论文标题
对压力引起的聚（N-异丙烯酰胺）线圈到全球形的分子见解
Molecular insights on Poly(N-isoproylacrylamide) coil-to-globule transition induced by pressure
论文作者
论文摘要
使用广泛的全部原子分子动力学模拟，在广泛的温度和压力下探索了聚-N-异丙基丙烯酰胺（PNIPAM）相图。通过利用一个脉冲线性聚合物链的简单模型，我们提供了对PNIPAM线圈到全球的新见解，以解决温度和压力扮演的角色。我们发现，线圈到全球的跃迁存在于巨大的压力，经历了较低的临界溶液温度的有趣的重新入侵行为，而压力的增加与实验观察结果一致。此外，我们在高压下报告了一种新型的球状状态，再次证实了实验结果：这是一个更结构化的水合壳的特征，在大气压对应物方面，它更接近PNIPAM疏水域。我们的结果清楚地表明，温度和压力通过不同的分子机制诱导PNIPAM线圈到全球的转变，为两个热力学参数系统使用开辟了道路，以调整过渡的位置和相关肿胀/倒塌状态的特性。
Poly-N-isopropylacrylamide (PNIPAM) phase diagram is explored in a wide range of temperature and pressure using extensive all-atom molecular dynamics simulations. By exploiting a simple model of an atactic linear polymer chain, we provide novel insights into PNIPAM coil-to-globule transition addressing the roles played by both temperature and pressure. We find that a coil-to-globule transition exists up to large pressures, undergoing an intriguing reentrant behavior of the lower critical solution temperature with increasing pressure in agreement with experimental observations. Furthermore, we report the existence of a new kind of globular state at high pressures, again confirming experimental results: this is characterized by a more structured hydration shell, that is closer to PNIPAM hydrophobic domains, with respect to the atmospheric pressure counterpart. Our results clearly show that temperature and pressure induce PNIPAM coil-to-globule transition through different molecular mechanisms, opening the way for a systematic use of both thermodynamic parameters to tune the location of the transition and the properties of the associated swollen/collapsed states.
