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Polymer (Korea), Vol. 28, No. 6, pp 545-550 (2004) /
Vâ, \28Ì \6x, 2004, pp 545-550
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ÄÐ ÌìÔ < DpQ °p, Qõ é L ÌÐ 1 DÐð é´ X´\ åA¸ - Ô Ì ì\ @, è| È$. QÌÐ $ì´¼ ì éÔ Ã , Äм ´éÌ X´ @ ô ééq´ 0ôØ° @5 5U´ (\ @@@ é´
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ÌÐÔ ÄÐ U ô\ Q´ ÉÔ L A-
´H ´ < 4$ ÒÌ dXô¼ DXì , Q
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X´ @å \ ( ,¨ ÈÔ ÄÐ 5Q
©ô¼ ìé, ùU A-\ QX `, Q D, A-< 8 < ´H ¸DA| °HÔ i Õ´ ´ ´éX È$.8-11
8 0¬\Ô Q X ¼|äÔ \ (´ 4ì(
8 ¬ôH´ø) PMMA <ìì ìì Ùô ÈÔ 5Q©ô¼ ìé, 5Q©ô °q p¸ ´H
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+5337# 44# 7¼# QX/#5337# 44# 56¼# ,#
Refractive Index Changes of Polymer Film by Photochemical Reactions
Jung Hwan Cho, Mi Young Shin, Jong Ha Lee, Sung Soo Kim, and Kigook Song% Department of Chemical Engineering and Materials Research Center for Information Display,
Kyung Hee University, 1 Seochon-ri, Yongin, Gyunggi-do 449-701, Korea
†e-mail : ksong@khu.ac.kr
(Received November 4, 2004;accepted November 23, 2004)
5¨¹Q°ì , \ ( Ä´¼ `¨|¨ ÄÐ ´H \ 5Q©ô U ´ H °H , FTIR< UV/Vis ÄQ $| ´H Aå 8Ô ¬° ¼ °ì@$.
Qq p¼ 5Q©ô U ´H ´ Ñ Ô Ã QX , \ ( ô C¼C ´Qð
©´ ôx ÄÐ ø9 ´ Ñ p x´$. ÅìXÔ Dpå iå ´Ô `
A¸ QX , Ä ´ É iå| ´ìÔ \ (´ |@ Ä´@ X´\ ÄÐ
Ä ´ É iå ´H ´ X iå\ 4$ IéÌ PÌ@$. ´ Y
ÄÐ U ô ´H h´¼ øQ ATR-FTIR $\ ûô Ô ÄÐ ùq |¬ ¼ ° ì, ÝÅ@$.
,-897,.9¹The refractive index of thin copolymer film was controlled by photo-degradation of chromophores in the copolymer. FTIR and UV/Vis spectroscopy were employed to elucidate the effect of chemical structure on refractive index changes after photobleaching. The decrease of refractive index of the film by photobleaching can be ascribed to the decrease of polarizability of polymer molecules through breakage of C¼C bond in the chromophore. Due to the selective photoreaction of the chromophores which align along the film plane, refractive index of the copolymer film measured in TE mode decreases faster than that in TM mode. Polarized ATR-FTIR spectroscopy was used to verify such a difference in refractive index of the film.
Keywords¹refractive index, polymer film, waveguide, photobleaching, ATR-FTIR.
Cho et al. Polymer (Korea), Vol. 28, No. 6, 2004/
°U# 1# Vâ, \28Ì \6x, 2004/
\ ( Qq , \XÔ ´H
¼ , ÄÐ ´H 8Ô ÄÐ ¬
° Aå °ì@$. QL \° ìéÔ ,,
´H °H iÕ Q Qq iÕ ÄÐ ,¨\ \ ( °ì, \ (´ Q´q 2Ô QÄ´
Xô $¸ ¬° ©| h|¨ ´H
äÔ iÕ|, D( å¼ ´é, ½Ì XÉ X È|°, photo-mask¼ ´é, $Ñ èÑ QL
\° Aé X Èô @å ´ ìéXÔ iÕ´$. Q Xq \ ( ,¨ ÈÔ 5Q©ô¼ ìé, ÄÐ U Qq ´é ´H $ ð
< ÄÐ 5Q©ô °q p¸ ´H
¼ p D, prism coupling $ iÕ ´é
, ÄÐ U ´H aU@ , FTIR< UV/Vis spectroscopy¼ ´é, ´H Aå 8Ô ÄÐ ¬° ¼ °ì@$.
