Unique Morphological and Thermal Behaviors ofReorganized Poly(ethylene terephthalates)

MIN WEI,1 TODD A. BULLIONS,2 CRISTIAN C. RUSA,1 XINGWU WANG,1 ALAN E. TONELLI1

1Fiber & Polymer Science Program, North Carolina State University, Campus Box 8301, 2401 Research Drive,Raleigh, North Carolina 27695-8301

2Center for High Performance Manufacturing, College of Engineering, Virginia Polytechnic Institute & State University,132 Norris Hall, Blacksburg, Virginia 24061-0219

Received 6 June 2003; revised 28 July 2003; accepted 17 August 2003

ABSTRACT: Bulk poly(ethylene terephthalate) PET has been reorganized both morpholog-ically and conformationally by processing from its inclusion complex (IC) formed with�-cyclodextrin (CD). In the narrow channels of its �-CD-IC crystals the included guest PETchains are isolated from neighboring PET chains and the ethylene glycol (EG) units adoptthe highly extended g�tg� kink conformations, whose cross-sectional diameters are �80%of the diameter of the fully extended, all-trans crystalline PET conformer, though they arenearly (�95%) as extended. When the highly extended, unentangled guest PET chains arecoalesced from their �-CD-IC crystals by exposure to hot water, host �-CDs are removedand the PET chains are presumably consolidated into a bulk sample with a morphology andconstituent chain conformations not normally found in PET samples solidified from theirrandomly coiling, possibly entangled, disordered melts and solutions. Observations bypolarized light and atomic force microscopies provide visual evidence for widely differentsemicrystalline morphologies developed in coalesced and as-received PETs when crystal-lized from their melts, with possibly chain extended, small crystals and spherulitic, chain-folded, large crystals, respectively. DSC observations reveal that coalesced PET is rapidlycrystallizable from the melt, while as-received PET is slow to crystallize and is easilyquenched into a totally amorphous sample. Analyses of 13C-NMR data strongly indicatethat the PET chains in the noncrystalline regions of the coalesced sample remain predom-inantly in the highly extended kink conformations, with g�tg� EG units, which arerequired by their inclusion into PET-�-CD-IC crystals, while the predominantly amorphousPET chains in the as-received sample have high concentrations of gauche�OCH2OCH2Oand trans OOOCH2O,OCH2OOO EG bond conformations. 13C-NMR T1(13C) andT1�(

1H) relaxation studies show no evidence of a glass transition for coalesced PET, whilethe as-received sample shows abrupt changes in both the MHz [T1(13C)] and kHz [T1�(

1H)]motions at T � Tg. Preliminary observations of differences in their macroscopic propertiesare attributed to the very different morphologies and conformations of the constituentchains in these PET samples. Apparently the kink conformers in the noncrystalline regionsof coalesced PET are at least partially retained for extended periods even in the melt andare rapidly crystallized upon cooling. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: PolymPhys 42: 386–394, 2004Keywords: morphology; thermal behavior; reorganized poly(ethylene terephthalates)

INTRODUCTION

Polymers may form noncovalent, crystalline com-plexes with several small-molecule hosts, such as

urea, perhydrotriphenylene, and cyclodextrins.1,2

In these inclusion complexes (ICs) the guest poly-mer chains occupy narrow cylindrical channels (D�5–10 Å) created by the crystalline host lattice.As a consequence, the included polymer chainsare constrained to assume highly extended con-formations, and are generally segregated fromneighboring included polymer chains by the chan-

Correspondence to: A. E. Tonelli (alan_tonelli@ncsu.edu)Journal of Polymer Science: Part B: Polymer Physics, Vol. 42, 386–394 (2004)© 2003 Wiley Periodicals, Inc.

386

nel walls of the host crystalline lattice, asshown schematically in Figure 1. When the hostis removed from the molecular complex, theguest polymer chains are forced to coalesce intoa bulk solid. Our results have shown that crys-tallizable polymers coalesced from their molec-ular complexes reveal semicrystalline charac-ters distinct from samples crystallized fromtheir completely disordered solutions or melts.3–5

These observations suggest an extended-chaincrystalline morphology for the IC-coalesced poly-mer samples.

