128.9, 129.88, 129.94, 129.98, 130.0, 130.3, 130.6, 130.7; 131.5, 131.7,
132.64, 132.68, 132.8, 132.9, 133.0, 134.0, 134.2, 134.3, 136.0, 137.0,
137.6, 137.7, 137.9, 140.3, 145.42, 145.45, 145.48, 145.7, 154.3, 194.5,
194.7, 195.0, 195.1. HRMS (ESI MS) m/z: theor, 1631.9764; found,
1631.9762 ([M + Na]+ detected).
The four expected regioisomers (I1−I4) resulting from the Suzuki
cross coupling reaction of 2-(4-bromophenyl)-2,2-dimethoxy-1-phenyl-
ethanone and 1-(4-bromophenyl)-2,2-dimethoxy-2-phenylethanone
with 2,7,12-tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-
hexahexyltruxene are depicted in Scheme 2. Because of the lack of
selectivity during the acetalization reaction of the diketones, an
equimolecular amount of the two possible brominated DMPA was
obtained as clearly evidenced by NMR spectroscopy. During the Suzuki
cross-coupling reaction and based on a similar reactivity of the two
brominated DMPA, a mixture of four unseparable regioisomers (1:3:3:1
ratio) was expected, two of these regioisomers corresponding to the
photoinitiator with the three acetal functions close or far from the
truxene core, the two others corresponding to mixture of position. Ratio
of each of the regioisomers could not be experimentally established due
to the superimposition of their respective NMR signals.
emission spectrum is given in Figure S1 in the Supporting Information);
(ii) polychromatic light from a Xe−Hg lamp (λ > 300 nm; I0 = 2 mW
cm−2); (iii) monochromatic light delivered by a laser diode at 405 nm
(cube, continuum; I0 ∼ 12 mW cm−2).
iv. Free Radical Photopolymerization Experiments. Trimethy-
lolpropane triacrylate (TMPTA from Cytec) was used as a low viscosity
monomer. The film polymerization experiments were carried out in
laminated conditions. The films (25 μm thick) deposited on a BaF2
pellet were irradiated (see the irradiation sources above). The evolution
of the double bond content was continuously followed by real time
FTIR spectroscopy (JASCO FTIR 4100) at about 1630 cm−1.55
v. Cationic Polymerization (CP). The photosensitive formulations
(25 μm thick) were deposited on a BaF2 pellet under air (or in laminated
conditions for DVE-3). The evolution of the epoxy group (for EPOX,
EPOX-Si) and the double bond (for vinyl ether monomer) contents
were continuously followed by real time FTIR spectroscopy (JASCO
FTIR 4100). The formation of the polyether was well characterized at
1080 cm−1.55
vi. Computational Procedure. Molecular orbital calculations were
carried out with the Gaussian 03 suite of programs.56 The electronic
absorption spectra for the different compounds were calculated with the
time-dependent density functional theory at B3LYP/6-31G* level on
the relaxed geometries calculated at UB3LYP/6-31G* level.
vii. Laser Flash Photolysis. Nanosecond laser flash photolysis
(LFP) experiments were carried out using a Qswitched nanosecond
Nd/YAG laser (λexc = 355 nm, 9 ns pulses; energy reduced down to 10
mJ) from Continuum (Minilite) and an analyzing system consisting of a
ceramic xenon lamp, a monochromator, a fast photomultiplier and a
transient digitizer (Luzchem LFP 212).55
viii. Electron Spin Resonance (ESR). ESR spectroscopy (X-band
ESR spectrometer equipped with a continuous photolysis device) was
used to study the radicals generated from Tr_DMPA upon irradiation
with a Xe−Hg lamp (Lumatec) under nitrogen. A X-band spectrometer
(MS 400 Magnettech) was used for the ESR spin trapping (ESR-ST)
experiments (a well-established technique for the identification of the
radical centers).57a,b The radicals generated by a light irradiation (Xe−
Hg lamp, Hamamatsu, L8252, 150 W; λ > 310 nm) under argon were
trapped by phenyl-N-tert-butylnitrone (PBN), 2,3,4,5,6-pentamethylni-
trosobenzene (PMNB) or 1,3,5-tri-tert-butyl-2-nitrosobenzene
(TBNB). The ESR spectra were simulated with the PEST WINSIM
program.57c
ii. Other Chemical Compounds. 2,2-Dimethoxy-2-phenylaceto-
phenone (DMPA from Aldrich) and a bisacylphosphineoxide (BAPO
from BASF) were used as reference Type I photoinitiators.
Methyldiethanolamine (MDEA) was obtained from Aldrich and
[methyl-4 phenyl(methyl-1-ethyl)-4-phenyl] iodonium tetrakis (penta
fluorophenyl) borate54 (Iod) from Bluestar Silicones-France. (3,4-
epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate (EPOX;
Uvacure 1500 from Cytec), (epoxycyclohexylethyl)methylsiloxane−
dimethylsiloxane copolymer (EPOX-Si; from Bluestar Silicones-France;
Silcolease UV POLY 200), triethylene glycol divinyl ether (DVE-3 from
Aldrich), and trimethylolpropane triacrylate (TMPTA from Cytec)
were selected as representative monomers (Scheme 3).
ix. Fluorescence Experiments. The fluorescence properties of the
compounds were studied using a JASCO FP-750 spectrometer.
