Abstract:

The effect of magnetic nanoparticles(MNPs) on the devitrification isothermal crystallization of typical vitrification solution Vs55 in the process of glass crystallization was systematically explored by Differential Scanning Calorimetry (DSC) and cryomicroscope system. The results show that:(1)The MNPs coated by both Carboxylic Acid (CA) and Polyethylene Glycol (PEG) have little effect on the glass transition temperature(T_g) of Vs55, but significant effect on the devitrification transition temperature(T_d) and devitrification enthalpy(H_Td);(2)At the range of the devitrification area (-85~-60℃), the MNPs coated by CA can significantly promote the devitrification of Vs55 as increasing of the isothermal temperatures and the cooling rates, and the ice growth rate was 0.37 μm·s^-1 at the isothermal temperature of -85℃, but it is about 2.19 μm·s^-1 for -75℃. Also, the ice growth rates raised from 1.72 μm·s^-1 to 3.54 μm·s^-1 when the cooling rates were increased from 2℃·min^-1 to 100℃·min^-1(at the isothermal temperature of -75℃); (3) Compared with Vs55, magnetic nanoparticles coated by both PEG and CA could promote the devitrification of Vs55. The crystal growth rates at the isothermal temperature of -80℃ were 0 for Vs55, but 1.04 μm·s^-1 and 2.31 μm·s^-1 for CA and PEG respectively. Compared with CA coating, the MNPs coated by PEG promoted the much more devitrification of Vs55, and the ice growth rates were 0.62 μm·s^-1 and 6.25 μm·s^-1 for the isothermal temperature of -85℃ and -75℃, respectively, which means that the surface coating of MNPs can significantly affect the crystallization of Vs55.

Key words: crystallization, nanoparticles, kinetics, devitrification, Vs55

摘要：

借助差示扫描量热仪（DSC）和低温显微系统，研究了磁纳米粒子对典型玻璃化溶液Vs55在反玻璃化过程中等温结晶行为的影响。结果表明：（1）磁纳米粒子经过羧酸（CA）和聚乙二醇（PEG）表面修饰后，对Vs55溶液的玻璃化转变温度（T_g）几乎没有影响，但对其反玻璃化转变温度（T_d）和反玻璃化结晶焓（H_Td）影响较大；（2）在Vs55的反玻璃化温区范围内（-85~-60℃），随着等温温度的升高和降温速率的增大，经CA修饰的磁纳米粒子均会显著促进Vs55的反玻璃化现象，在-85℃等温时的冰晶生长速率为0.37 μm·s^-1，75℃等温时则为2.19 μm·s^-1，而当降温速率从2℃·min^-1增大到100℃·min^-1时（在-75℃等温结晶），其反玻璃化冰晶生长的速率由1.72 μm·s^-1增大到3.54 μm·s^-1；（3）与Vs55相比，两种修饰均明显促进了其反玻璃化，在-80℃等温结晶时，Vs55溶液的生长速率为0，而CA和PEG修饰分别达到了1.04 μm·s^-1和2.31 μm·s^-1；与CA修饰相比，PEG修饰后的磁纳米粒子更加促进了Vs55溶液的反玻璃化现象，在-85℃等温时的冰晶生长速率为0.62 μm·s^-1，而-75℃等温时则达到了6.25 μm·s^-1，这个结果也充分说明了磁纳米粒子表面修饰物质的不同必定会显著影响Vs55的反玻璃化结晶生长。

关键词: 结晶, 纳米粒子, 动力学, 反玻璃化, Vs55