When guest poly(ethylene terephthalate)(PET) was coalesced from its IC formed with host�-cyclodextrin (�-CD), the coalesced PET wasfound5 to have a much higher crystallinity(�40%) than the as-received sample (�14%). Re-peated heating and cooling DSC scans observedbetween 30 and 280 °C on the coalesced PETrevealed an absence of both a glass transition anda crystallization exotherm upon heating, withonly a melting endotherm that remained large.Even after holding the coalesced PET in the meltfor 2 h, and following rapid cooling, the coalescedPET only showed a melting endotherm on subse-quent reheating. Unlike as-received PET, the co-alesced sample is apparently repeatedly and rap-idly crystallizable from its melt, with noncrystal-line portions of the sample that do not evidence aglass transition.

FTIR observations5 of both as-received and co-alesced samples were interpreted to indicate thatthe PET chains in their noncrystalline regionshave very different conformations, with predomi-

nantly trans (t) and gauche (g�) OCH2OCH2Oand OOOCH2O, OCH2OOO bonds, respec-tively, in coalesced PET and g� and tOCH2OCH2O and OOOCH2O, OCH2OOObonds, respectively, in the as-received sample. Itwas suggested that the kink conformers withg�tg� ethylene glycols (EGs) (see Fig. 2) adoptedby guest PET chains in the narrow host PET-�-CD-IC channels are largely retained in the non-crystalline regions of the coalesced PET, appar-ently even after extended periods in the melt. Theability of coalesced PET to crystallize rapidly wasattributed to facile interconversion of EGs withg�tg� kink conformations to the ttt crystallineconformation (see Fig. 2) made possible bycounter rotations about the OCH2OOO andOOOCH2O bonds, which do not require much“swept-out” volume.

The current investigation of coalesced PETseeks to further characterize its unique structureand thermal behavior at both the molecular andmacroscopic levels. Crystallization during coolingfrom the melts of as-received and coalesced PETsis monitored by cooling rate-dependent DSC mea-surements. High-resolution solid-state 13C-NMRis used to investigate the conformations and mo-bilities of the PET chains in coalesced and as-received PET samples, while polarized light andAtomic Force (AFM) microscopic examinationsare employed to compare the morphologies of both

Figure 1. Polymer chains in randomly coiling melt,crystal lattice, and inclusion complex.

Figure 2. Two views each of the all trans and kinkconformers of PET.

THERMAL BEHAVIORS OF REORGANIZED POLY(ETHYLENE TEREPHTHALATES) 387

PETs after crystallization from their melts. Fi-nally, preliminary differences in macroscopicproperties observed for as-received and coalescedPETs are ascribed to their very different morphol-ogies and constituent chain conformations.

EXPERIMENTAL

PET-�-CD-IC and Coalesced and Precipitated PETs

The PET-�-CD-IC was obtained as previously de-scribed.5 Briefly, 0.2 g of as-received PET ([�]� 0.59, Mv � 18,000, Aldrich) was dissolved in 40mL combined solvent of trifluoroacetic acid (TFA,Fisher) and chloroform (CLF, Fisher) (TFA/CLF� 6:4, v/v). The solution was allowed to stir forapproximately an additional 45 min before anaqueous solution of �-CD (Cerestar Co.) wasadded drop-wise to the PET solution held at 55°C. The aqueous �-CD solution was created bydissolving 4 g of �-CD in 15 mL of deionized waterat room temperature. The mixed solutions werestirred on a hot plate for 2 h at 55 °C and thencooled and filtered to collect the precipitate, whichwas washed with cool water and filtered and driedin a vacuum oven at 40 °C to obtain dry PET-�-CD-IC. Precipitated PET, with thermal and spec-troscopic properties resembling those of coalescedPET, was obtained similarly, but without the useof �-CD. To dissociate the PET-�-CD-IC, the sam-ple was placed into aqueous/HCl solution (pH� 1.0), while heating at 50 °C. The mixture wasstirred for 10 min and then filtered to removecoalesced polymer. The filtered, coalesced poly-mer was washed several times with cool waterand then dried in a vacuum oven at room temper-ature.

