preparation and properties of optically active polyurethane/tio2 nanocomposites derived from...

EUROPEAN

European Polymer Journal 43 (2007) 4151–4159

www.elsevier.com/locate/europolj

POLYMERJOURNAL

LO

GY

Macromolecular Nanotechnology

Preparation and properties of optically active polyurethane/TiO2

nanocomposites derived from optically pure 1,1 0-binaphthyl

Jing Chen, Yuming Zhou *, Qiuli Nan, Xiaoyun Ye, Yanqing Sun,Fengying Zhang, Zhiqiang Wang

School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People’s Republic of China

Received 8 April 2007; received in revised form 3 July 2007; accepted 8 July 2007Available online 20 July 2007

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

Abstract

In this study, optically active polyurethanes (PU) were prepared from chiral 1,1 0-binaphthyl (BINOL) and 2,4-toluenediisocyanate (TDI) by the simple hydrogen transfer addition reaction and the high-intensity ultrasonic was applied to thepreparation of polyurethane/TiO2 nanocomposites. The (R)-BPU and (S)-BPU were analyzed by 1H NMR, FT-IR spec-troscopy, thermogravimetric analysis (TGA), UV–vis spectroscopy and circular dichroism (CD) spectra. The results indi-cated that the polymers exhibited stronger CD signals with positive and negative Cotton effect in their CD spectra.Meanwhile, the nanocomposites were characterized by IR, powder X-ray diffraction, transmission electron microscopy(TEM) and scanning electron microscopy (SEM). The results manifested the improvement of heat stability of the nano-composites with the presence of TiO2 nanoparticles. As a result, the infrared emissivity (8–14 lm) study revealed thatthe nanocomposites possessed much lower infrared values compared with those of the neat polymers and nanoparticles,respectively.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Binaphthyl; Polyurethane; Nanocomposites; Emissivity

MA

1. Introduction

The synthesis and characterization of chiral poly-mers have attracted a great deal of interest in thepast few years for their important applications ofoptically active polymers as catalysts for asymmet-ric synthesis and as chiral stationary phases (CSP)for the direct optical resolution of enantiomers [1–3]. Chiral 1,1 0-binaphthol (BINOL) has beensuccessfully used to prepare many chiral polybi-

0014-3057/$ - see front matter � 2007 Elsevier Ltd. All rights reserved

doi:10.1016/j.eurpolymj.2007.07.006

* Corresponding author. Tel./fax: +86 25 52090617.E-mail address: [email protected] (Y. Zhou).

naphthalene polymers [4,5]. Since the resolutionbinaphthol has been carried out more conveniently[6], it has been attracting attention for use as a chiralbuilding block [7], chiral catalyst [8] or chiral auxil-iary [9–11] in asymmetric synthesis, molecular rec-ognition and enantioselective chromatographicseparation [12]. Recently, numerous studies onpolymer/nanoparticles nanocomposites arereported. For example, Xi et al. reported the poly-merization synthesis of optically active poly(ethersulfones) based on chiral 1,1 0-binaphthol whichcan form rings of various sizes [13]. Angelovskiand Eilbracht [14] reported the synthesis of

.

mailto:[email protected]

4152 J. Chen et al. / European Polymer Journal 43 (2007) 4151–4159

MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

LO

GY

macroheterocycles via regioselective hydroformyla-tion and reductive amination. Carriedo et al. [15]reported the properties of phenoxyphosphazenerandom copolymers containing optically activebinaphthoxy groups.

Polyurethanes (PUs) are types of high perfor-mance polymeric materials that have been widelyused in the aerospace, electronics, and microelec-tronic industries because of their outstanding ther-mal and chemical stabilities, mechanical propertiesand electrical properties [16–18]. In recent years,the synthesis of polyurethane nanocomposite mate-rials has been intensely studied due to their extraor-dinary properties and widespread potentialapplications [19,20]. As examples, stealth materials,optical devices, etc., and it may be used to kill thebacteria in liquid phase and keep thermal insulationeven solve environmental problems [21–23].