RESULTS AND DISCUSSION
■
1. Photochemical Properties of Tr_DMPA. 1-a. Absorp-
tion and Emission Properties. Tr_DMPA is characterized by
light absorption characteristics much better than those of DMPA
iii. Irradiation Sources. Several light sources were used: (i)
polychromatic light from a halogen lamp (Fiber-Lite, DC-950 - incident
light intensity: I0 ≈ 12 mW cm−2; in the 350−800 nm range; the
D
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(Figure 1): absorption maximum λmax ∼ 338 nm and a molar
extinction coefficient εmax of 63 000 M−1 cm−1 vs 332 nm and
For I2−I4, the other regioisomers of Tr_DMPA (Scheme 2),
similar properties than I1 were calculated.
The fluorescence quantum yields Φf of truxene Tr and
Tr_DMPA are in a 5.5 ratio (Figure S2 in the Supporting
Information). As Φf (Tr) = 0.07,46 Φf (Tr-DMPA) is around
0.01. Time resolved fluorescence experiments lead to a first
excited singlet state S1 lifetime of Tr_DMPA: τ ∼ 1.4 ns. The S1
state is quenched by the iodonium salt (kqτ = 27.4 M−1 where kq
stands for the bimolecular quenching rate constant); therefore,
the kq value (∼1.9 × 1010 M−1 s−1) is close to the diffusion limit.
The oxidation potential is Eox = 1.13 V (this work) and the
calculated free energy change is negative (ΔG = −1.87 eV; using
ES = 3.32 eV (extracted from the fluorescence spectrum); Ered
(iod) = −0.2 V1). This supports an electron transfer process (eq
1a where Ar2I+ stands for Iod) followed by the usual and known
decomposition of the iodonium salt , eq1b.
•+
1TrDMPA + Ar2I+ → TrDMPA + Ar2I•
(1a)
and
Ar2I• → Ar• + ArI
(1b)
1-b. The Cleavage Process of Tr-DMPA. Interestingly, upon a
UV (Xe−Hg lamp) or visible light (laser diode at 405 nm)
exposure, a fast bleaching of the Tr_DMPA solution is observed
(Figure 2): this suggests a high photoreactivity.
ESR-ST experiments (where different spin trap agents are
used: PBN, TBNB, PMNB) highlight a Norrish I cleavage of
Tr_DMPA leading to dimethoxybenzyl derived radicals (X-Ph−
•
C(OMe)2 ) and benzoyl derived radicals (X-Ph−C(O)•) (see eq
2). In this equation, eq2, X represents the substituent of the
DMPA moiety in Tr_DMPA as four regioisomers are present
(Scheme 2). In the ESR experiments, the hyperfine coupling
constants (hfcs) for the different benzoyl (or dimethoxybenzyl)
spin trap adducts can not be distinguished for the different
regioisomers; i.e., the hfcs are probably weakly affected by the
nature of X.
Figure 1. (A) UV−visible absorption spectra of Tr_DMPA and DMPA
in toluene. Inset: zoom for DMPA. (B) HOMO and LUMO of
Tr_DMPA (UB3LYP/6-31G* level).
∼400 M−1 cm−1. Therefore, Tr_DMPA allows a large and
efficient covering of the emission spectra of (i) the halogen lamp
that mostly delivers near UV/visible light, (ii) the Xe−Hg lamp
that delivers a UV−visible light (λ > 300 nm), and (iii) the laser
diode at 405 nm or LED at 395 nm. At 365 nm, a typical emission
band of Hg lamps, ε = 31 500 M−1 cm−1 for Tr-DMPA (ε ∼170
M−1 cm−1 for DMPA). The ground state absorption spectrum
spreads up to 450 nm with noticeable ε values: e.g., 3900 (395
nm), 2600 (405 nm), 1100 (440 nm), and 1000 (450 nm). To
the best of our knowledge, Tr_DMPA might be considered as
the cleavable PI that exhibits the never attained highest ε values
(see, in Table 1, typical examples of (λ, ε) couples for known or
recently proposed Type I PIs).
Molecular orbital calculations for I1 show that (i) the strong
coupling of the MOs of the DMPA units to those of the truxene
core in Tr_DMPA results in largely delocalized HOMO and
LUMO (Figure 1B) and (ii) the allowed lowest HOMO →
LUMO electronic transition (λmax = 338 nm; oscillator strength
(f) =1.68) exhibits a π→π* character. This is in contrast with
DMPA where the forbidden n→π* transition occurs at 332 nm.
As a consequence, (i) when going from DMPA to Tr_DMPA,
the lowest energy level moves from a nπ* to a ππ* state and (ii)
the π→π* transition of Tr_DMPA (338 nm) can be considered
as resulting from a strong coupling of the π and π* orbitals of
DMPA and truxene (Tr). These results are in line with the better
light absorption properties of Tr_DMPA compared to DMPA.
