Research Article Effects of Excess Cu Addition on ...downloads.hindawi.com/journals/amse/2013/854928.pdf · Effects of Excess Cu Addition on ... had been cured using UV-vis irradiation,

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2013 Article ID 854928 5 pageshttpdxdoiorg1011552013854928

Research ArticleEffects of Excess Cu Addition onPhotochromic Properties of AgCl-UrethaneResin Composite Films

Hidetoshi Miyazaki1 Hirochi Shimoguchi1 Hiroki Nakayama1

Hisao Suzuki2 and Toshitaka Ota3

1 Department of Material Science Interdisciplinary Faculty of Science and Engineering Shimane University1060 Nishikawatsu Matsue Shimane 690-8504 Japan

2Graduate School of Science and Technology Shizuoka University 3-5-1 Johoku Hamamatsu Shizuoka 432-8561 Japan3 Ceramic Research Laboratory Nagoya Institute of Technology 10-6-29 Asahigaoka Tajimi Gifu 507-0071 Japan

Correspondence should be addressed to Hidetoshi Miyazaki miyarikoshimane-uacjp

Received 30 April 2013 Accepted 11 July 2013

Academic Editor Yuanhua Lin

Copyright copy 2013 Hidetoshi Miyazaki et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

AgCl-resin photochromic composite films were prepared using AgNO3 HCl-EtOH CuCl

2ethanol solutions and a urethane resin

as startingmaterialsThe AgCl particle size in the composite films which was confirmed via TEM observations was 23ndash43 nmTheAgCl composite films showed photochromic properties coloring induced byUV-vis irradiation and bleaching induced by cessationof UV-vis irradiation The coloring and bleaching speed of the composite film increases with increasing CuCl

2mixing ratio

1 Introduction

A glass doped with silver chloride shows photochromicproperties [1 2] This phenomenon is effective for control-ling the transmittance of solar light through glass windowsPhotochromic materials containing AgCl nanoparticles havebeen fabricated as films [3] hybrid materials [4] and com-posite materials [5]

In photochromic materials containing the silver chlorideAgCl an AgCl particle is decomposed into an Ag particle andCl media by UV-light irradiation as shown in the followingequation

AgClℎ

(dark)Ag0 + Cl0 (1)

Forming Ag particles (Ag0) in matrix by decomposition ofAgCl particles the photochromicmaterials are coloring Fur-thermore addition of Cu1+ to AgCl photochromic glasses

increases the coloring speed of these glasses according to theequation given below [6]

ℎ

(dark)Ag+ + +Cu+ Ag0 Cu2+

(2)

From this equation the presence of Cu2+ in AgCl pho-tochromic glasses causes the equilibrium in (2) to shift to theleft-hand side while the Ag0 formed by UV-vis irradiation isconverted back to Ag+ In addition the excess Cu2+ causes adecrease in the coloring speed and an increase in the bleach-ing speed of AgCl [6]

In a previous study we fabricated AgCl-containing com-posite films and evaluated the photochromic properties ofthe films [5] A Cu sensitizer was added to the AgCl com-posite films using only a CuCl

2(Cu2+) source However the

Cu2+ ions acted as coloring and bleaching sensitizers forthe composite films which is not in agreement with the

2 Advances in Materials Science and Engineering

results expected from (2) In this study we fabricated AgCl-containing photochromic composite films with various Cucontents and observed the effects of excess Cu2+ ions on thephotochromic properties of the composite films

2 Experimental Procedure

AgNO3(995 Wako Pure Chemical Industries Ltd Osaka

Japan) HCl-EtOH (01molL Sigma-Aldrich Japan KKTokyo Japan) CuCl

2(95 Wako Pure Chemical Industries

Ltd Osaka Japan) and a liquid-state urethane resin (M-40density of 115 gcm3 Asahi Kasei Chemicals Corp TokyoJapan) were used as starting materials The urethane resincan be cured using UV-vis irradiation AgNO

3powder was

dissolved in ethanol at a concentration of 01molL TheAgNO

3solution thus prepared was mixed with a liquid

urethane resin (the Ag ion concentration in urethane resinwas 10 120583molcm3) and the HCl-EtOH solution was addedsequentially to the mixture with a ClAg atomic ratio (Here-inafter described as ldquoClAg ratiordquo) of 10 to form AgClnanoparticles CuCl

2powder was dissolved in ethanol at

various concentrations and the solution was added to theresulting mixture with varying CuAg atomic ratios (Here-inafter described as ldquoCuAg ratiordquo) ranging from 0 to 10These mixtures were stirred and thereafter the precursorsolution was prepared The mixture was degassed for 30minat 100 kPa and the resulting mixture was formed to a thick-ness of 1mm using slide glasses The precursor films werecured usingUV-vis irradiation (with a low-pressureHg lamp)for 5min thus producing composite films

