ポリビニールピロリドン中の銀ナノ粒子の光化学形成とマスクによる直接的金属光パターニング

愛総研・研究報告 第8

号

2006年

Photochemical Formation of Silver Nanoparticles in

Poly(N圃vinylpyrrolidone)Film and Direct Metal Photo-patterning b y a

M a s k

ポリビニールピロリドン中の銀ナノ粒子の光化学形成と

マスクによる直接的金属光パターニング

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張

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、 落合鎮康、 小嶋憲三、 内田悦行、 大 橋 朝 夫

Abstrad: Silver nanoparticle-poly (N・vinylpyrrolidone) composite films (called nano-AgIPVP) were prepared by Ag+ doped PVP thin films irradiated ultraviolet ligh

t

.

The Ag particles in the films exhibited typical fcc (face-centered-cubic) structural X-ray diffraction peaks with broadened nanopartic1e linewidth characteristics where the size of Ag nanop紅ticleis estimated to be approx.

25 nm. Coordination bonding formation between PVP carbonyl oxygen and si1ver atoms on nanopartic1e surfaces (>C=O--Ag) was also demonstrated by using an FTIR spec位ummeasurement The photo-generation processes of nano・AglPVP composite films with different Ag+ doping concentration were investigated by using UV-vis absorption spectroscopy. A photo-reduction growth mechanism of Ag nanoparticles in PVP films is presented， inc1uding both initial slow induction periods

，

to form small Ag particles and subsequent rapid growth stage of Ag p紅ticles.

Final1y， direct metal photo-patterning of PVP thin films was realized using 254nm light irradiation of Ag+ doped PVP thin films covered with a mask. So far

，

si1ver patterned arrays with a period of 12.5μm(5μm spacing) can be achieved.

1

.

Inh吋uction of composite systems of meta1 fums is of considerable interest at p民 間1t e油ibitnovel combinations of partic1e and I r applications Ilaging_ 間d circuits'l

，

magnl light-sensitive nature well known， therefore， develop light・sensitiveion doped polymer realize direct meta1photo-patterning by a sirnple combined wi也UV-lightirradiation.百 出 世ategy 企eeapproach血田issirnple and low-cost， from conventiona1photolithography te t Key Laboratory ofMolecular血dBiomolecular Electronics， :r-.住d蛇yofEducation， Southeast University(N叫ingin CH悶AN) ttDepar旬1entofElec位ica1Engineering， Aichi fustitute ofTechnology (Toyota) ttt Depar伽1entoffuformation Network Engineぽing，Aichi fustitute ofTechnology (Toyo匂) costs due to也ecomplex fa加cation coating

，

etching processes

，

high-energy li也.ographicsteps. To date， some doped pol戸ner syst回1S and 也 位 form metal nanopartic1es-polymer well as photo-patterning， have been scientists are seeking v叩 ous new reported the photochemical formation films made企omblends of poly (vinyl poly( acrylic acid)， P AA， where

t

1

!

e ons was initiated by excited pol戸nerO_}. of SPEEK (s凶fonated )wi也be回ophenonegroups was a1so A

ピぬ

n doped PVA system as a Ag'" ions， and 40 Ilffiwide Ag line せ1efilm surface using a mask PVP，加shigh solub

旭

町

ina 血dsuperb film forming capability， as for meta1colloids in solution which applied to various colloida1

∞

ntains a functiona1group of >C=O • Ithas been demonstrated吐mtthe can reduce Ag + to Ag in aq田 ous 43

愛知工業大学総合技術研究所研究報告、第8号、平成18年、 NO.8ヲ2006 0.1ウO

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白 0 30 s.oluti.on c.ontaining PVP wiせ1high c.onc阻 むatio.n9)at UV irradiati.on， yet detailed pho.to-reducti.on mechanisms were not presented Po.lymer elec位olytes c.ontaining silver salts are currently under intensive inve武igati.on because .of.血世 po.tential applicati.on in facilitated transp.ort membranesl_l).PVP is.0食.enused as a po.lymer c訂riぽ血the preparatio.n .of silver salt-p.olymer elec位。lyt白，while the hig酔l1叫S.ol曲ub副

t

勿y.ofA勾g+ions in PVP ha鎚s be鎚en d白巳:m.o叩n碕国s坑甜t位r瓜ated due tωo s町仕凶o叩ng int缶erac凶tti叩on 1

