Synthesis and stability of linear and star polymers containing [C₆₀] fullerene

Abstract

Linear and symmetric star block copolymers of styrene and isoprene containing [C60] fullerene were synthesized by anionic polymerization and appropriate linking postpolymerization chemistry. In all block copolymers, the C60 was connected to the terminal polyisoprene (PI) block. The composition of the copolymers was kept constant (∼30% wt PI), whereas the molecular weight of the diblock chains was varied. The polymers were characterized with a number of techniques, including size exclusion chromatography, membrane osmometry, and 1H NMR spectroscopy. The combined characterization results showed that the synthetic procedures followed led to well‐defined materials. However, degradation of the fractionated star‐shaped copolymers was observed after storage for 2 months at 4 °C, whereas the nonfractionated material was stable. To further elucidate the reasons for this degradation, we prepared and studied a four‐arm star copolymer with the polystyrene part connected to C60 and a six‐arm star homopolymer of styrene. These polymers as well as linear copolymers end‐capped, through N<, with C60 were stable. Possible reasons are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2494–2507, 2001

Thermal stability of the fullerene‐chain link in 6‐arm PS stars with a C60 core

“…It has been reported that the thermal stability of a polyisoprene‐C 60 link is reduced as compared to the PS‐fullerene bond,12 and our own observations made some time ago led to the same conclusion. Just for comparison we followed by SEC the thermal stability at 111 °C in solution in toluene of a 6‐arm polyisoprene star ( M n = 6200 g/mol, M w = 6900 g/mol, I = 1.11) prepared by reacting C 60 with a “living” PI‐Li ( M n = 1200 g/mol, M w = 1300 g/mol, I = 1.08).…”

“…A decreased thermal stability of PS containing covalently attached fullerenes has been reported and attributed to a preferential breaking of the chain‐C 60 bond 10, 11. A low stability of copolymer stars (PS‐b‐PI) 6 C 60 where a polyisoprene chain is directly attached to the fullerene has also been observed upon storing at room temperature 12…”

Revisit of polystyrene-modified fullerene core stars: A computational study

“…However, very recent experiments by temperature gradient interaction chromatography (TGIC) [8][9][10][11][12][13][14] observed the C 60 core stars with greater than six arms [15]. Although there have been plentiful studies on the arm-grafted C 60 fullerene both experimentally and theoretically [3][4][5][6][7][8][15][16][17], several questions still remain: why 6-arm-grafted C 60 core star is observed in every experiments with the most abundance; why greater than 6-arm-grafted C 60 core star is only observed by the latest experiments; how the arms are grafted on C 60 fullerene. In this work, we aim to systematically study the relationships between the grafted arms and C 60 fullerene by DFT calculations.…”

“…As a multifunctional core molecule, C 60 fullerenes have been used for the preparation of star-shaped polymers by grafting polymer or copolymer chains, in order to overcome the incompatibility between C 60 and most polymers [3][4][5][6][7]. In 1992, Samulski and coworkers reported the reaction of poly(styryl) lithium (PSLi) with C 60 fullerenes [3].…”

Degradation of the covalent carbon–carbon bond between fullerene‐C60 and poly(1,3‐cyclohexadiene)

“…The synthesis of fullerene‐C 60 (C 60 ) end‐capped polymers (C 60 ‐polymers) is one of the most interesting subjects in basic polymer research and is a practical method to obtain new functional materials for a wide range of applications. For example, C 60 ‐polystyrene (C 60 ‐PSt), 1 C 60 ‐polyisoprene (C 60 ‐PIp),1 C 60 ‐PIp‐PSt block copolymer (C 60 ‐PIp‐PSt),2 C 60 ‐PSt‐poly(1,3‐cyclohexadiene) (PCHD) block copolymer (C 60 ‐PSt‐PCHD),3 C 60 ‐PCHD,4 C 60 ‐poly( N ‐vinylcarbazole) (C 60 ‐PNVC),5 and C 60 ‐poly(4‐diphenylaminostyrene) (C 60 ‐PDAS)6 were synthesized by the grafting reaction of polymer carbanions onto C 60 . Among the innumerable combinations of C 60 and polymers, C 60 ‐poly( para ‐phenylene) (C 60 ‐PPP) has been recognized as one of the most attractive structures, because excellent optical, electrical, and opto‐electrical properties are expected from this polymer.…”