Lattice-Type Polymers from an Adduct of C 60 and 2-Methylaziridine
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Chemistry and Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California, 94025, U S A. ABSTRACT A one to ten adduct of C60 and 2-methylaziridine was prepared and copolymerized with
Novolac, Epon and Bisphenol A to obtain three dimensional polymers containing C60 with low
coefficients of friction and good wear properties, which bode well for their potential use as solid lubricants. INTRODUCTION The isolation1 of C60 as a stable allotrope of carbon and its subsequent synthesis2 in macroscopic amounts generated lot of interest among chemists all over the world. Its soccer ball like structure and high electron affinity prompted several research groups 3 to develop new chemistry for its functionalization. Along with the development of its chemistry, several different polymers incorporating C60 have been reported. 4 Amato eta!.5 have proposed that polymers of C60 could be of two different structural kinds: (i) pearl necklace, in which the C60 unit is a part of the polymer chain; and (ii) charm bracelet, in which the fullerene unit is pendant to the polymer chain. Later Taylor and Walton 3 b have proposed a lattice-type polymer, which is a two- or threedimensional variant of the pearl necklace polymers. Herein we report a simple synthesis of an adduct of 2-methylaziridine and C60 and preparation of lattice-type polymers from the adduct. PREPARATION AND CHARACTERIZATION OF AZIRIDINE ADDUCT Prompted by the work of Wudl 3d and coworkers showing the facile addition of amines to
C60, we investigated the addition of 2-methylaziridine to C60. Our motivation behind this study was the recognition that aziridine moieties would allow incorporation of the C60 cage into a variety of polymers. Typically the adduct was synthesized by stirring C60 in dry benzene with an excess
of freshly distilled 2-methylaziridine for several days. Initially the reaction mixture was purple colored and had excess C60 particles suspended in it. As the reaction progressed the mixture
became dark brown and finally turned into a very clear reddish brown homogenous solution. Upon evaporation of the solvent the adduct 1 was left as a shining dark brown colored solid. (For the sake of clarity only one methylaziridine ring is shown in the following equation, although the adduct on average has ten such rings.)
L\(30 eq.) Benzene, room temperature several days 1
Suspension in purple solution
Clear brown solution
347 Mat. Res. Soc. Symp. Proc. Vol. 359 01995 Materials Research Society
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Unlike the starting C6 0, the adduct was readily soluble in chloroform, tetrahydrofuran, benzene and toluene. The weight gain observed in the reaction (72.5%) suggests the formation of a one to ten adduct of C60 to methylaziridine viz., C60 (C3 H7 N)1 0 . The elemental analysis is also consistent with the addition of ten aziridine rings. The calculated values ( C, 83.69%; H, 5.46%; N, 10.84%) are in close agreement with those found (C,82.96% ; H,5.48%; N, 11.56%). Though a mixture of products with varying number of methylaziridine r
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