Atomistic simulations of liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2PhP and PhP14.
Atomistic simulations of liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2PhP and PhP14.
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烷氧基取代的苯基嘧啶 2PhP 和 PhP14 液晶混合物的原子模拟。
DOI：
10.1063/1.3692731
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
David J. Earl
中科院分区：
文献类型：
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作者：
Fangyong Yan;David J. Earl
我们使用全原子水平的分子动力学模拟研究了烷氧基取代的苯基嘧啶 2-[4-(丁氧基)苯基]-5-(辛氧基)嘧啶 (2PhP) 和 2-[4-(十四烷氧基)苯基]-5-(十四烷氧基)嘧啶 (PhP14) 的液晶混合物。 PhP14 的分子长度是 2PhP 的 1.8 倍，从而产生有趣的二元混合物相图。我们的模拟由 1000-1600 个分子组成，总共 80,000-130,000 个原子位点，总模拟时间为 60-100 ns。我们首先证明纯 2PhP 系统自组装成各向同性、向列、近晶 A 和近晶 C 相，纯 PhP14 系统自组装成各向同性和近晶 C 相。 PhP14 和 2PhP 的二元混合物显示出近晶 A 相的稳定性，但牺牲了近晶 C 和向列相。我们确定混合物中浓度诱导的从近晶 C 相到近晶 A 相的相变是由分子的层外波动排列驱动的。我们还观察到混合物中形成的近晶 C 相的倾斜角与浓度相关。我们的模拟结果与 Kapernaum 等人的实验结果非常吻合。 [J。组织。化学。 5, 65 (2009)]，从而表明原子模拟能够再现液晶混合物的相行为，并且还可以提供有关控制相稳定性的机制的微观细节。
We study liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2-[4-(butyloxy)phenyl]-5-(octyloxy)pyrimidine (2PhP) and 2-[4-(tetradecyloxy)phenyl]-5-(tetradecyloxy)pyrimidine (PhP14) using molecular dynamics simulations at the all atom level. The molecular length of PhP14 is 1.8 times that of 2PhP, resulting in an interesting binary mixture phase diagram. Our simulations are composed of 1000-1600 molecules for a total of 80,000-130,000 atomic sites, with total simulation times of 60-100 ns. We first show that a pure 2PhP system self-assembles into isotropic, nematic, smectic A and smectic C phases, and a pure PhP14 system self-assembles into isotropic and smectic C phases. Binary mixtures of PhP14 and 2PhP display a stabilization of the smectic A phase at the expense of the smectic C and nematic phases. We determine that the concentration-induced phase transition from the smectic C to the smectic A phase in the mixture is driven by an out-of-layer fluctuation arrangement of the molecules. We also observe that the tilt angle in the smectic C phases formed in the mixtures is concentration dependent. The results of our simulations are in good agreement with the experimental findings of Kapernaum et al. [J. Org. Chem. 5, 65 (2009)], thus showing that atomistic simulations are capable of reproducing the phase behavior of liquid crystal mixtures and can also provide microscopic details regarding the mechanisms that govern phase stability.