New fluorinated acrylic monomers for the surface modification of UV-curable systems

New Fluorinated Acrylic Monomers for the SurfaceModification of UV-Curable Systems

B. AMEDURI,1 R. BONGIOVANNI,2 G. MALUCELLI,2 A. POLLICINO,3 A. PRIOLA2

1 ESA 5076 CNRS 8, rue Ecole Normale 34296 Montpellier Cedex 5 France

2 Dipartimento di Scienza dei Materiali e Ingegneria Chimica Politecnico di Torino c.so Duca degli Abruzzi 24,10129 Torino, Italy

3 Istituto Chimico della Facolta di Ingegneria, Universita di Catania, V.le A.Doria, 6, 95125 Catania, Italy

Received 13 November 1997; accepted 2 June 1998

ABSTRACT: New fluorinated acrylates were synthesized and used as modifying addi-tives for acrylic UV-curable systems. Their chemical structure is: CnF2n11 R—OCO—CHACH2, where the linear perfluorinated chain contains from 4 to 10 carbon atoms,while R is a linear alkyl group containing or not a thioether group. Notwithstandingtheir very low concentration, the fluorinated monomers caused a dramatic change of thesurface properties of the films, without changing their curing conditions and their bulkproperties. X-ray photoelectron spectroscopy measurements showed that the monomerswere able to concentrate selectively on the surfaces of the films, depending on theirchemical structure and on the kind of substrate employed. The synthesis of the fluor-inated monomers and the relationship between their chemical structure and the finalsurface properties of the UV-cured films will be discussed. © 1999 John Wiley & Sons, Inc.J Polym Sci A: Polym Chem 37: 77–87, 1999Keywords: fluoroacrylates; UV curing; surface properties; fluorinated films; photo-polymerization

INTRODUCTION

The UV-curing technique has found wide applica-tion in many industrial fields for the production ofdifferent items in form of films, such as inks,coatings, adhesives, and microelectronics.1,2 Thistechnology guarantees a high productivity, selec-tivity and flexibility in the use, energy savings,and no environmental pollution due to the ab-sence of any solvent.1

The introduction of fluorine compounds inthe curable films could be promising because oftheir outstanding bulk properties such as chem-ical and thermal resistance, optical and electri-cal characteristics, and also because they can

give low wettability, low adhesion and friction,peculiar coating characteristics. Fluorinated prod-ucts are already proposed as protective films for theimpermeability of textiles,3,4 the production of elec-tronic devices,5 and the protection of optical fibers,6

stone,7 leather,8 metals,9 and paper.10 Moreover, fortheir antifouling properties they are applied aspaints for boats and any material to be used inwater.11

In this context we studied the thermal, me-chanical and optical properties of UV-curedacrylic films prepared from fluorinated oligomerssuch as modified perfluoropolyether.12

Another research line concerns the selectivemodification of the surface properties of UV-cur-able resins by copolymerizing them with lowamount of reactive acrylic monomers behavinglike surfactants.13–15 Even at very low concentra-tion they are able to deeply change the film sur-

Correspondence to: A. PriolaJournal of Polymer Science: Part A: Polymer Chemistry, Vol. 37, 77–87 (1999)© 1999 John Wiley & Sons, Inc. CCC 0887-624X/99/010077-11

77

face by selectively enriching its outermost layersas a function of the monomer structure, its con-centration and the curing conditions.16–17

As a consequence of these results, we started asystematic study on the structure–property rela-tionships of UV-cured systems containing differ-ent fluorinated monomers.

In this article the following structures havebeen taken into consideration:

C4F9—CH2—CH2—O—CO—CHACH2(C4F9Et)

C8F17—CH2—CH2—O—CO—CHACH2 (C8F17Et)

C0F21—CH2—CH2—O—CO—CHACH2

(C10F21Et)

C6F13—CH2—CH2—CH2—O—CO—CHACH2

(C6F13Pr)

C8F17—CH2—CH2—CH 2—S—CH2—CH2—O—

—CO—CHACH2 (C8F17S).

In particular, the last two compounds are newproducts, synthesized on purpose for the presentwork, and their preparation is reported.

