光固化材料

Properties of UV-curable coatings containing¯uorinated acrylic structuresR.Bongiovanni,G.Malucelli,M.Sangermano,A.Priola *Dipartimento di Scienza dei Materiali e Ingegneria Chimica,Politecnico di Torino,c.so Duca degli Abruzzi 24,10129Torino,ItalyReceived 3September 1998;accepted 12February 1999AbstractUV-curable systems based on the copolymerisation of typical acrylic resins with ¯uorinated derivatives were prepared and their properties investigated.Firstly we used as comonomer,4,4H -hexa¯uoroisopropylidendiphenoldihydroxyethyletherdiacrylate which gives rise to homogeneous systems when mixed with the corresponding hydrogenated monomer.By using per¯uoropolyetherurethanemetha-crylates,®lms having interesting properties were obtained.When copolymerising a low amount of ¯uorinated acrylates with acrylic resins,the bulk properties of the ®lms remained unchanged,but a selective modi®cation of the surface was obtained.A series of acrylic esters of alcohols having a per¯uorinated group ÀC n F 2n 1were investigated.In all cases,a selective enrichment of the ¯uorinated monomer on the ®lm surface was observed,depending on the monomer structure,its concentration and the type of substrate.#1999Elsevier Science S.A.All rights reserved.Keywords:UV-curable coatings;Photopolymerisation;Fluorinated acrylic oligomers;Surface properties1.IntroductionThe use of ¯uorinated monomers and oligomers for coatings is very attractive due to the peculiar characteristics given by the presence of ¯uorine:hydrophobicity,chemical stability,weathering resistance,good release properties,low coef®cient of friction,water impermeability and low refrac-tive index.Different ¯uorinated monomers are already used for many coating applications [1±3].It seemed interesting to employ ¯uorinated structures in UV-curable systems.Photopolymerisation processes offer many advantages that are of great interest in industrial applications.They include solvent-free formulations char-acterised by high production rates and high energy ef®-ciency compared to thermal systems.The advantages afforded by photopolymerisation pro-cesses have led to their rapid growth in applications in different ®elds as ®lms,inks and coatings on a variety of substrates,including paper,metal,plastic and wood.Moreover,a variety of high-tech and electronic applica-tions,such as coatings on optical ®bres and the fabrication of printed circuit boards,were developed.The more important developments and applications of UV-curing technique are reported in recent reviews [4,5].By introducing ¯uorinated monomers in UV-curable sys-tems,it would be possible to combine the advantages of both technologies giving rise to cure products with outstanding properties.Some papers have already described this research line [6,7].Our research was conducted following two different approaches:1.the homopolymerisation of ¯uorinated oligomers;and2.the copolymerisation of these oligomers with a hydro-genated acrylic resin.Firstly,we prepared ¯uorinated oligomers,starting from bis-hydroxy structures and synthesising the homologous acrylic derivatives.Then we investigated their behaviour in the UV-curing process and the thermal,mechanical and chemical properties of the cured ®lms.The copolymerisation approach was applied by using acrylic resins to which were added low amounts of ¯uori-nated oligomers.Moreover,a systematic investigation of the copolymerisation of an acrylic resin with monofunctional ¯uorinated monomers was performed.The products had the following structure:C n F 2n 1R ÀOCO ÀCH CH2Progress in Organic Coatings 36(1999)70±78*Corresponding author.Tel.:+39-11-5644656;fax:+39-11-5644699;e-mail:priola@fenice.polito.it0300-9440/99/$±see front matter #1999Elsevier Science S.A.All rights reserved.PII:S 0300-9440(99)00033-8changing both the linear