Serin Guillaume, Nguyen Hong Hanh, Marty Jean-Daniel, Micheau Jean-Claude, Gernigon Véronique, Mingotaud Anne-Françoise, Bajon Damienne, Soulet Thierry, Massenot Sébastien, Coudret Christophe
Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Université de Toulouse , 31055 Toulouse Cedex 4, France.
Laboratoire des IMRCP, Université de Toulouse, CNRS UMR 5623, Université Paul Sabatier, 118 route de Narbonne 31062 Toulouse Cedex 9, France.
J Phys Chem B. 2016 Sep 15;120(36):9778-87. doi: 10.1021/acs.jpcb.6b06859. Epub 2016 Sep 2.
The behavior of highly concentrated aqueous solutions of two thermoresponsive polymers poly(N-isopropylacrylamide) (PNIPAm) and poly(N-vinylcaprolactam) (PVCL) have been investigated by terahertz time-domain spectroscopy (THz-TDS). Measurements have been performed for concentrations up to 20 wt %, over a frequency range from 0.3 to 1.5 THz and for temperatures from 20 to 45 °C including the zone for lower critical solution temperature (LCST). THz-TDS enables the study of the behavior of water present in the solution (i.e., free or bound to the polymer). From these measurements, in addition to phase transition temperature, thermodynamic data such as variation of enthalpy and entropy can be inferred. Thanks to these data, further insights upon the mechanism involved during the dehydration phenomenon were obtained. These results were compared to the ones issued from dynamic light scattering, spectroscopy, or microscopy techniques to underline the interest to use THz-TDS as a powerful tool to characterize the behavior of thermoresponsive polymers in highly concentrated solutions.
通过太赫兹时域光谱（THz-TDS）研究了两种热响应聚合物聚（N-异丙基丙烯酰胺）（PNIPAm）和聚（N-乙烯基己内酰胺）（PVCL）的高浓度水溶液的行为。测量在浓度高达20 wt%、频率范围为0.3至1.5 THz以及温度从20至45°C（包括低临界溶液温度（LCST）区域）的条件下进行。太赫兹时域光谱能够研究溶液中存在的水的行为（即自由水或与聚合物结合的水）。从这些测量中，除了相变温度外，还可以推断出诸如焓变和熵变等热力学数据。基于这些数据，对脱水现象所涉及的机制有了进一步的了解。将这些结果与动态光散射、光谱或显微镜技术得到的结果进行比较，以强调使用太赫兹时域光谱作为表征高浓度溶液中热响应聚合物行为的有力工具的意义。