We investigated the properties of UV-curedfilms made of a typical acrylic oligomer, Bisphe-nolA–dihydroxyethyletherdiacrylate (BHEDA), inthe presence of low amount of the different fluori-nated additives. The surface properties of the films,such as wettability, are evaluated and correlated tothe surface composition, analyzed through X-rayphotoelectron spectroscopy (XPS). The results are

discussed in terms of the structure of the fluori-nated monomers.

RESULTS AND DISCUSSION

Synthesis of the Fluorinated Monomers

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluorononylacrylate

C6F13—CH2—CH2—CH2—O—CO—CHACH2

(C6F13Pr)

This synthesis was performed in three steps, asreported in Scheme 1. The first reaction is theaddition of perfluorohexyliodide 1 to allyl alcohol2: it required a partially continuous addition ofradical initiator to yield, after 8 h at 80°C, to analmost quantitative conversion of the iodide toproduct 3. The reaction was monitored by GC;after evaporation of traces of unreacted allyl al-cohol, the gross was characterized by 1H-NMRand 19F-NMR. The 1H-NMR spectrum showed theabsence of ethylenic protons of the allyl alcoholand the presence of complex systems centred at 2.8,3.8, and 4.4 ppm: these signals could be assigned tothe methylene group linked to the perfluorinatedchain, to the hydroxyl end-group and to themethyne group. The 19F-NMR spectrum exhibited ahigh field shift of the CF2 group adjacent to the CH2group (from 259.1 to 2115.5 ppm).

The reduction of the iodine atom of product 3was performed in the presence of SnBu3H:18–20

the reaction was selective and quantitative, giv-ing rise to product 4, as evidenced by the 1H-NMR

Scheme 1.

78 AMEDURI ET AL.

spectrum, which showed a high field shift from4.40 (CHI group) to 1.75 ppm of the central CH2group. The acrylation of 4 was carried out in abenzene solution, at 120°C, with acrylic acid.21

The reaction was monitored by measuring thequantity of water expelled as azeotropic mixturewith benzene. By FTIR the appearance of theacrylic double bond (n 5 1650 and 810 cm21) waschecked. The 1H-NMR spectrum (Fig. 1) showsthe general features of the product synthesized(C6F13Pr). It is observed besides the expectedcomplex system assigned to the protons of theacrylate function, the low field shift of the signalattributed to CH2OH (d 5 3.60 ppm) to d 5 4.2ppm for the same methylene group adjacent tothe acrylate group. Some small amount of impu-rities are present: they are discussed in the ex-perimental part and are mainly due the fluoroal-cohol 4 and to AIBN by-product. The gaschro-matografic analysis showed that the purity of themonomer is about 98.6%.

The overall yield of the final product 5 wasabout 77% from C6F13I.

Synthesis of7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14-Heptadecafluoro-3-thia-tetradecylacrylate

C8F17—CH2—CH2 —CH2S—CH2—CH2—O—

—CO—CH¢CH2 (C8F17S).

This monomer was obtained through a four-stepprocedure, according to Scheme 2. The synthesisof the fluoroolefin 9 by addition of the perfluorooc-tyliodide 6 to the allyl acetate 7 and deiodoaceta-tization of the addition product 8 was described ina previous article.22 The addition of 2-mercapto-ethanol to olefin 9 can be achieved either photo-chemically or in the presence of radical initiators.Because of the high transfer constants of mercap-tans and because allylic compounds do not oli-gomerize easily, a monoaddition is always pro-duced. After distillation, the original fluoroalcohol10 was characterized by 1H -NMR: the spectrumexhibited the absence of both the ethylenic pro-tons (5.5–6.5 ppm) and the SH group (triplet at1.5 ppm), the presence of the characteristic trip-lets of the methylene groups linked with the sul-phur atom at 2.61 and 2.72 ppm. Interestingly,the 1 H-NMR spectrum shows that the thiyl rad-ical is added on the less hindered side of theolefin, as evidenced by the absence of the doubletat about 0.8–1.3 ppm, which would be assigned tothe methyl group of C8F17—CH2—CH2 (CH3)S—CH2—CH2OH in the case of reversed addition.

The acrylation of 10 and its characterizationwere carried out as described for the previousmonomer. The 1H-NMR spectrum of the mono-mer is reported in Figure 2 and discussed in theexperimental part in detail. Some impuritiesare identified: the main one (at 3.6 and 4.4 ppm)

Figure 1. 1H-NMR spectrum of C6F13Pr (in CDCl3).

