Institute for Condensed Matter Physics of National Academy of Sciences of Ukraine, 1, Svientsitskii Str., 79011 Lviv, Ukraine.
J Chem Phys. 2011 Jul 28;135(4):044901. doi: 10.1063/1.3614499.
Photo-induced deformations in azobenzene-containing polymers (azo-polymers) are central to a number of applications, such as optical storage and fabrication of diffractive elements. The microscopic nature of the underlying opto-mechanical coupling is yet not clear. In this study, we address the experimental finding that the scenario of the effects depends on molecular architecture of the used azo-polymer. Typically, opposite deformations in respect to the direction of light polarization are observed for liquid crystalline and amorphous azo-polymers. In this study, we undertake molecular dynamics simulations of two different models that mimic these two types of azo-polymers. We employ hybrid force field modeling and consider only trans-isomers of azobenzene, represented as Gay-Berne sites. The effect of illumination on the orientation of the chromophores is considered on the level of orientational hole burning and emphasis is given to the resulting deformation of the polymer matrix. We reproduce deformations of opposite sign for the two models being considered here and discuss the relevant microscopic mechanisms in both cases.
含偶氮苯聚合物（azo-聚合物）的光致变形是许多应用的核心，例如光存储和衍射元件的制造。光机械耦合的微观性质尚不清楚。在这项研究中，我们解决了实验发现的问题，即该影响的情况取决于所使用的偶氮聚合物的分子结构。通常，对于液晶和无定形偶氮聚合物，观察到与光偏振方向相反的变形。在这项研究中，我们对模拟这两种类型偶氮聚合物的两个不同模型进行了分子动力学模拟。我们采用混合力场建模，仅考虑作为 Gay-Berne 位的反式偶氮苯异构体。在取向孔烧蚀的水平上考虑了光对发色团取向的影响，并强调了聚合物基质的相应变形。我们再现了所考虑的两种模型的相反符号的变形，并在两种情况下讨论了相关的微观机制。
