【作者】 郭宜鲁；

【导师】 武培怡；

【作者基本信息】 复旦大学 ， 高分子化学与物理， 2008， 博士

【摘要】 本论文围绕二维相关光谱技术在多个亲水性聚合物研究中的应用而展开。二维相关光谱技术的概念由Noda于1986年首先提出,由于其相对一维光谱来说,有较高的分辨率,同时能够辨明所研究的材料分子内各基团或分子间的相互关系,所以作为一维光谱的辅助分析手段,在很多研究领域得到了广泛应用。作为二维相关方法在高分子科学和生命科学交叉的前沿领域研究的一种尝试,我们选择了多个亲水性高分子材料,来研究它们的结构和性质。这些亲水性的高分子体系涵盖了当今前沿研究的热点领域,从人工智能材料,到天然生物大分子材料。不但如此,我们还对生物模拟材料进行了研究,尝试了二维相关方法直接对生命活动研究的可行性。论文正文共分六个章节,第一章为全文的绪论。第二章中,我们研究了一种重要的人工智能材料聚乙烯基甲基醚在水溶液中的热致相分离行为。实验过程中采用了中红外衰减全反射（ATR）光谱技术,以及近红外透射光谱技术。首先在ATR光谱的二维相关中,可以发现部分水合的C-H基团的变化要快于脱水的C-H基团,这暗示在PVME水溶液的相分离过程中,可能存在某一中间态;进一步由NIR光谱的二维相关结果,得到PVME主链上的CH₂基团的变化要快于侧链上O-CH₃的变化。这说明相分离过程中,首先发生主链的脱水,随着主链脱水后分子链构象的调整,导致了侧链基团的脱水。此外,加入无机盐后,盐离子与水分子之间相互作用使得水分子更加容易从PVME分子链上脱去,造成发生相分离的温度降低,但是相分离过程中的分子机理没有改变。第三章中,我们运用二维衰减全反射红外相关光谱,考察了一种典型的生物模拟材料AOT表面活性剂在非极性溶剂中形成反胶束的构象转变过程,以及由这种表面活性剂形成的油包水反相微乳液中的水分子结构。在升温过程中,反胶束中反式构象的AOT分子逐渐增多,并在38℃时达到最大比例,此时AOT反胶束具有最大的尺寸和最稳定的状态。这个温度又与人体的体温非常接近,而AOT等双烃链表面活性剂与生物体中组成细胞膜的磷脂分子的结构十分相似,从而可以猜测生物体体内的温度环境和两亲性分子的分子构象存在一定程度的关系。通过二维相关方法对AOT反胶束中水分子结构进行了研究,总结了水在弯曲振动区域的吸收峰归属,完善修正了水在反胶束中的四态模型,并为第四章的研究奠定了基础。第四章中,我们运用曲线拟合以及二维衰减全反射红外相关光谱,探讨了AOT反胶束对丙烯酰胺分子的包覆过程,从分子水平上解释了丙烯酰胺反相微乳液聚合的引发机理。丙烯酰胺分子进入反胶束后,首先与AOT的极性端相互作用,之后在反胶束的内核聚集。丙烯酰胺单体的含量较低时,倾向于吸附在反胶束的壳壁上,因此水溶性的引发剂可能效率不高,随着丙烯酰胺含量的增多,丙烯酰胺开始在内核聚集,水溶性引发剂的效率开始逐渐增强。对包覆丙烯酰胺的反胶束进行加热,发现反胶束内侧的一条碳氢长链首先发生结构调整,使得吸附在AOT极性端的AM分子受到扰动而脱离,聚集在反胶束的中心,这个过程中,AOT反胶束倾向于膨胀。向AOT反胶束中加入水后,丙烯酰胺分子在与水分子和AOT极性端相互作用的竞争中占据优势,导致更多的集聚水分子和游离水分子的出现,这就为反相微乳液的引发创造了更有利的条件。第五章中,我们研究了天然生物大分子纤维素的二醋酸酯化衍生物体系中的氢键网络。通过二维红外光谱和moving-window技术,我们得到:（1）在低温区域,主要发生体系内吸收水的脱离,伴随着分子内氢键的转化;（2）在高温区域,吸收水已经基本脱去,分子间氢键开始发生破坏。第六章是对全文所有体系的总结。对所有体系来说,我们的主要研究手段均为二维相关光谱。首先我们记录体系的动态光谱,然后利用二维相关光谱的优势分辨出若干小峰和弱峰,从而把体系中处于不同构象或不同相态的基团区分开来。然后再利用相关光谱可分辨光谱信号变化顺序的独特优点,找出各种状态下的基团在外扰影响下的相互关系,最终探寻相关的机理。对这些体系的研究,证实了二维相关光谱分析方法用于探寻生命现象中的本质是非常适合的。更多还原