NEW FLUORINATED MONOMERS 79

is due to the mercaptoethanol. The gas chro-matographic analysis gives a purity equal to98.5%. The overall yield of the final product 11was about 45%.

Films Characterization

The five acrylic monomers selected for this workwere copolymerized with the acrylic resin BHEDA

by means of the UV-curing technique. The concen-tration of the fluorinated monomers ranged from0.01% w/w up to their solubility limit in the resin.The mixtures, coated on glass substrates, upon UVirradiation gave rise to nice transparent films,which were 100 mm thick. The double-bond conver-sion of all the mixtures was 98%, corresponding tothe value obtained for the pure hydrogenated resin.

Scheme 2.

Figure 2. 1H-NMR spectrum of C8F17S (in CDCl3).

80 AMEDURI ET AL.

They showed a high gel percentage (always higherthan 96%). In the case of the addition of C8F17Et, itwas possible to check the crosslinking of the fluori-nated monomer in the acrylic network: after itsselective extraction, GPC analysis enabled the de-termination of the free monomer concentration,which was found lower than 1/100 of the quantityadded to the resin.

On all the films contact angle measurementswere performed. The wettability of the samplescontaining the monomers synthetized was remea-sured after washing them with ethanol (which isa solvent for the impurities): no difference wasobserved before and after the treatment.

The glass transition temperatures Tg of thefilms were measured by DSC and were foundindependent of the presence of the fluorinatedmonomer and always practically equal to that ofthe pure hydrogenated resin (70°C).

Surface Properties of the UV-Cured Filmsby Contact Angle

The contact angle of the pure acrylic resin withwater was around 65° on the glass side and 70° onthe air side.

When a fluorinated monomer was added to thecurable product and the mixture coated on the samesubstrate, i.e., glass, the wettability changed, asevidenced in Figures 3–7 by the contact angle re-sults, obtained with water. The data clearly showthat all the additives are effective only on the airside of the films, while the side in contact with thesubstrate keeps the same properties of the pureresin.

The contact angle measured on the air sideclearly depends on the fluorinated monomer con-centration.

The behavior of C4F9Et, C8F17Et, andC10F21Et is asymptotic and shows a plateauvalue that is reached at a concentration calledcritical value. Comparing the three plots, one seesthat the longer the fluorinated chain, i.e. thehigher the fluorine content, the lower the criticalvalue. The same dependence links the plateauvalue to the type of monomer employed. The high-est contact angle, which is around 120° and istypical of a complete hydrophobic surface such asPTFE, is obtained with C10F21Et. With C4F9Etand C8F17Et the results are 78 and 83°, respec-tively, i.e. a medium polarity surface is formed,containing hydrophobic groups (the fluorinatedchains) together with the polar groups of theacrylic oligomer.

The other additives, C6F13Pr and C8F17S,showed a more complex behavior as a function of

Figure 3. Advancing contact angle of UV-cured filmcontaining different concentration of C4F9Et.




the concentration and of the fluorine content inthe film. One can see that the trend of the contactangle plot vs. concentration is sigmoidal and hastwo distinct plateaux. Moreover, comparing theseadditives with the monomer having the same flu-orinated chain, the value of wettability is remark-ably higher.

Besides the contact angle and the surface ten-sion results, further information on the film sur-faces are obtained by the contact angle hysteresis,i.e., the difference between advancing and reced-ing angle. Hysteresis is expected from most ma-terials, particularly those containing at the sur-face both hydrophobic and hydrophilic groups.For the pure resin its value was 28 and 35° for theair side and the glass side, respectively. As far asthe glass side is concerned, in the presence of thefluorinated additives no change in the hysteresiswas observed. On the contrary, as Figures 8 and 9show, on the air side there is an increase of

hysteresis. It is clearly dependent on the mono-mer concentration and on the fluorinated chainlength. Therefore, it is connected to the hydropho-bicity of the monomers that form a heterogeneoussurface. In the case of C4F9Et, C8F17Et, andC10F21Et the behavior is asymptotic: the surfaceheterogeneity increases at first, then keeps a con-stant value, indicating the formation of an equi-librium surface layer corresponding to the compo-sition of the fluorinated monomer.