be~肺f倒j¥

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g+i附叩 卿on凶s組制dp.ol凶咽a訂rgr伊ou耶p戸s0ぱf>刈C=OQ叩n p伊.01加ymeぽr

ch:】ha註iinnsl砕山，21可3 t ω.op戸're叩pareSilver nanoparticle-PVP (nan・o.Ag/PVP)c.omp.osite films using an ultravio.let light-induced ph.ot.ochemical reacti.on， while也epho.to-generation procedure.of Ag nanoparticles in PVP films was studied by UV・visabso.rpti.on s戸C仕osc.opy. Direct silver pat回ningpo.l戸ner白血filmswere also realized using a simple mask metho.d co.mbined with

uv

-light irradiation. 80 Fig. 1 XRD patt佃 1.of nan.o-AglPVP c.ompo.site film (Sample c). 40 50 60 70 DitI目l'ac伽 11柚 gle[Dt"gI'tt] which are ch釘acteri副c.of n組oparticles. The average crystallite diamet，ぽ(ACD).of Ag nanoparticles was determined using the XRD linewid血.ofthe (111) peak using Scherrer's Form叫aI4)，明白血.ecalculated result being approx. 25 run. Fτ1R spec仕osc.opy was used to.study血e interacti.on betw田nsilver nan.oparticles and po.l紅 gr.oups.on PVP chains.

Figure 2 presents FTIR spectrum.of nano.-AglPVP c.ompo.site filmso.b也ined fr.om the precurso.r s.oluti.on wi也 AgN03 c.oncen回tion.oflOmM. 2.1 Cbemicals Silver nitrate

，

A酬 03(99.9%) was used as precurso.r .of Ag n叩op副 cles. Poly(N・vinylpyrr.olidone)σVPK30，1-何'40 000) was purchased fro.m Wako Pure ChemicalIndus出es，Ltd Eth四.01(EtOH， 99.5%)(Amakasu) W:鎚 国edas s.olvents. All of

the chernicals were used as re回ived企'omthe suppliers. 2. Experimental Sedion

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2.2 Preparation of Nano・A!UPVP Comoosite Films and Their Photo-patte Firs

，

t

P民curs.orsolutio.ns .of PVP (9mM， calculated pぽ p.olymer units) in e白血01c.on臼白血gA.酬03wi由 di庄町'ent co.ncen岡 山 田 (2.5， 5， and 10 mM) we日 prepared (R=[Ag"]/[pVP]=0.28， 0.56， 1.11， respectively). A 50μL precurs.or so.luti.on was cast directly.ont.oa cl伺ned glass

micro.sco.pe c.over slip. The f.ormed Ag" do.ped PVP films we記

せlen企ied at r.o.om tempera旬re fo.r 15

m

i

n

f.ollowed by UV-irr司diati.onin the ventilat.or at different times acc.ording t.o

UV-vis abs.orption variation.百 四 yell.ow Ag n姐opむticle c.omposite films WIぽe.obtained and marked as Samples

，

a

b，

組dc， res戸ctively.百1e

uv

1釘npused W:ωTo.shiba GL20・A 20 W l.ow-pressure mぽcurylamp wi血amain並radiati.on wavelen耕1o.f 254 run.百le glass micros

∞

pe cov，ぽ slip substrates w町ecl四 1edfo.r 15

m

i

n

.

in a freshly prep蹴 d1:3 mixture.of 30% H202 and 98% H2S04 (p包富由as.oluti.on)也m washed with a large am.ount.of dei.onized water血dethanol befo.re po.lymぽfilms films were .obtained PVP films c.overed by a mask whぽetransmission elec仕on microsc.opy (τ'EM) c.opper grids wi也differenth.ole sizes.of 200， 400 and 2000 mesh were used as

Fig.2FTIRs戸ctrum.ofn佃.o-AglPVPco.mpo.site film (Sample c).Insetsh.ows the spec仕umo.fs釘nple(c) atr，叩.ge.of

2000-4000cm".

