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PVT Analysis of Chain Molecules Exhibited Crystal-Liquid Crystal-Isotropic Phase Transition-Orientational Order Dependence of Intramolecular Interaction Potentials and Limitation of Mean-Field Theory

链状分子的PVT分析表现出晶体-液晶-各向同性相变-分子内相互作用势的取向顺序依赖性和平均场理论的局限性

基本信息

批准号：
16550112
负责人：
HIEJIMA Toshihiro
金额：
$ 1.98万
依托单位：
Tokyo Polytechnic University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

The effects of volume dependence of thermal-pressure coefficient on the estimation of constant-volume transition entropy (ΔS_m)_v were investigated by the analysis of PVT data of main-chain dimer compounds, the amount (approximately 10%) being reasonably small. The PVT analysis suggested that about 65% of the transition entropy arises from (ΔS_m)_v corresponding to the variation in the conformational distribution of the spacer. We pointed out that the order-disorder characteristics inherent in the primary structure of the flexible spacer are precisely controlled in order to develop the LC mesophase.The intermolecular interaction potentials such as ε=-η/V^m have been widely adopted in conventional mean-field theories of liquids including molten polymers. Here η is defined as a mean-field parameter representing the strength of the interaction field and the parameter m is often set equal to unity in the conventional treatment of liquid. In the analysis of PVT data, m approaches unity only … More within a narrow range of temperature. This results suggested that the conventional form of the potential in the above-mentioned is only valid within a certain limited range of temperature and volumes in both isotropic and nematic LC phases.Vibrational analyses were performed on dimer liquid crystals having a diethylene glycol spacer such as CN-φφ-(OCH_2CH_2)_2O-φφ-CN(CBE2). The specific IR active modes in CBE2 were found to show the frequency shift resembled in the qualitatively shape of nematic order parameter, while other vibrations remain unaltered. It is considered that the selective coupling between intramolecular vibration and the liquid crystalline order is relative to the intrinsic symmetry of the modes.Screw-sense inversion behaviors of a-helical polyaspartate differ substantially depending on the chemical structure of the ester group at the side-chain terminals. The cause of such phenomenological difference among polymers has been investigated by constructing the phase diagram as a function of solvent composition and temperature. Less

通过对主链二聚体的Δ数据的分析，考察了热压系数与体积的关系对估算等体积转变熵的影响，其量较小(约10%)。PVT分析表明，约65%的转变熵来自于(ΔS m)v，与间隔基构象分布的变化相对应。我们指出，为了发展液晶介相，可以精确地控制柔性间隔体一级结构中固有的有序-无序特性。ε=-η/V^m等分子间相互作用势被广泛地应用于包括熔融聚合物在内的液体的传统平均场理论中。这里，η被定义为表示相互作用场的强度的平均场参数，并且在传统的液体处理中，参数m通常被设置为等于1。在pvt数据的分析中，m逼近unity only…在较窄的温度范围内。这一结果表明，上述势能的传统形式仅适用于各向同性和向列相LC相在一定的温度和体积范围内。对具有二甘醇间隔基团的二聚体液晶CN-φφ-(OCH2CH2)2O-φφ-CN(CbE_2)进行了振动分析。结果表明，CBE_2中的特殊红外活性模式的频移与向列序参数的定性形状相似，而其他振动没有变化。认为分子内振动和液晶有序之间的选择性耦合与模式的固有对称性有关，α-螺旋聚天冬氨酸的螺旋反转行为与侧链末端酯基的化学结构有很大的不同。通过绘制溶剂组成和温度的相图，研究了聚合物之间存在这种唯象差异的原因。较少