Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2011 Jun 24;106(25):256103. doi: 10.1103/PhysRevLett.106.256103.
Surface self-diffusion has been measured for an organic glass for the first time. The flattening of 1000 nm surface gratings of liquid indomethacin occurs by viscous flow at 12 K or more above the glass transition temperature and by surface diffusion at lower temperatures. Surface diffusion is at least 10(6) times faster than bulk diffusion, indicating a highly mobile surface. Our data suggest that surface diffusion is the leading mechanism of surface evolution for organic glasses at micrometer to nanometer length scales.
首次测量了有机玻璃的表面自扩散系数。液态吲哚美辛的 1000nm 表面光栅在玻璃化转变温度以上 12K 或更高温度下通过粘性流动而变平，在较低温度下则通过表面扩散变平。表面扩散比体扩散至少快 10^6 倍，表明表面具有高度的迁移性。我们的数据表明，在微米到纳米的长度尺度上，表面扩散是有机玻璃表面演化的主要机制。