In the case of C6F13Pr and C8F17S the behav-ior is more complex, resembling to that of theadvancing contact angle.

X-rays Photoelectron Spectroscopy Analyses

The selective modification of the film surface isconfirmed by the XPS results. They allow the

Figure 6. Advancing contact angle of UV-cured filmcontaining different concentration of C6F13Pr.

Figure 7. Advancing contact angle of UV-cured filmcontaining different concentration of C8F17S.

Figure 8. Hysteresis of the air side of UV-cured filmscontaining fluorinated monomers.

Figure 9. Hysteresis of the air side of UV-cured filmscontaining fluorinated monomers.

82 AMEDURI ET AL.

estimation of the concentration of some elementsin the outermost layer of the sample. As the mea-surements were made at two different take-offangles, namely 30 and 90°, a concentration profileof the elements in the external layer of the samplecan be done.

The O1s/C1s ratios for a series of films contain-ing a concentration of fluorinated monomer aboveits critical value (i.e. where the film wettabilityreaches the asymptotic value) are collected in TableI. The values concerning the glass side are close tothose measured on the film made of the pure hydro-genated resin (0.30). The oxygen content is higherthan expected on the basis of the chemical compo-sition (ca. 0.24) and the C™O component is moreintense. In fact traces of O2 present in the curingprocess give rise to the formation of peroxy radicalsas previously observed.15 On the air side, a decreaseof the O/C ratio is observed when the most hydro-phobic monomers were used, i.e. C10F21Et andC8F17S.

The F1s/C1s ratios for the cured films are alsocollected in Table I. Examining these data, a clearasymmetry of the surface composition betweenthe air side and the glass side is noted, especiallyfor the acrylates having higher MW. On the airside the content of fluorine is much higher thanexpected on the basis of the film composition. Asfar as the monomers with the longest perfluori-nated chains are concerned, the surface enrich-ment in fluorine in the most external layers (re-sults at take-off angle 5 30°) is extremely strong:

in fact, the F/C ratio is even two order of magni-tude greater than that of the bulk.

Moreover, in the case of films containingC8F17Et, C8F17S, and C10F21Et, the F1s/C1sratio approaches the calculated value of the purefluorinated monomers (1.31, 1.06, and 1.40, re-spectively).

As far as the air side of the films containingC8F17S is concerned, the XPS results at take-offangle 5 30° are plotted in Figure 10, transformedin weight percentage of the fluorinated monomer.The curve has the same shape as that of the

Table I. XPS Results at Different Take-Off Angle

Sample DescriptionTake-Off Angle

F1s/C1s (Atomic Ratio) O1s/C1s (Atomic Ratio)

Glass Side Air Side Glass Side Air Side

90° 30° 90° 30° 90° 30° 90° 30°

0.9% C4F9Et 0.01 0.0 0.01 0.02 0.30 0.30 0.29 0.29theoretical values 0.0043a 0.24b

0.8% C8F17 Et 0.011 0.015 0.62 1.13 0.28 0.29 0.32 .31theoretical values 0.0045a 0.24b

0.3% C10F21Et 0.03 0.05 0.59 1.1 0.31 0.34 0.27 0.25theoretical values 0.0017a 0.24b

0.9% C6F13Pr 0.03 0.03 0.11 0.25 0.31 0.32 0.30 0.30theoretical values 0.0046a 0.24b

0.8% C8F17S 0.19 — 0.61 1.02 0.31 0.27 0.24 0.20theoretical values 0.0041a 0.24b

a Calculated on the basis of the bulk composition.b This value was calculated on the basis of the bulk composition; the value measured on the pure BHEDA film was 0.30, due to

the presence of peroxide groups (see text).

Figure 10. Surface concentration of C8F17S vs. bulkconcentration (air side).


contact angle plot of Figure 7: the wettability isclearly correlated to the fluorine concentration ofthe surface. At different concentration of themonomer in the bulk, a different surface concen-tration is observed, due to the selective migrationof the additive.

At different take-off angles, the F1s/C1s ratiois different, indicating that the fluorine concen-tration increases gradually to the outermost airside of the film. On the contrary, on the glass sideonly negligible variations of the composition aremeasured.