Recently, ultrasonic irradiation has beenemployed to synthesize the nanocomposites [24–26]. Ultrasonic has been widely used in cleaning,jointing, machining, medicine, chemistry and pre-paring nanosized materials [27–29]. At the sametime, the ultrasonic synthesis can well control thesize distribution and morphology of the nanosizedparticles. As was known, the aggregation of nano-particles is decreased and its dispersivity is highlyimproved [30–32]. Kwang-Pill Lee reported thepreparation of polydiphenylamine/silica-nanoparti-

OH

OH

CH3

NCO

NCO

2+

Scheme 1. Synthesis procedu

OH

OH

CH3

NCO

NCO

+ nn

Scheme 2. Synthesis proc

cle composites under ultrasonication and theirresults improved that this methodology could beextended to making conducting, processable nano-composites with other types of conducting polymers[33]. Wang studied the ultrasonic induced encapsu-lating emulsion polymerization and formed a novelPMMA/SiO2 composites. Meanwhile, they foundthe optimized conditions for preparing nanocom-posites and proposed the possible mechanism [34].

In this paper, optically active R-BPU/TiO2 andS-BPU/TiO2 nanocomposites were synthesizedthrough ultrasonic irradiation. The infrared proper-ties of nanocomposites and two components werestudied. To the best of our knowledge, PU/nano-particles utilized in the study of infrared emissivityhave not yet been reported (Schemes 1 and 2).

2. Experimental

2.1. Materials

TiO2 nanoparticles were prepared by homoge-neous precipitation method as described before[35], the average size of nanoparticles was about35–50 nm; Toluene 2,4-diisocyanate (TDI) was pur-chased from Lingfeng Chemical Reagent Co, Ltd.(Nanjing, China) and was used with low pressuredistilled; coupling agent (c-amidopropyl–triethoxylsilicane) (KH550), obtained from Yaohua Chemical

OCONH

OCONH

CH3

NCO

CH3

NCO

res of the polymer unit.

OCONH

O

CH3

NHOC

n

edures of the BPU.

J. Chen et al. / European Polymer Journal 43 (2007) 4151–4159 4153

Plant (Shanghai, China); N,N-dimethylacetamide(DMAc) was redistilled under reduced pressureand used freshly, all solvents were purchased fromcommercial A.R. grade. 1,1 0-Binaphthyl was syn-thesized according to the literature [36].

Y

2.2. Apparatus

The reaction was occurred on a JY 92-2D ultra-sonic cell crusher, which was purchased fromScientz Biotechnology Co, Ltd. (Ningbo, China).Ultrasonic irradiation was carried out with theprobe of the ultrasonic horn immersed directly inthe mixture solution system with frequency2 · 104–109 Hz and power 700 W.

MO

LE

CU

LA

RN

AN

OT

EC

HN

OL

OG

2.3. Polymer synthesis of S-BPU and R-BPU

First, TDI (0.9 mL) was dissolved in 10 mLDMAc in a 250 mL flask with a magnetic stirrerat 80 �C under N2. Then (R)- or (S)-binaphthol(6 mmol) was added at the refuxing temperaturefor 16 h. A little NaOH was added to neutralizeunreacted BINOL for 0.5 h. The mixture was cooleddown to room temperature, poured to 150 mLanhydrous ethanol and precipitate out white floccu-late. 10% aqueous HCl (150 mL) was added toadjust pH value to neutrality, the product filtered,washed with anhydrous ethanol several times, driedat 80 �C. White powder polymer was obtained. Fur-ther purification could be conducted by dissolvingthe polymer in DMF to precipitate in anhydrous

Fig. 1. The chemical scheme o

ethanol again. (The computer simulation of BINOLmolecular static structures are shown in Fig. 1.)

(S)-BPU spectroscopic data: mmax (KBr)/cm�1:3283.5, 3060.7, 2920.9, 1649.5, 1544.7, 1501.0,1431.1, 1273.8, 1217.0, 823.8, 753.9; 1H NMR(DMSO-d6): d 3.36 (s, 3H, CH3), 3.25 (s, 1H,PhH), 2.89 (s, 1H, OCONH), 2.74 (s , 1H,OCONH), 2.51 (s, 1H, PhH), 9.24 (s, 1H, PhH),6.93–7.05 (m, 2H, ArH), 7.15–7.18 (m, 2H, ArH),7.22–7.24 (m, 2H, ArH), 7.33–7.35 (d, 2H, ArH),7.84–7.87 (m, 2H, ArH), 7.96 (s, 2H, ArH).

