Modern Polymer Spect..

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2500 2008 I s00 WRVtNdMRtR CM-I Figure 2-27. <strong>Spect</strong>roscopic response of the FLCP upon changing the polarity of the applied electric field (1: 2926 cm-I, 2: 2854 cni-', 3: 1607 cm-'. 4: 1507 cm-I, 5: 1260 cm-I). I. 25 1.00 0. i5 0. 50 0. 25 n. 00 -0. 25' 0. 0 w u 1.2s z c 1.00 m Q 0.75 2 0.50 0. 25 1.0 2. 0 3.0 4.0 5. 0 6 0 Tinds i 0.00 -0.2s a -0.50 p ! o 5 10 15 20 25 30 35 40 45 0 Time/ms z 1 . z !. 00 0. i s 0. 50 0.25 n. 00 0. 25 01 "%, 5 ID 15 20 iE Timelms Figure 2-28. Normalized absorbance/time-plots for poling experiments of Ihe FLCP at different temperatures. (a) 28 "C, rapid-scan measurement, 20 V (DC): (b) 42 "C, step-scan measurement, 20 V,,, 20Hz; (c) 47"C, step-scan measurement, 20 V,,, 100 Ha, data acquisition for 2.5 periods. (1260 cm-' (o), 1607 cm-' (+), 2926 cni-' (0)).
about 1.5 s for 28 "C. The shape of the response curves are similar and can be described as exponential. The reorientation starts without time delay when the polarity of the applied field is changed. This means, that there is no retardation in the response of different structural segments. No distinct differences have been found in the orientation rates of the flexible and the rigid part of the molecules of ferroelectric nonpolynieric LCs [53, 581. However, it has been shown that the molecular motion cannot be described by a single exponential process but consists primarily of a fast and a subsequent slow process [52]. This motion also includes confornia tioiial changes in the flexible part of the molecule. In the polymeric ferroelectric system under investigation, such conforniational changes may take place in the spacer and the main chain. Due to the lack of conformationally sensitive absorptions in the FLCP, we were not able to detect or differentiate such changes. Taking into account the assignment of the absorption bands under consideration and their dichroic changes during poling the electric field, we can conclude from Figure 2-28 [83] that not only the mesogen but also the spacer and the main chain (at least some molecular groups which are in the neighborhood of the spacer attachment to the backbone) take part in the reorientation process during poling the electric field. This picture, however, is not supported by the 2D-correlation analysis, which shows, that there is a strong correlation between the ring-stretching bands (1506, 1607 cm-') and the two carbonyl bands around 1750 cni-' [16]. This is evidence that the mesogen reorients as a rigid unit. The strong correlation in the synchronous spectrum and no appreciable asynchronicity in the asynchronous spectrum between the mesogen bands and the v(CH2) bands (2926 and 2855 cin-'), which are mainly due to the spacer, indicates that the mesogen aiid the spacer reorient synchronously. Figure 2-29 compares the power spectrum of the FLCP to the reference spectrum (average spectrum of a reorientation process). One can easily notice, that the intensities of the spacer bands in the power spectrum are considerably reduced relative to the mesogen bands. Based on these data, we have to coiiclude that only a small part of the spacer, directly attached to the mesogen, takes part in the reorientation. The 2D analysis does not supply any evidence that the main chain of the FLCP participates in the reorientation. Based on these data, the picture shown in Figure 2-30 can be derived for the response of the FLCP to a poled electric field. 2.6 Alignment of Side-Chain Liquid-Crystalline Polyesters Under Laser Irradiation It has been demonstrated that the photo-induced orientation of dye-containing SCLCPs can be used for reversible optical data storage [85-901. FTIR polarization spectroscopy has been applied to monitor the orientation of the main chain and the mesogenic side-chains which are of critical importance in these storage processes [15, 91-94]. Here, some results obtained by laser irradiation of a homologous series
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Modern Polymer Spectroscopy Edited
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Modern Polymer Spectroscopy Edited
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Preface For unfortunate reasons the
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However, theory and calculations yi
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Contents 1 Two-Dimensional Infrared
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Con ten t~ xi Index 5.2 Force Field
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Contributors M. Del Zoppo Dipartime
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1 Two-Dimensional Infrared (2D IR)
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1.2 Brick~qrorrnrl 3 . Figure 1-3.