CONCLUSIONS

The results obtained in this work assess the highsurface activity of the fluorinated monomers inves-tigated. When they are introduced in a UV-curablemixture, notwithstanding the low concentration (al-ways lower than 1% w/w), they selectively modifythe surface properties of the cured films.

In the presence of a fluorinated acrylic mono-mer, a deep decrease of the wettability is obtainedon the air side, while the opposite side, in contactwith a polar substrate, is not modified and main-tains the polar characteristics of the pure resin.

The surface properties of the films depend onthe amount of reactive additive present in thecurable mixture. In the case of the monomersC4F9Et, C8F17Et, and C10F21Et, having twomethylene groups as the spacer between the flu-orinated chain and the ester function, the wetta-bility vs. concentration curve referred to the airside is asymptotic: at low concentration there is alinear variation of the contact angle as a functionof the amount of the additive, whereas above acritical concentration its value remains constant.As confirmed by XPS analyses, the plateau corre-sponds to the formation of a layer made of thefluorinated additive. Moreover, the surface activ-ity of these three monomers is proportional totheir fluorine content: the most efficient productis C10F21Et, which, when its concentration isgreater or equal to 0.3%, gives a very apolar sur-face (118°), as hydrophobic as a fully fluorinatedsystem such as PTFE.

The monomers with a longer hydrogenatedspacing group, and/or containing heteroatoms (S),cause a dramatic change of wettability, whichcould be due to their different packing on themonomer surfaces.

The contact angle and the hysteresis curveshave a sigmoidal trend and the plateau valuescould be attributed to different surface morphol-

ogies. The first one could be due to the formationof surface aggregates of the fluorinated groups,whereas the second one is due to the formation ofa continuous layer made of the additive as indi-cated by the XPS results.

EXPERIMENTAL

Materials

The monomers C4F9Et, C8F17Et, and C10F21Etwere purchased from Daikin Chemicals (Japan)and were all used as received.

The monomers C6F13Pr and C8F17S weresynthesized as reported below.

The main reagents for the synthesis, i.e. theperfluoroalkyliodides, were kindly supplied byElf Atochem; allyl alcohol, allyl acetate, zinc,2-mercaptoethanol were purchased from Ald-rich, azoisobutyrronitrile (AIBN) and benzoyl-peroxide from Merck. The reagents did not re-quire any purification prior to use.

The acrylic resin used in this work is Bisphe-nolAdihydroxyethyletherdiacrylate (trade nameEbecryl 150). It was generously supplied by UBC,Belgium. Its chemical structure is:

2-Hydroxy-2-methyl-1-phenylpropan-1-one (Daro-cure 1173, Merck) was used as the photoinitiator: itwas added to the curable mixtures at a concentra-tion equal to 4% w/w.

Analytical Techniques

After every reaction, both the intermediate andthe final products were worked up and analyzedby gas chromatography (GC) using a Delsi appa-ratus (model 330) equipped with an SE 30 col-umn, 1 m 3 1/8 inch. The nitrogen pressure at theentrance to the column was maintained at 0.6bar, and the detector and injector temperatureswere 260 and 255°C, respectively. The tempera-ture programme started from 50°C and attained250°C at a heating rate of 15°C/min. The GCapparatus was connected to a Hewlett Packard

84 AMEDURI ET AL.

integrator (model 3390) that automatically calcu-lated the area of each peak on the chromatogram.

The products were characterized by 1H-NMR,19F-NMR, and 13C-NMR spectroscopy, all under-taken at room temperature.

1H-NMR and 13C-NMR spectra were recordedon Bruker AC-200, AC-250, or MW-360 instru-ments using deuterated chloroform as the solventand TMS as the internal reference. The letters s,d, t, q, and m designate singlet, doublet, triplet,quintet, and multiplet, respectively. 19F-NMRspectra were also recorded on Bruker AC-200 orAC-250 instruments, with deuterated chloroformas lock and CFCl3 as the internal reference. Cou-pling constants and chemical shifts are given inHertz (Hz) and ppm, respectively.

The FTIR spectra were recorded by means of aGenesis ATI Mattson spectrometer.

