Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742-2111, USA.
J Am Chem Soc. 2011 Jun 8;133(22):8461-3. doi: 10.1021/ja202412z. Epub 2011 May 16.
We describe a new class of photorheological (PR) fluids whose rheological properties can be reversibly tuned by light. The fluids were obtained by doping lecithin/sodium deoxycholate (SDC) reverse micelles with a photochromic spiropyran (SP) compound. Initially, the lecithin/SDC/SP mixtures formed highly viscoelastic fluids, reflecting the presence of long, wormlike reverse micelles. Under UV irradiation, the SP was isomerized to the open merocyanine (MC) form, causing the fluid viscosity to decrease 10-fold. When the UV irradiation was switched off, the MC reverted to the SP form, and the viscosity recovered its initial value. This cycle could be repeated several times without loss of response. The rheological transitions are believed to reflect changes in the lengths of the reverse worms. To our knowledge, this is the first example of a simple, reversible PR fluid that can be made entirely from commercially available components.
我们描述了一类新的光流变（PR）流体，其流变性能可以通过光进行可逆调节。该流体通过掺杂磷脂/脱氧胆酸钠（SDC）反胶束与光致变色螺吡喃（SP）化合物制得。最初，磷脂/SDC/SP 混合物形成了高粘性流体，这反映了长的、蠕虫状反胶束的存在。在紫外光照射下，SP 异构化为开式变色氰（MC）形式，导致流体粘度降低 10 倍。当关闭紫外光照射时，MC 重新转化为 SP 形式，粘度恢复到初始值。这个循环可以重复多次，而不会失去响应。流变转变被认为反映了反蠕虫长度的变化。据我们所知，这是第一个完全由市售成分制成的简单、可逆的 PR 流体的例子。
