Hadad Elad, Edri Eitan, Shpaisman Hagay
Department of Chemistry, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel.
Polymers (Basel). 2019 Jul 23;11(7):1225. doi: 10.3390/polym11071225.
The shape and porosity of polymeric colloids are two properties that highly influence their ability to accomplish specific tasks. For micro-sized colloids, the control of both properties was demonstrated by the photo-induced phase separation of droplets of NOA81-a thiol-ene based UV-curable adhesive-mixed with acetone, water, and polyethylene glycol. The continuous phase was perfluoromethyldecalin, which does not promote phase separation prior to UV activation. A profound influence of the polymer concentration on the particle shape was observed. As the photo-induced phase separation is triggered by UV radiation, polymerization drives the extracted solution out of the polymeric matrix. The droplets of the extracted solution coalesce until they form a dimple correlated to the polymer concentration, significantly changing the shape of the formed solid colloids. Moreover, control could be gained over the porosity by varying the UV intensity, which governs the kinetics of the reaction, without changing the chemical composition; the number of nanopores was found to increase significantly at higher intensities.
聚合物胶体的形状和孔隙率是两个对其完成特定任务的能力有很大影响的特性。对于微米级胶体，通过将NOA81（一种基于硫醇-烯的紫外线可固化粘合剂）与丙酮、水和聚乙二醇混合形成的液滴进行光诱导相分离，证明了对这两种特性的控制。连续相是全氟甲基萘烷，它在紫外线活化之前不会促进相分离。观察到聚合物浓度对颗粒形状有深远影响。由于光诱导相分离是由紫外线辐射触发的，聚合作用将萃取溶液从聚合物基质中驱出。萃取溶液的液滴合并，直到形成与聚合物浓度相关的凹坑，显著改变所形成的固体胶体的形状。此外，通过改变控制反应动力学的紫外线强度，可以在不改变化学成分的情况下控制孔隙率；发现在较高强度下纳米孔的数量会显著增加。