Intrinsic viscosity5 and 1H NMR6 observationsof as-received, IC-coalesced, and precipitatedPETs in solution have shown that the IC forma-tion, coalescence, and precipitation processes didnot result in molecular weight degradation nor intransesterification.

Microscopy

Light micrographs of the overall melt-crystallizedPET morphologies were obtained with a Zeisspolarizing microscope. Tapping mode AFM im-ages were obtained at ambient conditions using aNanoScope Dimension 3000 (Digital Instru-ments) AFM. Phase images were recorded usingthe retrace signal with a Si tip and the scan ratewas in the range 0.5–1.5 Hz. To eliminate varia-

tions caused by different crystallization condi-tions, both as-received and coalesced PET sam-ples were placed on the same microscope slidesand held on the hot stage at 300 °C (�Tm of PET)for 2 min before cooling down for observation atroom temperature.

Differential Scanning Calorimetry (DSC)

The thermal scans of as-received and coalescedPET samples were performed with a Perkin-Elmer DSC-7 differential scanning calorimeter.The measurements were made after melting thesamples at 280 °C for 5 min and then cooling atdifferent controlled cooling rates. Nitrogen wasused as the purge gas.

CP/MAS 13C NMR

Solid-state NMR data were collected using aBruker DSX wide-bore system with a fieldstrength corresponding to a 1H Larmor frequencyof 300.13 MHz. Radiofrequency power levels were71 kHz for spin-locking and decoupling, corre-sponding to �/2 pulse widths of 3.5 �s. Data wereobtained using MAS speeds of 4–5 kHz on a com-mercial 7-mm probe. Cross-polarization (CP) con-tact times were 1 ms.

1H spin-lattice relaxation times in the rotatingframe [T1�(

1H)] were measured by proton spin-locking relaxation experiments. A resonant spin-lock field, phase-shifted 90° relative to the initialexciting pulse, was applied to lock the 1H trans-verse magnetization. 1H relaxation was observedindirectly from the intensities of 13C resonancesthrough cross-polarization after various spin-locktimes. The 13C spin-lattice relaxation times in thelaboratory frame [T1(13C)] were detected by mea-suring the intensities of 13C resonances in theinversion-recovery process, after the initial 13Cmagnetizations were enhanced by cross-polariza-tion.

RESULTS AND DISCUSSION

Microscopic Observations of Melt-Crystallized PETMorphologies

Melt-crystallized as-received and coalesced PETsamples were examined by polarized light micros-copy to study their overall crystalline morpholo-gies. Figure 3 shows the micrographs of the PETsamples observed with polarized light. When apolymer crystallizes from the melt without distur-

388 WEI ET AL.

bance, it normally forms spherical structurescalled “spherulites.” Investigations of the crystal-lization of polymers with various microscopieshave implied that polymer spherulites consist ofradiating fibrous crystals, which are comprised oflayerlike crystallites, that is, lamellae. As seen inFigure 3(a), the as-received PET formed typicalspherulites after crystallization from the melt,which have spherical shapes and dark crossesthrough their centers when viewed with polarizedlight. The average size of the as-received PETspherulites is about 25 �m. In contrast, the mor-phology of PET coalesced from its �-CD inclusioncomplex and subsequently crystallized from itsmelt [Fig. 3(b)] shows a distinct crystal patternwithout clear spherical shapes. Under polarizedlight, the coalesced, melt-crystallized PET showsmuch less dark areas than the as- received PET,although both samples were crystallized fromtheir melts under the same conditions. Becausethe crystallization of polymers from their melts isrelated to their microstructural properties, suchas chain conformations and entanglements,7 the

polarized light microscopy results suggests a mo-lecular-level difference between the coalesced andas-received PETs even in their melts.

Atomic force microscopy (AFM) has made itpossible to directly observe the morphology of var-ious kinds of polymer samples at very high reso-lution.8–10 By utilizing the unique advantages af-forded by AFM, the spherulites and lamellae ofvarious semicrystalline polymers have been in-vestigated. When the oscillating AFM probe isscanned along the surface, the soft amorphousmaterial is more compliant than the harder crys-talline material, which results in a phase differ-ence between the soft and hard regions of thesample, thus providing a distinct contrast be-tween the two phases. The PET samples (as-re-ceived and coalesced) were prepared by the sameprocess used for polarized light microscopy, thatis, crystallized from their melts side by side on thesame slide.

