Modern Polymer Spect..

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3.1 9 A Worked Example 199 The soliton solution gives the values of Oi which describes a twist in the chain which, in the absence of friction, propagates keeping the same shape and velocity v. The Utah-twist (twiston) is then approximated to a solitonic wave whose velocity of propagation is estimated by Mansfield (using some molecular parameters) to be - 10j cm s-I. The final concept which emerges is that in the orthorhonibic crystal one can conceive the existence of conforniational collective excitations thermally generated which extend over approximately 20 CH2 units and move along the chain with a certain velocity. The main problem is to prove the existence of such mobile twistons. The idea of using spectroscopy implies the fact that we should be able to detect somewhere in the vibrational spectrum absorption and/or scattering associated to vibrations localized on the twiston. Calculations have been made (i) of the density of vibrational states of a long polymethylene chain containing a random distribution of twistons and (ii) of the infrared spectrum (frequencies and intensities) of the molecule C19 containing a twiston. A comparison has been made with the infrared spectrum of C19 in the all-frans structure [169] (Figure 3-62). in these calculations the twiston is assumed not to be mobile, but pinned at a given site of the chain. The fact that the twiston is mobile along the chain in principle does not deny the possibility, under certain conditions, to observe its vibration in the infrared/Raman spectra. The conditions are the following: (a) Since the band width is inversely proportional to the vibrational lifetimes of each normal vibration, if the velocity of the twiston is small the vibrational lifetime is long enough to allow the formation of its own vibrational mode and can give rise to an observable IR or Raman band. if the twiston moves too fast, the vibrational lifetimes are too short and the band broadens and flattens in a broad continuum. Simple calculations show that if a band of the twiston has to be observed with Ai~,p M 20 cin-' it sets an upper limit to the velocity of the twiston of = lo4 cm-' which is not too different from the velocity estimated by Mansfield. (b) The concentration of twistons has to be large enough to generate a detectable absorption in IR or scattering in the Raman. The concentration of twistons depends on their energy of formation which has to be low if twistons are to be seen spectroscopically. The energies calculated for the Utah-twist [ 1661 are much too high and would make the twiston undetectable by spectroscopic techniques. The results of the theoretical calculations of the spectra of twistons and a few attempts to catch spectroscopic signals possibly associated to twistons are reported in [169]. The evidence collected so far is neither compelling nor completely negative. The model needs to be supported or dismissed by other physical techniques. The model of twistons which move as 'solitary waves' was also proposed by Dwey-Aharon et al. [ 1701 in the case of polyvinyljdene fluoride (CHz-CF?),, which upon poling transforms from the helical structure (TGTG') (labeled either as p form or form 11) into a planar all-tram one (a, or form I). Form I is technologically
200 3 Vibrutional <strong>Spect</strong>ra (IS CI Probe of Str'zictural Order Figure 3-62. Searching for twistons: section of the calculated spectruin of ti-nonadecane (-) in the all-trrrns planar conformation; (- - -) with the conformational distortion like a soliton according to Mansfield and Boyd. Both frequency and intensity were calculated.
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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
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1.2 Background 9 1.2.5 Two-Dimensio
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1.3 Bnsic Properties of 20 IR Corre
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2D IR spectrometer coupled with a d
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1.5 Applirtrtions 15 Unlike a dispe
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\ '\ Melliyleiie 1'7- -3000 Posiliv
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11 Amorphous Crystalline ,...." I F
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1.5 Applications 21 / I 1430 Figure
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1.5 Appliccitioiis 23 Methylene Fig
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1.5 Ajqdicrrtions 25 3024 Figure 1-
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1.5 Applicutions 27 Furthermore. th
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1.7 Coizclirsions 29 derived in a s
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1.9 References 31 [9] Colthup, N. B
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2 Segmental Mobility of Liquid Crys
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SRMPLE/DETECTOR e3 ‘retardation
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2.4 Srvuc me-Dependenr Alignment 37
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2.5 Electric Field-Innductid Orirnt
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2.5 Electric Field-nclticetl Orient
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a -@ COWER SRHPLE ._ 2.5 Elec tric
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2.5 Electric Field-Itzduced Orienta
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2.5 Electric Field-IwrElrced Orient
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2.5 Electric Field-Im/irced Orientu
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2.5 Electric Field-Induced Orientli
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2.5 Electric Field-Induced Orientat
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2.5 Electric Field-Induced Orienfat
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2.5 Elrc tric Field-Iiidircwl Orim
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2500 2008 I s00 WRVtNdMRtR CM-I Fig
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-3.6 Aligmient OJ' Side- Clinin Liy
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~ polyester 2.6 Alignnient qf Side-
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I." 0.9 0.8 Figure 2-34. FTlR 0.7 p
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induced alignment of the investigat
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2.7 Orientation oj Liquid Ci:i,stal
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2.7 Orieritation of Liquid Ciysttrl
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0 8 18 16 1 a W u z a m a 0 Ln m Q
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2.7 Orientation oj Liquid Crystals
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2.7 Orientation of Liquid Crjvtals
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2.7 Orientatioiz of Liquid Crystals
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2.8 Conclusions 81 strain. As A0 is
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3. I0 Refcreiice.r 83 [I 71 Hoffina
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2.10 References 85 [92] Wiesner, U.
