Effects of stereochemistry and copolymerization on the LCST of PNIPAm
Effects of stereochemistry and copolymerization on the LCST of PNIPAm
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DOI：
10.1063/1.4974165
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发表时间：
2017-01-21
影响因子：
4.4
通讯作者：
Netz, Paulo A.
中科院分区：
文献类型：
--
作者：
de Oliveira, Tiago E.;Mukherji, Debashish;Netz, Paulo A.
聚N-异丙基丙烯酰胺（PNIPAm）是一种低临界转变温度（LCST）为305 K的智能聚合物。有趣的是，该转变点福尔斯落在人体温度范围内，使得PNIPAma非常适合用于生物医学应用。然而，有时需要对这些聚合物的LCST进行相当灵活的调整以进一步增加其应用范围。在这项工作中，我们使用全原子分子动力学模拟来研究PNIPAm基（共）聚合物的LCST。我们研究了不同的分子结构，其中聚合物序列通过修改其立体化学或通过PNIPAm与丙烯酰胺（Am）单元的共聚来调节。我们的分析连接全球聚合物构象与微观分子间的相互作用。这些发现表明，PNIPAm链在加热时的崩溃取决于单体周围的水合结构，这强烈依赖于立构规整度和更亲水的丙烯酰胺单体的存在。我们的结果被发现是在良好的协议与现有的实验数据。出版社：AIP Publishing
Poly(N-isopropylacrylamide) (PNIPAm) is a smart polymer that presents a lower critical transition temperature (LCST) of 305 K. Interestingly, this transition point falls within the range of the human body temperature, making PNIPAma highly suitable candidate for bio-medical applications. However, it is sometimes desirable to have a rather flexible tuning of the LCST of these polymers to further increase their range of applications. In this work, we use all-atom molecular dynamics simulations to study the LCST of PNIPAm-based (co-)polymers. We study different molecular architectures where the polymer sequences are tuned either by modifying its stereochemistry or by the co-polymerization of PNIPAm with acrylamide (Am) units. Our analysis connects global polymer conformations with the microscopic intermolecular interactions. These findings suggest that the collapse of a PNIPAm chain upon heating is dependent on the hydration structure around the monomers, which is strongly dependent on the tacticity and the presence of more hydrophilic acrylamide monomers. Our results are found to be in good agreement with the existing experimental data. Published by AIP Publishing.