SYNTHESIS OF C6F13PR AND C8F17S

Procedures for the Synthesis of C6F13Pr

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluoro-2-iodononanol, 3

Fifty grams of perfluorohexyl-1-iodide 1 (0.112mol) and 6.96 g of allyl alcohol 2 (0.120 mol) wereintroduced in a three-necked round-bottomedflask equipped with a stirrer, a condenser, and athermometer. The mixture was warmed up at80°C, then 50 mg of AIBN (0.31 mmol) wereadded with small additions. The mixture wasthen maintained at 80°C for other 4 h. The prod-uct, a yellow wax at room temperature, was dis-tilled (b.p. 5 70°C, 0.15 Torr), and the yieldwas 70%.

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluorononanol, 4

In an ampoule containing 15.1 g of 3 (0.030 mol)equipped with a septum, saturated with nitrogen.and cooled in an ice bath, were dropwise added10.4 g of SnBu3H (0.0357 mol) by means of asyringe. After complete addition, the gross waskept stirring at room temperature for 1 h andthen heated up to 50°C for an additional hour.C6F13C3H6OH was extracted with diethylether,dried over MgSO4 and distilled (b.p. 5 71°C/20Torr). It appeared as a colorless liquid. The yieldwas 81.9%.

1H-NMR (CDCl3) d: 1.8 (m, central CH2, 2H),2.1 (m, CF2CH2, 2H), 3.6 (t, J57.0 Hz, CH2OH,

2H), 4.1 and 4.5 (broad s, shifted by dilutionOH, 1H).

13C-NMR (CDCl3) d: 120 –95 (m, CF3 and CF2groups, 6C), 67.6 (s, CH2OH, 1C), 36.3 (t,C6F13CH2™,CF

2 . J 521.6 Hz, 1C), 20.8 (s,CH2CH2CH2OH, 1C), 16.2 (s, CH2OH, 1C).

19F-NMR spectrum (CDCl3) d: 281.9 (t, CF3, 3F),2113.5 and 2115.5 (2m, CF2CH2, 2F), 2122.4 (m,CF2,CF2CH2, 2F), 2123.6 (m, C3F7CF2, 2F), 2124.3(m, C2F5CF2, 2F), 2127.1(m, CF3CF2, 2F).

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluorononanylacrylate, 5 (C6F13Pr)

Five grams of 4 (13.3 mmol) were dissolved in 80mL of benzene in a three-necked round-bottomedflask equipped with a stirrer, a Markusson con-denser, and a thermometer. Acrylic acid (1.24 g)(17.3 mmol, equal to 30% excess with respect tothe alcohol 4), 0.5 mL of methansulphonic acid,and 0.5 g of p-toluensulphonic acid were added.By means of a thermostatic bath the mixture waswarmed up to 120°C and maintained at that tem-perature for 8 h, during which the water wasdistilled as an azeotropic solution with benzene.After cooling down the reaction mixture, potas-sium carbonate was added to neutralise the ex-cess of acrylic acid. The suspension was filtered.The benzene was evaporated from the remainingsolution The product was a yellowish liquid; thefinal yield was 93%.

1H-NMR (CDCl3) (Fig. 1) d: 2.0 (m, Rf™CH2CH2,2H), 2.2 (m, RfCH2, 2H), 4.2 (t, J5 7.2 Hz,CH2OCO, 2H), 6.2 (t, acrylic CH, 1H), 5.9 and 6.5(d, acrylic CH2, 2H). Some impurities are present:one is the nonacrylated alcohol at 4.4 ppm. Tracesof benzene and CHCl3 are recognizable at about7.3 ppm; the peaks at 1.6 and 1.2 ppm can be dueto the AIBN decomposition products (recombina-tion product of isobutyrronitril radical) alsopresent in the precursor alcohol.

19F-NMR (CDCl3): similar characteristics asthose of the fluoroalcohol 4.

Procedures for the Synthesis of C8F17S

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-Heptadecafluoro-2-iodo-undecyl-acetate, 8

Four hundred forty grams of perfluorooctyl iodide6 (0.8 mol) were introduced in a three-neckedround-bottomed flask equipped with a stirrer, acondenser, and a thermometer. Eighty grams ofallyl acetate 7 (0.8 mol) were added. By a thermo-static bath the temperature was raised up to 90°C


and, under stirring, 0.3 g of dibenzoyl peroxidewere added in three portions every 10 min. Thereaction was monitored by GC, and the conver-sion was quantitative after 20 min.

