Effect of nanoparticle loading and magnetic field application on the thermodynamic, optical, and rheological behavior of thermoresponsive polymer solutions
Effect of nanoparticle loading and magnetic field application on the thermodynamic, optical, and rheological behavior of thermoresponsive polymer solutions
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DOI：
10.1002/vnl.21968
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发表时间：
2022-12
影响因子：
2.7
通讯作者：
C. A. Neal;Grace Kresge;M. Quan;V. León;Nondumiso O. Chibambo;M. Calabrese
中科院分区：
文献类型：
--
作者：
C. A. Neal;Grace Kresge;M. Quan;V. León;Nondumiso O. Chibambo;M. Calabrese
虽然通过外部刺激加工是一种很有前途的技术，可以调整聚合物材料的结构和性能，但磁场对热敏聚合物溶液中相变的影响还没有得到很好的理解。由于纳米颗粒（NP）的加入也会影响这些热力学和光学性质，因此将磁场与NP结合产生的协同效应为调节材料性质提供了一种新的途径。在这里，通过傅里叶变换红外光谱（FTIR）、磁比浊法、差示扫描量热法（DSC）和磁流变学，分别和共同研究了亲水性二氧化硅NPs和磁场存在下的聚（N -异丙基丙烯酰胺）（PNIPAM）溶液的热力学、光学和流变学性质。虽然NPs和磁场都通过改变氢键（H -键）来降低相分离能垒和降低光学转变温度，但红外光谱表明这些变化发生的机制是不同的。磁场主要改变溶剂极化，而NPs提供PNIPAM-NP氢键位点。将NP添加与现场应用相结合，独特地改变了溶液环境，并产生了仅在聚合物溶液中看不到的依赖于场的流变行为。这些研究提供了对磁场和NP添加对PNIPAM热响应性的相互作用的基本理解，可以用于越来越复杂的刺激响应材料。
Although processing via external stimuli is a promising technique to tune the structure and properties of polymeric materials, the impact of magnetic fields on phase transitions in thermoresponsive polymer solutions is not well‐understood. As nanoparticle (NP) addition is also known to impact these thermodynamic and optical properties, synergistic effects from combining magnetic fields with NP incorporation provide a novel route for tuning material properties. Here, the thermodynamic, optical, and rheological properties of aqueous poly(N‐isopropyl acrylamide) (PNIPAM) solutions are examined in the presence of hydrophilic silica NPs and magnetic fields, individually and jointly, via Fourier‐transform infrared spectroscopy (FTIR), magneto‐turbidimetry, differential scanning calorimetry (DSC), and magneto‐rheology. While NPs and magnetic fields both reduce the phase separation energy barrier and lower optical transition temperatures by altering hydrogen bonding (H‐bonding), infrared spectra demonstrate that the mechanism by which these changes occur is distinct. Magnetic fields primarily alter solvent polarization while NPs provide PNIPAM–NP H‐bonding sites. Combining NP addition with field application uniquely alters the solution environment and results in field‐dependent rheological behavior that is unseen in polymer‐only solutions. These investigations provide fundamental understanding on the interplay of magnetic fields and NP addition on PNIPAM thermoresponsivity which can be harnessed for increasingly complex stimuli‐responsive materials.