#aU
8 0¬\ ìé 5Q©ôÔ 8 Hoechst Celanese
Corp.\ ÄÐ Qõ ÌÐ ép D, \\
`U Q ÄÐ\4-6 (`U Q) 8
¬ôH´ø (MMA)¼ X5 (D Ô <ìì \ (| 4,4'-T88¸øä8ä (DANS) ì ì @ ÈÔ MMA DANS 5Q©ô´$ (Figure
1¹P2ANS Å). 5Q©ô P2ANSÔ DANS MMA
h´ 50:50, 35:65, 25:75 8ì 10:90¸ 4 Å \
$¸ °q ¼ ´é@$. UV/Vis ÄQ $
D´\ P2ANS 5Q©ô¼ cyclohexanone ¹, 5 wt%
é¡ , quartz pP D 3000 rpm| ä
E , ¼ @@|°, Hitachi U-2000 UV/Vis ÄQp¼ ´é, $ XÉ@$. FTIR ÄQÕ ´ é $ 20 wt% P2ANS é¡ KBr pP D 1500 rpm| ä E, U @ , Perkin- Elmer System 2000 FTIR ìé, 4 cm-1 Ä´å| 32 Èi äÔ, aU@$. FTIR attenuated total reflec- tion (ATR) $ ´é ÄÐ U ´ Ä]
PIKE Technologies\ \° variable angle horizontal ATR accessory¼ ìé@|° mercury cadmium telluride
(MCT) À p¼ ìé, 200È äÔ , äÙ
ø< û$. øQ (polarized) FTIR $ aU Harrick ì\ \° KRS-5 wire grid U øQP ´é, X 2Ô É| øQ\ IR ìé¨|¨ AA øQ iå @ äÙø< û$.
Qq (photo-bleaching) $ 500 W X 1
ìé, ÄÐ U X| Q°ì¼ XÉ@|
°, ÄÐ U ´H Figure 2 4´Ô å
He-Ne H´@ GGG DìØ (n¼1.965)| $$\
\Ñ prism coupling å¼ ´é, aU@$. Prism coupling iÕ ´é ÄÐ U ´H aU $
\Ô P2ANS 20 wt% é¡ 1500 rpm| `ì pP D ä E, 2 Ä| 150
\ 24D ´° $ ´é@$. Prism coupling åÔ ÌDP D\ DìØ ÄÐ U < QI\
ùU ÅìA\ DìØ Åì\ H´@ ´ ÄÐ U ôÀ É X ÈÌ Ô, É Dð© (coupling)
´ ¼ôØÌ Ô $ iÕ´$. H´@ ÅìA
ÌDP| 0.005°i U@Ì °H´\ ÅìA p¼ DìØ X@ø\ ÜìXÔ H´@ xp¼ a UÌ X´, Dð©´ ¼ôØ DìØ\
DXìXô ] UqÌ X° Dð© ,
Lè¼ Uq ´ ÄÐ U ôÀ D, X| U @ô° À `| Ø Ü$. ´,
Dð©´ ¼ôà Åì A¼ aU, U
´H ð@$.