(R)-BPU spectroscopic data: mmax (KBr)/cm�1:3279.1, 3056.3, 2925.2, 1649.5, 1544.7, 1501.0,1387.4, 1234.5, 1212.6, 815.0, 753.9; 1H NMR(DMSO-d6): d 3.36 (s, 3H, CH3), 3.25 (s, 1H,PhH), 2.89 (s, 1H, OCONH), 2.74 (s, 1H,OCONH), 2.51 (s, 1H, PhH), 9.24 (s, 1H, PhH),6.93–7.05 (m, 2H, ArH), 7.15–7.18 (m, 2H, ArH),7.22–7.24 (m, 2H, ArH), 7.33–7.35 (d, 2H, ArH),7.84–7.87 (m, 2H, ArH), 7.96 (s, 2H, ArH).

2.4. Preparation of BPU/TiO2 nanocomposites

Preparation of BPU/TiO2 nanocomposites wascarried out in an ultrasonic wave irradiation pro-cess. Nanoparticles were firstly treated with silanecoupling agent (KH550). In a series of controlexperiments we found that 10% weight percentageof KH550 was optimized. Different amounts ofTiO2 (5, 10, 15, 20 wt%) nanoparticles were mixedwith the BPU and the mixture was dispersed in20 mL absolute ethanol, followed by irradiationwith high-intensity ultrasonic wave for 4 h at

f chiral 1,1 0-binaphthol.

MA

CR

O

Table 1Solubility of BPUs

Solvents (R)-BPU (S)-BPU

DMAc + +DMF + +NMP + +DMSO + +THF � �EtOH � �CHCl3 � �CH2Cl2 � �CH3CN � �Acetone � �H2O � �+, soluble and �, insoluble.

260 280 300 320 340 3600.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

b

a

Inte

nsity

(a.

u.)

Wavelength (nm)

Fig. 2. UV spectra of (a) S-BPU and (b) R-BPU. The two spectrawere normalized to a concentration of 4 · 10�2 mg/mL (DMF).


MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

LO

GY

30 �C. After irradiation, the resulting suspensionwas cooled to room temperature and then centri-fuged, and the precipitate was washed twice withabsolute ethanol and distilled water, respectively.The solid was dried in vacuum at room temperaturefor 6 h. The obtained product was kept for furthercharacterization.

(S)-BPU/TiO2 (15 wt%) nanocomposites spectro-

scopic data: mmax (KBr)/cm�1: 3381.3, 3251.5,1722.3, 1631.5, 1535.6, 1123.7, 1067.3, 756.6,655.0, 542.1.

(R)-BPU/TiO2 (15 wt%) nanocomposites spectro-scopic data: mmax (KBr)/cm�1: 3392.5, 3268.4,1721.7, 1637.1, 1541.2, 1197.0, 1129.3, 751.0,643.2, 540.1.

2.5. Characterization

1H NMR spectra measurements (all in DMSO-d6)were recorded on a DXT-500 MHz Bruker spec-trometer with TMS as internal standard. FT-IRspectra were recorded on a Nicolet Magna-IR 750(USA) spectrometer using KBr pellets. UV–vis spec-tra were carried out on a SHIMADZU UV-2201.ircular dichroism (CD) spectra were carried onJASCO J-810 spectropolarimeter. The surface mor-phology of the samples was monitored with scanningelectron microscopy (SEM). SEM was obtained onthe microscope of LEO-1530vp. X-ray diffractionmeasurements of polymer and nanocomposites wererecorded using a Rigaku D/MAX-R with a coppertarget at 40 kV and 30 mA. The powder sampleswere spread on a sample holder and the diffracto-grams were recorded in the range 5–80� at the speedof 5�/min. Thermal analysis experiments were per-formed using a TGA apparatus operated in the con-ventional TGA mode (TA Q-600, TA Instrument) atthe heating rate of 20 �C/min to simultaneouslydetermine the correlation of temperature and weightloss in a nitrogen atmosphere. Infrared emissivityvalues of the samples were carried out on an IRE-IInfrared Emissometer of Shanghai Institute of Tech-nology and Physics, China.