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t Order/Disorder in Chain Molecules
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onds which hold atoms together thro
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3.2 The Dyriamical Case qf Simll ar
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3.2 The Dyrinniical Case of Sinnll
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3.4 S11or.f- and Loizg-Rcrizye Vibr
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3.4 Slzort- and Loiig-Range Vibrati
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eyularity), e.g., 2. During the pol
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3.5 Towards Lnrger Molecules: From
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3.5 TOIIYW~ Laiyer Molertiles: Fvoi
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3.5 Towmu" Larger Molecules: F~om O
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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.
Page 164 and 165: 3.14 Case Studies 149 GI A V E N U
Page 166 and 167: 3.14 Case Studies 15 1 correspond t
Page 168 and 169: 3.14 Case Studies 153 (I10 + 200) +
Page 170 and 171: 3.14 Case Studies 155 1500 1480 146
Page 172 and 173: 3.14 Case Studies 157 the molecular
Page 174 and 175: 17E (ir 1, R): (iii) z = 4, t = 1,
Page 176 and 177: 3.16 Stnictural Znlioi~zogeneity an
Page 178 and 179: 3.1 7 Fermi Resonancrs 163 stants.
Page 180 and 181: 3.1 7 Femi Resorinnces 165 2 L 1 29
Page 182 and 183: lowing. The CHl-bending mode 6 [cer
Page 184 and 185: 3.17 Ferini Re.sonrriire.s 169 a Fi
Page 186 and 187: 3. I7 Fernii Resoiiances 17 1 terin
Page 188 and 189: 3.18 Band Broadening and Confonnati
Page 190 and 191: 3.18 Bmd Brourleiziriy md Cmforrnat
Page 192 and 193: 3.18 Band Bvoaderiing arid Conjonna
Page 194 and 195: 3.18 Band Broadening and Confornmti
Page 196 and 197: 3.19 A Worked E.utinple 181 pre-mel
Page 198 and 199: 3.19 A Wovh-ecl E.uanzple 183
Page 200 and 201: 3.19 A Worked Example 185 19 5°C 2
Page 202 and 203: 3.19 A Workrd Example 187 Figure 3-
Page 204 and 205: 3.19 A Worked E.rcnniplr 189 LAM I
Page 206 and 207: 3.19 A Worked E.xuniple 191 Figure
Page 208 and 209: 3.19 A Worked E.vnn~yle 193 Figure
Page 210 and 211: 3.19 A Worked E.vnrqde 195 009.1 00
Page 212 and 213: 3.19 A Worked Example 197 existence
Page 216 and 217: 3.20 References 201 very important,
Page 218 and 219: 3.20 References 203 [41] M. Gussoni
Page 220 and 221: 3.20 Refeeveiicrs 205 [I 171 P. Jon
Page 222 and 223: 4 Vibrational Spectroscopy of Intac
Page 224 and 225: 4.3 Georrietvy oj Intuct Po1vniev.r
Page 226 and 227: 1'45 4.4 Geometric Chunges I?zditce
Page 228 and 229: 4.4 Geometric Chmges Iiid~lrcecl bj
Page 230 and 231: 4 5 Mer1iodolog.v of Raiii~11 Studi
Page 232 and 233: 4.7 Poly(p-pheiq.lene) 217 with an
Page 234 and 235: 4.7 Pol)~(p-pheiz~~lene) 219 ENERGY
Page 236 and 237: is worthwhile pointing out that the
Page 238 and 239: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 801 Table 4-3
Page 240 and 241: 4.7 Poly(y-phenylene) 225 Figure 4-
Page 242 and 243: Table 4-4. Observed Raman frequenci
Page 244 and 245: 4.8 Other Polwieys 229 Table 4-5. T
Page 246 and 247: under various models. According to
Page 248 and 249: 4. I0 Mechnriism oj Charge. Transpo
Page 250 and 251: 4.12 Reftrences 235 [ 131 Kuzmany,
Page 252 and 253: 4.12 References 237 [98j Matsunuma,
Page 254 and 255: 5 Vibrational Spectroscopy of Polyp
Page 256 and 257: 5.2 FOYCC Fields 241 such calculati
Page 258 and 259: 5.2 Force Fields 243 accounts for o
Page 260 and 261: 5.2 Force Fields 245 centers of the
Page 262 and 263: 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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