High pressure and high temperature induced polymerization of C₆₀ quantum dots

We synthesized C₆₀ quantum dots (QDs) with a uniform size by a modified ultrasonic process and studied its polymerization under high pressure and high temperature (HPHT). Raman spectra showed that a phase assemblage of a dimer (D) phase (62 vol%) and a one-dimensional chain orthorhombic (O) phase (38 vol%) was obtained at 1.5 GPa and 300 °C. At 2.0 GPa and 430 °C, the proportion of the O phase increased to 46 vol%, while the corresponding D phase decreased to 54 vol%. Compared with bulk and nanosized C₆₀, C₆₀ QDs cannot easily form a high-dimensional polymeric structure. This fact is probably caused by the small particle size, orientation of the disordered structure of C₆₀ QDs, and the barrier of oxide function groups between C₆₀ molecules. Our studies enhance the understanding of the polymerization behavior of low-dimension C₆₀ nanomaterials under HPHT conditions.