Other investigations with AFM have indicatedthat a polymer spherulite may develop from astack of lamellae.11 During the growth process,the stacked lamellae continually splay apart,branch occasionally, and are twisted. Figure 4illustrates the AFM images of samples at 2D res-olutions of 4 � 4 �m and 1 � 1 �m. In Figure 4(a),the lamellar structures in the as-received PETspherulites are clearly visualized. It can be seenthat numbers of small crystals stack together andare arranged along the radial direction. At highermagnification in Figure 4(c), the lamellae can beseen both edge and flat on due to twisting.12 Theas-received, melt-crystallized PET crystals ap-pear tightly packed, and the amorphous regionsbetween the different crystalline lamellae are dif-ficult to locate in the spherulites. The individuallamellae have a thickness of a few tens of nano-meters, that is, a few hundreds of angstroms. Forcomparison, the AFM phase mode images of melt-crystallized, coalesced PET are shown in Figure4(b) and (d). From Figure 4(b), the bunching orbundling of layer like crystals is not found. In-stead of the clear, tight radial orientation for in-dividual crystals observed in the spherulites ofthe melt-crystallized as-received PET, most crys-tals in the melt-crystallized coalesced PET sam-ple are randomly aggregated. In Figure 4(d), thethickness of melt-crystallized, coalesced PETcrystals are found to be �10 nm, which is aboutthe same as for as-received PET lamellae whenviewed edge on. Interestingly, the lengths of mostof the individual crystals in IC-coalesced PET arein the range of �300 nm, which is much shorterthan observed for the as-received, melt-crystal-

Figure 3. Polarized light micrographs of melt-crys-tallized (a) as-received PET and (b) coalesced PET.

THERMAL BEHAVIORS OF REORGANIZED POLY(ETHYLENE TEREPHTHALATES) 389

lized sample, but which is comparable to thelength of PET chains with the extended, all transcrystalline conformation (the length of PET withM � 18,000 in the all trans conformation is �100nm). These results suggest that the coalescedPET crystallizes by a mechanism different fromas-received PET, even when both are crystallizedfrom their melts.

In previous studies, we have found that guestpolymer chains with extended conformations in-cluded in their cyclodextrin molecular inclusioncomplexes, because the host CDs form the rigidcolumnar structure, very quickly consolidate withneighboring guest polymer molecules and retaintheir extended conformations when coalesced in anonsolvent environment.13,14 Moreover, less en-tanglement would be expected in the coalescedpolymer sample, because the polymer chains are

segregated and extended in their inclusion com-plex. Consequently, the individual crystals in thecoalesced PET may be composed of a collection offully extended PET molecules, and therefore, maynot be produced by the usual chain-folding crys-tallization mechanism. The much smaller lateralsizes of crystals found in melt-crystallized, coa-lesced PET may be attributed to a crystallizationprocess so fast that there is not sufficient time forcrystals to grow laterally, that is, the crystals arequickly formed by aggregation of several neigh-boring guest polymer chains with extended con-formations formerly belonging to the same PET-�-CD-IC crystals.

Another unique characteristic of melt-crystal-lized, �-CD-IC coalesced PET is that the amor-phous regions between the individual crystals canbe readily observed, while the crystals observed

Figure 4. Atomic force micrographs (phase mode) for melt-crystallized as-received (a:4 � 4 �m and c: 1 � 1 �m) and coalesced (b: 4 � 4 �m and d: 1 � 1 �m ) PET samples.

390 WEI ET AL.

for the as-received PET spherulites appear muchmore tightly packed making observation of theamorphous regions difficult. This indicates, onceagain, that the crystallization of coalesced PETfrom its melt is predominantly a local process,primarily involving PET chains with extendedkink conformations that were formerly includedproximally in neighboring �-CD host channels ofthe same PET-�-CD-IC crystals.