Itis found也atc訂'b.onylgr.oups e油ibita broad and splitting

abso.rpti.on band at 1676.6 and 1652.3 cm".百lef.ormer band bel.ongs t.o企'ee carb.onyl gr.oups， while也e la枕ぽ C血 be attributed t.oa new carbo.nyl s仕etchingband which shifts t.othe I.ower frequency due to.carb.onyl gr.oups b.ound t.o也esurfaceo.f Ag nan.oparticles也r.ough血e coo.rdination bo.ndingo.f >C=O-Ag.古田 re叩lt is c.onsistent with the previ.ously repo.rted results f.or the in匂racti.on.of Ag+ i.ons and P W12).Th巴 abs.orptio.n band at appro.x. 1290.1 is attributed t.oC-N stretching vibrati.on.百leinset in .Figure 2 als.osho.ws a br.oad abs.orptio.n band at 3425.9 cm"， caused by也.e s仕etching vibrati.on o.f H20 ads.orbedo.n PVP chains.百leabs.orpti.on band at2962.3 2.3 Charaderization Techniques

UV-vis可Jectrawere recorded using a

u

v

・2450UV-visible spectr.opho.to.meter (Shima也u). FTlR (F.ourier凶 lsf.orm

m

企'aredspectr.osc.opy) measurements were pぽf.ormedo.n a FTIR-8400S spectr.oph.ot.ometer (Shimaむu).X-ray diffracti.on (XRD) measurements were perf.ormed .on a Vo.yager 1000 X -ray diffracto.meter with Cu K，αradiatio.n (λ=1.5406 A) . operated at 40 kV and 40 m A Silver pho.to-pa社erningp.olymer films were o.bserved using transmissi.on o.ptical microsc.opy (01戸npusBX 50) with a DP 11 digita1 camera (2.5 M pixels). Figure 1 sh.ows an X-ray diffractio.n p出 回1of nano-AglPVP comp.osite films.obtained from血eprecurs.or s.oluti.on wi白 血 A酬03co.ncentr油.on.oflOmM.百lecharact出sticdiffracti.on peaks.of (111)， (200)， (220)， and (311) indicatef1ω s飢lC旬ral silver. The broadened di借acti.onpe法sc組 be.observedヲ 3. Results and Discussion

45 Photochemical Fonnation of Silver Nanoparticles in PVP Fihn and Direct Metal Photo-patteming by a

Ma

sk

narrowing for all曲 目 S副 plesc姐 beobserved while the shapes of世leabsorption bandu1timately obtainedぽ'ealmost symme仕ical

，

sugges也19也enanoparticles are well dispersed in PVP films and sphere-shaped as the aggregation of nanoparticles leads to red-shifted and broadened surface plas

I

n

on absorptionsI8)， while the anisotropic silver n叩 oparticlesresult in splitting into multiple bandsI6).

Table 1 provides the optical parameters of silver nanoparticles in PVP ft1ms obtained from the fmal absorption spec仕umin Figure3 a， b， and c， including the maximum absorption wavelen尉1ofAmax， the maximum absorbance，姐d the full bandwidth at half-maximum (FWHM). cm・1can be at住ibutedto groups of -CH2・and-CH・.Silver partic1es reduced to nanometer dimensions e油ibitunique optical properties in the visible spectra1range due to也e excitation of col1ective osci11ations of conducting elec仕'Ons kn'Own as plasm'On res'On血ces'Or surface plasmai5).UV-vis abs'Orpti'On s戸C凶 havebeen sh'Own t'Obe q国tesensitive to也e 恒 久 shape， 血d也e田 町oundingdielectric envir'Omnent 'Of silver nanop紅 白1自 由 国 t' O 也 町 f'Ormati'On processes in s'Oluti'On 'Or f11mslC>-lll. Figure 3 sh'Ows UV・vis spec仕d ev'Oluti'Ons during也，eformati'On 'Of n組0・A

g

J

P

VP

∞

mposite films'Obtained fr'Om the precurs'Or s'Oluti'Ons wi也 di庄 町 田t Aρ~03 conc四 国ti'Ons'Of 2，.5 5， and 10m M markedぉ Samples

，

a

b， and c， respectively. Table1.Optical p紅'ametぽSof silver nan'Oparticles in PVP films'Obtained企omfmal abs'Orpti'On spectrum'Of Sample

，

a

b and c in Figures 3 SampleName Sample Sample Sample I a b c ASoilutionCs (omncbeontration 立1 2.5 5 10 Ag+ Amount inFilms 0.26 0.52 1.03 (xlO・7m'OVcm'

勺

λ由 也(mn) 414 415 432 Adsorbance atλ百 四 0.35 0.52 0.79 FWl削 (mn) 92 96 120 55min 45附n 35min 25min 10min (a)

