Pervin Rumiaya, Ghosh Pijush, Basavaraj Madivala G
Department of Chemical Engineering, Indian Institute of Technology Madras Chennai 600036 India
Department of Applied Mechanics, Indian Institute of Technology Madras Chennai 600036 India.
RSC Adv. 2019 May 17;9(27):15593-15605. doi: 10.1039/c9ra01331h. eCollection 2019 May 14.
By considering a mixture of poly(methyl methacrylate)-tetrahydrofuran-water (PMMA-THF-HO), we report an experimental approach to tune the distribution of pores in polymer films formed evaporation induced phase separation (EIPS). We show that the drying induced composition and microstructural changes that occur due to the evaporation of the solvent (THF) and the nonsolvent (HO) delineate the ultimate polymer film morphology. The temporal evolution of the microstructure, the phase behavior and the change in the composition of the PMMA-THF-HO mixture at air-solution (top surface) and solution-substrate (bottom surface) interfaces is monitored to provide insights into the origin of the pore distribution in the final polymer films. The effects of various parameters such as nonsolvent and polymer concentration in the casting solution, casting solution thickness, relative humidity and temperature on the final film morphology are investigated to correlate how the composition path (CP) change under various conditions ultimately dictates the film morphology. We show that depending on the change in the composition of the polymer solution (evolution of CP) and the water/PMMA ratio at the time of phase separation, the morphology of the final film formed varies as - (1) non porous , dense film (2) a film with pores only at the bottom surface (3) an asymmetric film , films with a top dense layer (non-porous) supported by porous sub-layers (4) a porous film with uniform pores distributed across the entire film thickness and (5) a film with pores only at the top surface. In addition, we show that the morphology of the PMMA film can also be tuned by varying the composition of low and high molecular weight PMMA in the casting solution. These porous PMMA structures, being biocompatible, are useful for applications in cell culture, drug delivery and wound dressing.
通过研究聚（甲基丙烯酸甲酯）-四氢呋喃-水（PMMA-THF-H₂O）的混合物，我们报告了一种实验方法，用于调节通过蒸发诱导相分离（EIPS）形成的聚合物薄膜中的孔分布。我们表明，由于溶剂（THF）和非溶剂（H₂O）的蒸发而发生的干燥诱导的组成和微观结构变化描绘了最终聚合物薄膜的形态。监测PMMA-THF-H₂O混合物在气-溶液（上表面）和溶液-基底（下表面）界面处的微观结构、相行为和组成变化的时间演变，以深入了解最终聚合物薄膜中孔分布的起源。研究了诸如浇铸溶液中的非溶剂和聚合物浓度、浇铸溶液厚度、相对湿度和温度等各种参数对最终薄膜形态的影响，以关联在各种条件下组成路径（CP）的变化如何最终决定薄膜形态。我们表明，根据聚合物溶液组成的变化（CP的演变）以及相分离时的水/PMMA比率，形成的最终薄膜的形态变化如下：（1）无孔致密薄膜；（2）仅在下表面有孔的薄膜；（3）不对称薄膜，具有由多孔子层支撑的顶部致密层（无孔）的薄膜；（4）在整个薄膜厚度上具有均匀分布孔的多孔薄膜；（5）仅在上表面有孔的薄膜。此外，我们表明，通过改变浇铸溶液中低分子量和高分子量PMMA的组成，也可以调节PMMA薄膜的形态。这些多孔PMMA结构具有生物相容性，可用于细胞培养、药物递送和伤口敷料等应用。