per¯uorinated chain and the R group [7].In this case,because of the low solubility of the ¯uorinated products,the modi®cation of the ®lms was limited to the surface properties,while the bulk ones remained practically constant.The interesting aspect of this research was that a strong modi®cation of the surface properties was obtained at a very low concentration of the ¯uorinated products.They showed a peculiar ability to migrate selectively to the outermost layers of the ®lm,behaving as surfactants.The selective enrichment of the ¯uorinated monomers on the ®lm surface is due to the minimisation of the interfacial energy by the reduction of the surface tension of the ®lm.In this context,the use of ¯uorinated monomers is very promising because of their very low surface tension [8,9].The ®nal properties of the ®lms were correlated to the monomer structure,its concentration and the curing condi-tions.2.Experimental 2.1.MaterialsA typical UV-curable resin,kindly supplied by UCB Belgium,was used as reference product.Its structure cor-responds to bisphenolA-dihydroxyethyl diacrylate (BHE-DA).The ¯uorinated oligomers were:1.4,4H hexa¯uoroisopropylidendiphenoldihydroxyethyleth-erdiacrylate (BHEDAF),which was synthesised by esteri®cation with acrylic acid [10]of the corresponding diol kindly supplied byAtochem:2.two perfluoropolyether bis-urethanemethacrylates (PFEUMA),with a macromeric segmented structure,Rh±Rf±Rh,where Rhisand Rf isÀCF 2O À CF 2ÀCF 2ÀO p À CF 2ÀO q ÀCF 2Àwith p %q .They were synthesised by the reaction of the corresponding perfluoropolyetherdiol (trade name ZDOL 1,by Ausimont S.p.A.;M.W.1000and 2000)and isocyanate-ethyl-methacrylate [9].3.the following monomers were used for the selective surface modification of BHEDA films:C 4F 9ÀCH 2ÀCH 2ÀO ÀCO ÀCH CH 2 C4F9Et C 8F 17ÀCH 2ÀCH 2ÀO ÀCO ÀCH CH 2 C8F17Et C 10F 21ÀCH 2ÀCH 2ÀO ÀCO ÀCH CH 2 C10F21Et C 6F 13ÀCH 2ÀCH 2ÀCH 2ÀO ÀCO ÀCH CH 2 C6F13Pr C 8F 17ÀCH 2ÀCH 2ÀCH 2S ÀCH 2ÀCH 2ÀO ÀCO ÀCH CH 2 C8F17SThe monomers C4F9Et,C8F17Et and C10F21Et were purchased from Daikin Chemicals (Japan);C6F13Pr and C8F17S were synthesised according to the procedure reported elsewhere [11].2.2.Film preparationFilms,100m m thick,were prepared by UV-curing the pure acrylates and their mixtures,coated onto a glass or a polyethylene substrate.The complete procedure is reported elsewhere [12].The ®lm side in contact with the substrate was labelled as the glass or PE side and the opposite one as the air side.2,2-dimethoxy-2-phenylacetophenone (Iraga-cure 651,Ciba-Geigy)or 2-hydroxy-2-methyl-1-phenylpro-pan-1-one (Darocure 1173,Merck)were added as photoinitiators (4%w/w);the latter was used mainly with the pure ¯uorinated derivatives.The curing was performed under nitrogen atmosphere with a mercury lamp having an intensity of about 12mW cm À2:three shots of 10s assured the maximum constant conversion value of the acrylic double bonds.2.3.Film characterisationThe ®lm thickness was measured using a Minitest 3000Instr.(Elektrophysik KoÈln,Germany).The double bond conversion was determined by Fourier Transform Infra-Red spectroscopy (FTIR)by measuring the change in the area of the absorption band at 1640cm À1before and after the UV irradiation.The FTIR measurements were performed by using an ATI Mattson Genesis Series II spectrometer.The gel content was determined by measuring the decrease in weight after a 24h treatment at room tempera-ture with chloroform.For a few ®lms,the amount of the unreacted monomer was evaluated by gel permeation chro-matography (GPC)after extraction with hot THF.GPC analyses were performed on a Varian 5020Instruments,in THF solutions at 258C with a series of Styragel columns (Polymer Laboratories)and a Hewlett-Packard UV-detector.Polystyrene was used as standard.DSC analyses were performed by