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0.1 C姐 besaid t'Oenhance lin回rlywith Ag + i'On doping c'Oncentrati'On in PVP fi1mswh悶 'Of PVP is c'Onstant.白骨 slightincrl回 ses訂'eseen

a四db. while柑'Ongenhancements匂keplace f'Or

Samples a and b forAm蹴血dFWl剖. αl. rl句'Orted世leph'Ot'Ochemical f'Ormati'On 'Of Ag in aqueous soluti'On in吐le戸esenceof PVP and 伽 tthe variati'On of A

正

ionconcentration only

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ze and size dis出buti'On 'Of Ag in solution"'.百lUSwe infer也at也eirbehavi'Or is se formati'On 'Of Ag nan'Opartic1es f'Or 組db叩，thl'Ow Ag + i'On

∞

nceI帥 .ti'On.This is in wi白血~ehigh s'Olubility'Of Ag+ i'Ons in PVP rep'Orted al"'''I. H'Owever. i'On田 町 武artt'Of'Orm foll'Owed 'Order i'Onic aggregates12) at silver c'Oncentrati'On relative t'O carb'Onyl'Oxygen. F'Or Sample c， =0]=1.1l.百lUS we conclude也at也.e high of Ag T i'Ons f'Or Sample c leads t'O社lef'Ormati'On wi也 l紅ge and br'Oad dis仕ibuti'On f'Or bothせlelargeAm蹴組dFWHM. It has been l'Onger as p釘tic1esbec'Ome larger".lInHuang's studies， wi也 anaverage size of 15.2 t'O22.4 mn were

f

T

.

，

e c'Orresponding UV-VIs abs'Orpti'On peaks fr'Om nm町.It is reas'Onable t'Oestimate sizes f'Or 'Our Ag in PVP fi1msat a r，血gefr'Om 15 t'O30 mn UV-VIs abs'Orption spec回 伽tagreeWl'也吐les国s fr'Om XDR by co_nsidering也ee能ct'Of四rr'Ounding SIO) (PVP -f11mhas higher refractive water s'Oluti'Ons， res叫 也19in a red-shi食'Of血e band).τ'he'Oretical calculati'Ons have revealed血at abs凹pti'On is dOlninant in也is s包e the symmetric absorpti'On田 北sfor也巴 fi1ms 'Obtained can be obsぽved. ーincreaseand abs'Orpti'On band blue-shift ervedc1early in Fi伊lTe3 for all世rreeSamples at UV may be difficult to decipher the blue-shifts as白e 'Of Ag particles sh'Ou1d lead t'Osize increases， red-shi食ofthe abs'Orpti'On band acc'Ording t'Othe si'On. The'Oretical investigati'Ons have indicated吐lat 'Of surface plasma in meta1

n'Ot 'On1v depends on effectivee1ec往'Onmass，the 語 信 有 印

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(c) 500 600 7

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川危velength(nm) 400 コ 0.6 官官 Q)

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0.4

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0.2 0.0 300 Fig. 3 UV-vis spectral ev'Oluti'On during nano・A

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P

VP c'Omp'Osite film f'Ormation fr'Om prec山富'Ors'Oluti'Ons with differentA似03concentrati'Ons: (a) 2.5mM; (b) 5mM; (c) 10mM冒

The films were irradiated with 254 mn UV light. The irradiati'On time is indicated in也eFigure f'Or回.chspectrum.

The absorption spectra of Ag particles in PVP films continu'Ously devel'Op wi也 也neuntil也.eyreach a stable state

when a11the silver ions have been reduced at 254 mn light irradiati'On. An 'Obvi'Ous abs'Orption band blue-shift and

愛知工業大学総合技術研究所研究報告、第

8

号、平成

18

年

、

No.8，2006 andshapeof也ech

紅

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edis出butio

，

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but is also a

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ected by density of electrons1oJ.四ewavelen尉lof也eabsorption ot of血e Henglein 伽 tthe surfi蹴 A

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ionabsorptions can gr'曲世yreduce density of企eeelectrons in Ag nanoparticles dispersed in s solution，出国resultin血eabsorption peak red-shi食by e nanometer百20).Compared wi也仕leres凶tsof Huang's 也.ee

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ect of size incrl田seson A官 蹴ismuch smaller也 組 of surface ion absorption.As a res凶

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世le observed shift in Figure 3 c組 beexplained by the consumption of ions in也ephoto・.reductionreactio

