Here, we report the observation of an unusual thermoresponsive volume phase transition behavior of cubic poly(N-isopropylacrylamide) (PNIPAM) microgels. Cubic PNIPAM microgels with a mean edge size of 125 ± 41 nm were synthesized via electrochemical-initiated radical polymerization with a photovoltaic cell as power supply. In turbidity and laser light scattering studies on dilute aqueous dispersions of these cubic microgels, both the light attenuation and hydrodynamic radius variations with temperature reveal an additional transition at about 25.0 °C, besides the widely reported volume phase transition at the PNIPAM LCST that is typically found for (quasi-)spherical microgels. This unusual thermoresponsive volume phase transition behavior of the cubic microgels can be elucidated by using a core–corona model, with the contribution from each part varying at different temperatures. The finding is also checked by thermal analysis.

中文翻译：

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观察立方聚（N-异丙基丙烯酰胺）微凝胶的异常热响应体积相变行为

在这里，我们报告了对立方聚（N-异丙基丙烯酰胺）（PNIPAM）微凝胶。以光伏电池为电源，通过电化学引发的自由基聚合合成了平均边缘尺寸为 125 ± 41 nm 的立方 PNIPAM 微凝胶。在对这些立方微凝胶的稀释水分散体进行的浊度和激光散射研究中，除了广泛报道的 PNIPAM LCST 的体积相变（通常为发现用于（准）球形微凝胶。立方微凝胶的这种不寻常的热响应体积相变行为可以通过使用核心 - 电晕模型来阐明，每个部分的贡献在不同温度下变化。还通过热分析检查了这一发现。