Effect of polymer molecular structure on the quality of thin‐walled hollow microspheres for inertial confinement fusion

Abstract

Polymer microspheres can be used as fuel containers for laser inertial confinement fusion (ICF) due to their low atomic number, low density, and high thermal stability. The thin-walled polymer microspheres are prone to cracking due to an increase in the diameter to thickness ratio (diameter/wall thickness).The effect of polystyrene (PS) and Poly (α-methyl styrene) (PAMS) materials commonly used in ICF experiments on the quality of thin-walled microspheres is investigated. PS hollow microspheres show better sphericity, smoother surface, and lower cracking rate than PAMS microspheres. Moreover, the heat treatment of solidified PS microspheres can improve the strength so that the cracking rate of the microspheres decreases. The relative mechanism of how the molecular structure affect the quality is also discussed. This study provides some guidance for the preparation of thin-walled polymer microspheres with high quality for ICF experiments.

Enhanced performance of hollow polystyrene spheres for inertial confined fusion by noncovalent interactions

“…Therefore, for thin‐walled spheres, kinds of failure modes including depressed deformation, craze and crack occur easily in the drying process. By the optimization of PS weight‐average molecular weight and drying process, there is no depressed deformation, but there are still craze and crack occurring in the drying process for thin‐walled PS spheres 10 . As shown in Table 2, with the introduction of PCBM into PS spheres, the craze and crack yield of PS spheres decreases from 23% to ~12%, improving the production yield of the spheres.…”

“…Our previous work enhanced both the wall thickness uniformity and sphericity of these spheres by optimizing the density matching and the viscous shear force 7–9 . Nevertheless, there are still some craze and crack occurring in the fabrication of these polymer spheres, especially for polymer spheres with thin wall, which seriously reduces the production yield 10 . Therefore, it is also important to improve the mechanical properties of these spheres and maintain high sphericity, excellent surface finishing and so on at the same time.…”