Isotropic-to-cholesteric transition in liquid crystal elastomers
Isotropic-to-cholesteric transition in liquid crystal elastomers
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DOI：
10.1103/physreve.67.011701
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发表时间：
2003-01-01
影响因子：
2.4
通讯作者：
Warner, M
中科院分区：
文献类型：
--
作者：
Warner, M
液晶弹性体试图在进入局部向列相时自发伸长，但可能必须扭曲以降低其Frank弹性能。极端是传统的横向胆甾体结构(它降低了它的弗兰克能量)和均匀排列的状态(它可以最大限度地自发地扩展和降低它的弹性能量)。在这两者之间，它可以采用圆锥状态，其中也有弯曲，但同样部分满足弹性要求。锥态和横态之间的一级跃迁结束，变成一条二级跃迁，这取决于链的各向异性、Frank弯曲和扭转常数的比率，以及弯曲能量减去的弹性模数。给出了锥角的连续和不连续变化、自发伸长和剪切，以及圆锥丢失到横态时指向矢奇异变化的解析形式。给出了多临界点随Frank常数之比的变化规律。
A liquid crystal elastomer tries to spontaneously elongate on entering the locally nematic phase, but may have to twist to reduce its Frank elastic energy. The extremes are a conventional, transverse cholesteric structure (where it reduces its Frank energy), and a uniformly aligned state (where it can maximally spontaneously extend and reduce its elastic energy). Between these it can adopt a conical state where there is also bend but equally a partial satisfaction of the elastic requirements. A line of first-order transitions between conical and transverse states ends and becomes a line of second-order transitions, depending on chain anisotropy, the ratio of the Frank bend and twist constants, and on the elastic modulus reduced by the bend energy. Continuous and discontinuous variation of cone angles, and spontaneous elongations and shears are given, as are analytic forms for the singular variation of director as cones are lost to the transverse state. The variation of the multicritical point with the ratio of Frank constants is also given.