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1.0 , Figure 1-6. The in-phtrse and
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1.2 Bcrckgroinizd 7 where AA (i~) i
Page 24 and 25: 1.2 Background 9 1.2.5 Two-Dimensio
Page 26 and 27: 1.3 Bnsic Properties of 20 IR Corre
Page 28 and 29: 2D IR spectrometer coupled with a d
Page 30 and 31: 1.5 Applirtrtions 15 Unlike a dispe
Page 32 and 33: \ '\ Melliyleiie 1'7- -3000 Posiliv
Page 34 and 35: 11 Amorphous Crystalline ,...." I F
Page 36 and 37: 1.5 Applications 21 / I 1430 Figure
Page 38 and 39: 1.5 Appliccitioiis 23 Methylene Fig
Page 40 and 41: 1.5 Ajqdicrrtions 25 3024 Figure 1-
Page 42 and 43: 1.5 Applicutions 27 Furthermore. th
Page 44 and 45: 1.7 Coizclirsions 29 derived in a s
Page 46 and 47: 1.9 References 31 [9] Colthup, N. B
Page 48 and 49: 2 Segmental Mobility of Liquid Crys
Page 50 and 51: SRMPLE/DETECTOR e3 ‘retardation
Page 52 and 53: 2.4 Srvuc me-Dependenr Alignment 37
Page 54 and 55: 2.5 Electric Field-Innductid Orirnt
Page 56 and 57: 2.5 Electric Field-nclticetl Orient
Page 58 and 59: a -@ COWER SRHPLE ._ 2.5 Elec tric
Page 60 and 61: 2.5 Electric Field-Itzduced Orienta
Page 62 and 63: 2.5 Electric Field-IwrElrced Orient
Page 64 and 65: 2.5 Electric Field-Im/irced Orientu
Page 66 and 67: 2.5 Electric Field-Induced Orientli
Page 68 and 69: 2.5 Electric Field-Induced Orientat
Page 70 and 71: 2.5 Electric Field-Induced Orienfat
Page 72 and 73: 2.5 Elrc tric Field-Iiidircwl Orim
Page 76 and 77: -3.6 Aligmient OJ' Side- Clinin Liy
Page 78 and 79: ~ polyester 2.6 Alignnient qf Side-
Page 80 and 81: I." 0.9 0.8 Figure 2-34. FTlR 0.7 p
Page 82 and 83: induced alignment of the investigat
Page 84 and 85: 2.7 Orientation oj Liquid Ci:i,stal
Page 86 and 87: 2.7 Orieritation of Liquid Ciysttrl
Page 88 and 89: 0 8 18 16 1 a W u z a m a 0 Ln m Q
Page 90 and 91: 2.7 Orientation oj Liquid Crystals
Page 92 and 93: 2.7 Orientation of Liquid Crjvtals
Page 94 and 95: 2.7 Orientatioiz of Liquid Crystals
Page 96 and 97: 2.8 Conclusions 81 strain. As A0 is
Page 98 and 99: 3. I0 Refcreiice.r 83 [I 71 Hoffina
Page 100 and 101: 2.10 References 85 [92] Wiesner, U.
Page 102 and 103: t Order/Disorder in Chain Molecules
Page 104 and 105: onds which hold atoms together thro
Page 106 and 107: 3.2 The Dyriamical Case qf Simll ar
Page 108 and 109: 3.2 The Dyrinniical Case of Sinnll
Page 110 and 111: 3.4 S11or.f- and Loizg-Rcrizye Vibr
Page 112 and 113: 3.4 Slzort- and Loiig-Range Vibrati
Page 114 and 115: eyularity), e.g., 2. During the pol
Page 116 and 117: 3.5 Towards Lnrger Molecules: From
Page 118 and 119: 3.5 TOIIYW~ Laiyer Molertiles: Fvoi
Page 120 and 121: 3.5 Towmu" Larger Molecules: F~om O
Page 122 and 123: 1700 - CIO --- ca c 22 _- c 12 l l
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3.6 From Dynamics to Vibrational Sp
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3.6 Froin Dynaiiiics to T’ihratio
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3.7 The Case of Isotactic Polypropy
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3.7 The Cuse of Isotactic Polypvop.
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3.8 Density of Vibrational States a
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3.8 Dtvz.sit,v of L’ihrntioizal S
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3.8 Driisity of Vibratioiid StLitrs
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3 9 Mouiiiq ToIvmds Rerrlitv: From
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3.9 Moving Towards Reality: From Or
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3.9 Moving Towards Reality: Froin O
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3.10 Wlmt Do We Learn from Cnlcailc
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+ 3.11 A Very Siriiple Ccrse: Latti
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3 I1 A Yey) Siiiiple Case: LLittice
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3.11 A Vq> Siiiiplc Crrw: Luttice D
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Figure 3-22. Sample eigenvectors in
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3.12 CIS-trans Opening @the Double
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3.13 Defect Modes cis Structtrr.al
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3.13 Defect Mo&s cis Structurcil Pr
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0 3.14 Case Studies N 0 d - Y N o m
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3.14 Case Studies 147 OC 60 58 57.