•
TrDMPA → X−Ph−C(O)• + X−Ph−C(OMe)2
(hν)
(2)
Indeed, the PBN radical adduct of a benzoyl type radical (aN =
14.2 G; aH = 4.4 G; Figure 3A; see reference hfcs58) is observed
during the irradiation of Tr_DMPA in tert-butylbenzene. Using
TBNB as a spin trap, the hfcs (aN = 9.9 G; aH = 1.9 G; Figure 3B)
of the adduct are also in agreement with the known data for a
benzoyl radical.59 The presence of the dimethoxybenzyl derived
radical (Ph−C(OMe)2 ) is revealed in Figure 3C (PMNB as a
spin trap; aN = 13.52 G; see reference data in ref 59). No radicals
are observed in the absence of irradiation.
Upon irradiation of a Tr_DMPA/Iod solution in ESR-spin
trapping experiments, the PBN radical adduct of an aryl radical is
observed (aN = 14.2 G; aH = 2.2 G). The aryl can be formed
through reactions 1 (see above) and 3 (as a result of the known
oxidation of the dimethoxybenzyl radicals generated through 2).
•
R• + Ar2I+ → R+ + Ar• + ArI
(3)
Remarkably, free radicals are directly observed in ESR upon
direct steady-state photolysis at low temperature (Figure 3D).
This confirms an efficient formation of free radicals upon light
exposure in full agreement with the Type I character of
Tr_DMPA. The associated ESR spectrum, however, is a
superposition of the different radicals generated in 2 for the
E
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Table 1. Examples of Ground State Absorption Wavelengths λ and Molar Extinction Coefficients ε of Typical Cleavable
a
Photoinitiators
a
From refs 1 and 2d.
The fast decomposition of Tr_DMPA in laser flash photolysis
experiments prevents any systematic studies. A strong bleaching
together with a partial recovery of the ground state absorption is
observed at 360 nm (Figure 4) in line with the cleavage reaction
2. No triplet or radical absorption is recorded on the investigated
time scale and wavelength range.
The cleavage process of Tr_DMPA in the triplet state is
expected to be exothermic according to the calculations (at the
UB3LYP/6-31G* level) of the triplet state energy level (ET is
57.5 kcal/mol) and the C−C bond dissociation energy (BDE =
54.5 kcal/mol). A singlet state cleavage cannot be ruled out as the
singlet state energy level is higher than ET rendering the
dissociation process more exothermic. This is in contrast with
DMPA where the cleavage is considered as exclusively triplet
(indeed, the ET of DMPA is noticeably higher (experimental
value, 66.2 kcal/mol;60 calculated value, 68.2 kcal/mol; see in ref
1) whereas the BDE has almost the same value (56 kcal/mol)61).
The lower ET of Tr_DMPA can be associated with a lower
reactivity of this compound for the cleavage from the triplet state.
In the presence of Iod (3 × 10−2 M) as in the polymerization
experiments (see below), the quenching of S1 by Iod competes
(kq[Iod] ∼ 109 s−1) with the intersystem crossing kisc, the internal
conversion kic and the possible S1 cleavage kc processes (kisc + kic
+ kc ∼ 109 s−1). On these kinetic grounds, both Tr_DMPA•+ 1a
Figure 2. Photolysis of Tr_DMPA in acetonitrile/toluene (50%/50%)
under air: UV−visible absorption spectra recorded at different
irradiation times. Xe−Hg lamp exposure (very low light intensity: 1
mW/cm2).
different regioisomers (Scheme 2) and will not be investigated
further.
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Figure 3. ESR spin-trapping experiments for the irradiation of Tr_DMPA solution with different spin trap agents: (A) phenyl-N-tert-butylnitrone
(PBN); (B) 1,3,5-tri-tert-butyl-2-nitrosobenzene (TBNB) and (C) 2,3,4,5,6-pentamethylnitrosobenzene (PMNB). (D) Steady-state ESR spectrum for
the irradiation of Tr_DMPA at 223 K. In tert-butylbenzene (experimental (a) and simulated (b) spectra).
free coating is only obtained for Tr_DMPA as the final
conversion is about 10% higher to that obtained for DMPA −
Figure 5A. The calculated amount of energy absorbed Iabs
(evaluated as presented in ref 62) being in a ratio 1/10 for
DMPA and Tr_DMPA and the polymerization rates (Rps)
almost similar (Figure 5A), the initiation quantum yields are in
the same ratio. Therefore, the photochemical/chemical reactivity
of Tr_DMPA (expressed by Φisc, cleavage rate constants,
addition rate constants of the radicals to the acrylate double
bond) appears lower than that of DMPA. Its lower reactivity is
largely counterbalanced by its higher Iabs. The extractability of the
initiator from the synthesized polymers (evaluated as presented
by us in29) is found to be very low i.e. this highlights that the
fragments (X-Ph−C(O)• and X-Ph−C(OMe)2 ) are directly
•
Figure 4. Kinetic observed at 360 nm after laser excitation of Tr_DMPA
at 355 nm.
linked to the polymer network.
