J O U R N A L O F C H E M I S T R Y Materials Synthesis of fullerene- and fullerol-containing polymers Liming Dai,*a Albert W. H. Maua and Xiaoqing Zhangb aCSIRO, Division of Chemicals and Polymers,† Private Bag 10, RosebankMDC, Clayton, VIC 3169, Australia bDepartment of Chemical Engineering, T he University of Melbourne, Parkville, VIC 3052, Australia Fullerenes have been covalently attached along polydiene chains via a lithiation reaction.Ultraviolet–visible (UV–VIS), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements, together with thermal gravimetric analyses (TGA), indicate that both highly soluble and crosslinked polymeric fullerene derivatives can be prepared under appropriate reaction conditions. Furthermore, an aqueous methanol solution of hydrochloric acid is shown to be an eYcient reagent for the conversion of the polymer-bound fullerenes to fullerols.Introduction Experimental Materials Fullerenes have attracted a great deal of interest since the discovery that [60]fullerene, C60, has a soccer-ball like While cis-1,4-polybutadiene (98% cis, Mw=2 500 000) was structure—a truncated icosahedron.1 Fullerenes and their purchased from Aldrich, the cis-1,4-polyisoprene was anionderivatives have been shown to possess unusual photonic, ically synthesised in cyclohexane at room temp.(20 °C) using electronic, superconducting and magnetic properties.2 The n-butyllithium as the initiator. The synthesis and characterizlarge- scale synthesis of fullerenes3 has made C60 readily ation of the cis-1,4-polyisoprene have been previously reported available and chemical modification of fullerenes has since in detail elsewhere.20–23 The fullerene sample was purchased attracted considerable attention.4–14 In particular, the combifrom Aldrich, as were the analytical grade tetramethylethylenenation of the unique molecular characteristics of fullerenes diamine (TMEDA), BusLi (supplied in cyclohexane), cyclohexwith good processability of certain polymers through chemical ane and methanol.Hydrochloric acid in water (36 mass%) modification has proved promising for making advanced was used as supplied by Ajax Chemicals. polymeric materials with novel physicochemical properties. In this regard, fullerenes have been chemically bonded onto some tractable polymer chains either as pendant groups or as Synthesis constituent units of the polymer backbones.For instance, the In a typical experiment, we carried out the grafting reaction chemical or photo-polymerization of C60 has been demonshown in Scheme 1 (reactions 1–3) by dissolving 100 mg of strated to produce polymer backbones containing C60 enticis- 1,4-polyisoprene or cis-1,4-polybutadiene in 10 ml of dry ties,15 while the amine addition of amino-polymers into cyclohexane (or benzene) under an argon atmosphere at room fullerene double bonds16 and the cycloaddition reaction of temp.Then, a predetermined amount of BusLi was added with functionalized polymers with C6017,18 have been shown to stirring,24 and to the stirred solution TMEDA was subgenerate fullerene-grafted polymer chains.sequently injected at a 151 molar ratio with respect to BusLi We have recently demonstrated that C60 can also be (TMEDA was used to enhance the eYciency of the metallation covalently attached onto 1,4-polydiene chains, such as 1,4- of diene polymers19). The colour of the reaction mixture polybutadiene and 1,4-polyisoprene, through lithiation of the changed from pale-yellow to dark-red in a few minutes, as the polymer chains with sec-butyllithium (BusLi), followed by reaction progressed. The reaction mixture was further stirred chemically bonding fullerenes onto the lithiated polymer at room temp.for about 2 h before a selected amount of C60 chains and quenching with MeOH. Preliminary