Preparation and Characterization of SiO2-coated 2,4-H exa diyn- 1,6-bis（ ethylurea ） Mic rocapsules

A novel kind of time-temperature indicator, SiO2-coated 2,4-hexadiyn-1,6-bis（ethylurea） microcapsules, has been fabricated by coating SiO2 on 2,4-hexadiyn-1,6-bis（ethylurea）. This kind of microcapsules is a model hydrophilic indicator, its stability is improved. And temperature-induced color change is irreversible even under varying irradiation. The influences of ammonia, tetraethyl orthosilicate（TEOS） and temperature on the product have been investigated. 2,4-Hexadiyn-1,6-bis（ethylurea） and the coated particles have been characterized by means of elemental analysis, mass spectrum, FTIR and Raman spectra and DSC, SEM, TEM and DLS analyses. The results indicate that 2,4-hexadiyn-1,6-bis（ethylurea）/SiO2 ratios, ammonia concentration and temperature could modulate the monodis- persity and size of the microcapsules. The experiments indicate that when the molar ratio of 2,4-hexadiyn- 1,6-bis（ethylurea）/SiO2/ammonia is 1：3：3.5 and temperature is 40℃ , the obtained microcapsules are well coated with the best monodispersity. Such sustained-release and hydrophilic microcapsules have very good prospects as a novel time-temoerature chromatic indicator.

疫苗温度标签的制备及显色动力学

目的以2,4-己二炔-1,6-二烷基脲为原料制备疫苗温度标签,并对其重结晶和共结晶的制备,以及显色动力学规律进行研究,为疫苗温度标签的商业化应用提供理论指导。方法通过使用不同溶剂对2,4-己二炔-1,6-二乙基脲的重结晶,以及不同比例的2,4-己二炔-1,6-二乙基脲和2,4-己二炔-1,6-二丙基脲的共结晶进行实验,确定最适宜的配方,并对其显色动力学规律进行研究,利用分光密度仪对光密度值进行测定,进而通过计算得到反应活化能。结果不同溶解度的溶剂重结晶2,4-己二炔-1,6-二乙基脲后的固相聚合反应速率不同,通过实验发现以m乙醇∶m水=3∶1的混合溶液为溶剂重结晶,以及mKE∶mKPR=2∶1共结晶得到的产物热反应性较好,颜色变化较为鲜明,且通过计算得到该固相聚合反应的活化能为31.94 kJ/mol。结论将2,4-己二炔-1,6-二烷基脲作为新型的化学型疫苗温度标签,其视觉响应信号易于识别;通过重结晶和共结晶的改性来匹配不同种类的疫苗,可直观反映疫苗在冷链运输、保存和使用环节的质量。