The transmission spectra of the obtained composite filmswere measured using a spectrophotometer (UV-1600 Shi-madzu Corp Japan) at a wavelength range of 200ndash1100 nmHg lamp was used for measuring the photochromic proper-ties To observe the microstructure of the films the obtainedsample was ground with an agate mortar and the groundsample powder was supported by a copper grid The micro-structure of the composite films was then observed usingtransmission electron microscopy (TEM EM-002B TopconCorp Japan)

3 Results and Discussion

Theas-prepared filmswere brownbecause the precursor filmshad been cured using UV-vis irradiation and the compositefilm was coloredThe darkened films were bleached in a darkroom for 7 days and the resulting transparent films wereused to evaluate the photochromic properties Figure 1 showsthe transmission spectra for a representative composite film(CuAg ratio of 10) measured before and after UV-vis irradi-ation for 1ndash20min As shown in the figure the transparentcomposite film was colored by UV irradiation Thereforethe resulting composite film shows photochromism Theinset photographs in Figure 1 show the film before and afterUV-vis irradiation The film showed coloring because ofirradiation and the colored film showed broad absorption atthe absorption peak of 450 nm

Figure 2 presents the coloring and bleaching propertiesof the films with CuAg ratios ranging from 0 to 10 the

300 400 500 600 700

100

80

60

40

20

0

Tran

smitt

ance

()

0

5

1020

1

2

UV irradiation time (min)

Wavelength (nm)800

0min 20min

Figure 1 Transmission spectra of composite films with CuAgatomic ratio of 10 at different UV-vis irradiation times

employed wavelength was 450 nm The coloring propertywas evaluated with the time interval of 1min Increasing Cucontents in the composite films caused a slightly decrease ofthe transmittance at the bleached condition Though we areconsidering the reason it is assumed that excess Cu contentsaffect the initial transmittance of the composite films forexample deterioration or coloration of the matrix by exis-tence of excess Cu ions and so on

Using the optical property of the composite films thereaction rate constant 119896 was estimated at the wavelengthof 450 nm which represents a remarkable absorption peakof the film for the coloring condition In this study theabsorbance of the films was calculated using the value of thetransmittanceThemethod for calculating the photochromic-reaction rate constant was described in a previous study [7]The reaction rate equation is

minus ln( [119860][1198600]) = 119896119905 (3)

where 1198600is the initial absorbance and 119860 is the absorbance

after time 119905 from the initial state 1198600 The calculated reaction

rate constants of the films with CuAg ratios of 0 01 1 2 5and 75 were 0092 0118 0132 0134 0124 and 0133minminus1respectively The coloring speeds of Cu-added films werehigher than those of films without Cu addition The coloringspeeds of films whose CuAg ratios were greater than 1 wereclose to those of films whose CuAg ratio was 1 This increasein the coloring speed with the addition of Cu2+ was not inagreement with the result expected from (2) and the conflictwas discussed later

In the case of bleaching increasing the CuAg ratio inthe films resulted in an increase in the bleaching speed Tocompare the bleaching speeds of the films semiquantitativelywe calculated the half-life period of the films 120591(ℎ) where 120591was the time taken from the transmittance of the sufficientlycoloring state (20min UV-vis irradiation) to the transmit-tance of the on a half of its initial stateThe calculated half-lifeperiods 120591 of the films with CuAg ratios of 1 2 5 and 75 were144 569 298 and 280 h respectively the films with CuAg

Advances in Materials Science and Engineering 3

100

80

60

40

20

00 5 10 15 20

CuAg

0

01

1

2 (dashed line)

5

75

Tran

smitt

ance

()

Time (min)

(a)

100

80

60

40

20

00 2 104 6 8

Tran

smitt

ance

()

Time (day)

CuAg

0

01

1

25

75

(b)

Figure 2 Coloring and bleaching properties of the composite films with different CuAg ratios and the employed wavelength of 450 nm

100

80

60

40

20

01100500300 700 900

Tran

smitt

ance

()

Wavelength (nm)

0min

10min

Figure 3 Transmittance spectra of CuCl2-urethane-resin compos-

ite films (without AgCl) at UV-vis irradiation times of 0 1 2 5 and10min

ratios of 0 and 01 did not return to the initial state in 10 daysTherefore increasing the CuAg ratio in the films resultedin a decrease in the half-life periods 120591 corresponding to thebleaching speedThe acceleration of the bleaching speed withthe addition of Cu2+ agreed with the result expected from(2) Furthermore CuCl

