One-pot surfactant-free modulation of size and functional group distribution in thermoresponsive microgels
One-pot surfactant-free modulation of size and functional group distribution in thermoresponsive microgels
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DOI：
10.1016/j.jcis.2020.02.057
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发表时间：
2020-05-15
影响因子：
9.9
通讯作者：
Ullal, Chaitanya K.
中科院分区：
文献类型：
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作者：
Karanastasis, Apostolos A.;Kenath, Gopal S.;Ullal, Chaitanya K.
控制软响应性水凝胶颗粒的尺寸和官能团分布对于诸如药物递送、催化和化学传感的应用是必不可少的。传统上，目标官能团分布是通过需要专门设备的半间歇技术实现的，而尺寸定制颗粒的制备通常涉及使用表面活性剂。在这里，我们提出了一个简单而强大的无表面活性剂的方法，用于调制聚（N-异丙基丙烯酰胺）温敏微凝胶的大小和羧酸官能团分布，采用反应pH值作为单一的实验参数。羧酸残基的不同分布是由于动力学反应性的差异而产生的，动力学反应性是甲基丙烯酸解离程度的函数，因此是反应pH值的函数。在颗粒成核阶段，掺入的带电残基诱导表面活性剂样作用，并影响最终的粒度。动态光散射和电子显微镜的表征一致支持微凝胶的pH定制形态。一个数学模型，占成像基板上的颗粒变形也表现出良好的协议与实验结果。(C)2020爱思唯尔公司All rights reserved.
Control over the size and functional group distribution of soft responsive hydrogel particles is essential for applications such as drug delivery, catalysis and chemical sensing. Traditionally, targeted functional group distributions are achieved with semi-batch techniques which require specialized equipment, while the preparation of size-tailored particles typically involves the use of surfactants. Herein, we present a simple and robust surfactant-free method for the modulation of size and carboxylic acid functional group distribution in poly(N-isopropylacrylamide) thermoresponsive microgels, employing reaction pH as the single experimental parameter. The varying distributions of carboxylic acid residues arise due to differences in kinetic reactivity, which are a function of the degree of dissociation of methacrylic acid, and thus of reaction pH. Incorporated charged residues induce a surfactant-like action during the particle nucleation stage, and impact the final particle size. Characterization with dynamic light scattering, and electron microscopy consistently supports the pH-tailored morphology of the microgels. A mathematical model which accounts for particle deformation on the imaging substrate also shows excellent agreement with the experimental results. (C) 2020 Elsevier Inc. All rights reserved.