Interestingly, when using a halogen lamp exposure, the
efficiencies of both compounds decrease (the light distribution of
this source is less favorable than for the Xe−Hg lamp) but the
difference is larger (35% vs <10% conversion at 300 s for
Tr_DMPA and DMPA, respectively). When adding MDEA to
Tr_DMPA, higher Rps and final conversions (∼50%) of TMPTA
are obtained (Figure 5B, curve 2); the final coating is tack-free
e.g. within 3 min of irradiation. The acceleration of the
polymerization in the presence of an amine (MDEA) can result
from the reduction of the oxygen inhibition. Using DMPA/
MDEA, the conversion reaches a maximum of ∼30%, the Rp is
low and the inhibition time is much more important (Figure 5B,
curve 1). This trend of reactivity is in agreement with the light
absorption properties of the different PIs at λ > 370 nm:
Tr_DMPA ≫ DMPAsee Figure 1A. Under the laser diode at
and R+ species 3 are present. They should be able to initiate a
cationic polymerization (see below). The crowded and
delocalized structure of Tr_DMPA•+, however, might probably
make more difficult its addition to the epoxide.
2. Tr_DMPA as a New Type I Photoinitiator. 2-a. Free
Radical Photopolymerization FRP of TMPTA. The best typical
conversion−time profiles for the photopolymerization of
trimethylolpropane triacrylate (TMPTA) under a polychromatic
light exposure (Xe−Hg lamp) in laminated conditions are
displayed in Figure 5. They outline the high efficiency of
Tr_DMPA compared to DMPA using a very low light intensity
(2 mW/cm2) as well as a low photoinitiator content (0.1% w/w;
[Tr_DMPA] = 6.4 × 10−4 M, [DMPA] = 5 × 10−3 M), i.e., a tack
G
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Figure 5. Photopolymerization profiles of TMPTA in laminated conditions: (A) upon the Xe−Hg lamp exposure in the presence of (1) DMPA (0.1%
w/w) and (2) Tr_DMPA (0.1% w/w); (B) upon the halogen lamp exposure in the presence of (1) DMPA/MDEA (0.5%/2% w/w) and (2)
Tr_DMPA/MDEA (0.5%/2% w/w).
Figure 6. (A) Photopolymerization profiles of EPOX, upon halogen lamp irradiation in the presence of (1) DMPA/Iod (0.5%/3% w/w), (2)
Tr_DMPA/Iod (0.5%/3% w/w), and (3) BAPO/Iod (0.5%/3% w/w). (B) Photopolymerization profiles of EPOX-Si, upon halogen lamp irradiation
in the presence of (1) DMPA/Iod (0.5%/3% w/w) and (2) Tr_DMPA/Iod (0.5%/3% w/w); inset, IR spectra recorded during the
photopolymerization of curve 2 (a) before and after (b) light irradiation. (C) Photopolymerization profiles of EPOX, upon the laser diode exposure
at 405 nm in the presence of (1) DMPA/Iod (0.5%/3% w/w) and (2) Tr_DMPA/Iod (0.5%/3% w/w). (D) Photopolymerization profiles of EPOX-Si,
upon laser diode exposure at 405 nm in the presence of (1) DMPA/Iod (0.5%/3% w/w) and (2) Tr_DMPA/Iod (0.5%/3% w/w), under air.
H
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405 nm, Tr_DMPA obviously works contrary to DMPA (final
conversion 40% vs <10% at 300 s for Tr_DMPA and DMPA,
respectively). For LED at 395 nm, an efficient process is also only
observed for Tr_DMPA.
photoinitiator Tr_DMPA whose the fast Norrish I cleavage is
similar to that of DMPA. The high molar extinction coefficients
of Tr_DMPA (εmax > 60 000 M−1 cm−1) have never been
reported for PIs in the near UV wavelength range and probably in
any cleavable PIs described so far. The most striking performance
is undoubtedly observed in the polymerization of an epoxide and
a divinylether under air at 405 nm where PIs such as DMPA or
BAPO are almost inefficient.
This present work suggests that the incorporation of PI units
into a truxene structure can be the starting point for the design of
a new high performance class of Type I or Type II PIs being able
to behave as light harvesting systems and to work in the near UV/
visible range under “extreme” experimental conditions (low
viscosity media, low intensity light sources) as radical PIs in free
radical and cationic polymerizations. The synthesis of
Tr_DMPA is relatively easy; its shell life stability is good and
its solubility in organic formulations is excellent. The
introduction of PI units onto a triazine skeleton was also
recently achieved.47 Other cores for the development of
trifunctional TfcPIs (or even difunctional DfcPIs) architectures
as well as new strongly coupled bifunctional structures BfcPIs can
probably be proposed in the future.
2-b. Cationic Photopolymerization of EPOX and EPOX-Si.
The photopolymerizations of EPOX and EPOX-Si using
Tr_DMPA/Iod under the halogen lamp and the laser diode
irradiation were carried out under air (Figure 6). The induction
period can be ascribed to the presence of inhibitors e.g. the free
radicals must be oxidized by iodonium salt for the formation of
the polymerization initiating cations. Therefore, the oxygen must
be first consumed, i.e., the free radicals react with oxygen (with
formation of peroxyl radicals) preventing their oxidation by
iodonium salt. In Figure 6, low light intensities are used and the
polymerization starts when the oxygen concentration is low.