2was used as a source material and

thus the Cl concentration in the composite film increasedslightly with an increase in the Cu concentration in the filmIn addition according to (1) the equilibrium in the compositefilm shifted to the right-hand side and it was assumed that thebleaching speed increased

In general the presence of Cu2+ inhibits the formation ofa Ag0 cluster in AgCl photochromic glasses thereby decreas-ing the coloring speed of the AgCl photochromic glass owingto the addition ofCu2+ In contrast theCu2+ ions in this studyact as coloring sensitizers for the composite films To clarifythe state of Cu ions in the composite film we prepared a Cu-urethane-resin composite film without silver and confirmedthe optical properties of the film using UV-vis irradiation

as a blank test The Cu-urethane-resin composite film wasprepared as follows ACuCl

2ethanol solutionwasmixedwith

the urethane resin with a Cu concentration of 20120583molcm3and the precursor was cured using UV-vis irradiation Forthe clarification of the Cu-urethane-resin composite film itwas placed in a dark room for 7 days Figure 3 shows thetransmittance spectra for the composite films before andafter UV-vis irradiation The composite film before UV-visirradiation showed absorption at the range of 600ndash900 nm[8 9] the color was attributed to the presence of Cu2+ After2-3min of UV-vis irradiation of the film the absorptionpeak diminished and after 10min of UV-vis irradiation theabsorption peak disappeared This result suggests that Cu2+ions in the composite film were reduced to Cu+ via UV-visirradiation as indicated by the following

Cu2+ + eminus ℎ120592997888997888rarr Cu+ (4)

In previous study related to MoO3thin film based pho-

tochromic materials [10 11] in the case of existence of watermolecule in the films electron-hole pairs were generated byvisible light irradiation and the generated hole reduced waterand induce of protons The protons caused reduction of thehost MoO

3cluster and the photochromism (the coloring

property) of the MoO3thin film was improved [10 11]

In the present study to distribute Ag Cl and Cu ions inthe urethane matrix we used ethanol as a solvent In thecomposite films we assumed the following protons weregenerated from ethanol by the UV-vis light irradiation andthe generated protons promoted reduction of Cu2+ ions aswell as the previous investigations [10 11]The reduction timefrom Cu2+ to Cu+ was about 2 minutes and the time wasfaster than that from Ag+ (as AgCl) to Ag0 in the nondopedAgCl-based composite film (sim10min see Figure 2) The Cu+caused acceleration of reduction of Ag+ to Ag0 (2) Thusthe coloring speed of the composite film increased with theaddition of Cu2+ The blank test and bleaching proved thatthe Cu2+ ions added to AgCl photochromic composite filmsact as coloring and bleaching sensitizers


100nm

(a)

100nm

(b)

Figure 4 TEM image of composite films with (a) CuAg = 01 and (b) CuAg = 10

Generally the particle size of AgCl in photochromicglasses is less than tens of nanometers [6 12] To confirmthe AgCl particle size in the composite films and the effectsof Cu addition on the AgCl particle size the microstructureof the composite films was evaluated using TEM Figure 4shows the bright field TEM images of the composite filmswith CuAg ratios of 01 and 10 The average AgCl particlesizes in the composite films with CuAg ratios of 01 and10 were approximately 23 and 43 nm respectively and wereclose to the AgCl particle sizes (30ndash50 nm) of silver chloridecontaining photochromic glasses [12] The AgCl particle sizein a film with a CuAg ratio of 10 (including excess Cu ions)was 18 times larger than that in a film with a CuAg ratio of01 The AgCl particle size in the composite films was largerthan that with the CuAg ratio and thus it is assumed thatthe coloring and bleaching speeds also depended slightly onthe AgCl particle size in the composite

4 Conclusion

In this study AgCl-based photochromic composite filmswere fabricated and the effects of the Cu2+ sensitizer on thecomposite films were evaluated Additive Cu2+ ions acted ascoloring and bleaching sensitizers in the AgCl photochromiccomposite films which is different from the case of AgClphotochromic glasses Cu2+ ions in the composite film werereduced to Cu+ byUV-vis irradiation and the reducing speedwas faster than that of Ag+ toAgThe generatedCu+ ion actedsubsequently to reduce Ag+ ions and thus the coloring speedof the composite films was accelerated The AgCl particlesizes in the composite films were 23ndash43 nm and were closeto those of silver-chloride-based photochromic glasses TheAgCl particle sizes in the composite films depended slightlyon the Cu concentration in the film