【Abstract】 This thesis centers on the application of two-dimensional infrared and near-infrared correlation spectroscopy（2DCOS） on the study of several hydrophilic polymers.2DCOS was proposed by Noda in 1986.Compared with conventional one-dimensional（1D） spectroscopy,2DCOS owns the high resolution and can distinguish the motion sequential order of the different functionalities of polymers. Thus,it is often looked upon as a useful initial probing tool to aid in the analysis of complex 1D spectra and has received wide applications in the different fields.In this thesis,the structure and performance of several hydrophilic polymers in the forefront of polymer science intercrossing with life science were characterized by 2DCOS, which included artificial intelligence materials and natural macromolecules.Moreover, the structure and property of bio-simulation material was also studied,which was supposed to be the direct investigation on the life activities.The thesis contains six chapters.Chapter one is the introduction of the whole research work.In chapter two,Thermo-sensitive phase transition behavior of poly（vinyl methyl ether）（PVME） in an aqueous solution during heating was investigated by Fourier transform infrared（FTIR） spectroscopy with attenuated total reflection（ATR） accessory,and Fourier transform near-infrared（FTNIR） spectroscopy.2D ATR analysis results indicate that hydrated C-H groups change prior to dehydrated C-H groups with increasing temperature around the phase transition, which suggests the existence of an intermediate state during the phase separation.2D NIR analysis results indicate that the dehydration of CH₂ groups occurs earlier than that of O-CH₃ groups.This result suggests that it is the change of the hydrophobic hydrocarbon chain conformation induced by heating that indirectly leads to the dehydration of the hydrophilic ether oxygen side groups.Thus,a two-step phase separation molecular dynamics mechanism during gradual heating has been established.When 0.5 M KC1 was added into a PVME aqueous solution,IR spectra showed that the phase transition temperature was reduced,and the features of 2DCOS did not change compared to PVME aqueous solution in the absence of KC1.The result indicates that the underlying phase transition mechanism itself was not altered by the presence of KC1,although the transition temperature is shifted.In chapter three,The states of sodium bis（2-ethylhexyl） sulfosuccinate（AOT） reversed micelles and of the water confined in the reversed micelles have been investigated by Fourier transform infrared spectroscopy with an attenuated total reflection（ATR） accessory.2DCOS revealed that a process of AOT molecules transforming from the trans conformation into the gauche conformation exists during heating.The quantitative analysis of the C=O stretching vibration band shows that the reversed micelles have the maximum size and lowest energy at the temperature of 38℃.The assignments of water confined in AOT reversed micelles in the O-H bending vibration region were concluded,which was considered to be the supplement for the former study results and laid a foundation of the studies in the next chapter.In chapter four,the state of acrylamide（AM） confined within the hydrophilic core of AOT reversed micelles has been investigated by Fourier transform infrared spectroscopy with an attenuated total reflection（ATR） accessory.2DCOS and curve fitting revealed that the acrylamide molecule tended to stick at the interface of the inverse emulsion at lower acrylamide-to-AOT molar ratio value（X）;when X increased to some higher values,the acrylamide would tend to congregate in the micellar core.Therefore,it is important to choose the suitable initiator for the inverse emulsion polymerization under different experimental conditions.In chapter five,Temperature-dependent structural changes in hydrogen bonds in cellulose diacetate（CDA） were investigated by Fourier transform infrared spectroscopy（FT-IR）.2DCOS in combination with moving-window technique was applied to analyze the overlapping O-H band due to various kinds of hydrogen bonds. In the temperature region of 35-100℃,the absorbed water in the hydrogen-bond matrix broke away,and the intra-chain hydrogen bonds in CDA changed accordingly. When temperature increased into a higher region,the inter-chain hydrogen bonds began to be weakened;both the inter-chain and intra-chain hydrogen bonds O-H groups change into free ones finally.Chapter six is the conclusion to the whole research work.The main technique used in all the work is the 2D correlation spectroscopy.Firstly,we record the dynamic spectra of the polymeric materials.Secondly,we take advantage of the high resolution of 2D spectroscopy to separate the weak bands and originally overlapped bands in the 1D spectra.Accordingly,we can distinguish the groups in different states and conformations.Thirdly,2DCOS analysis can often simplify spectral features corresponding to various inter-and intramolecular interactions,so we can elucidate the relationships between different groups and further search the related mechanism.更多还原