results, (pre-dissolved in toluene or benzene) was added at a fixed previously reported in a short communication,19 have shown molar ratio of BusLi to C60, depending on whether a soluble that the resulting C60-functionalized polydiene materials with or a crosslinked form of the final product was desired.24 multiple pendant fullerenes dispersed along their polymer Consequently, a colour change from dark-red to dark-brown backbones are highly soluble and thermally processable, was observed. Thereafter, the fullerene-functionalized polywhich could open up novel applications for fullerenes.In our meric adduct was quenched and precipitated by addition of further investigation on fullerene-containing polymers, we methanol. The soluble C60-grafted polymer was then redisfound that C60-crosslinked polydiene elastomers can also be solved into THF and this was followed by centrifugation to prepared via the lithiation reaction under certain reaction remove unreacted C60 (if any), as the solubility of free fullerenes conditions.Furthermore, an aqueous methanol solution of in THF is negligibly low.25 The soluble C60-grafted polymer hydrochloric acid was shown, for the first time, to be an was finally separated into THF as a brass-coloured solution.eYcient reagent for the conversion of the polymer-bound In cases where C60-crosslinked polymer gels were produced, fullerenes to fullerols. In this paper, we present these new any unreacted C60 and uncrosslinked polymer chains were findings, together with the details of syntheses and spectroremoved by thoroughly washing with pure benzene.scopic characterization of the fullerene- and fullerol-contain- Fullerol-containing polydienes were prepared in two diVeing polymers. rent ways. Method 1: during the synthesis of the C60-containing polydienes, the lithiated C60-containing intermediate (i.e. Product III of Scheme 1) was terminated by an undegassed aqueous HCl (36 mass%)–methanol solution (151 v/v) instead † Currently renamed as: CSIRO Molecular Science.J. Mater. Chem., 1998, 8(2), 325–330 325Fig. 1 UV–VIS absorption spectra of (a) C60 in cyclohexane; (b) the purified MeOH-terminated C60-grafted polybutadiene diluted in THF Scheme 1 Lithiation of polydienes followed by reaction with fullerene and its subsequent conversion to fullerols (The exact position and number of the hydroxy group(s) in Product VI are yet to be determined).Reagents and conditions: (1) Bu s Li, TMEDA; (2) C60; (3) MeOH; (4) HCl, H2O, MeOH (O2); (5) HCl, H2O, MeOH (O2). of methanol alone (reaction 4 of Scheme 1). Method 2: the purified C60-grafted polymers (i.e. Product IV of Scheme 1) were treated with the undegassed aqueous HCl–MeOH solution at room temp. (reaction 5 of Scheme 1).Characterization Fig. 2 GPC chromatograms of (a) the pristine cis-1,4-polyisoprene in The ultraviolet–visible (UV–VIS) spectroscopic measurements THF recorded by the refractive index detector; (b) C60-grafted polywere carried out using a Hewlett-Packard HP-8451A spec- isoprene in THF recorded by the refractive index detector trometer. FTIR spectra were measured on polymer samples cast on a KRS-5 crystal, using a Mattson Alpha Centauri a continuous red-shift in the UV–VIS spectrum. The UV–VIS FTIR spectrometer with a resolution of 4 cm-1.Solution spectra of pure C60 and the resulting brass-coloured solution NMR measurements were performed on a Bruker AC-200 of C60-grafted polydienes diluted in THF are shown in Fig. 1(a) NMR spectrometer using deuterated chloroform (99.8% D) as and (b), respectively.Comparison of curve (b) with curve (a) solvent. High-resolution solid state 13C NMR spectra of dried shows the appearance of several new absorption bands. This samples were collected on a Varian Unity Inova-300 specis accompanied by the