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Q X ¼|äÔ \ (´ ìì ÙôÈÔ 5Q©ô¼ ìé, \° U ´H 5Q©ô
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)LJXUH Chemical structure of MMA/DANS (P2ANS) copoly- mer./
Polymer (Korea), Vol. 28, No. 6, 2004 Refractive Index Changes ofPolymer Film
Vâ, \28Ì \6x, 2004 QX ´H # #
°q ä° °H@$. DANS MMA ° q@ \ $¸ P2ANS 5Q©ô$ ´H aU
, ´ ð<¼ FTIR< UV/Vis ÄQ $ ´é, Ä]@$. DANS:MMA °q h´ 50:50, 35:65, 25:75 8ì 10:90¸ 5Q©ô é¡$ ä E, \°
2 U ´H 633 nm He-Ne H´@¼ ìé prism coupling iÕ| aU, 5Q©ô °q
p¼ Figure 3 Ø ô$. PMMA <ìì @
ð©Xô ÈÔ \ ( DANS ¨ ´ Ý@ X
´H ´ ´Ì Ý@¨ X È$. ´H ÄÐ
ø9 (polarizability) ¬p , «-DÐ$´ 5
¡ ¬° 0ðXô Èô (Figure 1 x°) $$À ø9
@ Ô DANS 89´ ìì Ùô ÈÔ P2ANS 5 Q©ô ýð DANS ¨ p¼ ÄÐ ´H ´ ¬ Ì Ý@Ô Ã´$. ´Ô FTIR äÙø<\ ûô
DANS 89 ùq |¬ 1335cm-1 (NO2 symmetric stretching)
xp@ ´H ° ¼Ì DANS Ñ
p¼ Ý@Ô Ã|Àp ¸ X È$. ´H ´ 1.49¸ PMMA¼ DANS 5Q©ô $ ýð DANS Ñ Ý@ p¼ ´H ´ Ý@, 50:50 5Q©ô¸
P2ANS50 ýð 0.22@ Ý@ 1.71´ X , 5Q©ô
°q °H , ÄÐ U ´H 8x
°H X ÈÔ Ã X È$.
5Q©ô °q °H, ´H è ð
<¼ Q°ì iÕ| ÄÐ U ´H è ýð @$. ÄÐ UV A- °ì,
\ ( Ä´¼ `¨|¨ ÄÐ ´H
äÔ Qq iÕ åP D( å¼ ´é,
$ XÉ X Èô $Ñ èÑ QL \°
Aé X ÈÔ Ã´$. QqXô Ô ÄÐ ´H ´|Àp PA| Q°ì °´ p¼
´¼ °H, ùU R @ Ô ÄÐ U
| ´é X È$.12,13 Qq iÕ| P2ANS 5Q©
ô U ´H °Hp D, Q°ì D p
¸ ´H ¼ aU , FTIR< UV/Vis ÄQ $
| QX p¸ ¬° ¼ Ä]@$. P2ANS50 (DANS:MMA °q´ 50:50¸ 5Q©ô) Ä Q°ì
Slit
X- Y stage M otorized
Rotation Stage
Photo diode 2
com puter Lens
Rotation Stage Controller Polarizer
Photo diode 1 1/4 λ plate Laser
Lock-In Aplifier Chopper
Slit
X- Y stage M otorized
Rotation Stage
Photo diode 2
com puter Lens
Rotation Stage Controller Polarizer
Photo diode 1 1/4 λ plate Laser
Lock-In Aplifier Chopper
)LJXUH Experimental setup for refractive index measurements using the prism coupling method./
)LJXUH Refractive index changes of P2ANS copolymer films as functions of comonomer composition and photo-bleaching time./
83# 73# 63# 53# 43#
DANS Content
Refractive Index
41:5 41:3 419;
4199 4197 4195 4193 418;
4189
Exposure time (min)
3# 83# 433# 483# 533# 583# 633#
C opolym er ratio P hotobleaching
Cho et al. Polymer (Korea), Vol. 28, No. 6, 2004/
°U# 1# Vâ, \28Ì \6x, 2004/
° @p Figure 4 UV/Vis äÙø<\ «-DÐ$´
5¡ ¬° 0ð\ DANSÔ ¡X ¸A DÐ$ $l D´@ «©* « 430 nm |¬
«© * n 300 nm |¬\ Ø ØÔ Ã´ 4¸$. Q
