Energetics of polymerized fullerites

Comparative Raman study of photo-oligomer stability in the donor-acceptor fullerene complex {Pt(dbdtc)2}•C60 and pristine C60

“…The temperature dependence of the polymer content probed by the same constant laser power density shows the decomposition of photo-oligomers to monomers near ∼ 350 K in the fullerene complex and at ∼ 410 K in the pristine C 60 . These values are considerably smaller than the decomposition temperature of 525 -565 K for crystalline polymers of C 60 [10].…”

“…The stability study of photo-oligomers at elevated temperatures showed that their decomposition to a monomer occurred near 350 K in the fullerene complex {Pt(dbdtc 2 )}·C 60 and at ∼ 410 K in pristine C 60 . These values are considerably smaller than the decomposition temperature 525 -565 K for crystalline C 60 polymers [10]. This difference, to a significant extent, may be related to the structural transformations and the deformation of the fullerene molecular cage during the creation of the HPHT crystalline polymers, whereas the photopolymerization is less energetically demanding because of the disordered structure of the photo-oligomers and their small fragment size.…”

“…In the 2D-T polymer (planar tetragonal polymer, 8 sp 3 -like coordinated carbon atoms), the peak downshifts to 1446 cm −1 , while in the case of the 2D-R phase (planar rhombohedral polymer, 12 sp 3 -like coordinated carbon atoms) the A g (2) mode exhibits the strongest softening and is observed at 1408 cm −1 [9]. The stability of the HPHT C 60 polymers at elevated temperature has been studied by differential scanning calorimetry (DSC) [10][11][12]. Under a heating rate of 10 -20 K/min, DSC measurements show a strong endothermic peak between 525 and 565 K, but no signal was observed during the cooling scan [10].…”

“…The stability of the HPHT C 60 polymers at elevated temperature has been studied by differential scanning calorimetry (DSC) [10][11][12]. Under a heating rate of 10 -20 K/min, DSC measurements show a strong endothermic peak between 525 and 565 K, but no signal was observed during the cooling scan [10]. The transition temperature depends on the polymeric phase and somewhat on the scanning rate, indicating that the polymer decomposition process is kinetically-controlled.…”

Stability at high temperature and decomposition kinetics of the fullerene dimers and photopolymers

“…The lowering of the C 60 molecular symmetry leads to the splitting and softening of phonon bands and the Raman examination of polymers is based on the behavior of the A g (2) pentagon pinch (PP) mode frequency which decreases from 1468 cm −1 for the C 60 monomer to 1463, 1458, 1446 and 1408 cm −1 for the dimers, linear orthorhombic, planar tetragonal and rhombohedral polymers, respectively [5,6]. Fullerene polymers are stable at ambient conditions but revert to the monomeric state at elevated temperature [7,8]. The differential scanning calorimetry (DSC) of the HPHT polymers shows transitions in the range 170 -280…”