3. Results and discussion

3.1. Solubility properties

The solubility properties of R-BPU and S-BPUwere studied in different solvents (Table 1). Thepolymers are soluble in amide type solvents suchas NMP, DMF, DMAc and to some extent in

DMSO. This property is mainly due to the changeof the dihedral angle at each binaphthyl unit, whichdecreases the non-coplanar structures of the molec-ular main chains, improves the interactions betweenthe molecular chains, and intensifies its compactorder [37].

On the other hand, the salvation between the poly-mer and the low-pole solvents is not strong enough todestroy the interactions among those molecularchains. So they are insoluble in solvents such aswater, acetone, chloroform and dichloromethane.

3.2. UV absorption spectra

Fig. 2 shows that UV spectra of (R)-BINOL and(S)-BINOL are almost similar when determined inDMF solution. It is clear that UV strongest absorp-tion kmax of both polymers appeared at 267 nm,which corresponded to E2 band absorption of naph-


RO

MO

LE

CU

LA

RN

AN

OT

EC

HN

OL

OG

Y

thalene ring unit and B band absorption of benzylassociation due to the adding of TDI [38]. And aweak B band absorption of (R)-BINOL and (S)-BINOL appeared at 340 nm due to naphthalenering unit [38].

3.3. CD spectra

Although the rotation values (½a�25D ) monomers

(R)-BINOL and (S)-BINOL are +35.1 and �35.4,their corresponding polymers R-BPU and S-BPUare +54.6 and �78.0, respectively. The absolute val-ues of the optical rotation (½a�25

D ) of two polymersare larger than the monomers. Both monomersand two polymers exhibit stronger CD signals withnegative and positive Cotton effects in their CDspectra (Fig. 3). Monomers and two polymers haveopposite signs for their optical rotation and CDspectra, but their position and intensity is almostidentical. The molecular ellipiticity of (R)-BINOLis: [h]k = +8.27 (281 nm), [h]k = +8.75 (290 nm),[h]k = +12.44 (323 nm), [h]k = �1.18 (346 nm), themolecular ellipiticity of (S)-BINOL is: [h]k = �5.25(281 nm), [h]k = �5.64 (290 nm), [h]k = �8.12(322 nm), [h]k = +0.90 (347 nm). The CD spectrumfrom (R)-binaphthol of BPU with positive chiralityexhibited two broad positive peaks at 290 and323 nm. The cotton curve of (S)-BINOL with nega-tive chirality showed two negative absorption at 290and 322 nm. These absorption peaks are attribut-able to the n–P* transition of carbonyl groupsand the P–P* transition of the aromatic groups inthe chiral cyclic compounds [39]. The long wave-lengths CD effect of polymers (R)-BINOL appeared

280 300 320 340 360

-8

-6

-4

-2

0

2

4

6

8

10

12

14

(b)

(a)

Elli

ptic

ity (

mde

g)

Wavelength (nm)

Fig. 3. CD spectra of (a) R-BPU and (b) S-BPU. The two spectrawere normalized to a concentration of 4 · 10�2 mg/mL (DMF).

C

at 323 nm, and (S)-BINOL appeared at 322 nm,which can be regarded as the more extended conju-gated structure and a high rigidity backbone in thepolymer chain [40,41].

3.4. X-ray diffraction data

Fig. 4 shows the powder XRD patterns of R-BPU, S-BPU, TiO2, R-BPU/TiO2 (15 wt%) and S-BPU/TiO2 (15 wt%). From the spectra, it can beobserved that the (R)- and (S)-BPU are the amor-phous polymers and exhibit no anisotropic behav-iors, which may be due to the presence of thenaphthyl ring and aromatic structures in the mainchain, thus limiting the molecular mobility of thepolymer. When adding TiO2 particles to BPU, asshown in Fig. 4, it appears the characteristic peaksof anatase TiO2. It also can be seen that two curvesof nanocomposites (d)–(e) are almost the same inboth position and width of peaks, indicating thatthe morphology of TiO2 particles has not beenchanged during the process. Meanwhile, it is inter-esting to note that all the diffraction peaks becomebroad in these cases when comparing with theXRD spectra of TiO2 (c), which should be attrib-uted to the presence of the small-sized nanoparticles[42]. The average crystalline size of nano-TiO2,which is determined from the half-width of the dif-fraction using the Debye–Scherrer equation, isapproximately 15–20 nm.

