由聚乙二醇二甲基丙烯酸酯交联的聚（N-异丙基丙烯酰胺）温敏微凝胶的不同去溶胀行为。

Different deswelling behavior of temperature-sensitive microgels of poly(N-isopropylacrylamide) crosslinked by polyethyleneglycol dimethacrylates.

作者信息

Ma Xiaomei, Cui Yanjun, Zhao Xian, Zheng Sixun, Tang Xiaozhen

机构信息

School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.

出版信息

J Colloid Interface Sci. 2004 Aug 1;276(1):53-9. doi: 10.1016/j.jcis.2004.03.023.

DOI:10.1016/j.jcis.2004.03.023

PMID:15219429

Abstract

Polymerization of N-isopropylacrylamide (NIPAM) with polyethyleneglycol dimethacrylates (n G, n representing the number of --CH2CH2O-- units in polyethyleneglycol dimethacrylates) through surfactant-free radical polymerization was used to prepare the temperature-sensitive microgels. The morphology, dispersity, and deswelling behavior of the microgels were investigated by means of transmission electron microscopy (TEM), ultraviolet-visible spectroscopy, differential scanning calorimetry (DSC), and dynamic light scattering (DLS) techniques. TEM micrographs revealed that it was feasible to obtain regular spherical microgels for crosslinking agents with short chain. Turbidity, DSC, and DLS analysis showed that in marked contrast to 1G and 3G crosslinked microgels, the collapse of microgels crosslinked by 9G, 14G, and 23G proceeded in a two-step mechanism. The amide groups dehydrated at the lower temperature leading to the first-step transition. In the transition, the hydrophilic long --(--CH2CH2O--)n-- segments could be enriched on the surface of the microgels, which was further verified by variable temperature 1H NMR spectroscopy. The hydrophilic long --(--CH2CH2O--)n-- segments can be dehydrated at the higher temperature.

摘要

通过无表面活性剂自由基聚合，将N-异丙基丙烯酰胺（NIPAM）与聚乙二醇二甲基丙烯酸酯（nG，n表示聚乙二醇二甲基丙烯酸酯中–CH2CH2O–单元的数量）聚合，制备了温度敏感型微凝胶。采用透射电子显微镜（TEM）、紫外可见光谱、差示扫描量热法（DSC）和动态光散射（DLS）技术研究了微凝胶的形态、分散性和溶胀行为。TEM显微照片显示，对于短链交联剂，获得规则球形微凝胶是可行的。浊度、DSC和DLS分析表明，与1G和3G交联微凝胶形成鲜明对比的是，9G、14G和23G交联的微凝胶的塌陷过程遵循两步机制。酰胺基团在较低温度下脱水，导致第一步转变。在转变过程中，亲水性长–（–CH2CH2O–）n–链段可富集在微凝胶表面，变温1H NMR光谱进一步证实了这一点。亲水性长–（–CH2CH2O–）n–链段可在较高温度下脱水。