共轴微反应器制备单分散聚N-异丙基丙烯酰胺/蒙脱石纳米复合微凝胶

Preparation of monodisperse poly(N-isopropylacrylamide)/clay nanocomposite hydrogel microspheres using coaxial microfluidic device

以蒙脱石(Clay)为交联剂,采用含有N,N,N′N′-四甲基乙二胺(TEMED)的豆油溶液为连续相,含有单体N-异丙基丙烯酰胺(NIPAm)、引发剂过硫酸钾(KPS)和分散有蒙脱石的水溶液为分散相,在共轴毛细管微反应器中制备了单分散聚N-异丙基丙烯酰胺/蒙脱石(PNIPAm/Clay)复合微凝胶。红外光谱分析表明:单体的C C双键的红外特征峰917、965 cm-1和992 cm-1在聚合后的微凝胶红外谱图中消失,而Clay的Si—O键特征峰1 000 cm-1则出现在微凝胶的红外谱图中。研究了不同内径的管头、分散相的流速和表面活性剂的浓度对微凝胶大小的影响。结果表明通过更换微反应器内管管头可以将微凝胶的直径从300μm变为450μm左右;通过调节连续相的流速可以制备粒径分散系数<5%、粒径在315～435μm的微凝胶;连续相中加入表面活性剂聚甘油聚蓖麻醇酯(PGPR)也可以有效降低微凝胶粒径。

A monodisperse nanocomposite poly （ N-isopropylacrylamide ）/clay （ PNIPAm/Clay ） microspheres is synthesized with coaxial microfluidie device using clay as cross-linker. The disperse phase contains the monomer （N-isopropylacrylamide） （ NIPAm ）, the initiator （ potassium peroxydisulfate ） （ KPS ） , the cross-linker （ clay ） and deionized water. The immiscible continuous phase is composed of soya-bean oil and the catalyst （tetramethyl ethylene diamine ） （TEMED）. The monomer, NIPAm, has three distinctive absorbance peaks at 917,965,992 cm-1 ,indicating the vibration of the monomer＇s C=C double bond. However, these characteristic peaks disappear in the FT-IR spectra of PNIPAm/Clay and the Si-O characteristic peaks of clay, 1 000 cm - 1, appears in the FT-IR spectra of PNIPAm/Clay. The effects of changing tips, the flow rate of continuous phase and the content of the surfactant on the size of the microgels are studied. The results show that the microgels from 300μm to 450μm can be synthesized by changing the tips of the dispersed phase injection tube;The size of the microgels between 315 and 435μm with dispersion coefficient below 5% can be adjusted by changing the flow rate of continuous phase;The diameter of the microgels decreases when the content of the surfactant（ polyglyeerol polyricinoleate）（PGPR） in the continuous phase increases.