DSC Observations of PETs

During heating we previously observed,5 thatwhile the as-received sample exhibits a glasstransition, a crystallization exotherm, and finallya melting endotherm, coalesced PET only showeda melting endotherm. In the present work, coa-lesced and as-received PETs are observed in DSCcooling scans recorded from the melt with variouscooling rates, and are presented in Figure 5. Thecontrasting thermal behaviors of the samples are further illustrated in Figure 6, where for as-re-

ceived PET, both the crystallization temperature(TCC) and crystallization enthalpy (HCC) observedon cooling decrease with increasing cooling rate.When TCC is close to the glass transition temper-ature (Tg) of PET (�80 °C), HCC is almost zeroand crystallization for molten as-received PETceases. However, the IC coalesced PET maintainsa relatively constant HCC with decreasing TCCwhen TCC � Tg, and the crystallization of coa-lesced PET remains substantial even at TCC � Tg.These observations provide additional evidencethat coalesced and as-received PETs are rapidlyand slowly crystallizable, respectively. In fact, itcan be estimated that the rate of crystallization ofcoalesced PET from its melt is �1000 timesgreater than that for the as-received molten sam-ple. Here, it is clearly demonstrated that thehighly extended, unentangled polymer chains inthe cyclodextrin inclusion complex are largely re-tained in the coalesced PET, and so locally aremore readily able to rapidly crystallize. The pre-cipitated PET sample showed thermal behaviorobserved by DSC that was very similar to coa-lesced PET.

13C-NMR Observations of PETs

The CP/MAS 13C-NMR spectra of as-received,precipitated, and coalesced or included PETs aredisplayed in Figure 7, where only the carbonyland methylene carbon regions are presented.Note that in both spectral regions the leastshielded, downfield resonance belongs to as-re-ceived PET, the most shielded, upfield resonance

Figure 5. The cooling crystallization of as received(upper) and IC-coalesced (lower) PET observed by DSCwith different cooling rates: (a) 10.0, (b) 30.0, (c) 60.0,(d) 100.0, (e) 150.0, (f) 200.0, and (g) 250.0 °C/min.

Figure 6. Cooling crystallization enthalpies, Hcc(open symbols), and temperatures, Tcc (filled symbols),observed at different DSC cooling rates for as-received(squares) and coalesced (diamonds) PET samples.

THERMAL BEHAVIORS OF REORGANIZED POLY(ETHYLENE TEREPHTHALATES) 391

comes from coalesced or included5 PETs, and theprecipitated PET seems to contain �30 and �70%material resonating at the frequencies of thesedownfield and upfield, as-received, and coalescedor included5 PET peaks, respectively. We expect15

that carbonyl carbons terminating EG fragmentswhose OCH2OOO and OOOCH2O bonds haveg� conformations to resonate upfield from thosewith t conformations. This is consistent with con-clusions drawn previously from modeling the con-formations of included PET chains16,17 and theFTIR analysis5 of as-received and coalesced PETconformations.18

We would normally expect the methylene car-bon resonances of these PET samples to exhibitthe same order of resonance frequencies, becausethey are � to the carbonyl carbons and are eithert or g� to them conformationally across the sameOCH2OOO and OOOCH2O bonds. This is, infact, what we observe in Figure 7. However, arecent solid-state 13C-NMR study of PETs by Kajiand Schmidt-Rohr19 has convincingly establishedthat the resonance frequencies of methylene car-bons in PETs are insensitive to the conformationsof the EG OCH2OOO and OOOCH2O bonds,and instead seem to only depend on the confor-mations of the OCH2OCH2O bond connectingthem. On highly crystalline and predominantlyamorphous PET samples with 13C-enriched meth-ylene carbons they were able to separately ob-serve methylene carbon resonances belonging to tand to g�OCH2OCH2O bonds. They found that

in both PET samples the methylene carbons be-longing to t OCH2OCH2O bonds resonated �2ppm upfield from those methylene carbons withg� OCH2OCH2O bonds, even though theOCH2OOO and OOOCH2O bonds are predom-inantly t in the highly crystalline PET and signif-icantly g� in the nearly completely amorphousPET sample. As a consequence, we can concludethat our coalesced and included PETs have pre-dominantly t OCH2OCH2O bonds, as-receivedPET predominantly g� OCH2OCH2O bonds,and our precipitated PET sample seems to haveabout 30% g� and 70% t OCH2OCH2O bonds.Again, this is consistent with our molecular mod-eling16–18 and FTIR5 results, so as-received PEThas predominantly g� OCH2OCH2O bonds andsubstantial amounts of t OCH2OOO,OOOCH2O bonds, while coalesced, included,and precipitated PETs have preponderantly t andg�OCH2OCH2O andOCH2OOO,OOOCH2Obonds, respectively.

