【作者】 付维贵；

【导师】 李宝会； 孙平川；

【作者基本信息】 南开大学 ， 凝聚态物理， 2010， 博士

【摘要】 设计和制备性能优异的多相聚合物材料是现代高分子科学研究的主要任务之一,其中多相聚合物体系的微相结构、相容性、分子间相互作用及动力学是直接影响材料性能的关键因素,也是高分子物理理论研究的基本问题。本文以苯乙烯-丁二烯嵌段共聚物、聚甲基丙烯酸甲酯/聚乙烯苯酚(PMMA/PVPh)共混物等多相聚合物为研究对象,综合利用多种固体NMR技术并发展新的检测方法,同时结合量子化学计算对多相聚合物体系的相容性、相区尺寸、界面厚度、链间弱相互作用及分子运动等问题开展了系统深入的研究。本文主要包含以下两部分内容：(一)采用偶极滤波-自旋扩散固体NMR技术研究了具有不同嵌段结构的苯乙烯-丁二烯嵌段共聚物(两嵌段共聚物SB和三嵌段共聚物SBS)的界面相厚度随温度的演化规律。研究发现在实验温度范围内(25-80℃),含有相同刚性相PS (32 wt%)、不同嵌段结构的苯乙烯-丁二烯的嵌段共聚物的界面厚度均随温度的增加而增加,该趋势与自洽平均场理论(SCFT)的计算结果相符；但二者的界面厚度不同,SBS界面厚度大于SB,表明刚性-柔性嵌段共聚物的界面厚度不仅与链段间的相互作用参数(χ)有关还与其分子结构有关,这与嵌段共聚物熔体界面相演化的经典SCFT理论预言不同,这一发现深化了关于嵌段共聚物微相分离的高分子物理理论的认识。(二)以PMMA/PVPh聚合物共混物为研究对象,基于多脉冲相位调制技术,发展了利用化学位移滤波(CSF)结合自旋扩散测定刚性/刚性共混物微相结构的固体高分辨NMR新技术。利用该技术结合自旋扩散方程数值模拟测定了体系的相区大小,并对共混体系的相容性进行了深入研究；通过高分辨二维1H-1H自旋交换谱和13C-1H异核相关谱(HETCOR)检测到该体系中的氢键相互作用位点；并首次结合13C化学位移各向异性(CSA)的量子化学计算及检测CSA的NMR技术(SUPER)研究了该体系中链间的氢键相互作用和分子结构的空间排布；采用检测13C-1H偶极相互作用的分离局域场NMR技术(PISEMA)还观测到该刚性-刚性体系中由于氢键相互作用导致的局域链段的协同运动。以上研究表明固体NMR技术是从分子水平研究多相聚合物界面相结构、相互作用及分子运动的有力工具,本研究对于多相聚合物结构检测技术的发展以及新型聚合物材料的研究和开发具有重要意义。更多还原

【Abstract】 The design and preparation of multiphase polymer materials is one of the main targets in modern polymer science. The microstructure, miscibility, intermolecular interaction and molecular dynamics of the multiphase polymer system are responsible directly for the material properties. Therefore, they have been the basic problems and attracted significant attention in polymer physics. In this thesis, a variety of solid-state NMR methods and a new developed NMR technique by our group, in combination with the quantum chemical calculations were utilized to investigate the miscibility, domain size, interphase thickness, intermolecular interaction and molecular dynamics for two kinds of multiphase polymer systems. They are styrene-butadiene copolymers with the same volume percent and different molecular architectures, and poly (methyl methacrylate) (PMMA) and poly (4-vinyl phenol) (PVPh) hydrogen-bonded polymer blends prepared under different conditions.1H spin diffusion solid-state NMR, in combination with other techniques, was utilized to investigate the effect of molecular architecture and temperature on the interphase thickness and domain size in poly (styrene)-block-poly (butadiene) and poly (styrene)-block-poly (butadiene)-block-poly (styrene) copolymers (SB and SBS) over the temperature from 25℃to 80℃. These two block copolymers contain equal PS weight fraction of 32 wt%, and especially, polystyrene (PS) and polybutadiene (PB) blocks are in glass and melt state, respectively, within the experimental temperature range. It was found that with increasing temperature the domain sizes of the dispersed phase and interphase thicknesses in these two block copolymers increased. Surprisingly we found that the interphase thicknesses in these two block copolymers were obviously different, which was inconsistent with the theoretical predictions about the evolution of interphase in block copolymer melts by self-consistent mean-field theory (SCFT). This implies that the interphase thickness not only depends strongly on the binary thermodynamic interaction (χ) between the PS and PB blocks, but also is influenced by their molecular architectures in the experimental temperature range. These results provide new insights into the theory of polymer physics for the microphase separation of block polymers.In combination with quantum chemical calculations, a variety of advanced multi-scale solid-state NMR techniques were used to investigate the microstructure and dynamics in PMMA/PVPh polymer blends. First, a new chemical-shift filtered high-resolution NMR pulse sequence based on a recently developed continuous phase modulation technique was proposed to characterize the microphase structure and miscibility in rigid/rigid polymer blends. The miscibility and domain sizes of the samples with different treated conditions were well elucidated by this new NMR technique combined with spin-diffusion experiments and the numerical simulation for the spin-diffusion process. Second, the possible hydrogen-bonding interactions between the carbonyl group of PMMA and hydroxyl group of PVPh were successfully elucidated by two-dimensional 1H-1H spin-exchange and 13C-1H heteronuclear chemical-shift correlation (HETCOR) NMR experiments at different mixing time. Furthermore, the 13C 2D SUPER experiments were applied to determine chemical shift anisotropy-separation of undistorted powder patterns and quantum chemical calculations for the theoretical predictions of CSA parameters were utilized to investigate the intermolecular hydrogen-bonding interactions and molecular conformation of the blends. The chemical shift and conformation predicted by quantum chemical calculations were confirmed by solid-state NMR experiments. A possible interaction model of the blends was proposed. Finally,13C-1H polarization inversion and spin exchange at magic angle (PISEMA) experiments at different temperature were used to reveal the heterogeneous dynamics resulting from the cooperative motion associated with the hydrogen bonding interaction. It provides clear evidence that the motion of aromatic group in PVPh is affected by the rotating motions of methyl in PMMA for both the annealed powder blend at 120℃and cast film sample at room temperature. In addition, with increasing temperature the local mobility of the cast film sample increases.更多还原