3.5. Thermal properties

Fig. 5 shows the thermogravimetric curves of theR-BPU and R-BPU/TiO2 nanocomposites with the

10 20 30 40 50 60 70 80

(e)

(d)

(c)

(b)

(a)

Inte

nsity

(a.

u.)

2 /degrees

Fig. 4. XRD powder patterns of (a) R-BPU, (b) S-BPU, (c) TiO2,(d) R-BPU/TiO2 (15 wt%) and (e) S-BPU/TiO2 (15 wt%).

MA

100 200 300 400 500 6000

20

40

60

80

100

(a) R-BPU (0 wt%)(b) R-BPU/TiO2 ( 5 wt%)(c) R-BPU/TiO2 (10 wt%)(d) R-BPU/TiO2 (15 wt%)(e) R-BPU/TiO2 (20 wt%)

(e)

(d)(c)

(b)

(a)

Wei

ght (

%)

Temperature ( )

Fig. 5. TGA curves of R-BPU and R-BPU/TiO2

nanocomposites.


MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

LO

GY

different TiO2 contents. Since the thermal stabilityof R-BPU is better than S-BPU [43], the thermalproperty of former nanocomposites is only investi-gated only. It is clear that the sample exhibits a verygood thermal stability before 130 �C and decom-pose around 140–150 �C in N2 gas. The 5% weightloss temperature is about 160 �C, which is attributedto the loss of residual water and organic solvent.The second temperature of weight loss, which startsat around 250 �C, corresponds to polymer degrada-tion. This peak is much higher than that of the com-mon PU [44], which may result from the presence ofhard naphthyl group unit [44].

It was evident that the R-BPU had a high decom-position temperature of about 250 �C, which wasfurther improved when TiO2 was introduced. How-

Fig. 6. TEM images of BPU/TiO

ever, the initial temperature of the nanocompositesweight loss does not increase with increasing TiO2

content until at a weight loss of 40%, this increasein the thermal stability may result from the highthermal stability of TiO2 network and the physicalcrosslink points of the TiO2 particles, which limitedthe movement of the molecular chain of R-BPU.After adding TiO2 nanoparticles with high meltingpoint to the polymer matrix, the TiO2 particlescan serve as a good thermal cover layer, avoidingthe direct thermal decomposition of polymer matrixby heat. In addition, the TiO2 is a nanoscale parti-cle, which offers a larger surface area and improvesthe effect of thermal cover.

3.6. Morphology

The direct evidences of the formation of a truenanocomposite were provided by TEM investiga-tion. Fig. 6a and b shows the morphology ofBPU/TiO2 nanocomposites. The micrographs con-firmed that the titania particles were well-dispersedin the BPU matrix. As can be seen, the average sizeof BPU/TiO2 nanocomposites was 50–60 nm.Moreover, this result was consistent with the XRDresult concluded earlier.

As can be seen in Fig. 7, the morphology devel-opment of polyurethane nanocomposites illustratedthe diversity of microstructures attained. In Fig. 7a,the average crystalline size of TiO2 nanoparticleswas about 15–20 nm. Fig. 7b–e displayed that theaverage size of BPU/TiO2 nanocomposites was50–60 and 70–80 nm, respectively. As expected, in

2 (15 wt%) nanocomposites.

Fig. 7. SEM images of nanoparticles and BPU/TiO2 (5, 10, 15, 25 wt%) nanocomposites.


MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

LO

GY

Fig. 7b–c, the nanocomposites presented a homoge-neous microstructure and dispersed as global beads.However, it should be noted that, as far as the con-tent of TiO2 is 25 wt%, Fig. 7d–e shows that thenanocomposites presented some irregularities in sizeand shape. This phenomenon had been explainedultrasonic cavitation, which can generate very rigor-ous environment, local temperature up to 5000 K,local pressure up to 500 atm, etc. [43], under suchconditions the growth of particles had some differ-ence, compared with the common methods.

3.7. Infrared emissivity

IR emissivity testing results indicated that the R-PU, S-BPU and TiO2 possessed high emissivity of0.90, 0.85, and 0.93, respectively. Polyurethane hasa high infrared emissivity value because of strong

absorbability at infrared wave band [45]. TiO2 hasa high infrared emissivity value due to the highrefractive index (commonly larger than 0.8) [46].The IR emissvity of nanocomposites (0.45–0.77)was much lower than that of BPU or TiO2 nanopar-ticles, respectively, which could be contributed tointerfacial synergism forces such as hydrogen bondsor electrostatic interactions between the organic andinorganic components [47,48]. These interactionscan alter the original vibration mode of molecules,atoms or pendant groups on interface betweenorganic and inorganic components [49,50], thusthe composites possessed lower emissivity than thatof two components.