Remarkably, the new proposed system is very efficient for the
selected very soft irradiations conditions. An increase of the IR
band at 1080 cm−1 is concomitantly observed due to the
formation of the polyether network. Quite excellent conversion−
time profiles are noted compared to those recorded in the
presence of DMPA/Iod (no ring-opening photopolymerization
occurs) or BAPO/Iod (Figure 6A, curve 2 vs curves 1 and 3).
Final conversions (about 60%) are reached after 13 min of
irradiation and tack free coatings are obtained (Figure 6 curves
2). This is still in line with the strongly red-shifted absorption of
Tr_DMPA compared to DMPA (Figure 1) which allows a good
matching with the emission spectra of the light sources.
ASSOCIATED CONTENT
■
S
* Supporting Information
Figure S1, emission spectrum for the halogen lamp, and Figure
S2, emission spectra for Tr and Tr_DMPA. This material is
available free of charge via the Internet: http://pubs.acs.org.
2-c. Cationic Photopolymerization of DVE-3. The photo-
polymerization of DVE-3 was carried out in laminated conditions
using the laser diode (405 nm) irradiation. In the presence of the
Tr_DMPA/Iod system, an excellent polymerization is noted
with a conversion ∼90% after 2 min of irradiation (Figure 7). No
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: (J.L.) jacques.lalevee@uha.fr; (D.G.) didier.gigmes@
univ-amu.fr.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was partly supported by the “Agence Nationale de la
Recherche” grant ANR 2010-BLAN-0802. J.L. thanks the Institut
Universitaire de France for the financial support. The authors
thank Jean Marc Frances (Bluestar Silicones-France) for the gifts
of Iod & EPOX-Si. M.A.T., J.L., and D,G, thank the “TGE
Renard” for the help for ESR experiments.
REFERENCES
(1) Fouassier, J. P.; Lalevee
■
́
, J. Photoinitiators for Polymer Synthesis:
Scope, Reactivity and Efficiency; Wiley-VCH: Weinheim, Germany, 2012.
(2) (a) Fouassier, J. P. Photoinitiation, Photopolymerization, Photo-
curing; Hanser: Munich, Germany, 1995. (b) Radiation Curing in
Polymer Science and Technology; Fouassier, J. P., Rabek, J. F., Eds.;
Chapman & Hall: London, 1993. (c) Crivello, J. V.; Dietliker, K.
Photoinitiators for Free Radical, Cationic and Anionic Photopolymerization;
Surface Coatings Technology Series; Bradley, G. , Ed., Wiley: New York,
1999; Vol. III. (d) Dietliker, K. A Compilation of Photoinitiators
Commercially Available for UV Today: Sita Technology Ltd.: London,
2002. (e) Photoinitiated Polymerization; Belfied, K. D., Crivello, J. V.,
Eds.; ACS Symposium Series 847; American Chemical Society:
Washington DC, 2003;. (f) Photochemistry and Photophysics of Polymer
Materials, Allen, N. S., Ed., Wiley: Hoboken, NJ, 2010. (g)
Photopolymerization: Fundamentals and Applications; Scranton, A. B.,
Bowman, A., Peiffer, R. W., Eds.; ACS Symposium Series 673; American
Chemical Society: Washington DC, 1997. (h) Green, W. A. Industrial
Photoinitiators; CRC Press: Boca Raton, FL, 2010. (i) Handbook of Vinyl
Figure 7. Photopolymerization profiles of DVE-3 in laminated
conditions. Upon the laser diode exposure at 405 nm in the presence
of (1) DMPA/Iod (0.5%/3% w/w) and (2) Tr_DMPA/Iod (0.5%/3%
w/w).
polymerization is observed when using DMPA/Iod in the same
experimental conditions. This is in full agreement with the higher
efficiency of Tr_DMPA to initiate cationic polymerizations (see
above for epoxy).
CONCLUSIONS
■
In this paper, the coupling of the MOs of three 2,2′-dimethoxy 2-
phenyl acetophenone (DMPA) units linked to a truxene (Tr)
scaffold leads to the design of a one-component trifunctional
I
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Article
Polymers, Mishra, M. K.; Yagci, Y., Eds.; CRC Press: Boca Raton, FL,
2008.
(3) Ganster, B.; Fischer, U. K.; Moszner, N.; Liska, R. Macromol. Rapid
(31) Sevinc Esen, D.; Karasu, F.; Arsu, N. Prog. in Org. Coat. 2011, 70,
102−107.
́
(32) (a) Pietrzak, M.; Wrzyszczynski, A. J. Appl. Polym. Sci. 2011, 122,
Commun. 2008, 29, 57−62.
2604−2608. (b) Wei, J.; Wang, B. Macromol. Chem. Phys. 2011, 212,
88−95.
́
(4) Lalevee, J.; Fouassier, J. P. In Encyclopedia of Radicals in Chemistry,
Biology and Materials; Studer, A.; Chatgilialoglu, C., Eds.; Wiley: New
York, 2012; Vol. 1, Chapter 2.
́
(33) Gil, M.; Gawdzik, B.; Podkoscielna, B. J. Appl. Polym. Sci. 2012,
125, 2839−2845.