disappearance of the characteristic trometer at resonance frequency 75.4 MHz under conditions peaks of fullerene at 213 and 329 nm,26 suggesting the formaof magic angle sample spinning (MAS) and high-power dipolar tion of polymeric fullerene derivatives.A similar decrease in decoupling (DD) by using either a single 90° pulse sequence the absorption at 329 nm observed for calixfullerene was with a repetition time of 2 s or the cross-polarization (CP) attributed to the isolation of C60 by the intramolecularly linked pulse sequence at a contact time of 2 ms and a repetition time calix[8]arene,27 while the appearance of peaks at 213, 248, of 3 s.The 90° pulse-width was of 3.7 ms while the rate of MAS 257, 308 and 326 nm had been taken as evidence for monowas 9–10 kHz. The chemical shift of 13C spectra was deteraddition of fullerenes in other cases.6,16,28 The expected absorpmined by taking the carbonyl carbon of solid glycine tion characteristic of the fullerene mono-adduct in the region (176.03 ppm relative to SiMe4) as an external reference stan- 415–435 nm16,29 was very weak, with respect to those peaks dard.Gel permeation chromatographic (GPC) measurements in the UV region, and became apparent only after scaling up were made on a Waters Associates GPC unit using tetrahydrothe axis of absorbance as was the case for C60-capped vinyl furan (THF) as solvent and a polystyrene standard.All the ether oligomers.29 The other newly appeared weak absorption spectroscopic measurements were made at room temp. unless bands seen in Fig. 1(b), however, may indicate the occurrence otherwise stated. Thermal analyses were made using a thermal of slightly higher degrees of addition onto traces of C60.gravimetric analyser (TGA, Mettler TG50). The grafting reaction shown in Scheme 1 (reactions 1–3) was also followed by GPC measurements. The GPC chromato- Results and Discussion grams for the pristine polyisoprene [curve (a)] and a purified C60-grafted polyisoprene [curve (b)] recorded with a refractive Soluble fullerene-containing polymers index (RI) detector are shown in Fig. 2. As can be seen in Fig. 2(a), the anionically polymerized polyisoprene has a very Soluble fullerene-functionalized polydiene chains were prepared according to the reactions shown in Scheme 1 (reactions narrow molecular mass distribution (Mw/Mn=1.1) with a weight-average molar mass (polystyrene equivalent) Mw= 1–3) at low molar ratios of BusLi to C60 (i.e.[BusLi]/ [C60]<1).24 The lithiation reaction was reflected by a color 44 000 g mol-1. Fig. 2(b), however, shows the appearance of a shoulder at higher molecular mass while the peak correspond- change from colorless, through pale-yellow, to dark-red, and 326 J. Mater. Chem., 1998, 8(2), 325–330ing to that of Fig. 2(a) remained unshifted. As a result, new pristine polybutadiene chains are observed at 1445 cm-1 and 2700–3000 cm-1, respectively.31–33 For the C60-grafted polybu- values ofMw=95 000 g mol-1 andMw/Mn=1.8 were obtained for the modified polymer. A similar change in GPC chromato- tadiene after being terminated by pure MeOH [Fig. 3(b)], the absorption band characteristic of MCH2M deformation grams has previously been observed for the cycloaddition of C60 onto azido-substituted polystyrenes with mono-addition vibration at 1445 cm-1 changed shape considerably. This was accompanied by the appearance of several broad absorption being the dominant process.17 Thus, the reasonably small value of the polydispersity (i.e.Mw/Mn=1.8) for the C60-grafted peaks centered at 1470, 1140 and 500 cm-1 which are assigned to [60]fullerene, with the expected peaks26,34 at 1428, 1181, polyisoprene suggests that cross-linking, if any, was insignifi- cant at the low ratio of [BusLi]/[C60] although gel formation 578 and 