Synthesis of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-Heptadecafluoroundecene, 9

Five hundred twenty grams of iodoacetate 8 (0.8mol) was dissolved in 330 mL of methanol andintroduced dropwise in a two-necked round-bot-tom flask containing 96 g of zinc (1.6 mol) understirring. The mixture was warmed up to and keptat that temperature for 3 h. After filtering theremaining zinc, the product 9 was distilled, b.p.5 65–68°C/24 Torr (in ref. 22: 55–60°C/20 Torr).The yield was 45% from C8F17I.

Synthesis of7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14-Heptadecafluoro-3-thia-tetradecanol, 10

Fifty grams of heptadecafluoroundecene 9 (0.108)were put in a two-necked round-bottom flask to-gether with 8.48 g of 2-mercaptoethanol (0.108mol) in 20 mL of acetonitrile, in the presence of0.27 g of AIBN (initial (AIBN)/(olefin) molar ratio5 0.015). The mixture was warmed up at 80°Cand stirred for 6 h.

After removing the solvent, product 10 wasdistilled (b.p. 5 118–122°C/0.03 mbar). The finalyield was 40%.

1H-NMR d: 1.90 (complex q, RfCH2CH2, 2H), 2.16(m, RfCH2, 2H), 2.50 ( broad s, shifted with dilution,OH, 1H), 2.61 (t, J57.0 Hz, Rf™C2H4™CH2S, 2H),2.72 (t, J56.0 Hz, SCH2CH2OH, 2H), 3.73 (t, J56.0Hz, CH2OH, 2H). Impurities: traces of benzoic acidat 7.2–7.8 ppm due to the decomposition of thedibenzoyl peroxide used for the synthesis of 8; traceof 2-mercaptoethanol at 3.6 ppm.

Synthesis of7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14-Heptadecafluoro-3-thia-tetradecylacrylate, 11(C8F17S)

The synthesis of fluoroacrylate 11 was performedwith the similar procedure as that of acrylate 5from 10.22 g of 10 (0.0185 mol), dissolved in 80mL of benzene, and 1.77 ml of acrylic acid (0.0241mol, equal to a 30% excess with respect to thealcohol 10), together with 0.5 mL of methansul-phonic acid and 0.5 g of p-toluensulphonic acid.

The product was a yellowish liquid; the finalyield was 91%.

1H-NMR spectrum (Fig. 2): the same spectro-scopic parameters as those of the alcohol and thetypical signals of the acrylic protons as discussedabove for the spectrum of product 5. Some impu-rities are present: the main one is due to themercaptoethanol present in the fluoroalcohol 10(3.6 ppm). The signal at 4.4 ppm is due to themethylene group of the product obtained by theacrylation of the mercaptoethanol. In the region7.2–7.8 ppm, the signals can be assigned to thebenzoic acid formed by decomposition of benzoylperoxide used for the synthesis of 8. Traces ofbenzene and CHCl3 are recognizable at about7.3 ppm.

Film Preparation

The films were obtained by coating the photopo-lymerisable mixture on a glass slide with a cali-brated wire-wound applicator to obtain a thick-ness of about 100 mm. The curing reaction wasperformed in a small box equipped with a quartzwindow under N2 atmosphere (O2 content , 20ppm) by UV irradiation with a 500 W mediumpressure Hg lamp (light intensity 5 12 mW cm 22

on the film surface), equipped with a water jacketfor IR radiation screening and a camera shutterto control the UV exposure time. The irradiationwas stopped when a constant double-bond conver-sion was found, as determined by FTIR measure-ments. The films were peeled away from the sub-strate; the surface in contact with the substratewas labeled as the glass side, the other one as theair side. The complete procedure is reported else-where.14

Films Characterisation Methods

The film thickness was measured using a Minit-est 3000 Instr. (Elektrophysik Koln, Germany).The double-bond conversion was determinedby Fourier Transform Infrared spectroscopy(FTIR) by measuring the change of the area ofthe absorption band at 1640 cm21. The FTIRmeasurements were performed by using an ATIMattson Genesis spectrometer, computer con-trolled. The gel content was determined by mea-suring the weight decrease after 24-h treatmentat room temperature with chloroform.