(5) (a) Kiskan, B.; Zhang, J.; Wang, X.; Antonietti, M.; Yagci, Y. ACS
Macro Lett. 2012, 1, 546−549. (b) Gilmaz, G.; Iskin, B.; Yilmaz, F.;
Yagci, Y. ACS Macro Lett. 2012, 1, 1212−1215.
(34) (a) Visconti, M. In Photochemistry and UV Curing: New Trends;
Fouassier, J. P., Ed.; Research Signpost: Trivandrum, India, 2006; pp
́
153−163. (b) Dietlin, C.; Lalevee, J.; Allonas, X.; Fouassier, J. P.;
́
(6) Lalevee, J.; Telitel, S.; Tehfe, M. A.; Fouassier, J. P.; Curran, D. P.;
Visconti, M.; Li Bassi, G.; Norcini, G. J. Appl. Polym. Sci. 2008, 107, 246−
Lacote, E. Angew. Chem., Int. Ed. 2012, 51, 5958−5961.
(7) Jiang, M.; Wang, K.; Ma, G.; Jian, L.; Juan, X.; Yu, Q.; Nie, J. J. Appl.
Polym. Sci. 2011, 121, 2013−2017.
252.
́
(35) Lalevee, J.; Allonas, X.; Fouassier, J. P.; Visconti, M.; Li Bassi, G. In
Photochemistry and UV Curing: new trends; Fouassier, J. P., Ed.; Research
Signpost: Trivandrum, India, 2006; pp 79−90.
(36) (a) Yilmaz, G.; Tuzun, A.; Yagci, Y. J. Polym. Sci., Part A: Polym.
Chem. 2010, 48, 5120−5125. (b) Balta, D. K.; Arsu, N.; Yagci, Y.;
Jockusch, S.; Turro, N. J. Macromolecules 2007, 40, 4138−4141.
(c) Yagci, Y.; Jockusch, S.; Turro, N. J. Macromolecules 2010, 43, 6245−
6260.
(8) Keskin Dogruyol, S.; Dogruyol, Z.; Arsu, N. J. Polym. Sci., Part A:
Polym. Chem. 2011, 49, 4037−4040.
(9) Yin, R.; Wang, K.; Liu, J.; Nie, J. J. Appl. Polym. Sci. 2012, 125,
2371−2375.
(10) Asvos, X.; Siskos, M. G.; Zarkadis, A. K.; Hermann, R.; Brede, O. J.
Photochem. Photobiol. A: Chem. 2011, 219, 255−264.
(11) Chen, H.; Yang, J.; Guo, D.; Wang, L.; Nie, J. J. Photochem.
Photobiol. A: Chem. 2012, 232, 57−63.
(37) Tunc, D.; Yagci, Y. Polym. Chem. 2011, 2, 2557−2563.
(38) Gilmaz, G.; Acik, G.; Yagci, Y. Macromolecules 2012, 45, 2219−
2224.
(12) Wang, K.; Jiang, S.; Liu, J.; Nie, J.; Yu, Q. Prog. Org. Coatings 2011,
72, 517−521.
(39) (a) Burget, D.; Fouassier, J. P.; Amat-Guerri, F.; Mallavia, R.;
Sastre, R. Acta Polym. 1999, 50, 337−346. (b) Xu, J.; Ma, G.; Wang, K.;
Gu, J.; Jiang, S.; Nie, J. J. Appl. Polym. Sci. 2012, 123, 725−731.
(40) Kawamura, K. J. Photochem. Photobiol. Part A: Chem. 2004, 162,
329−338.
(13) Temel, G.; Enginol, B.; Aydin, M.; Karaca Balta, D.; Arsu, N. J.
Photochem. Photobiol. A: Chem. 2011, 219, 26−31.
(14) Marzena Szymczak, A.; Podsiadły, R.; Podemska, K.; Sokołowska,
J. Color. Technol. 2012, 128, 378−386.
(15) Czech, Z.; Kowalczyk, A.; Gąsiorowska, M.; Soroka, J.; Kabatc, J. J
Adhes. Adhes. 2011, 31, 634−638.
́
(41) Lalevee, J.; Tehfe, M. A.; Dumur, F.; Gigmes, D.; Blanchard, N.;
Morlet-Savary, F.; Graff, B.; Fouassier, J. P. ACS Macro Lett. 2012, 1,
286−290.
́
(16) Tehfe, M. A.; Zein-Fakih, A.; Lalevee, J.; Dumur, F.; Gigmes, D.;
Morlet-Savary, F.; Hamieh, T.; Fouassier, J. P. Eur. Polym. J. 2012,
DOI: 10.1016/j.eurpolymj.2012.10.010.
́
(42) Tehfe, M. A.; Lalevee, J.; Telitel, S.; Sun, J.; Zhao, J.; Morlet-
Savary, F.; Graff, B.; Fouassier, J. P. Polymer 2012, DOI: 101016/
j.polymer.2012.05.009.
(17) Chen, Y.; Li, G.; Han, J.; Wang, T. J. Photochem. Photobiol. A:
Chem. 2011, 222, 330−335.
(43) Kreutzer, J.; Dogan Demir, K.; Yagci, Y. Eur. Polym. J. 2011, 47,
792−799.