means of a Perkin Elmer 2C or a Mettler DSC 20instruments in the range À120± 1508C with a heating rate of 108C min À1.Dynamic-mechanical analyses (DMTA)were performed on a MK II Polymer Laboratories Instr.at 5Hz frequency in the tensile con®guration.The size of the specimen was about 14mm Â9mm Â0.1mm.The storage modulus,E H ,theR.Bongiovanni et al./Progress in Organic Coatings 36(1999)70±7871loss factor and tan ,were measured up to the temperature at which the rubbery state was attained.The T g value was assumed to be the maximum of the loss factor curve. Contact angle measurements were taken on both sides of the®lms after peeling them off the substrate.They were performed with a Kruss G1instrument,at room temperature (208C)by means of the sessile drop technique[13].On every sample,at least six measurements were performed;the difference from the average value was no more than28 for the advancing angle and48for the receding angle.On the homopolymeric®lms,the measurements were con®rmed when possible with the Cahn balance(immersion rate 80m m sÀ1)and were made by means of the Wilhelmy technique[9].The measuring liquids were doubly distilled water and methylene iodide(Fluka,98%),whose surface tension at 208C was72.1and50.8mN mÀ1,respectively.The advancing contact angle values were processed according to the harmonic mean method[14]in order to calculate the surface tension of the®lms.XPS measurements were performed by means of a VG Instrument MT500equipped with a CLAM II analyser,Twin Anod Mg/Al.The take-off angle was either308or908. The refractive index was evaluated either by measuring the re¯ectance of the®lm using a UV-near IR instrument (Perkin Elmer)or with an Abbe refractometer at208C,using white light.3.Results and discussion3.1.Homopolymerisation of BHEDAF and PFEUMATable1collects some results concerning the bulk proper-ties of the UV-cured®lms obtained from BHEDAF and PFEUMA oligomers compared to the BHEDA ones. The acrylic double bonds conversion is rather high;the gel content is always higher than98%.BHEDAF®lms show a higher T g value compared to BHEDA:in fact,the presence of the tri¯uoromethyl groups linked to the polymer chain reduces the chain¯exibility[1].The thermal behaviour of PFEUMA®lms is more com-plex.While the BHEDAF systems are homogeneous,the PFEUMA ones contain two phases:the former,having higher T g values,is likely to be due to either a mixed phase or an interphase region,containing both¯uorinated and hydrogenated segments.The latter shows very low T g values close to those of the corresponding diols and is,therefore, attributable to the PFPE chains.In Fig.1,a typical DMTA spectrum of the UV-cured PFEUMA1000®lm is reported:it clearly con®rms the biphasic nature of the product.In Table1,the refractive indices of the®lms are reported: they are lower for the¯uorinated®lms than for those of BHEDA,according to the general behaviour of¯uorinated polymers[1].The PFEUMA®lms,although they are heterogeneous,as shown by the thermal and DMTA analyses,are completely transparent.As the¯uorinated phase has a refractive index very different from that of the hydrogenated moiety,i.e.1.31 and1.50,respectively,the transparency must be attributed to the small dimension of the domains,which must be smaller than the wavelength of the visible light.The measured refractive indices of the®lms(1.375and 1.347for the PFEUMA1000and PFEUMA2000,respec-tively)are in agreement with the calculated ones,on the basis of the refractive index of the hydrogenated and¯uori-nated phases and their volume fractions:the calculated refractive index of the PFEUMA1000film: 0X63Â1X31 0X37Â1X50 1X38experimental value 1X375the calculated refractive index of the PFEUMA2000film: 0X76Â1X30 0X24Â1X50 1X35experimental value 1X347In Table2,the surface properties of the films obtained