Liu Haisheng, Deng Yuhao, Ye Yang, Liu Xingqiang
School of Physics and Electronics, Hunan University, Changsha 410082, China.
Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
Materials (Basel). 2023 Jul 21;16(14):5150. doi: 10.3390/ma16145150.
The common, commercial reversible thermochromic (RT) melamine-formaldehyde resin microcapsules containing formaldehyde are very harmful to human health. To address this issue, we successfully prepared a novel formaldehyde-free microcapsule via interfacial polymerization using RT compositions as the core and poly(urethane-urea) (PUU) as the shell. The core material consisted of a color former (crystal violet lactone), a developer (bisphenol AF), and a solvent (methyl stearate). To optimize the synthesis of the microcapsules, an L (3) orthogonal design and single-factor experiments were employed to analyze the effects of four factors (N3300-to-L75 shell material mass ratio, core-to-shell material mass ratio, emulsifier concentration, and shear rate during emulsification) on the encapsulation efficiency. The results showed that the optimal parameter values were as follows: a shear rate of 2500 rpm, N3300-to-L75 shell material mass ratio of 1:4, core-to-shell material mass ratio of 11:5, and emulsifier concentration of 3.5%. The influence of the shear rate on the particle size and distribution, surface morphology, dispersibility, and reversible thermochromic properties of the microcapsules was investigated. Furthermore, analyses on the phase-change characteristics, thermal stability, ultraviolet aging, and solvent and acid-base resistances of the microcapsules were conducted systematically. Finally, a reversible thermochromic mark containing the RTPUU microcapsules was designed and fabricated, which could be used against falsification. Moreover, these RTPUU microcapsules can be potentially used for anticounterfeiting applications.
常见的商用含甲醛可逆热致变色（RT）三聚氰胺 - 甲醛树脂微胶囊对人体健康危害极大。为解决这一问题，我们以RT组合物为芯材、聚（聚氨酯 - 脲）（PUU）为壳材，通过界面聚合法成功制备了一种新型无甲醛微胶囊。芯材由成色剂（结晶紫内酯）、显色剂（双酚AF）和溶剂（硬脂酸甲酯）组成。为优化微胶囊的合成，采用L（3）正交设计和单因素实验分析了四个因素（N3300与L75壳材质量比、芯材与壳材质量比、乳化剂浓度以及乳化过程中的剪切速率）对包封率的影响。结果表明，最佳参数值如下：剪切速率2500 rpm、N3300与L75壳材质量比1:4、芯材与壳材质量比11:5以及乳化剂浓度3.5%。研究了剪切速率对微胶囊粒径及分布、表面形貌、分散性和可逆热致变色性能的影响。此外，还系统地对微胶囊的相变特性、热稳定性、紫外老化以及耐溶剂性和耐酸碱性能进行了分析。最后，设计并制备了一种含有RTPUU微胶囊的可逆热致变色标记，可用于防伪。而且，这些RTPUU微胶囊在防伪应用中具有潜在用途。