528 cm-1 shifted somewhat as a result of chemical interactions with the polymer backbone. However, almost no was observed for the grafting reactions carried out at high degrees of lithiation and a low molar ratio of C60, as we shall detectable change was observed for the characteristic absorption bands of the CNC bonds at 715 and 1670 cm-1.These see later. The corresponding GPC result measured by a UV–VIS detector at l=326 nm, a wavelength at which only spectroscopic changes confirm the occurrence of the intended coupling reaction (Scheme 1) with C60 being attached onto the fullerene absorbs,21,22,26 confirms that the higher molecular mass species associated with the shoulder in Fig. 2(b) corre- saturated aliphatic carbons along the polydiene chains. spond to the fullerene-grafted polyisoprene chains, as only the species of higher molar masses were observed by the UV–VIS Fullerene-crosslinked polymer gels detector.As a control, GPC measurements were also made on A sol–gel transformation occurred when the grafting reaction the lithiated, fullerene-free polyisoprene, after it had been (reactions 1–3 of Scheme 1) was carried out at a high molar quenched by MeOH in the same manner as for the fullereneratio of BusLi to C60 (i.e. [BusLi]/[C60]>1). The mass% of grafted polyisoprene.No change in the molecular mass with C60 incorporation into the fullerene containing polymers was respect to the polyisoprene precursor was found. Therefore, measured by TGA analyses. Fig. 4 shows the mass loss for the diVerences between curves (a) and (b) in Fig. 2 can be both the pristine cis-1,4-polybutadiene [curve (a)] and the C60- attributed to the grafting reaction of C60 onto the polymer crosslinked polybutadiene elastomer [curve (b)].Comparing chains. curve (b) with curve (a) of Fig. 4 shows that polybutadiene The presence of the peak corresponding to the cis-1,4- backbones in the C60-containing polymer sample completely polyisoprene precursor in Fig. 2(b), however, indicates that a decomposed at 350–500 °C with no mass loss for C60 up to significant amount of the polyisoprene chains did not react 650 °C.As a result, about 51 mass% incorporation of C60 with C60 in this particular case, presumably due to a low was obtained. eYciency of lithiation and/or the aggregation of polyisoprenyl- The degree of swelling for the as-synthesized C60-crosslinked lithium chains30 which could physically trap some of the ‘living’ cis-1,4-polybutadiene in benzene was determined according to: lithium sites away from the grafting reaction.It is also worth (wet mass-dry mass)/dry mass,35 from which a value of about pointing out that GPC measures the hydrodynamic volume of 9000% was obtained for the sample with 51 mass% C60 a macromolecular chain rather than its absolute molar mass. incorporation. The resultant dry C60-crosslinked cis-1,4- From the GPC results, therefore, a calculation of the molar polybutadiene elastomers were studied by high-resolution percentage of C60 in the host polymeric chains cannot be made solid-state NMR spectroscopy, and the results are shown in without detailed information on changes in the polymer confor- Fig. 5. A single 90° pulse sequence with a repetition time of mation upon the grafting reaction.10 Nevertheless, the percent- 2 s, together with MAS–DD techniques, was used to measure age incorporation of C60 into the polydiene chains can be the 13C spectra for the pristine cis-1,4-polybutadiene and estimated from the thermal gravimetric analyses (see below).17 mobile regions of the C60-crosslinked polybutadiene, as the The purified C60-grafted polydiene chains (Product IV of resonances from C60 or rigid domains adjacent to C60- Scheme 1) were analysed by FTIR measurements.As shown crosslinking sites were unobservable