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3.14 Case Studies 149 GI A V E N U
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3.14 Case Studies 15 1 correspond t
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3.14 Case Studies 153 (I10 + 200) +
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3.14 Case Studies 155 1500 1480 146
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3.14 Case Studies 157 the molecular
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17E (ir 1, R): (iii) z = 4, t = 1,
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3.16 Stnictural Znlioi~zogeneity an
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3.1 7 Fermi Resonancrs 163 stants.
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3.1 7 Femi Resorinnces 165 2 L 1 29
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lowing. The CHl-bending mode 6 [cer
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3.17 Ferini Re.sonrriire.s 169 a Fi
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3. I7 Fernii Resoiiances 17 1 terin
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3.18 Band Broadening and Confonnati
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3.18 Bmd Brourleiziriy md Cmforrnat
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3.18 Band Bvoaderiing arid Conjonna
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3.18 Band Broadening and Confornmti
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3.19 A Worked E.utinple 181 pre-mel
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3.19 A Wovh-ecl E.uanzple 183
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3.19 A Worked Example 185 19 5°C 2
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3.19 A Workrd Example 187 Figure 3-
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3.19 A Worked E.rcnniplr 189 LAM I
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3.19 A Worked E.xuniple 191 Figure
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3.19 A Worked E.vnn~yle 193 Figure
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3.19 A Worked E.vnrqde 195 009.1 00
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3.19 A Worked Example 197 existence
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3.1 9 A Worked Example 199 The soli
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3.20 References 201 very important,
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3.20 References 203 [41] M. Gussoni
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3.20 Refeeveiicrs 205 [I 171 P. Jon
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4 Vibrational Spectroscopy of Intac
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4.3 Georrietvy oj Intuct Po1vniev.r
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1'45 4.4 Geometric Chunges I?zditce
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4.4 Geometric Chmges Iiid~lrcecl bj
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4 5 Mer1iodolog.v of Raiii~11 Studi
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4.7 Poly(p-pheiq.lene) 217 with an
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4.7 Pol)~(p-pheiz~~lene) 219 ENERGY
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is worthwhile pointing out that the
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~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 801 Table 4-3
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4.7 Poly(y-phenylene) 225 Figure 4-
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Table 4-4. Observed Raman frequenci
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4.8 Other Polwieys 229 Table 4-5. T
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under various models. According to
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4. I0 Mechnriism oj Charge. Transpo
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4.12 Reftrences 235 [ 131 Kuzmany,
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4.12 References 237 [98j Matsunuma,
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5 Vibrational Spectroscopy of Polyp
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5.2 FOYCC Fields 241 such calculati
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5.2 Force Fields 243 accounts for o
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5.2 Force Fields 245 centers of the
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5.2 Force Fields 247 ture with conf
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5.3 Amide Modes 249 to the nh initi
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5.3 Ainide Modes 251 Table 5-1. Ami
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Table 5-2. Some amide modes of four
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5.3 Amidc Modes 255 Figure 5-1. Opt
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5.4 Polypeptides 257 nonhydrogen-bo
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5.4 Polvpeptida 259 Figure 5-2. Ant
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I 5.4 Polypeptides 261 )I .- + $ 80
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1226M 1222s (1 1165W 1167s (1 1120V
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135s 9 1 Ms1i 122Wbr 147 NH ob(37)
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5.4 Polypeptides 267 glycine residu
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5.4 Polypeptides 269 Raman bands in
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5.4 Polypeptides 271 Figure 5-7. St
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Frequency (cm-'1 100% b 700 500 300
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5.4 Polypptidt~s 215 Table 5-9. Obs
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~~ ~~ ~~~ ~ ~ ~~ 5.4 Polypeptides 2
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5.4 Poliyeptides 219 Table 5-11. Co
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Table 5-12. Aniide mode frequencies
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1351 Lifson, S., Stern, P. S., J. C
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5.6 Refeverices 285 [130] Tiffany,
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Index Amide modes 249 Amorphous pol
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Step-scan FTIR spectroscopy 14,34 -
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