Thermally stimulated desorption of C60 and C70 fullerenes from rigid-chain polyimide films

Thermal imidization of polyamic acid–fullerene composites: 'in situ' X-ray diffraction study

“…It has to be noted that C 60 was not completely dissolved in the mixed solution obtained, and sediment formation was observed. This effect was also found for C 60 concentrations higher than 2% (dry basis polymer), being independent of the selected route for the C 60 addition [2,15,19]. Thus, the actual concentration of fullerene inside the PI matrix could be lower than the rated one.…”

“…Fullerene C 60 is a strong electron acceptor, being capable of reacting with primary [26], secondary [26 -28] and tertiary amines [29,30]. Analysis of the thermal desorption spectra of PAA/C 60 composite coatings indicates that C 60 molecules, in the initial PAA/C 60 solutions, interact with terminal amine groups of the polyamic acid [15,19,20]. Such an interaction is confirmed by the increase of the intrinsic viscosity in the PAA/C 60 solutions compared to that of the pure PAA solutions [2].…”

Thermal desorption of fullerene C60 from polymer matrices

“…The model enables to obtain the value of prefactor by extrapolation the log D 0 versus u dif plot (for different penetrant molecules in the same matrix) to zero, the slope of the curve being a measure of thermal changes of elastic modulus of the matrix [32]. Our earlier results point at the adequacy of both approaches for analysis of C 60 and C 70 desorption from the PI matrix [19]. Comparison between activation energies and prefactors for different polymers can be helpful for understanding diffusion mechanisms of fullerene molecules in polymers and their relation to the physical and mechanical properties of the polymer-fullerene composites.…”

“…D 0 can be derived from TSD experiment by extrapolation the log D versus 1/T plot to zero. The value of d calculated using this relation from D 0 is about 1 nm for C 60 in PI [19]. Higher values of D 0 are obtained for C 60 diffusion in PDMS and PS.…”

“…PI samples were prepared from PI prepolymer, i.e., polyamic acid. Polyamic acid was synthesized from 3,3 0 ,4,4 0 -oxydiphthalic anhydride (ODPA), p-phenylenediamine (PPD), and 2,5-bis(4-aminophenyl) pyrimidine (APP) [19]. As it has been shown in the first works on tribology of the PI-fullerene composites, the fullerene introduction into polyamic acid leads to the decrease in the wear rates of the composite coatings [20,21].…”