due to long 13C relaxation in Fig. 3(a), the band at 715 cm-1 is characteristic of the NCH times.36 The 13C signals of C60 and those polybutadiene out of plane (bending) deformation of the pristine polybutadisegments near to the C60-crosslinking sites were, however, ene, while the band at 1670 cm-1 corresponds to the stretching detected by the cross-polarization (CP) method under vibration of the isolated CNC bonds.31–33 The deformation MAS–DD conditions.In this case, the 13C resonances from and stretching vibration of MCH2M/MCHM bonds in the mobile segments in the C60-crosslinked polymer sample became unobservable due to their weak capability of cross-polarization, as also was the case for the pristine (amorphous) cis-1,4- polybutadiene. For comparative purposes, Fig. 5(a) and (b) show the MAS–DD 13C NMR spectrum for the pristine cis- 1,4-polybutadiene and the C60-crosslinked polybutadiene, Fig. 3 FTIR spectra of (a) the pristine cis-1,4-polybutadiene; (b) C60- Fig. 4 TGA mass loss data of (a) cis-1,4-polybutadiene; (b) C60- crosslinked cis-1,4-polybutadiene. Scanning rate, 10 °C min-1. grafted cis-1,4-polybutadiene terminated by MeOH J. Mater. Chem., 1998, 8(2), 325–330 327Fig. 6 FTIR spectra of (a) the pristine cis-1,4-polybutadiene; (b) C60- grafted cis-1,4-polybutadiene terminated by an undegassed aqueous HCl (36 mass%)–MeOH solution (151 v/v) rigid regions.Several new resonances were also observed as compared to Fig. 5(b). The resonances at 43.7 and 39.6 ppm are attributed to the aliphatic carbons at and next to the C60- grafting sites, respectively, as shown in the structural unit of MCH(C60)MCH2M.31,32 The band with a chemical shift around 143.4 ppm was assigned to unreacted olefinic carbons on the polymer-bound C60 moieties.26,37,38 The appearance of weak resonances at about 71.9 and 168.4 ppm may suggest a partial conversion of the polymer-bound fullerenes to fullerols (see below) and further rearrangements to ketone–hemiketal moieties.37–40 Fullerol-containing polymers Previously reported syntheses of fullerols from fullerenes have involved the use of strong acids, such as sulfuric acid and nitric acid, at a relatively high temperature (typically, Fig. 5 Solid state 13C NMR spectra of (a) the unreacted cis-1,4- polybutadiene (MAS–DD); (b) C60-crosslinked cis-1,4-polybutadiene 85–115 °C).34,37–42 However, we found that an aqueous HCl– (MAS–DD); (c) C60-crosslinked cis-1,4-polybutadiene (CP–MAS–DD) methanol solution is an eYcient reagent for the conversion of the polymer-bound fullerenes to fullerols even at room temperature.Fig. 6 reproduces FTIR spectra for cis-1,4-polybuta- respectively. The similar overall appearance of the narrow resonances seen in Fig. 5(a) and (b) indicates that the major diene before and after the C60-grafting, followed by quenching with an undegassed aqueous HCl(36 mass%)–MeOH (151 v/v) contribution to the mobile regions in the C60-crosslinked sample is from those non-crosslinked or lightly crosslinked solution (Method 1).Comparing spectrum (b) with (a) of Fig. 6 shows a strong hydroxy absorption band around 3400 cm-1, polybutadiene segments. The ratio of aliphatic carbons to olefinic carbons was assessed by integration of the resonance together with several other new absorption bands characteristic of fullerols centred at 1595, 1392 and 1084 cm-1.37 peaks at 27.8 and 129.8 ppm.31 This ratio was found to reduce from 1.00 [Fig. 5(a)] to 0.95 [Fig. 5(b)] upon grafting with Further evidence for the C60 grafting reaction and/or the subsequent conversion from the polymer-bound fullerenes to C60, indicating, once again, that C60 was grafted onto the aliphatic carbons. Assuming that the loss of the aliphatic fullerols was obtained by NMR measurements.The solution 1H NMR