́
(18) (a) Telitel, S.; Lalevee, J.; Blanchard, N.; Kavalli, T.; Tehfe, M. A.;
Morlet-Savary, F.; Graff, B.; Fouassier, J. P. Macromolecules 2012, 45,
6864−6868. (b) Telitel, S.; Blanchard, N.; Schweitzer, S.; Morlet-
(44) (a) Aydogan, B.; Yagci, Y.; Toppare, L.; Jockusch, S.; Turro, N. J.
Macromolecules 2012, 45, 7829−7834. (b) Aydogan, B.; Durmaz, Y. Y.;
Kahveci, M. U.; Uygun, M.; Tasdelen, M. A.; Yagci, Y. Macromol. Symp.
2011, 308, 25−34. (c) Aydogan, B.; Gunbas, G. E.; Durmus, A.;
Toppare, L.; Yagci, Y. Macromolecules 2010, 43, 101−106. (d) Bulut, U.;
Gunbas, G. E.; Toppare, L. J. Polym. Sci., Part A: Polym. Chem. 2010, 48,
209−213. (e) Bulut, U.; Balan, A.; Caliskan, C. J. Polym. Sci., Part A:
Polym. Chem. 2011, 49, 729−733. (f) Yagci, Y.; Jockusch, S.; Turro, N. J.
Macromolecules 2007, 40, 4481−4485.
Savary, F.; Graff, B.; Fouassier, J. P.; Lalevee
(19) (a) Tehfe, M. A.; Lalevee
Blanchard, N.; Fouassier, J. P. ACS Macro Lett. 2012, 1, 198−203.
(b) Tehfe, M. A.; Lalevee, J.; Morlet-Savary, F.; Graff, B.; Blanchard, N.;
́
, J. Polymer, to be publ.
, J.; Morlet-Savary, F.; Graff, B.;
́
́
Fouassier, J. P. Macromolecules 2012, 45, 1746−1752. (c) Tehfe, M. A.;
Dumur, F.; Contal, E.; Graff, B.; Gigmes, D.; Morlet-Savary, F.;
Fouassier, J. P.; Lalevee
c2py20950k.
(20) Lalevee
P. Macromolecules 2012, 45, 356−361.
(21) Tehfe, M. A.; Lalevee, J.; Dumur, F.; Zein-Fakih, A.; Gigmes, D.;
́
, J. Polym. Chem. 2012, DOI: 10.1039/
(45) Telitel, S.; Lalevee
published.
(46) Lalevee
Morlet-Savary, F.; Fouassier, J.-P. Macromol. Rapid Commun. 2012,
DOI: 10.1002/marc.201200578.
́
, J.; Fouassier, J. P.; Detrembleur, C. To be
́
, J.; Tehfe, M. A.; Morlet-Savary, F.; Graff, B.; Fouassier, J.
́
, J.; Tehfe, M.-A.; Dumur, F.; Gigmes, D.; Graff, B.;
́
Morlet-Savary, F.; Fouassier, J. P. Polymer 2012, DOI: 10.1016/
j.polymer.2012.08.067.
(47) Tehfe, M. A.; Dumur, F.; Morlet-Savary, F.; Graff, B.; Fouassier, J.
(22) Kabatc, J.; Jurek, K. Polymer 2012, 53, 1973−1980.
(23) Podemska, K.; Podsiadły, R.; Szymczak, A. M.; Sokołowska, J.
Dyes Pigm. 2012, 94, 113−119.
́
P.; Gigmes, D.; Lalevee, J. Macromolecules 2012, 45, 8639−8647.
(48) Morlet-Savary, F.; Allonas, X.; Fouassier, J. P. in Photochemistry
and UV curing: new trends; Fouassier, J. P., Ed., Research Signpost:
Trivandrum, India, 2006; pp 69−81.
(24) Lalevee
P. Macromolecules 2010, 43, 6608−6615.
(25) Lalevee, J.; Peter, M.; Dumur, F.; Gigmes, D.; Blanchard, N.;
́
, J.; Tehfe, M. A.; Gigmes, D.; Blanchard, N.; Fouassier, J.
(49) Brunisholz, J.; Kirchmayr, R. US patent 4,190,602 (1980).
(50) Wang, J.-L.; Chan, Y.-T.; Moorefield, C. N.; Pei, J.; Modarelli, D.
A.; Romano, N. C.; Newkome, G. R. Macromol. Rapid Commun. 2010,
31, 850−855.
́
Tehfe, M. A.; Morlet-Savary, F.; Fouassier, J. P. Chem., Eur. J. 2011, 17,
15027−15031.
(26) Tehfe, M. A.; Ma, L.; Morlet-Savary, F.; Graff, B.; Fouassier, J. P.;
́
(51) Tehfe, M. A.; Lalevee, J.; Telitel, S.; Contal, E.; Dumur, F.;
Zhao, J.; Lalevee
(27) Tehfe, M. A.; Lalevee
́
, J. Macromol. Chem. Phys. 2012, 213, 2282−2286.
Gigmes, D.; Bertin, D.; Nechab, M.; Graff, B.; Morlet-Savary, F.;
Fouassier, J. P. Macromolecules 2012, 45, 4454−4460.
