Dispersion of submicron-sized SiO2/Al2O3-coated TiO2 particles and efficient encapsulation via the emulsion copolymerization of methacrylates using a thermoresponsive polymerizable nonionic surfactant
Dispersion of submicron-sized SiO2/Al2O3-coated TiO2 particles and efficient encapsulation via the emulsion copolymerization of methacrylates using a thermoresponsive polymerizable nonionic surfactant
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DOI：
10.1038/s41428-023-00757-w
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发表时间：
2023-01-27
期刊：
影响因子：
2.8
通讯作者：
Kawaguchi, Seigou
中科院分区：
文献类型：
--
作者：
Hasan, Md. Kamrul;Enomoto, Kazushi;Kawaguchi, Seigou
采用热敏性可聚合非离子表面活性剂NE-10，通过甲基丙烯酸酯乳液共聚，对亚微米级的SiO_2/Al_2O_3(Si/Al)包覆二氧化钛(Si/Al-Ti02)粒子进行了包覆。研究了超声均质机、涂料振荡器和部分中和聚(异丁烯-α-马来酸)搅拌罐(PMR)等多种分散方法对Si/Al-TiO2超细粉的分散效果。超声波均质机成功地将Si/Al-TiO2分散到水中，而涂料振荡器和PMR则造成了过度分散，使SiO_2/Al_2O_3壳层破裂。最佳分散条件为：固含量40wt%，SiO_2微珠0.3 mm，ISOBAM-600 0.25wt%(中和度=0.7)，转速100rpm，搅拌时间4h，包封率(F-en)受单体和引发剂种类、NE-10和十二烷基磺酸钠浓度以及间歇还是半间歇工艺的影响。NE-10浓度对F-EN有显著影响，最佳NE-10加入量为1.4~2.5 mg/1.0g Si/Al-TiO2.以0.25g甲基丙烯酸甲酯和0.75g甲基丙烯酸正丁酯为原料，在优化条件下进行两步半间歇乳液共聚合，F-EN>；可达90%。与裸Si/Al-Ti02相比，包覆的杂化粒子在水中表现出更高的反射率和色散稳定性。
Submicron-sized SiO2/Al2O3(Si/Al)-coated titanium dioxide (Si/Al-TiO2) particles were encapsulated through the emulsion copolymerization of methacrylates using a thermoresponsive polymerizable nonionic surfactant, NE-10. An optimized water-dispersion method was developed to disperse Si/Al-TiO2 dried powders after various methods were investigated, such as using an ultrasonic homogenizer, a paint shaker, and a pot mill rotator (PMR) in the presence of partially neutralized poly(isobutylene-alt-maleic acid). The ultrasonic homogenizer successfully dispersed Si/Al-TiO2 in water, whereas the paint shaker and PMR caused overdispersion and broke the SiO2/Al2O3 shell. The optimal dispersion of Si/Al-TiO2 was obtained under the following conditions: 40 wt% solid content, 0.3 mm SiO2 beads, 0.25 wt% ISOBAM-600 (neutralization degree = 0.7), rotating speed < 100 rpm, and rotating time < 4 h. The encapsulation efficiency (F-en) was affected by the monomer and initiator types, NE-10 and sodium dodecyl sulfonate concentrations, and whether the process was batch or semibatch. The NE-10 concentration exhibited a significant effect on F-en; the optimal NE-10 addition was 1.4-2.5 mg for 1.0 g of Si/Al-TiO2. F-en > 90% was achieved using 0.25 g methyl methacrylate and 0.75 g n-butyl methacrylate, following a two-step semibatch emulsion copolymerization under optimized conditions. Compared to bare Si/Al-TiO2, the encapsulated hybrid particles showed a higher reflectance and dispersion stability in water.