spectra for the pristine cis-1,4-polybutadiene and a carbon resonance at 27.8 ppm resulted fully from the grafting reaction, it can be estimated that the percentage incorporation soluble C60-grafted cis-1,4-polybutadiene after having been terminated by an undegassed aqueous HCl–MeOH solution of C60 should be about 57 mass% for a mono-addition, 40 mass% for a bis-addition, and 30 mass% for a tris-addition are given in Fig. 7. By referring to Fig. 7(a), the peaks at 2.08 and 5.40 ppm seen in Fig. 7(b) correspond to the aliphatic and onto each of the C60 entities. The observed value of 51 mass% from the TGA measurement on the crosslinked sample, which olefinic protons in the cis-1,4-polybutadiene chains.31 The weak, broad peaks centred at about 2.70 and 5.60 ppm may was also used for the NMR measurement, indicates that the polymer-gel contains a significant amount of mono-func- be attributed to the expected aliphatic and olefinic proton resonances of MCH(C60)M and NCHMC(C60)M, respec- tionalized C60 dangling groups in addition to various multiattached fullerenes at the crosslinking sites.These mono- tively. The observed downfield shift for these 1H NMR peaks of the 1,4-polybutadiene upon grafting with C60 is consistent functionalized C60 pendant groups should allow the final product to retain the physicochemical properties characteristic with an electron-withdrawing influence from the grafted fullerenes. 5,6 The broad bands centred at ca. 3.95 ppm may arise of C60. The 13C CP–MAS–DD spectrum of the C60-crosslinked from those hydroxy protons on the polymer-bound fullerols. 37–40 The sharp peaks at about 7.25 and 3.40 ppm are polybutadiene (Fig. 5(c)) shows rather wide linewidths for almost all resonances, suggesting a broad chemical-shift iso- attributable to impurities associated with CHCl3 and MeOH, respectively.32 tropic distribution of the resonances associated with rather 328 J.Mater. Chem., 1998, 8(2), 325–330on the lithiated, fullerene-free polybutadiene, after it had been quenched by MeOH in the same manner as for the C60-grafted polybutadiene. No change in the FTIR spectrum with respect to that of the pristine polybutadiene was observed. Therefore, Fig. 8 clearly suggests a conversion from fullerenes to fullerols for the unsymmetrically perturbed, polymer-bound C60 under the mild conditions.Prolonged acid treatment, however, may cause subsequent rearrangements from the newly formed fullerols to ketone–hemiketal moieties.37–40 Conclusions In summary, we have demonstrated that fullerenefunctionalized polydienes with multiple pendant fullerenes dispersed along their polymer backbones can be prepared by firstly lithiating polydienes with BusLi, which was followed by covalently grafting C60 onto the lithiated polymer chains.Both highly soluble C60-grafted polymers and C60-crosslinked polydiene elastomers can be prepared by properly controlling the reaction conditions. Furthermore, an aqueous methanol solution of hydrochloric acid is shown to be an eYcient reagent for the conversion of the polymer-bound fullerenes to fullerols at room temperature.Given that the lithiation reaction is a very versatile method for preparation of organolithium materials,43 the grafting Fig. 7 1H NMR spectrum, measured in CDCl3, of (a) cis-1,4-polybutadiene; (b) soluble C60-grafted cis-1,4-polybutadiene terminated by an reaction described in this paper should have important impliundegassed aqueous HCl (36 mass%)–MeOH solution (151 v/v) cations for covalent grafting of fullerenes onto various polymer chains.44–46 While the soluble and/or crosslinked fullerenecontaining polymers thus prepared may open up novel appli- The above results prompted us to investigate the conversion cations for the fullerenes, the acid treatment is