Elastic Properties, Thermal Expansion, and Polymorphism of Acetylsalicylic Acid
Elastic Properties, Thermal Expansion, and Polymorphism of Acetylsalicylic Acid
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DOI：
10.1021/cg100241c
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发表时间：
2010-07-01
影响因子：
3.8
通讯作者：
Robertson, Struan
中科院分区：
文献类型：
--
作者：
Bauer, Johannes D.;Haussuehl, Eiken;Robertson, Struan
从饱和溶液中生长出尺寸高达约30 cm（3）的高质量乙酰水杨酸（阿司匹林）单晶。通过两种不同的超声技术确定了完整的弹性刚度张量。热膨胀系数用膨胀法测定。热膨胀是各向异性的，平行于方向的纵向效应最小[010]。垂直于这个方向的膨胀是2倍。纵向弹性刚度的各向异性不太明显;最小值和最大值之间的差异约为30%。观察到最大弹性刚度沿着连接中心对称的乙酰水杨酸二聚体的氢键的方向。实验确定的弹性刚度系数和观察到的形态进行了比较，从原子模型计算的结果。这种比较使我们能够评估对潜在多晶型所做预测的可靠性。
High quality single crystals of acetylsalicylic acid (aspirin) with dimensions up to about 30 cm(3) were grown from saturated solutions. The complete elastic stiffness tensor was determined by two different ultrasonic techniques. The thermal expansion coefficients were measured by dilatometry. The thermal expansion is anisotropic, with a minimum of the longitudinal effect parallel to the direction [010]. The expansion perpendicular to this direction is larger by a factor of 2. The anisotropy of the longitudinal elastic stiffness is less pronounced; the difference between the minimum and maximum values is approximately 30%. The maximum elastic stiffness is observed along the directions of the hydrogen bonds linking the centrosymmetric acetylsalicylic acid dimers. The experimentally determined elastic stiffness coefficients and the observed morphology have been compared to results from atomistic model calculations. This comparison allows us to assess the reliability of predictions made with respect to a potential polymorph.