(52) Wong, Y.-C.; Parthasarathy, K.; Cheng, C.-H. Org. Lett. 2010, 12,
1736−1739.
́
, J.; Dumur, F.; Zein-Fakih, A.; Gigmes, D.;
Contal, E.; Bertin, D.; Fouassier, J. P. To be published.
(28) Rosspeintner, A.; Griesser, M.; Pucher, N.; Iskra, K.; Liska, R.;
Gescheidt, G. Macromolecules 2009, 42, 8034−8038.
(53) Ren, W.; Xia, Y.; Ji, S.-J.; Zhang, Y.; Wan, X.; Zhao, J. Org. Lett.
2009, 11, 1841−1844.
(54) (a) Castellanos, F.; Fouassier, J. P.; Priou, D.; Cavezzan, A. US
Pat. 5668192, 16/9/1997, Rhone Poulenc. (b) Castellanos, F.;
́
(29) Lalevee, J.; Blanchard, N.; Fries, C.; Tehfe, M. A.; Morlet-Savary,
F.; Fouassier, J. P. Polym. Chem. 2011, 2, 1077−1084.
(30) Karaka-Balta, D.; Temel, G.; Okal, N.; Yagci, Y. Macromolecules
2012, 45, 119−125.
J
dx.doi.org/10.1021/ma3024359 | Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Fouassier, J. P.; Priou, C.; Cavezzan, J. J. Appl. Polym. Sci. 1996, 60, 705−
713.
(55) (a) Lalevee
Fouassier, J. P. Macromolecules 2010, 43, 10191−10195. (b) Lalevee
Blanchard, N.; Tehfe, M. A.; Peter, M.; Morlet-Savary, F.; Gigmes, D.;
Fouassier, J. P. Polym. Chem. 2011, 2, 1986−1991. (c) Lalevee, J.;
Blanchard, N.; Tehfe, M. A.; Peter, M.; Morlet-Savary, F.; Fouassier, J. P.
, J.;
́
, J.; Blanchard, N.; Tehfe, M.-A.; Morlet-Savary, F.;
́
, J.;
́
Macromol. Rapid Commun. 2011, 32, 917−920. (d) Lalevee
́
Blanchard, N.; Tehfe, M. A.; Peter, M.; Morlet-Savary, F.; Fouassier, J.
P. Polym. Bull. 2011, 68, 341−347.
(56) (a) Gaussian 03, Revision B-2, Frisch, M. J.; Trucks, G. W.;
Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.;
Zakrzewski, V. G.; Montgomery, J. A.; , Jr., Stratmann, R. E.; Burant, J.
C.; Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K. N.; Strain, M.
C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi, M.; Cammi, R.; Mennucci,
B.; Pomelli, C.; Adamo, C.; Clifford, S.; Ochterski, J.; Petersson, G. A.;
Ayala, P. Y.; Cui, Q.; Morokuma, K.; Salvador, P.; Dannenberg, J.J.;
Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J.; Keith, T.; M. A. Al-Laham, Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Andres, J. L.; Gonzalez, C.; M. Head-Gordon, Replogle, E. S.; Pople, J.
A., Gaussian, Inc.: Pittsburgh PA, 2003. (b) Foresman, J. B.; Frisch, A. In
Exploring Chemistry with Electronic Structure Methods, 2nd ed., Gaussian.
Inc.: Pittsburgh, PA, 1996.
(57) (a) Tordo, P. Spin-trapping: recent developments and
applications. In Atherton, N. M., Davies, M. J., Gilbert, B. C. Electron
Spin Resonance; Cambridge, The Royal Society of Chemistry; 1998; Vol
́
18. (b) Lalevee, J.; Dumur, F.; Mayer, C. R.; Gigmes, D.; Nasr, G.; Tehfe,
M. A.; Telitel, S.; Morlet-Savary, F.; Graff, B.; Fouassier, J. P.
Macromolecules 2012, 45, 4134−4141. (c) Duling, D. R. J. Magn.
Reson., Ser. B 1994, 104, 105−110.
(58) Baumann, H.; Timpe, H. J.; Zubarev, V. E.; Fok, N. V.; Mel’nikov,
M. V. J. Photochem. 1985, 30, 487−500.
(59) Terabe, S.; Kuruma, K.; Konaka, R. J.Chem.Soc., Perkin Trans.II
1973, 1252−1256.
(60) Rutsch, W.; Berner, G.; Kirchmayr, R.; Husler, R.; Rist, G.; Buhler,
N. In Organic Coatings Science and Technology; Parfit, G. D., Patsis, A. V.,
Eds.; 1986; Vol. 8, 175−192, Marcel Dekker: N.Y.
(61) Lalevee
Chem 2003, 159, 127−133.
(62) Lalevee, J.; Blanchard, N.; Chany, A. C.; Souane, R.; El-Roz, M.;
́
, J.; Allonas, X.; Fouassier, J. P. J. Photochem. Photobiol. A:
́
Graff, B.; Allonas, X.; Fouassier, J. P. Macromolecules 2009, 42, 6031−
6037.
K
dx.doi.org/10.1021/ma3024359 | Macromolecules XXXX, XXX, XXX−XXX