The amount of the unreacted monomer in thecured films was evaluated by gel permeation chro-matography (GPC) after extraction with hot THF.GPC analyses were performed on a Varian 5020

86 AMEDURI ET AL.

Instruments, in THF solutions at 25°C with aseries of Styragel columns (Polymer Laboratories)and a Hewlett-Packard UV-detector. Polystyrenewas used as standard.

DSC analyses were performed by a MettlerDSC 20 (initial T 5 250°C, final T 5 150°C,heating rate 10°C/s).

Contact angle measurements were performedwith a Kruss G1 instrument, at room tempera-ture (20°C) by means of the sessile drop tech-nique. On every sample at least six measure-ments were performed; the difference from theaverage value was no more than 2° for the ad-vancing angle, 4° for the receding angle. The mea-suring liquid was doubly distilled water whosesurface tension at 20°C was 72.1 mN/m.

XPS measurements were performed by meansof a VG Instrument MT500 equipped with aCLAM II analyzer, Twin Anod Mg/Al. The take-off angle was either 30 or 90°.

We thank Dr. S. Spera (Istituto Donegani, Enichem) foruseful discussions on the NMR spectra interpretation.Elf Atochem (France) and UCB (Belgium) are acknowl-edged for supplying some of the products used for thiswork.

REFERENCES AND NOTES

1. Fouassier, J. P.; Rabek, J. F. Eds.; Radiation Cur-ing in Polymer Science and Technology, vols. 1–4,Elsevier: London, 1993.

2. Pappas, S. P.; Ed.; Radiation Curing, Science andTechnology, Plenum Press: New York, 1992.

3. Gavet, L.; Amboise, G.; Giorgio, A. French Instituteof Textile, Eur. Pat. Appl. 0446082, 1991.

4. Sherman, P. O.; Smith, S. 3M, Fr. Pat. 1520078, 1968.

5. Sillion, B.; Rabilloud, G. In New Methods of Poly-mer Synthesis, McGrath, J. E., Ed.; Plenum Press:New York, 1995; p 115.

6. Klinger, L.; Griffith, J. R. Org Coat Appl Polym Sci1983, 48, 407.

7. Castelvetro, V.; Aglietto, M.; Montagnini, L.; ProcFluorine in Coatings II, Munich, 1997, paper no.27.

8. Bonardi, C.; Elf Atochem, Eur. Pat. Appl. EP426530, 1991.

9. Vanoye, D.; Ballot, E.; Legros, R.; Loubet, O.;Boutevin, B.; Ameduri, B. Elf Atochem, Fr. Pat.9414367, 1994.

10. Deisenroth, T. Proc Fluorine in Coatings II, Mu-nich, 1997, paper no. 39.

11. Brady, R. Jr. In Modern Fluoropolymers, Scheirs,J. Ed., Excel Pas Australia: Victoria, 1997; p 127.

12. Priola, A.; Bongiovanni, R.; Malucelli, G.; Tonelli,C. Makrom Chem Phys 1997, 198, 1893.

13. Priola, A.; Gozzelino, G.; Ferrero, F. Int J AdhesAdhes 1990, 10, 77.

14. Torstensson, M.; Ranby, B.; Hult, A. Macromole-cules 1990, 23, 126.

15. Bongiovanni, R.; Malucelli, G.; Priola, A. J ColloidInterface Sci 1995, 171, 283.

16. Bongiovanni, R.; Pollicino, A.; Malucelli, G.; Priola,A.; Ameduri, B. Pol Adv Technol 1996, 7, 403.

17. van der Grinten, M. G. D; Clough, A. S.; Shearmur,T. E.; Bongiovanni, R.; Priola, A. J Colloid InterfaceSci 1996, 182, 511.

18. Kotora, M.; Hajek, M.; Ameduri, B. Boutevin, B.; JFluorine Chem 1994, 68, 49.

19. Newmann, W. J. Synthesis, 1987, 665.20. Balague, J.; Ameduri, B.; Boutevin, B.; Caporiccio,

G. J Fluorine Chem 1995, 74, 49.21. Malucelli, G.; Gozzelino, G.;. Ferrero, F.; Bongio-

vanni, R.; Priola, A. J Appl Polym Sci 1997, 5, 491.22. Ameduri, B.; Boutevin, B.; Nouiri, M.; Talbi, M. J

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New fluorinated acrylic monomers for the surface modification of UV-curable systems

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