Hollow poly(alpha-methylstyrene) (PAMS) shows application in inertial confinement fusion experiments as the degradable mandrels of glow plasma polymer shells. However, the molecular weight of PAMS has great influence on the quality of mandrels. In this work, this influence was systematically studied using several PAMS samples with different molecular weights. For PAMS shells with 900 μm inner diameter and different wall thickness, when the molecular weight of PAMS is in the range of 300-500 kg·mol^-1, perfect sphericity and good wall thickness uniformity can be obtained. In contrast, when increasing molecular weight to 800 kg·mol ^-1, the sphericity and the wall thickness uniformity become worse. Moreover, compared with the wall uniformity, the sphericity of PAMS shells was much less sensitive to the molecular weight. The results also showed that the stability of W1/O compound droplets of PAMS shells were less affected by the molecular weight. It was revealed that the wall uniformity and the sphericity of the PAMS shells were associated with the diffusion rates of fluorobenzene (FB).

Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF) experiments. Driven by the need to control the shape of water-in-oil (W1/O) compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2) were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS) shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2) interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.Physics for financial support (2014B0302052) and National Natural Science Foundation of China (U1530260).

采用化学气相沉积-氧化烧结法，在不同工作压强条件下，制备了惯性约束聚变靶用空心玻璃微球（HGM）。利用扫描电子显微镜、原子力显微镜、VMR显微镜系统和能谱仪对HGM的表面形貌、球形度、壁厚均匀性以及成分进行了表征。分析了工作压强对HGM表面形貌、球形度、壁厚均匀性和成分的影响以及相互关系。研究表明：HGM的表面形貌随工作压强的增大而变得平滑致密，表面均方根粗糙度逐渐减小。随工作压强增大，HGM的球形度没有发生明显变化，而壁厚均匀性得到不断提高，微球中C元素浓度逐渐降低，Si元素浓度不断升高，O元素浓度基本保持不变。

在乳液微封装技术制备聚苯乙烯空心微球的工艺中，固化过程是决定微球球形度及壁厚均匀性的关键阶段。基于乳粒发生器制备内径(850±10) μm、壁厚(250±25) μm的复合乳粒，以25 ℃,45 ℃和65 ℃作为固化温度，考察了固化温度对微球球形度和壁厚均匀性的影响。结果表明，固化温度越低，界面张力越高，乳液固化速率越慢，微球球形度和壁厚均匀性越好。当固化温度为25 ℃时，批次微球中球形偏离值优于2 μm的微球产率为90%，壁厚偏差值优于2 μm的微球产率为40%，明显优于固化温度为45 ℃和65 ℃时微球的质量。

为建立高效简洁的厚壁空心微球球形度和壁厚均匀性的表征和测量方法, 以内径850 μm、壁厚25 μm的厚壁聚苯乙烯(PS)微球为测量对象, 分析球形度和壁厚均匀性的表征方法, 探讨测量过程中采样方式对表征微球球形度和壁厚均匀性的影响。研究表明: 对于批量微球球形度和壁厚均匀性的表征, 当抽样数目不小于30时, 测量结果之间的差异很小; 而对于单一微球的球形度和壁厚均匀性的表征, 至少3个不同投影面的测量结果的平均值才趋于稳定。不同投影面导致球形度或壁厚均匀性较差的批次样品的测量结果有一定差异, 多次投影测量可提高测量结果的可靠性。