Conflict of Interests

The authors state that they have no conflict of interests

References

[1] S L Kraevskii and V F Solinov ldquoInterface models for the pho-tochromism and thermochromism of glasses with nanocrys-talsrdquo Journal of Non-Crystalline Solids vol 316 no 2-3 pp 372ndash383 2003

[2] W H Armistead and S D Stookey ldquoPhotochromic silicateglasses sensitized by silver halidesrdquo Science vol 144 no 3615pp 150ndash154 1964

[3] H Tomonaga and T Morimoto ldquoPhotochromic coatings con-taining Ag(Cl

1minus119909Br119909) microcrystalsrdquo Journal of Sol-Gel Science

and Technology vol 19 no 1ndash3 pp 681ndash685 2000[4] X Dong J Wang X Feng et al ldquoFabrication and charac-

terization of nanometer-sized AgClPMMA hybrid materialsrdquoModern Applied Science vol 2 no 6 pp 49ndash54 2008

[5] H Miyazaki H Shimoguchi H Suzuki and T Ota ldquoSyn-thesis of photochromic AgCl-urethane resin composite filmsrdquoAdvances inMaterials Science and Engineering vol 2012 ArticleID 784202 4 pages 2012

[6] I Yasui ldquoHikarizairyo amorphous-to-tankessyordquo DainihonTosho pp 178ndash184 1991 Japanese

[7] H Miyazaki Y Baba M Inada A Nose H Suzuki and T OtaldquoFabrication of photochromic tungsten oxide based compositefilm using peroxoisopolytungstic acidrdquo Bulletin of the ChemicalSociety of Japan vol 84 no 12 pp 1390ndash1392 2011

[8] H Miyazaki M Inada H Suzuki and T Ota ldquoFabricationof WO

3-based composite films and improvement its pho-

tochromic properties by copper dopingrdquo Bulletin of the Chemi-cal Society of Japan vol 85 no 9 pp 1053ndash1056 2012

[9] R K Pathak V KHinge PMondal andC P Rao ldquoRatiometricfluorescence off-on-off sensor for Cu2+ in aqueous bufferby a lower rim triazole linked benzimidazole conjugate ofcalix[4]arenerdquo Dalton Transactions vol 41 no 35 pp 10652ndash10660 2012

[10] T He Y Ma Y Cao Y Yin W Yang and J Yao ldquoEnhancedvisible-light coloration and its mechanism of MoO

3thin films

by Au nanoparticlesrdquo Applied Surface Science vol 180 no 3-4pp 336ndash340 2001

[11] T He Y Ma Y Cao et al ldquoEnhancement effect of goldnanoparticles on the UV-light photochromism of molybdenum


trioxide thin filmsrdquo Langmuir vol 17 no 26 pp 8024ndash80272001

[12] R Pascova and I Gutzow ldquoModel investigation of the mecha-nismof formation of phototropic silver halide phases in glassesrdquoGlastechnische Berichte vol 56 no 12 pp 324ndash330 1983

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Nano

materials


Journal ofNanomaterials


results expected from (2) In this study we fabricated AgCl-containing photochromic composite films with various Cucontents and observed the effects of excess Cu2+ ions on thephotochromic properties of the composite films

2 Experimental Procedure

AgNO3(995 Wako Pure Chemical Industries Ltd Osaka

Japan) HCl-EtOH (01molL Sigma-Aldrich Japan KKTokyo Japan) CuCl

2(95 Wako Pure Chemical Industries

Ltd Osaka Japan) and a liquid-state urethane resin (M-40density of 115 gcm3 Asahi Kasei Chemicals Corp TokyoJapan) were used as starting materials The urethane resincan be cured using UV-vis irradiation AgNO

3powder was

dissolved in ethanol at a concentration of 01molL TheAgNO

3solution thus prepared was mixed with a liquid

urethane resin (the Ag ion concentration in urethane resinwas 10 120583molcm3) and the HCl-EtOH solution was addedsequentially to the mixture with a ClAg atomic ratio (Here-inafter described as ldquoClAg ratiordquo) of 10 to form AgClnanoparticles CuCl

2powder was dissolved in ethanol at

various concentrations and the solution was added to theresulting mixture with varying CuAg atomic ratios (Here-inafter described as ldquoCuAg ratiordquo) ranging from 0 to 10These mixtures were stirred and thereafter the precursorsolution was prepared The mixture was degassed for 30minat 100 kPa and the resulting mixture was formed to a thick-ness of 1mm using slide glasses The precursor films werecured usingUV-vis irradiation (with a low-pressureHg lamp)for 5min thus producing composite films