expected to be between the polymer-bound fullerenes to fullerols in a more of use for making a wide range of new polymer-modified controllable manner by using the C60-grafted polybutadiene fullerene derivatives from the fullerol-containing polymers via after having been terminated with MeOH (i.e.Product IV of reactions characteristic of hydroxy groups.Scheme 1) as the starting material for the treatment in an aqueous HCl–MeOH solution (Method 2). Fig. 8 shows FTIR spectra for the MeOH-terminated C60-grafted polybutadiene References before and after the acid treatment. As mentioned above, the 1 H. W. Kroto, J. R. Heath, S. C. O’Brien, R. F. Curl and broad absorption peaks centred at 1470, 1140 and 500 cm-1 R. F. Smalley, Nature, 1985, 318, 162.seen in Fig. 8(a) characterize the polymer-bound fullerene C60 2 See, for example: Acc. Chem. Res., 1992, 25 (special issue on fuller- in the starting material. Upon treating it with an undegassed enes); A. F. Hebard, Ann. Rev. Mater. Sci., 1993, 23, 159; aqueous HCl (36 mass%)–MeOH (151 v/v) solution at room R. M. Baum, CE News, 1993, Nov. 22, 8; A. Hirsch, Angew.Chem., temperature [Fig. 8(b)], the strong hydroxy absorption bands Int. Ed. Engl., 1993, 32, 1138; ed. H. W. Kroto, J. E. Fischer and characteristic of fullerols developed, notably at 3424 and D. E. Cox, T he Fullerenes, Pergamon, Oxford, 1993; ed. K. M. Kadish and R. S. RuoV, Recent Advances in the Chemistry and 1084 cm-1, while the bands centred at 1470, 1140 and 500 cm-1 Physics of Fullerenes and Related Materials, The Electrochemical corresponding to the polymer-bound C60 decreased signifi- Society Inc., Pennington, NJ, 1994; ed.W. Andreoni, T he Chemical cantly. As a control, the same acid treatment was carried out Physics of Fullerenes 10 (and 5) Years L ater, NATO ASI Ser. E, 316, Kluwer Academic, Dordrecht, 1996. 3 W. Kratschmer, L. D. Lamb, K.Fostiropolous and D. R. HuVman, Nature, 1990, 347, 354. 4 For recent reviews see: F. Wudl, Acc. Chem. Res., 1992, 25(3), 157; A. Hirsh, Adv.Mater., 1993, 5, 859; A. Hirsch, T he Chemistry of the Fullerenes, Thieme Verlag, Stuttgart, 1994; F. Diederich, L. Isaacs and D. Philp, Chem. Soc. Rev., 1994, 23, 243; ed. R. Taylor, The Chemistry of Fullerenes, World Scientific, Singapore, 1995; F.Diederich and C. Thilgen, Science, 1996, 271, 317; M. Prato, J.Mater. Chem., 1997, 7, 1097. 5 A. Hirsch, Q. Li and F. Wudl, Angew. Chem., Int. Ed. Engl., 1991, 30(10), 1309. 6 A. Hirsch, A. Soi and H. R. Karfunkel, Angew. Chem., Int. Ed. Engl., 1992, 31(6), 766. 7 P. J. Fagan, P. J. Krusic, D. H. Evans, S. A. Lerke and E. Johnston, J. Am. Chem. Soc., 1992, 114, 9697. 8 D. A. Loy and R. A. Assink, J. Am. Chem. Soc., 1992, 114, 3977. 9 R. Seshadri, A. Govindaraj, R. Nagarajan, T. Pradeep and C. N. R. Rao, T etrahedron L ett., 1992, 33(15), 2069. 10 E. T. Samulski, J. M. DeSimone, M. O. Hunt, (Jr.), Y. Z. Menceloglu, R. C. Jarnagin, G. A. York, K. B. Labat and H.Wang, Chem. Mater., 1992, 4, 1153. 11 P. J. Fagan, P. J. Krusic, C. N. McEwen, J. Lazar, D.H. Parker, N. Herron and E. Wasserman, Science, 1993, 262, 404; and refer- Fig. 8 FTIR spectra of (a) C60-grafted cis-1,4-polybutadiene terminated ences therein. 12 M. Prato, Q. Chan and F.Wudl, J. Am. Chem. Soc., 1993, 115, 1148. by MeOH; (b) the MeOH-terminated C60-grafted cis-1,4-polybutadiene after having been treated in an undegassed aqueous HCl (36 13 A. O. Patil, G. W. Schriver, B.Carstensen and R. D. Lundberg, Polym. Bull., 1993, 30, 187. mass%)–MeOH solution (151 v/v) for 35 min J. Mater. Chem., 1998, 8(2), 325–330 32914 W. K. Fullagar, I. R. Gentle, G. A. Haeth and J. W. White, J. Chem. 32 See, for example: T he Aldrich L ibrary of NMR Spectra, Vol. II(1), Soc., Chem. Commun., 1993, 525; C. J. Hawker, P. M. Saville and ed. C. J. Pouchert, Aldrich Chemical Company, Inc., Wisconsin, J.W. White, J. Org. Chem., 1994, 59, 3503. 