°ì , \ ( DANS 430< 300 nm |¬$
xp@ PP Dô$ Lå\ ô S |
¬@ Ø ØÔ Ã Figure 4\ < X È$. ´,
UV/Vis ¡X|¬ blue-shift D \ ( ,¨X ô ÈÔ 5¡¬° -ð© 0ð´ QX , ô p x´$. Q°ì p¸ ´ Y ÄÐ ¬°
Ô FTIR ´é $\ DANS 89 ô ä8ä
´Q ð©´ ô Ô Ã|Àp ¸ X È$.14 5Q©ô P2ANS50 U Qq p¸ ´H
¼ Figure 3 5Q©ô °q , Ø ô$. Q°ì D´ xôX U ´H ´ Ñ
Ô Ã QX , DANS 89 ô ä8ä C¼C
´Q ð©´ ô p x´$.14 QX| DANS ô
-ð© 5¡ ¬°@ ì¼ Ô ÄÐ ¬° x ø 9 ´ Ñx ´H ´ î Ô Ã´$. Q°ì p
¼ DANS ô ä8ä C¼C ´Q ð©´ ôx DANS ¬
°@ Ô Ã UV/Vis ÄQ $\ DANS ùq |
¬¸ 430 nm xp@ DôÔ Ã´ 4´Ô Figure 4
P2ANS 5Q©ô¼ Qq° °ì FTIR $ ð<
\ DANS 89 ùq |¬ xp@ PÌÔ Ã|
Àp ¸ X È$.14 5Q©ô °q p¼ ÍA
| ´H ´ Ô ýð $´Ì Qq ýð
Ô ´H ´ HpÔ ´Ì PÌØ Q°ì D´ x ô ´ ¼U R ,, Ô Ã 4,<
$. P2ANS50 5Q©ô ýð Qq iÕ| Hp 1.71
¸ ´H 1.62 ì X È$. Q°ì Ñ
p¼ ´H ´ Ô U¼ FTIR $\ ûô
DANS 89 ùq |¬ (1335 cm-1) PÌh, É DANS 8 9 5¡ ¬°@ ô Ô U ð<¼ Figure 5 @$. Qq p¸ ´H PÌ@ DANS ô 5¡ ¬° Ñ h , PÌÔ ´ Y
$ ð<\ Q°ì , Ø ØÔ P2ANS50 U
´H PÌ @ÀÄ DANS 89 ¬°
p,¼Ô Ã X È$.
´ ÄÐ Ä ô QL¼ É , P2ANS50
Ä ´H Dpå qÄ´ Ä ´< É
TE (transverse electric) è Ä ´ X TM (tran- sverse magnetic) è ØDô Qq D p¼ aU
, Figure 6 @$. Q°ì , Ä ´ H TE TM è\ è PÌÔ° ´Ô \
dÅ@/´ DANS \ (´ QX , Ä´X p x´$. Q°ì D aU P2ANS50 Ä ´H
)LJXUH UV/Vis spectra changes of P2ANS50 film with photo- bleaching time./
# 583# 633# 683# 733# 783# 833# 883# 933# 983 Wavelength (nm)
Absorbance
31<
319
316
313
/ / / / / / / / /
)LJXUH Plot of IR absorbance ratio against refractive index ratio of P2ANS50 films after photo-bleaching./
)LJXUH Refractive index (TE and TM mode) changes in P2ANS50 film with photo-bleaching time./
4133# 31<;# 31<9# 31<7 n/n0
I (1335 cm-1 )/I (1335 cm-1 )0 415 413 31;
319
317 315 313
3# 83# 433# 483# 533
Exposure time (min)
Refractive Index
41:5 41:3 419;
4199 4197 4195
Polymer (Korea), Vol. 28, No. 6, 2004 Refractive Index Changes ofPolymer Film
Vâ, \28Ì \6x, 2004 QX ´H # #
Ä ´ ÉÌ QL¼ p¼ Dpå
´ ÉÔ TE è\ aU ´H R´ Dpå q Ä´ Ä´ X \ ÉÔ TM è û
R4$ ½D ¬Ì @pX$. ´, ´H h´
Ô ä E ´é, ÄÐ U \° ýð, ÄÐ ìì ô ä` 89$´ 5¡ ¬° 0ð\ ÀÄ´
(( Xô ä E ,e , Ä ´ ɸ iå| D\ ´ìÔ ´ Ä
´ X| \ ÈÔ 4$ ¬p x´$. P2ANS 5 Q©ô ìì Q (( ÀÄ, É DANS 89 ø9 ´
$\ ´H R´ ìì $¸ ÀÄ4$ ¬ TE è
´H R´ ¬Ì ØdÔ Ã´$. ,e´ ´ Ä
Ô bar E iÕ ´éÌ X´ ÄÐ ìì
$´ pP ´ D\ Ä p4Ì X bar E Õ| U \°, ä E| ûô
@$. Prism coupling| aU bar E P2ANS50 Ä 5´H R 0.810-3 ä EÕ ´ \
°\ Ä 5´H 0.5710-2 , ¬Ì Ñx Ä ô 5´H´ ° ´ì Ô Ã X È$.
