Formation of polymer microrods in shear flow by emulsification - Solvent attrition mechanism
Formation of polymer microrods in shear flow by emulsification - Solvent attrition mechanism
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DOI：
10.1021/la051825v
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发表时间：
2006-01-17
期刊：
影响因子：
3.9
通讯作者：
Velev, OD
中科院分区：
文献类型：
--
作者：
Alargova, RG;Paunov, VN;Velev, OD
棒状聚合物颗粒可能具有令人感兴趣的性质，并且可以找到许多实际应用;然而，很少有生产这种颗粒的方法可用。我们报告了一个系统的研究液滴剪切过程中形成的聚合物棒与微米或亚微米直径和长度高达几十微米。该方法基于聚合物溶液在剪切下的乳化，结合周围有机介质中的溶剂磨损。液滴变形并伸长成圆柱体，当溶剂转移到分散介质时，其固化。停止流动实验允许区分该机制的所有阶段。根据液滴在剪切作用下的伸长和破碎理论对实验结果进行了解释。粘度比和剪切应力的影响与理论预期相匹配。该方法简单，高效，可扩展，我们演示了如何控制和修改。允许改变棒尺寸和纵横比的实验参数包括剪切速率、介质粘度和聚合物浓度。聚合物棒的具体性质的例子，包括自组织，在外部领域和流体流动中的对齐，和稳定的气泡，液滴，和胶囊，提出。
Rodlike polymer particles could have interesting properties and could find many practical applications; however, few methods for the production of such particles are available. We report a systematic study of a droplet shearing process for the formation of polymer rods with micrometer or submicrometer diameter and a length of up to tens of micrometers. The process is based on emulsification of a polymer solution under shear, combined with solvent attrition in the surrounding organic medium. The droplets deform and elongate into cylinders, which solidify when the solvent transfers to the dispersion medium. Stopped flow experiments allow distinguishing all stages of the mechanism. The results are interpreted on the basis of the theory of droplet elongation and breakup under shear. The effects of the viscosity ratio and shear stress are matched against the theoretical expectations. The method is simple, efficient, and scalable, and we demonstrate how it can be controlled and modified. The experimental parameters that allow varying the rod size and aspect ratio include shear rate, medium viscosity, and polymer concentration. Examples of the specific properties of the polymer rods, including self-organization, alignment in external fields and in fluid flows, and stabilization of bubbles, droplets, and capsules, are presented.