from the aforementioned monomers are collected.The films containing fluorine show a clear increase in the contact angle with water;its value is higher than908C,thus indicating that the surfaces are highly hydrophobic and non-wettable by water.For the PFEUMA®lms,wettability is lower than that of the BHEDAF®lms due to the higher¯uorine content and the peculiar properties of PFPE chains.Moreover,it can be noted that the air side of the®lm shows a higher contact angle and hysteresis value(i.e.the difference between the advancing and receding contact angle)with respect to the glass side,indicating that the¯uorinated chains are pre-dominant at the less polar®lm±air interface.Table1Bulk properties of the homopolymeric filmsBulk properties BHEDA BHEDAF PFEUMA1000PFEUMA2000 Double bond conversion(%)83.182.596.797.0Gel content(%)98.299.099.598.2T g DSC(8C)34.157.0 3.0 2.0À92.0aÀ111.0aN D 1.983 1.931 1.375 1.347a T g of the PFPE phase.72R.Bongiovanni et al./Progress in Organic Coatings36(1999)70±78XPS analyses of the ®lm surfaces con®rm the previous data (Table 3),showing a different surface composition between the sides of the ®lms,especially for the oligomer having higher MW.Measurements at different take-off angles indicate that the ¯uorine concentration increases gradually from the bulk to theoutermostairsideofthe®lm.Infact,thelowertheangle,the smaller is the sampling depth and a higher F/C ratio is measured.On the contrary,on the glass side,only negligible variations of the composition are measured.3.2.Copolymerisation of BHEDA with fluorinated additives3.2.1.Copolymerisation with BHEDAFBHEDA and BHEDAF are miscible in all ratios.The mixtures can be UV-cured in the same conditions as the puremonomers,giving rise to homogeneous and transparent ®lms showing similar values of the double bond conversion as the homopolymers.The bulk and surface properties of the ®lms were examined.In Fig.2,the reciprocal value of T g of the UV-cured ®lms determinedbyDSCanalysisisplottedagainstthecomposition.The results can be ®tted by the Fox equation;therefore,we can conclude that the copolymerisation between the two mono-mers is homogeneous and of the random type.In Fig.3,the refractive index n measured at different wavelengths is plotted as a function of the ¯uorinated monomer concentration:an almost linear decrease of n by increasing the BHEDAF content isobserved.Fig.1.Typical DMTA spectrum of the UV-cured PFEUMA 1000film.Table 2Surface properties of the homopolymeric films Surface properties BHEDA BHEDAF PFEUMA 1000PFEUMA 2000 air side 7591124127Hysteresis (8)8987 glass side 7092106112Hysteresis (8)±±4445Table 3XPS analyses of PFEUMA films aTake-off anglePFEUMA 1000PFEUMA 2000F/C F/C 308 1.27 1.52Theoretical bulk values 1.08 1.40Glass side908 1.04 1.153081.131.24aF/C atomic ratio.R.Bongiovanni et al./Progress in Organic Coatings 36(1999)70±7873Fig.2.1/T g as a function of BHEDAF concentration for BHEDA±BHEDAFmixtures.Fig.3.Refractive index as a function of BHEDAF concentration for BHEDA±BHEDAF mixtures.74R.Bongiovanni et al./Progress in Organic Coatings 36(1999)70±78Table4collects the surface tension value as a function of the¯uorinated monomer content.The main result can be summarised as follows:1. decreases mainly on the air side and its value depends on the¯uorinated monomer concentration;and2.the two sides of the films have different ;the glass side is clearly more polar than the air side.The asymmetry of the copolymeric®lm surfaces is more evident when examining the surface tension components:on the glass side, and p remain constant when the BHEDAF content is increased;on the air side,g p decreases nearly to one-half when the BHEDAF content reaches50%. Table5collects the XPS analyses performed on the cured ®lms having a BHEDAF content equal to25%.The F/C ratios