8, P2ANS 5Q©ô U \° ,e
, (( DANS 89´ pP ÉÌ p4XÔ ä
E ýðÔ ,ì bar E| Ä \°Ì X
´ ä` 89$´ 0ð\ DANS 89 Ä ´< X 2Ô X| Ä p4Ô Ã´$.
P2ANS50 U Q°ì¼ ´ TE è ´H R´
´Ì PÌ, ' TM è ´H R4$ Ñ ,
R h´, É U 5´H R´ 60Ä @@ (∆n
¼0.02) X$@ $ DôÔ D Figure 6\ <
X È$. QX ÍÔ °ì\ Dpå iå< Q Xp transition dipole iå´ ¼@
@ ¡X@ ¼ôØ @å ´Ì É Ì \$. 8,
ä E| \°\ P2ANS50 U ô\ ÉX Ô QX ýðÔ Qq D, °ìÔ D på iå´ Ä ´ ÉÌ Åì QX Í
@ Ä ´ ÉÌ DÈÔ DANS (l èh A| ´(ô Ì \$. ÅìXÔ Dpå iå
´Ô `A¸ QX , Ä ´ É
iå| ´ìÔ DANS 89´ |@ Ä´@ X´\ Ä ´ É iå¸ TE è ´H ´ TM è\
4$ IéÌ PÌp x Figure 6 ð<@ Ø ØÔ Ã´$.
TE TM è\ ´H @ ´ Y
dÅ ÝÅp D, ATR (attenuated total reflection)
FTIR $ XÉ@$. UV¼ P2ANS50 Ä ¼U
D °ì, QX ` Ä ´ ÉÌ (TE
mode) øQ\ IR ´é, aU øQ ATR-FTIR äÙø< (Figure 7)< Ä ´ X øQ| aU
(TM mode) ATR-FTIR äÙø< ûô A è\ Q
q ͼ @$. DANS ô ä8ä 89 C¼C
´Q ð©´ ô ä` 89 5¡ ¬° ù q |¬¸ 1584 cm-1 |¬ xp@ IéÌ DôÔ Ã´ Ø Ø°, 8 ð< DANS \ ( ÙôÈÔ NO2 89´ ôx 1335 cm-1 NO289 sym. Stretching
ô |¬@ DôÔ Ã´ @p\$. DôA|
÷ ¼ 4´Ô TE TM è øQ ATR-FTIR ä Ùø<ô\ 1335 cm-1 |¬ ¼ x@Ì @ p@$. ä E ð< Ä ´ ÉÌ p4
Ì XÔ DANS 89 ô NO2 89 sym. stretching
ô transition moment iå Ä ´< É TE è\ Y , Ä ´ X| p4\ DANS Ù ôÈÔ NO289 ô iå TM è iå< Y
$. Q°ì D p¼ AA øQ FTIR $\ ûô
)LJXUH Polarized ATR-FTIR spectra (TE mode) change of P2ANS50 film with photo-bleaching time./
)LJXUH Decrease in 1335 cm-1 peak (TE and TM mode) intensity of P2ANS50 film with photo-bleaching time./
Absorbance
4;33# 4:33# 4933# 4833# 4733# 4633# 4533#
Wavenumber (cm-1)
3# 43# 53# 63# 73# 83# 93#
Exposure Time (min) A/A0 (1335 cm-1 )
