Role of Non-Equilibrium Pinned Layers on the Thermodynamics of Confined Polymer Blends

这项工作将明智地结合联合收割机的实验和理论，以探讨钉扎的聚合物层，这是已知的形成在润湿基板上的表观热力学上的约束聚合物混合物的作用。这项研究的动机是研究这个问题，因为最近的实验上的相行为的限制聚合物共混物，它利用了各种互补的工具，表明相分离[“双节点”]温度几乎不受限制。这些结论与现有的平衡理论是定性的不一致，这些理论一致地预测了相混合态在禁闭时的强稳定性。由于平衡的情况下没有出现来解释这些结果，它是澄清，实验结果产生的众所周知的事实，即在紧邻的一个热塑性基板的熔体链被有效地钉在这个边界上的时间尺度的实验。然后，它自然地遵循的表观热力学的剩余，非钉扎，链的影响，这钉扎层的存在下，从而提供了一种手段，合理化的实验结果。这项研究将使用薄的聚合物混合物和填充纳米颗粒的聚合物共混物来彻底探索这一推测。小角中子散射和准弹性中子散射实验将补充理论和模拟，描绘这种钉扎聚合物层的存在，并深刻理解其后果的聚合物共混物的覆盖层的相行为。这些活动与两门新课程的开发密切相关，这两门课程分别名为“纳米材料导论”和“复杂流体的多尺度建模”，将提供给高年级本科生。PI还将与特洛伊的少年博物馆合作开发IMAX风格的电影，针对K-12儿童，关于聚合物的行为，特别是在表面附近。聚合物材料可用于无数的薄膜应用，例如油漆、润滑剂、阻隔涂层、纳米光刻和所提出的光电器件。拟议的研究表明，近表面层，这是钉扎在宏观时间尺度上，深刻地影响受限聚合物的热力学性质。这些钉扎层也可以强烈地改变这些薄膜的结构，从而改变其机械、热和电性能。这些结论如果得到证实，可能会影响聚合物在当前和未来各种应用中的设计和使用。教育和推广活动针对从幼儿园到高级研究生的学生：这些活动将强调基础表面科学和聚合物在日常生活中的重要性。

This work will judiciously combine experiments and theory to probe the role of pinned polymer layers, which are known to form at wetting substrates, on the apparent thermodynamics of confined polymer mixtures. This research is motivated to study this issue since recent experiments on the phase behavior of confined polymer blends, which utilize a variety of complementary tools, suggest that the phase separation ["binodal"] temperatures are hardly affected on confinement. These conclusions are in qualitative disagreement with existing equilibrium theories, which uniformly predict a strong stabilization of the phase mixed state on confinement. Since equilibrium scenarios do not appear to explain these results, it is conjectured that the experimental findings arise from the well known fact that melt chains in the immediate vicinity of a wettable substrate are effectively pinned to this boundary over the time scale of the experiments. It then naturally follows that the apparent thermodynamics of the remaining, non-pinned, chains are affected by the presence of this pinned layer, thus providing a means of rationalizing the experimental results. This research will use thin polymer mixtures and polymer blends filled with nanoparticles to exhaustively probe this speculation. Small angle neutron scattering and quasi-elastic neutron scattering experiments will be complemented with theory and simulations, to delineate the existence of this pinned polymer layer, and to incisively understand its consequences on the phase behavior of an overlayer of a polymer blend. These activities are strongly coupled to the development of two new courses, titled "Introduction to Nanomaterials" and "Multiscale Modeling of Complex Fluids," which will be offered to senior undergraduate students. The PI will also partner with the Junior Museum in Troy to develop IMAX style movies, aimed at K-12 children, on the behavior of polymers, especially in the vicinity of surfaces.%%%Polymeric materials find use in a myriad of thin film applications, such as paints, lubricants, barrier coatings, in nanolithography and in proposed optoelectronic devices. The proposed research conjectures that a near-surface layer, which is pinned on macroscopic time scales, profoundly affects the thermodynamic properties of confined polymers. These pinned layers could also strongly alter the structure and hence the mechanical, thermal and electrical properties of these thin films. These conclusions, if verified, could impact the design and use of polymers in these wide variety of current and future applications. The educational and outreach activities target students from kindergarten to the advanced graduate: these activities will stress the importance of fundamental surface science and polymers in everyday life.***