，

n

which ca回 目 a

in the amount of Ag+ ions ad悶 'bedon particle

es， al也 叩.ghAg particles grad叫 lyincrease.The Ag + ion most likely takes place from the photo-reduction adsorbed Ag+ ions on p副 cle surfaces. 1刀取T五'h溜ee白削釧llo叩wirn will discuss the photo-reduction of Ag

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+

ions tωofiお01ロmAg sinPVP gure 4 shows也e absorption intensity atA.m臨悩 a of仕lephoto-reduction reaction time for Samples

，

a

b shown in Figure Fig. 4 Absorption in回 sityatλ阻 asa function of photoreduction reaction也nefor samples(め，(b)，and (c) shown in Figure1. We use the change of absorption intensity to reflect the photo-reduction reaction of Ag + ions， alth

∞

.gh也eabsorption intensity is relative not only to也eparticle concentration formed， but also to也.epぼticles包e，aggregate s包.te，etc..Thぽe 紅 白two distinct r回ctionはagesbefore也efmal武ableはate.百le frrst stage is from the beginning of the reaction toせle也neat 25・30min.

，

in which也eformation mte of Ag p紅ticlesis ve巧f

slow and a wide absorption region坑M也gfrom 300 nm is observed前 世lout也echaracteristic absorption peak of Ag n阻op訂ticles.Ag clusters of a few atoms ofAgn (n=l・3

，

4・7

，

叩d8・12)wlぽ'echaract，出zedwi也UVabsorption bands at 292， 325， and 370・380nm， respectively in the e紅liぽ

7

也radiation study of aqueous silver nitrate solution 21)羽 田 世1巴 wide absorption region observed in也e present study can be reasonably attributed to吐leexistence of Ag clusters wi也 di

t

I

erentn values， as well as small Ag particles.In世lesecond 由 民 也e formation rate of Ag p副 cles is dramatically accelerated while the characteristic absorption peak of Ag nanoparticles appears and blue-必ifts occur wi白 血e consumption of Ag + ions. PVP contains a functional group of >C=O which adsorbs 254 nm light more s住onglyせlanAg + ions in our experimental conditions and hぉ 甜0昭 interaction明 白A

ぜ

ionsor Ag nanoparticles出roughthe coordination bonding as shown by 血.eFTIR spectrum.百leformation of the coordination bonding induces a食actionalelec仕on仕ansferfrom the carbonyl group 10 silver. According 10 Henglein's work，出iseffect induces a displacement ofthe metal Fenni level toward the more negative potentials20.) Simultaneously， the carbonyl group redox potential increases and becomes easier to photo-oxidize.The excited s戸ciesof>C=O箪 canreduce Ag + ions to Ag atom as a result at 254 nm light irradiation. Subsequent agglomeration of Ag atoms occurs to form Ag clusters and small Ag particles. Possible reaction mechanismsぽ'eas follows. >C=O-Ag+. hv >C=O・+AgU nAgO

一

一

一

一

.

.

(AgO)n >C=O.-Ag+ >C=O

・+

H20 (or EtOH)

一 一 +

>C=O +

W

+OH. (orEtO・)

一一一+

(1) (2) (3) 百le企'eeradicals of>C=O・formedare reverted to >C=O by也e reaction with water or e白 血01adsorbed in PVP films. Similar free radical rl田ctionwas also shown in the previous reports on the photo-reduction of Ag + ions in surface-modified polyimide layers wtぽethe carboxyl mdicals of-C02・undergoa s泊rilar reaction~J. Hengleinet al. performed a detailed investigated of the photo-reduction of A

ぜ

ionsin aqueous solution in也e presence of acetone and 2・propanol

，

where the photo-reduction was initiated by acetone ketyl radicals with a low rate of reaction20 S.)imilar low reaction rates should also appe紅 血our reaction syst回 1for

E

q

.

1.百由 slowr伺ctionp出odc阻 be called an induction period for silver reduction， corresponding to the frrst託ageshown in Figure 3. Wi也 也.egrad田1formation of the small Ag particles， a second reduction process occurs， in油ichAg + ions are reduced on也esurface of the Ag pぽticles，as Ag n組opartid田 伺nact as an electron storage皿d transfer medium. It has be田 observed by Henglein20)組d Brus22) et al.世lat也ぽ'eISa displacem四tof plasmon民son組 問 a食erelectron iniection inside Ag n阻op副icles，and組 mcre渇se of吐le chemical reactivity on particle surfaces.百1由 也 巴 excitedspecies of >C=O. frrst transfer an elec仕onto Ag particles， then the Ag + ions adsorbed on由 surfacesare reduced by stored electrons in 由esecond s也.ge，resulting in the gradual grow也ofAg particles wi也 a fastぽ rate.百le electron transfer procedures are illus仕atedin Figure 5‘ Fig. 5 Elec位'ontransfer process企omexcited species of>C=O. to Ag + ions adsorbed on Ag nanop副 clesurfaces. S出rilarly，both the slow induction p白odand rapid particle growth stage could be observed for allせrreesamples with di