The 13C-observed 1H spin-lattice relaxationtimes observed in the rotating frame [T1�(

1H)],which reflect motions in the kHz frequency re-gime, are presented as a function of temperaturefor our PET samples in Figure 8. Generally thecoalesced sample has the longest and the as-re-ceived sample the shortest T1�(

1H), indicating anincreasing kHz mobility for PET chains in thecoalesced, precipitated, and as-received samples,respectively. Also note that the T1�(

1H)s of as-received PET show a marked sensitivity to tem-

Figure 7. Methylene carbon (�60–65 ppm) and carbonyl carbon (�163–168 ppm)resonance peaks for PET: (a) as-received; (b) precipitated; and (c) included in orcoalesced from PET-�-CD-IC.

392 WEI ET AL.

perature at T � Tg, which is largely unobserved inthe coalesced and precipitated samples. Initially,the molecular motion increases with temperatureresulting in shorter T1�(

1H)s for all the PET sam-ples. However, the T1�(

1H) of the as-received PETreaches a minimum near Tg, and further heatingresults in molecular motions that are too rapid forefficient nuclear spin energy transfer, so T1�(

1H)increases for T � Tg. This is consistent with thepresence and absence of a glass transition ob-served5 in the DSC scans of as-received and coa-lesced or precipitated PETs, respectively. Thus,both macroscopic (DSC) and microscopic (NMR)observations point to the absence of a glass tran-sition in the noncrystalline regions of coalesced orprecipitated PETs.

At room temperature, the 13C spin-lattice re-laxation times, T1(13C) in seconds, for the as-re-ceived (asr), precipitated (ppt), and coalesced(coa) PETS are CAO 3 31.8s (asr) and 36.2s(coa,ppt); nonprotonated aromatic 3 28.6s (asr)and 36.2 (coa,ppt); protonated aromatic 3 14.4s(asr) and 21.0s (coa,ppt); and CH2 3 7.1s (asr)and 9.6s (coa,ppt). Coalesced and precipitatedPETs have longer T1(13C)s than as received PET.Thus, motions in the MHz frequency regime are

also more restricted in the coalesced and precipi-tated PETs, compared with as-received PET, pos-sibly because of both their higher crystallinities5

and the tighter packing of kink conformers intheir noncrystalline regions. Temperature depen-dencies similar to those observed in the rotatingframe for 1Hs, T1�(

1H)s, are also observed for the13C spin-lattice relaxation times, T1(13C). This be-havior implies that the noncrystalline regions ofcoalesced and precipitated PETs are distinct fromthe amorphous regions in as-received PET, be-cause only in as-received PET are the kHz, MHzmotions important to T1�(

1H), T1(13C) relaxationssensitive to whether or not the sample is below orabove its Tg. Again, this is consistent with thefailure to observe a glass transition by DSC forcoalesced5 and precipitated PETs.

In summary, microscopic and thermal observa-tions of PET samples coalesced from their crys-talline �-CD-IC suggest crystalline charactersand melt-crystallized morphologies that are dif-ferent from normal samples. After coalescence oftheir segregated, extended chains from the nar-row channels of the crystalline inclusion complexformed with �-cyclodextrin host, PET chains aremuch more readily crystallizable, and, locally,quickly form small, possibly chain-extended crys-tals. In addition, the noncrystalline regions ofcoalesced PET exhibit conformational and mo-tional behavior quite distinct from as-receivedPET. The extended kink conformations adoptedby guest PET chains included in the PET-�-CD-ICcrystals are largely retained upon coalescence,and as such, are not only readily crystallizable,but result in the absence of normal glassy behav-ior for those coalesced PET chains that do notcrystallize. What remains puzzling5 is the appar-ent retention of the extended kink PET conform-ers in the coalesced melt, even after holding it atT � Tm for extended periods, and which stillresults in their rapid crystallization upon coolingto a distinct, possibly chain-extended crystallinemorphology.