Fig. 8 shows the IR emissivity of BPU/TiO2

nanocomposites with different TiO2 nanoparticlecontent, as could be seen, with the increasing theratio of TiO2 and BPU monomer, the IR emissivity

Fig. 8. Infrared emissivity values of (a) R-BPU/TiO2 emin = 0.53and (b) S-BPU /TiO2 emin = 0.45.


MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

LO

GY

increased initiatively and then decreased, the lowestand highest value was 0.45 (BPU/TiO2 (15 wt%))and 0.77 (BPU/TiO2 (15 wt%)), respectively. It canbe indicated the nanocomposites with appropriatequantity TiO2 nanoparticles possessed higher sur-face area, surface area energy, quantity of surfaceatom and dangling bonds, thus possessed the stron-ger surface effect, polarity effect, multiply dissoci-ated radiation and lower IR emissvity. And theseresults were also in good agreement with the previ-ous SEM analysis. On the other hand, it is worthnoting that S-BPU/TiO2 had lower infrared valuesthan those of R-BPU/TiO2, which could be contrib-uted to the different optical properties betweenS-BPU and R-BPU [51].

4. Conclusions

In conclusion, we have devised a simple route tosynthesize optically active polyurethane. The poly-urethane exhibit stronger CD signals with positiveand negative cotton effect in their CD spectra.Meanwhile, a sonochemical method has been usedfor the preparation of BPU/TiO2 nanocomposites.TGA studies indicated that thermal stability ofthe nanocomposites has improved with increasingnanoparticles content. Infrared emissivity studyshowed that the nanocomposites possessed loweremissivity value than those of BPU and TiO2,respectively. The ultrasonic method employed heremay be a simple and inexpensive route to synthe-size the polymer/nanoparticles, which can beextended to prepare a novel low infrared emissivitymaterial.

Acknowledgements

The authors are grateful to ‘‘Six Talents PinnacleProgram’’ of Jiangsu Province of China (06-A-033),‘‘the New Century Talents Program’’ of Ministry ofEducation of China (NCET-04-0482) and theNational Nature Science Foundation of China(50377005) for financial supports.

References

[1] Chen YH, Tseng H. J Polym Sci: Part A: Polym Chem1993;31:1719–21.

[2] Gong AJ, Chen YM, Zhang X, Chen CF, Xi F. Tetrahe-dron: Asymm 1998;9:4175–81.

[3] Yeganeh H, Tamami B, Ghazi I. Eur Polym J2002;38:2179–85.

[4] Pu L. Chem Rev 1998;98:2405–94.[5] Zhang HC, Pu L. Macromolecules 2004;37:2602–95.[6] Cai D, Hughes DL, Verhoeven R, Reider PJ. Tetrahedron

Lett 1995;36:7991–4.[7] Nozaki K, Terakawa T, Takaya H, Hiyama T. Angew Chem

Int Ed Engl 1998;37:131–3.[8] Krouse N. Angew Chem Int Ed Engl 1998;37:283–5.[9] Kiyooka S, Tada M, Kan S, Fujio M. Bull Chem Soc Jpn

1996;69:2595–7.[10] Xu MH, Lin J, Hu QS, Pu L. J Am Chem Soc

2002;124:14239–46.[11] Moore D, Pu L. Org Lett 2002;4:1855–7.[12] Sogah GY, Cram DJ. J Am Chem Soc 1979;101:3035–42.[13] Gong AJ, Liu WH, Chen YM, Zhang X, Chen CF, Xi F.

Tetrahedron: Asymm 1999;10:2079–86.[14] Angelovski G, Eilbracht P. Tetrahedron 2003;59:8265–74.[15] Carriedo GA, Alonso FJG, Tarazona MP, Saiz E, Vazquez

JT, Padron JI. Macromolecules 2000;33:3671–9.[16] Frisch KC. Rubber Chem Technol 1980:126.[17] Meckel W, Goyert W, Wieder W. In: Legge NR, Holden G,

Schroeder HE, editors. Thermoplastic elastomers. Munich:Hanser; 1987.