t

I

erent initial Ag + concentrations σigure 4). However， the inal absorbance in the two 陶 酔sincreases wi也 也e凶 凶Ag+ concentrations in PVP films官記increaseof the initial Ag + concentrations re四ltsin forming more coordination bonding of >C=O-A

ピ

in the induction perio，d which is helpful to facilitate the photo-reduction of Ag+ ions. Yet in the second stage， the largest rate of increぉe in absorbance may be observed for Sample b in comparison to Sample a and c， suggesting仕留tthe Ag particle formation rate is de戸ndentnot onlyon社leinitial Ag + concen回1ionbut also on the relative

Photochemical Fonnation of Silver N血oparticlesin PVP Fibn and Direct Metal Photo-patterr由19bya

民

1

a

sk Fig. 6 Transmission optical microscopy images of silver pa故 田ledpolymer也infllms formed from UV irradiation of Ag + ion doped PVP曲ns(Ion concentration:1.03x 10・7 moνcm-2_{) for 90min. Using a copper grid as mask with} different hole sizes: (a) 200 mes，h(b) 400 mesh，(c) 2000 mesh. amOlmt of PVP to Ag+.The relatively high PVP concentration may be usefiu for electron transfcぽ forrning PVP 10 Ag particles. PVP has good solub益ityin wat，ぽandethanol. However， the nano-Ag/PVP composite fllms obtained e油ibit very good stab姐ityfor water and eせlanol.No changes in absorption spec国 W悶 observedwhen immersing the fi1ms in10 wa脂 血d e仕lanolfor 3 hours.百uscan be reasonably at回buted10也E cross-linking interaction between PVP血dAgnanop紅ticles. An application for direct metal photo-pa枕 田ringpolymer 也infllms has been realized using Ag + ion doped PVP thin films and a TEM copper grid as a mask Figure 6 shows the obtained silvlぽ patternedPVP thinfilms wi也differ

田

.

t

periods. Pa性 四1dimensions are in s仕ongagreement wi也仕1ephotomask used. An array period of 12.5 l1lIl and resolution of 5問narray spacing are achieved as observed in Figure 6 c.百1eultimate resolution of this pat匂lIlingmethod remains unknown. Fur仕1ぽ study is currently being conducted. 4. Condusions Nano・Ag/PVP composite fi1ms were fabricated using ultraviolet ligh1 irradiation of Ag + doped PVP白血 fi1ms obtained from an A

gN

03-PVP-e白 血01mixing solution with a simple casting method.百出isa simple photo-reduction system to fabricate silver/polymer composite fi1ms， where PVP ac包 sm叫 凶1eouslyas film matrix and photo叩 ductant.百1eAg nanop氾ticlesin設1ePVP fi1ms have a typical fcωs位 協tllre characterized by X-ray diffraction.τbe coordination bonding foロnationbetween PVP carbonyl oxygen叩dsilver atom on nanoparticle surfaces (>C=O・-Ag)was also d四10ns回tedby FTIR spectrum measurement.The photo-generation process図

。

fnano・Ag/PVPcomposite fi1ms wi也 differentA

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doping

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nc阻むations were investigated using UV-vis abso叩tion spec仕oscopy. A photo-reduction growth mechanism of Ag n叩.op紅ticlesin PVP films was presented， including both initial slow induction periods to form small Ag particles叩d也e subsequent rapid grow也s

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eof Ag p訂ticles.白leapplication is direct meta1photo-patteming of PVPせrinfilms realized using 254nm light irradiation of A

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dopedPVP也血fi1ms cov，ぽedwith a mask. So 11眠 silverpa社eredarrays wi也aperiod of12.5四n(5問nspacing) can be formed. Acknowledgments 百1epresent work was

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nducted as part of也.eresearch pr句ect日Materialsfor血e21st_{Century-Materials Development} for Environmen

，

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Energy， and Information" (ゐ，rfiscal year 2002-2006)四pportedby也eMinis町 ofEducation， Culture， Sports

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Science

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