413 31;
319 317 315 313
Cho et al. Polymer (Korea), Vol. 28, No. 6, 2004/
°U# 1# Vâ, \28Ì \6x, 2004/
Ô 1335 cm-1 |¬ xp PÌ UÔ TE è û
ATR-FTIR äÙø<\ ´Ì PÌÔ Ã Figure 8
\ ¸ X È$. ´Ô Figure 6 Qq
´H $\ TE è aU ´H ´ ´Ì PÌÔ Ã< Y ´`´$. Q°ì@ Ä ´
X iå| ÉX Dpå iå Ä
´ ÉÌ °ìXÔ°, ä E| ¸, Ä
´ iå| DÈÔ DANS 89$´ X| ´ì
Ô DANS$4$ ´Ì QX , Ä´@ ¼ôØ
° 1335 cm-1 |¬@ PÌÌ \$. 8, Ä ´
X | û øQ ATR-FTIR äÙø<\ DANS ù q |¬ xp PÌØ øQ prism coupling $\ TE è
û ´H PÌ@ AA TM è\ û ð
<4$ ´Ì Ø ØÔ Ã´$.
%-Ý
Q°ì , \ ( Ä´¼ `, ÄÐ Ä ´H äÔ Qq iÕ| P2ANS 5Q
©ô U ´H °H , FTIR< UV/Vis ÄQ $
| ´H Aå 8Ô ÄÐ ¬° ¼ ° ì@$. Qq p¼ P2ANS50 U ´H ´ 1.71
\ 1.62 Ñ Ô Ã QX , DANS 8 9 ô ä8ä C¼C ´Q ð©´ ôx ÄÐ ø9 ´ Ñ p x´$. Q°ì p¸ P2ANS50 U
´H PÌÔ DANS 89 ¬° p,
@ ¬$Ô Ã X È$. 5Q©ô °q p¼ ` UA| ´H ´ Ô ýð $´Ì Qq ý ðÔ ´H ´ HpÔ ´Ì PÌØ Q°ì D
´ xô ´ ¼U R ,, Ô Ã 4,
<$.
P2ANS U ´H Ä ´ ÉÌ QL
¼ p¼ Dpå´ ÉÔ TE è\ aU ´ H R´ Dpå qÄ´ Ä´ X \ ÉÔ TM è û R4$ ½D ¬Ì @pX$.
´, ´H h´Ô ä E ´é, ÄÐ U \° ýð, ÄÐ ìì ô ä` 89$´ 5¡
¬° 0ðXô ÈÔ ÀÄ´ (( Xô
ä E ,e , Ä ´ ɸ iå|
D\ ´ìÔ ´ Ä ´ X| ÈÔ
4$ ¬p x´$. P2ANS U Q°ì¼ Ì X
´ TE è ´H R´ ´Ì PÌÔ Ã < X È
$. QX ÍÔ °ì\ Dpå iå< QX
p transition dipole iå´ ¼@ @å ´Ì
É Ì X , ä E| \°\ P2ANS50 U ô\Ô Ä ´ ÉÌ DÈÔ DANS ( l èhA| QX´ ¼ôØÌ \$. ÅìXÔ
Dpå iå ´Ô `A¸ QX , Ä
´ É iå| ´ìÔ DANS 89´ |@ Ä
´@ X´\ Ä ´ É iå¸ TE è ´H
´ TM è\ 4$ IéÌ PÌÔ Ã´$. ´
Y TE TM è\ ´H ¼ øQ ATR-FTIR
$\ ûô Ô NO2 @ Õô |¬ xp
¼ °ì, ÝÅ@$.
)Õ }8 0¬Ô ðÐÀ hx@ p`\\
ì L¼ä1 Ql` p`\\ ì( | X ÉXõ$.
7DEDKDGBDL
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