[18] Oertel G, editor. Polyurethane Kunststoff Handbuch, 3rded., vol. 7. Munich: Hanser; 1993.

[19] Nagai A, Ishikawa J, Kudo H, Endo T. J Polym Sci: Part A:Polym Chem 2004;42:1143–53.

[20] Bayer O, Muller E, Petersen S, Piepenbrink HF, WindemuthE. Angew Chem Int Ed 1950;62:57–61.

[21] Kumar KNP, Keizer K, Burggraaf AJ, Okubo T, NagamotoH, Morooka S. Nature 1992;358:438–42.

[22] Karlsson C, Best AS, Swenson J, Kohlbrecher J, BorjessonL. Macromolecules 2005;38(15):6666–71.

[23] Okamoto M, Morita S, Kotaka T. Polymer2001;42(6):2685–8.

[24] Ray SS. Mater Res Bull 2002;37:813–24.[25] Price GJ, Lenz EJ, Ansell CWG. Eur Polym J

2002;38:1531–6.[26] Qiu XF, Zhu JJ. Chinese J Inorg Chem 2003;19:766–70.[27] Mason TJ, editor. Chemistry with ultrasound, vol. 1. Lon-

don and New York: Society of Chemical Industry byElsevier Applied Science; 1991.

[28] Wei F, Zhang TR, Liu Y, Lu R, Zhao YY, Yao JN. J SolidState Chem 2002;169:1–5.


GY

[29] McNamara III WB, Didenko YT, Suslick KS. Nature1999;401:728–72.

[30] Xiang XJ, Qian JW, Yang WY. J Appl Polym Sci2006;100:4333–7.

[31] Sahoo NG, Jung YC, Yoo HJ, Cho JW. Comp Sci Technol2007;67:1920–9.

[32] Khaled SM, Sui R, Charpentier PA, Rizkalla AS. Langmuir2007;23(7):3988–95.

[33] Lee K-P, Gopalan AI, Lee S-H, Showkat AM, Nho YC. JAppl Polym Sci 2006;102:3912–8.

[34] Xia HS, Wang Q. J Appl Polym Sci 2001;80:1130–5.[35] Hu XL, Yin H, Hu XH. China Ceramics 1997;33:5–8.[36] Ding KL, Wang Y, Zhang LJ, et al. Tetrahedron

1996;52:1005–10.[37] Song NH. Design, synthesis and chiroptical properties of

optically active polymers containing 1,10-binaphth-yls. China: Changchun Institute of Applied Chemistry,Chinese Academy of Sciences; 1999.

[38] An DL, Yang SH, Zhang ZY, et al. Chem J ChineseUniversities 2005;26:1268–70.

LO

[39] Chow HF, Ng MK. Tetrahedron: Asymm 1996;7:2251–62.[40] Hua C, Pu L. Macromol Chem Phys 1999;200:1274–8.[41] Ke CM, Wang HZ, Jin YF, Hu Y. J Wuhan Universities and

Technol 2005;28:1–4.[42] Zhang CS, Wang JH, Shi YG, et al. Synthetic Mater Aging

Appl 2005;34:28–31.[43] Raghu AV, Gadaginamath GS, Aminabhavi TM. J Appl

Polym Sci 2005;98:2236–44.[44] Suslick KS. Science 1990;3:1439–41.[45] Guinier A. X-ray diffraction. San Francisco (CA): Free-

man; 1963.[46] Andersson SK, Staaf O, Olsson PO, Malmport A, Ribbing

CG. Opt Mater 1998;10:85–93.[47] Li DC, Zhou DL, Chen CZ, Hu HF. J Funct Mater

1995;3:278–85.[48] Kittle PA. US Patent 4034129; 1977.[49] Davis RJ, Liu Z. Chem Mater 1997;9:2311–24.[50] Shan Y, Zhou YM, Cao Y. Mater Lett 2004;58:1655–60.[51] Tagaya H, Takeshi K, Ara K, Karasu M. Mater Res Bull

1995;30:1161–71.

MA

CR

OM

OL

EC

UL

AR

NA

NO

TE

CH

NO

preparation and properties of optically active polyurethane/tio2 nanocomposites derived from...

Documents