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

通过分析主链二聚体化合物的PVT数据，研究了热-压系数的体积依赖性对定容转变熵（ΔS_m）_v估算的影响，其影响量（约10%）相当小. PVT分析表明，约65%的跃迁熵来自于（ΔS_m）_v，对应于间隔区构象分布的变化。指出液晶相的形成是通过精确控制柔性间隔层一级结构中固有的有序-无序特性实现的，分子间相互作用势ε=-η/V^m已被广泛应用于包括熔融聚合物在内的液体的常规平均场理论中。这里η被定义为表示相互作用场强度的平均场参数，并且在常规的液体处理中，参数m通常被设置为等于1。在PVT资料分析中，m只趋于1 ...更多信息 在很窄的温度范围内。本文对具有二甘醇间隔基的二聚体液晶如CN-φφ-（OCH_2CH_2）_2O-φφ-CN（CBE_2）进行了振动分析。CBE 2中特定的红外活动模式被发现表现出类似于质量形状的频率偏移，而其他振动保持不变。认为分子内振动与液晶有序性之间的选择性耦合与模式的内在对称性有关，α-螺旋聚天冬氨酸的螺旋反转行为因侧链末端酯基的化学结构不同而有很大差异。通过绘制溶剂组成和温度对聚合物相图的影响，研究了聚合物之间这种现象差异的原因。少

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