clearly show a surface enrichment of BHEDAF on the air side.Analyses at different take-off angles show the decrease in the¯uorinated monomer concentration from the air side towards the bulk.These data can explain the increase in the contact angle observed with water on the air side and the asymmetry of the surface.3.2.2.Copolymerisation with PFEUMAThe PFEUMA solubility in the BHEDA resin is limited to 0.5%w/w;therefore,the investigation was limited to this concentration level.The concentration being so low,the copolymeric®lms maintained the same bulk properties as the pure BHEDA ones.On the contrary,the surface properties changed strongly, as evidenced in Figs.4and5.The data clearly show that ¯uorinated oligomers are effective only on the air side of the ®lms,while the side in contact with the substrate keeps the same properties as the pure BHEDA resin[10].The contact angle measured on the air side depends on the additive concentration.The dependence is asymptotic;at the plateau, is greater than1008(which is the typical value of a totally hydrophobic surface)and approaches the value obtained on the homopolymeric PFEUMA®lms(Table2).This suggests that the surface of the air side of the®lms is composed mainly of the¯uorinated oligomer.The XPS measurements of the¯uorine content of the top layer of the glass side of the samples containing PFEUMA 1000(Fig.6,take-off angle 308)show that the F/C ratio is very low,although slightly higher than the theoretical value, and nearly constant all over the explored compositional range. On the air side,the¯uorine content increases dramatically as soon as PFEUMA1000is added to the mixture(Fig.6)and reachesavalueveryclosetothatreportedpreviouslyinTable3 for the homopolymeric PFEUMA1000®lm.The results found for the®lm containing PFEUMA2000 lead to the same consideration as reported before for the homologous macromer.When the®lms were prepared on a PE substrate,both sides were modi®ed as shown in Table6,where the contact angles of water are reported.While the pure BHEDA resin wettability has similar values on the two sides,in the presence of an increasing amount of¯uorinated oligomers, both the®lm surfaces become more hydrophobic.3.2.3.Copolymerisation with fluorinated monomers Several acrylic monofunctional monomers containing ¯uorinated chains were studied in mixture with BHEDA:Table4Surface properties of films from BHEDA±BHEDAF mixtures%BHEDAF(w/w)Surface tension (in brackets p)(mN mÀ1)Air side Glass side1541(12)42(12) 2538(7)41(12) 5039(7)41(12)Table5XPS results for films containing25%of BHEDAFTake-off angle Glass side Air sideF/C atomic ratio(theoretical F/C value:0.060) 9080.0510.114Fig.4.Contact angle vs.concentration of PFEUMA1000. Fig.5.Contact angle vs.concentration of PFEUMA2000.R.Bongiovanni et al./Progress in Organic Coatings36(1999)70±7875their concentration could reach only about 1%w/w due to their low solubility in the BHEDA resin.The complete description is reported elsewhere [6].The double bond conversion did not change with respect to the pure BHEDA resin.The gel content was always higher than 96%.In the case of the addition of C8F17Et,it was possible to check the linking of the ¯uorinated monomer to the acrylic network.After a selective extraction,GPC analysis enabled the determination of the free monomer concentration,which was found to be lower than 1/100of the quantity added to the resin.The bulk properties of the ®lms were found to be practi-cally constant and equal to those of the pure BHEDA resin.Otherwise,the presence of ¯uorinated monomers,not-withstanding their low concentration,dramatically changed the wettability of the ®lm.The contact angle data plotted in Figs.7±10as a function of the monomer concentration clearly show that the addi-tives are effective only on the air side of the ®lms,while