The transmission spectra of the obtained composite filmswere measured using a spectrophotometer (UV-1600 Shi-madzu Corp Japan) at a wavelength range of 200ndash1100 nmHg lamp was used for measuring the photochromic proper-ties To observe the microstructure of the films the obtainedsample was ground with an agate mortar and the groundsample powder was supported by a copper grid The micro-structure of the composite films was then observed usingtransmission electron microscopy (TEM EM-002B TopconCorp Japan)

3 Results and Discussion

Theas-prepared filmswere brownbecause the precursor filmshad been cured using UV-vis irradiation and the compositefilm was coloredThe darkened films were bleached in a darkroom for 7 days and the resulting transparent films wereused to evaluate the photochromic properties Figure 1 showsthe transmission spectra for a representative composite film(CuAg ratio of 10) measured before and after UV-vis irradi-ation for 1ndash20min As shown in the figure the transparentcomposite film was colored by UV irradiation Thereforethe resulting composite film shows photochromism Theinset photographs in Figure 1 show the film before and afterUV-vis irradiation The film showed coloring because ofirradiation and the colored film showed broad absorption atthe absorption peak of 450 nm

Figure 2 presents the coloring and bleaching propertiesof the films with CuAg ratios ranging from 0 to 10 the

300 400 500 600 700

100

80

60

40

20

0

Tran

smitt

ance

()

0

5

1020

1

2

UV irradiation time (min)

Wavelength (nm)800

0min 20min

Figure 1 Transmission spectra of composite films with CuAgatomic ratio of 10 at different UV-vis irradiation times

employed wavelength was 450 nm The coloring propertywas evaluated with the time interval of 1min Increasing Cucontents in the composite films caused a slightly decrease ofthe transmittance at the bleached condition Though we areconsidering the reason it is assumed that excess Cu contentsaffect the initial transmittance of the composite films forexample deterioration or coloration of the matrix by exis-tence of excess Cu ions and so on

Using the optical property of the composite films thereaction rate constant 119896 was estimated at the wavelengthof 450 nm which represents a remarkable absorption peakof the film for the coloring condition In this study theabsorbance of the films was calculated using the value of thetransmittanceThemethod for calculating the photochromic-reaction rate constant was described in a previous study [7]The reaction rate equation is

minus ln( [119860][1198600]) = 119896119905 (3)

where 1198600is the initial absorbance and 119860 is the absorbance

after time 119905 from the initial state 1198600 The calculated reaction

rate constants of the films with CuAg ratios of 0 01 1 2 5and 75 were 0092 0118 0132 0134 0124 and 0133minminus1respectively The coloring speeds of Cu-added films werehigher than those of films without Cu addition The coloringspeeds of films whose CuAg ratios were greater than 1 wereclose to those of films whose CuAg ratio was 1 This increasein the coloring speed with the addition of Cu2+ was not inagreement with the result expected from (2) and the conflictwas discussed later

In the case of bleaching increasing the CuAg ratio inthe films resulted in an increase in the bleaching speed Tocompare the bleaching speeds of the films semiquantitativelywe calculated the half-life period of the films 120591(ℎ) where 120591was the time taken from the transmittance of the sufficientlycoloring state (20min UV-vis irradiation) to the transmit-tance of the on a half of its initial stateThe calculated half-lifeperiods 120591 of the films with CuAg ratios of 1 2 5 and 75 were144 569 298 and 280 h respectively the films with CuAg


100

80

60

40

20

00 5 10 15 20

CuAg

0

01

1

2 (dashed line)

5

75

Tran

smitt

ance

()

Time (min)

(a)

100

80

60

40

20

00 2 104 6 8

Tran

smitt

ance

()

Time (day)

CuAg

0

01

1

25

75

(b)


100

80

60

40

20

01100500300 700 900

Tran

smitt

ance

()

Wavelength (nm)

0min

10min

















100nm

(a)

100nm

(b)



4 Conclusion




References















3thin films













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




100

80

60

40

20

00 5 10 15 20

CuAg

0

01

1

2 (dashed line)

5

75

Tran

smitt

ance

()

Time (min)

(a)

100

80

60

40

20

00 2 104 6 8

Tran

smitt

ance

()

Time (day)

CuAg

0

01

1

25

75

(b)


100

80

60

40

20

01100500300 700 900

Tran

smitt

ance

()

Wavelength (nm)

0min

10min

















100nm

(a)

100nm

(b)



4 Conclusion




References















3thin films













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




100nm

(a)

100nm

(b)



4 Conclusion




References















3thin films













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article Effects of Excess Cu Addition on ...downloads.hindawi.com/journals/amse/2013/854928.pdf · Effects of Excess Cu Addition on ... had been cured using UV-vis irradiation,