1983; T ables of Spectral Data for Structure Determination of 15 See, for example: A. Hassanien, T. Mrzel, P. Venturini, F. Wudl, Organic Compounds, ed. W. Fresenius, J. F. K. Huber, E. Pungor, D. Mihailovic, J. Gasperic, B. Kralj, D. Zigon, S. Milicev and G. A. Rechnitz, W. Simon, and Th. S. West, Springer-Verlag, A.Demsar, in Electronic Properties of Fullerenes; Springer Ser. Berlin, 1989. Solid-State Sci., 1993, 117, 316; N. Zhang, S. R. Schricker, F.Wudl, 33 L. Dai, H. J. Griesser, X. Hong, A. Mau, T. H. Spurling, Y. Yang M. Prato, M. Maggini and G. Scorrano, Chem. Mater., 1995, 7(3), and J. W. White,Macromolecules, 1996, 29, 282. 441. 34 L. Y. Chiang, R. Upasani, J.W. Swirczewski and K. Creegan, 16 K. E. Geckeler and A. Hirsch, J. Am. Chem. Soc., 1993, 115, 3850; Mater. Res. Soc. Symp. Proc., 1992, 247, 285. C. Weis, C. Friedrich, R. Mu�lhaupt and H. Frey, Macromolecules, 35 S. Wibullucksanakul, K. Hashimoto and M. Okada, Macromol. 1995, 28, 403. Chem. Phys., 1996, 197, 1865. 17 C. J. Hawker, Macromolecules, 1994, 27, 4836. 36 H. Ajie, M. M.Alvarez, S. J. Anz, R. D. Beck, F. Diederich, 18 K. I. Guhr, M. D. Greaves and V. M. Rotello, J. Am. Chem. Soc., K. Fostiropoulos, D. R. HuVman, W. Kra�tschmer, Y. Rubin, 1994, 116, 5997. K. E. Schriver, D. Sensharma and R. L. Whetten, J. Phys. Chem., 19 L. Dai, A. W. H. Mau, H. J. Griesser, T. H. Spurling and 1990, 94, 8630. J. W. White, J. Phys. Chem., 1995, 99, 17 302. 37 L. Y.Chiang, R. B. Upasani, J. W. Swirczewski and S. Soled, J. Am. 20 L. Dai and J. W. White, J. Polym. Sci., Part B, 1993, 31, 3. Chem. Soc., 1993, 115, 5453. 21 L. Dai and J. W. White, Polymer, 1991, 32, 2120. 38 L. Y. Chiang, R. B. Upasani and J. W. Swirczewski, J. Am. Chem. 22 L. Dai, J. Phys. Chem., 1992, 96, 6469. Soc., 1992, 114, 10 154. 23 L. Dai,Macromol. Chem. Phys., 1997, 198, 1723. 39 L. Y. Chiang and L.-Y. Wang, TRIP, 1996, 4, 298. 24 The molar ratio of BusLi to C60 determines the number of attach- 40 L. Y. Chiang, L.-Y. Wang, J. W. Swirczewski, S. Soled and ment points onto a single C60 entity. With [BusLi]/[C60]>1, mul- S. Cameron, J. Org. Chem., 1994, 59, 3960. tiple addition could occur leading to the formation of C60- 41 L. Y. Chiang, L.-Y. Wang and C. S. Kuo, Macromolecules, 1995, crosslinked polydiene gels. 28, 7574. 25 A. O. Patil, G. W. Schriver and R. D. Lundberg, ACS Polym. Prep., 42 L. Y. Chiang, J. W. Swirczewski, C. S. Hsu, S. K. Chowdhury, 1993, 34(2), 592. S. Cameron and K. Creegan, J. Chem. Soc., Chem. Commun., 1992, 26 H. W. Kroto, A. W. Allaf and S. P. Balm, Chem. Rev., 1991, 91, 1791. 1213. 43 B. Mudryk and T. Cohen, J. Am. Chem. Soc., 1993, 115, 3855. 27 M. Takeshita, T. Suzuki and S. Shinkai, J. Chem. Soc., Chem. 44 A. J. Chalk, J. Polym. Sci., Part B, Polym. Phys., 1968, 6, 649; Commun., 1994, 2587. A. J. Plate, M. A. Jampolskaya, S. L. Davydova and V. A. Kargin, 28 T. Suzuki, Q. Li, K. C. Khemani, F. Wudl and O. Almarsson, J. Polym. Sci., Part C, 1969, 22, 547; H. Tomita and R. A. Register, Science, 1991, 254, 1186. Macromolecules, 1993, 26, 2791, and references therein. 29 H. Okamura, M. Minoda, K. Komatsu and T. Miyamoto, 45 M. D. Guiver and G. P. Robertson,Macromolecules, 1995, 28, 294. Macromol. Chem. Phys., 1997, 198, 777. 46 D. E. Bergbreiter, H. N. Gray and B. Srinivas, Macromolecules, 30 J. N. Hay, D. S. Harris and M. Wiles, Polymer, 1976, 17, 613; 1993, 26, 3245. C. A. Ogle, F. H. Strickler and B. Gordon III, Macromolecules, 1993, 26, 5803, and references cited therein. 31 L. Dai, A. W. H. Mau, H. J. Griesser and D. A. Winkler, Macromolecules, 1994, 27, 6728. Paper 7/03764C; received 30thMay, 1997 330 J. Mater. Chem., 1998, 8(2), 325&ndash