We are grateful to the National Textile Center (Dept. ofCommerce) and North Carolina State University forfinancial support of this research.

REFERENCES AND NOTES

1. Huang, L; Tonelli A. E. J Macromol Sci Rev Mac-romol Chem Phys 1998, C38, 781.

2. Harada, A.; Li, J.; Kamachi, M. Nature 1994, 370,126.

Figure 8. Dependence of 1H rotating-frame relax-ation time T1�(

1H) on temperature. asr (as-receivedPET); ppt (precipitated PET); and coa (coalescedPET).

THERMAL BEHAVIORS OF REORGANIZED POLY(ETHYLENE TEREPHTHALATES) 393

3. Wei, M.; Davis, W.; Urban, B.; Song, Y.-Q.; Porbeni,P. E.; Wang, X.; White, J. L.; Balik, C. M.; Rusa,C. C.; Fox, J.; Tonelli, A. E. Macromolecules 2002,35, 8039.

4. Shuai, X. T.; Porbeni, P. E.; Wei, M.; Shin, I. D.;Tonelli, A. E. Macromolecules 2001, 34, 7355.

5. Bullions, T. A.; Wei, M.; Porbeni, P. E.; Gerber,M. J.; Peet, J.; Balik, C. M.; White, J. L.; Tonelli,A. E. J Polym Sci Part B: Polym Phys 2002, 40, 992.

6. Bullions, T. A.; Edeki, E. M.; Porbeni, F. E.; Wei,M.; Shuai, X.; Rusa, C. C.; Tonelli, A. E. J Polym SciPart B: Polym Phys 2002, 41, 139.

7. Psarski, M.; Piorkowska, E.; Galeski, A. Macromol-ecules 2000, 33, 916.

8. Kurokawa, T.; Gong, J. P.; Osada, Y. Macromole-cules 2002, 35, 8161.

9. Brodowsky, H. M.; Boehnke, U. C.; Kremer, F.;Gebhard, E.; Zentel, R. Langmuir 1997, 13, 5378.

10. Francis, R.; Skolnik, A. M.; Carino, S. R.; Logan,J. L.; Underhill, R. S.; Angot, S.; Taton, D.;Gnanou, Y.; Duran, R. S. Macromolecules 2002, 35,6483.

11. Ivanov, D. A.; Nysten, B.; Jonas, A. M. Polymer1999, 40, 5899.

12. Hobbes, J. K.; Winkel, A. K.; McMaster, T. J.;Humphris, A. D.; Baker, A. A.; Blakely, S. S.; Ais-

saoui, M.; Miles, M. Macromol Chem Symp 2001,167, 1.

13. Wei, M.; Tonelli, A. E. Macromolecules 2001, 34,4061.

14. Shuai, X.; Porbeni, P. E.; Wei, M.; Bullions, T. A.;Tonelli, A. E. Macromolecules 2002, 35, 2401.

15. Tonelli, A. E. NMR Spectroscopy and Polymer Mi-crostructure: The Conformational Connection;Wiley: New York, 1989.

16. Tonelli, A. E. Comput Theor Polym Sci 1992, 2, 80.17. Tonelli, A. E. Polymer 2002, 43, 637.18. Though all nine EG conformers with transOCH2OCH2O bonds, i.e., xty, where x,y � t,g�,were found16,17 to fit in cylinders with diameterscomparable to those found in �-CD (�8 Å), only theall trans (ttt) crystalline conformer was unable tointerconvert to the other eighy xty channel con-formers without leaving the 8 Å channel. Thus, thePET g�tg� kink conformers, in addition to beingnearly as extended (�95% of the ttt conformer fiberrepeat) and narrower (�80% of the ttt conformercross-section), are also entropically favored for in-clusion in PET-�-CD-IC compared with the alltrans crystalline PET conformation.

19. Kaji, H.; Schmidt-Rohr, K. Macromolecules 2002,35, 7993.

394 WEI ET AL.