the glass side keeps the same properties as the pure resin.The trend of the contact angle of C4F9Et,C8F17Et and C10F21Et monomers is asymptotic,as obtained by using the PFEUMA macromers (Section 2.2).By comparing Figs.7,8,9,we can see that the longer the ¯uorinated chain,the lower is the concentration at which the plateau is reached.At the same time,the plateau value increases by increasing the¯uorinated chain length.The highest asymptotic value (1208)was obtained by using C10F21Et;it is typical of a completely hydrophobic surface such as PTFE.In the pre-sence of C4F9Et and C8F17Et,the values are 788and 838,respectively,i.e.a medium polarity surface is formed,that contains hydrophobic groups (the ¯uorinated chains)together with polar groups.The other additives,C6F13Pr and C8F17S,showed a more complex behaviour which is shown in Fig.10,related to the C8F17S monomer.The trend of the contact angle plot versus concentration is sigmoidal and has two distinct plateaux,corresponding to two different critical values of the monomer concentration.The behaviour of these addi-tives can be attributed to a different surface morphology.The ®rst plateau could be caused by surface aggregation of the ¯uorinated monomer,whereas the second one could be attributed to the formation of a continuous layer of the additive according to XPS data.By comparing these mono-mers with those having the same ¯uorinated chainlength,Fig.6.XPS F1s/C1s atomic ratio of PFEUMA 1000.Table 6Contact angle of water on films BHEDA±PFEUMA 1000and BHEDA±PFEUMA 2000coated on PE PEFUMA 1000%w/w 00.050.10.20.5100Air side 75±104±10298PE side 70±75±7892PFEIMA 2000%w/w 00.050.10.20.5100Air side 7510310310310498PE side706165698692Fig.7.Contact angle vs.concentration of UV-cured BHEDA±C 4F 9CH 2CH 2OCOCH=CH 2mixtures.Fig.8.Contact angle vs.concentration of UV-cured BHEDA±C 8F 17CH 2CH 2OCOCH=CH 2mixtures.76R.Bongiovanni et al./Progress in Organic Coatings 36(1999)70±78the value of hydrophobicity is found to be remarkably higher.The selective modi®cation of the ®lm surface is con®rmed by XPS analyses,performed on the ®lms containing a concentration of ¯uorinated monomer above its critical value.The results are collected in Table 7.The concentration of oxygen is practically the same both in the bulk and on the glass side of the ®lms.The values are very close to those calculated on the basis of the chemical composition (ca.0.30).On the air side,a decrease in the O/C ratio is observed when the most hydrophobic monomers are used,i.e.C10F21Et and C8F17S.The oxygen content can be higher than expected as it is in¯uenced by the formation of peroxy radicals because of the presence of traces of O 2.Examining the data of ¯uorine concentration,a clear asymmetry of the surface composition between the air side and the glass side is observed,especially for the monomers having higher MW.On the air side,the content of ¯uorine is much higher than expected on the basis of the ®lm composi-tion.As far as the monomers with the longest per¯uorinated chains are concerned,the surface enrichment in ¯uorine in the most external layers (results at take-off angle 308)isextremely strong:in fact,the F/C ratio is even two orders of magnitude greater than that of the bulk.Moreover,in the case of ®lms containing C8F17Et,C8F17S and C10F21Et,the F/C ratio approaches the calculated value of the pure ¯uorinated monomer.As observed for the ®lms containing the PFEUMA oli-gomers,the substrate in¯uences the surface properties of the ®lm.Table 8shows the contact angle and the XPS data for the ®lms containing 1%of C8F17Et coated on glass and PE.They clearly con®rm the migration of the ¯uorinated mono-mer to the less polar interface.When the substrate is polar (glass),the migration selectively concerns the air side;when the substrate is apolar (PE),the ¯uorinated monomer enriches both external layers of the coating.4.ConclusionsThe use of ¯uorine containing monomers in UV-curable formulations allows one to obtain interesting modi®cations either of the bulk properties are concerned or of the surface properties of the®lms.Fig.9.Contact angle vs.concentration of UV-cured BHEDA±C 10F 21CH 2CH 2OCOCH=CH 2mixtures.Fig.10.Contact angle vs.concentration of UV-cured BHEDA±C 8F 17CH 2CH 2SCH 2CH 2OCOCH=CH 2mixtures.Table 7XPS results for films containing fluorinated monomers Sample descriptionF/C (atomic ratio)O/C (atomic ratio)Glass sideAir side Glass side Air side Take-off angle9083089083089083089083080.9%C4F9Et 0.010.00.010.020.300.300.290.29Theoretical value 0.00430.300.8%C8F17Et 0.0110.0150.62 1.130.390.480.320.31Theoretical value 0.00450.310.03%C10F21Et 0.030.050.59 1.10.310.340.270.25Theoretical value 0.00170.310.9%C6F13Pr 0.030.030.110.250.310.320.300.30Theoretical value 0.00460.310.8%C8F17S 0.19±0.611.020.310.270.240.20Theoretical value0.00410.31R.Bongiovanni et al./Progress in Organic Coatings 36(1999)70±7877The bulk properties investigated involve T g,mechanical and dynamic-mechanical properties,and optical properties, such as refractive index and transparency,which can be conserved in heterogeneous systems too,due to the forma-tion of very small microdispersions(nanostructures).The surface properties are related to the wettability and surface tension.The®lm surface can be deeply modi®ed also in the presence of very low amounts of¯uorinated monomers.Selective enrichment of the¯uorinated monomers on the ®lm surface can be obtained as con®rmed by XPS analysis, depending on the monomer structure and the type of sub-strate.Thus,completely hydrophobic surfaces containing practically pure¯uorinated monomer can be obtained by using mixtures containing very low amounts of the additive (<0.3%w/w).In conclusion,the results obtained indicate the high ¯exibility of these systems which allow to modulate the properties of the cured®lms by changing the structure of the additives and the experimental conditions.AcknowledgementsThis work was supported by Italian Murst40%Funds. Thanks are due to Dr.C.Tonelli(Ausimont Milano)for the synthesis of PFEUMA monomers,Dr.B.Ameduri for the ¯uorinated alcohols used in the synthesis of C6F13Pr and C8F17S,and to Dr.A.Pollicino(University of Catania)for XPS measurements.UCB,Atochem and Ciba-Geigy are thanked for supplying monomers and photoinitiators.References[1]A.A.Wall,Fluoropolymers,Wiley-Interscience,New York,1972.[2]T.Deisenroth,Proc.Fluorine in Coatings II,Munich,paper no.39,1997.[3]J.Scheirs,S.Burks,A.Locaspi,Trends Polym.Sci.3(1995)74.[4]S.P.Pappas(Ed.),Radiation Curing,Science and Technology,Plenum Press,New York,1992.[5]J.P.Fouassier,J.C.Rabek(Eds.),Radiation Curing in PolymerScience and Technology,vol.1±4,Elsevier,London,1993.[6]J.Pakrovsky,R.J.Waltman,.Coat.18(1990)79.[7]M.Torstersson,B.Ranly,A.Hult,Macromolecules23(1990)126.[8]R.Bongiovanni,A.Pollicino,G.Malucelli,A.Priola,B.Ameduri,Pol.Adv.Tech.7(1996)403.[9]R.Bongiovanni,G.Malucelli,A.Pollicino,A.Priola,J.Appl.Polym.Sci.63(1997)979.[10]R.Bongiovanni,G.Malucelli,A.Pollicino,C.Tonelli,A.Priola,Macromol.Chem.Phys.199(1998)1099.[11]B.Ameduri,R.Bongiovanni,G.Malucelli,A.Priola,in preparation.[12]R.Bongiovanni,G.Malucelli,A.Priola,J.Colloid.Interface Sci.171(1995)283.[13]S.Wu,Polymer Interface and Adhesion,M.Dekker,New York,1982.[14]R.E.Johnson Jr.,R.H.Dettre,in:E.Matijevic(Ed.),Surface andColloid Science2,Academic Press,New York,1969,p.85.Table8Contact angle and XPS results for films containing1%C8F17Et aSubstrate Substrate side Air sideF/C F/CGlass700.013900.62PE920.34900.48a Take-off angle 908.F/C atomic ratio(theoretical value 0.0056).78R.Bongiovanni et al./Progress in Organic Coatings36(1999)70±78。