温敏性高聚物是一类应用极为广泛的功能高分子材料。温敏性高聚物分子相互作用的细节及相变过程的分子机制，特别是水溶液中共存的渗透溶质如何影响相变动力学的途径，一直是目前学术界颇为关注的科学问题。本项目拟用国内首台高分辨宽带和频振动光谱仪，结合本研究组多年来已发展成熟的和频光谱偏振选择定律与实验构型分析方法，系统研究气/液界面上温敏性高分子聚合物pNIPAM与水分子之间、高分子链内部、高分子链之间氢键相互作用以及渗透溶质对这些氢键结构的影响。研究中将通过测量pNIPAM高分子链的酰胺I带、异丁基以及水分子在高聚物/液体水界面的SFG-VS，重点探究不同的渗透溶质分子是否通过"直接作用"或"间接作用"机理参与温敏性高分子界面的相变动力学。本项目不仅对温敏性高聚物功能材料的设计有指导意义，而且其相关成果也可以用于解释渗透至溶质分子引起蛋白质变性的分子反应动力学机制。

Thermo-responsive polymers are widely used functional polymer materials. The detailed molecular interactions and phase transition mechanisms of the thermo-responsive polymers, especially on how the coexsiting osmolytes in aqueous solutions affect the pahse transition dynamics, have been the focus of a great number of research efforts. In this project, a high-resolution broad-band sum frequency generation vibrational spectrometer which is the first one in China, combined with the sum frequency generation (SFG) selection rules and experimental configuration analysis methods well developed by our group, will be employed to study the phase transition mechanisms of thermo-responsive polymers at the air/liquid interface. We will systematically study the hydrogen bonding between thermo-resposive pNIPAM polymers and water molecules as well as the intra- and inter-chain hydrogen bonding in polymes themselves. The effects caused by the coexisting osmolytes will be carefully evaluated. By measuring the SFG spectra of amide I band, isopropyl group and water molecules at the air/water interface, we aim to reveal whether the osmoyes paticipate in the phase transition dynamics of thermo-responsive polymer interface via a "direct" or "indirect" mechanism. The results of this porject will not only help design the new-generation thermo-responsive functional materials, but also can be used to explian the mechanisms of protein denaturation caused by osmolytes in a point of view of moelcular reaction dynamics.