Okhamafe A O, York P
J Pharm Pharmacol. 1985 Jun;37(6):385-90. doi: 10.1111/j.2042-7158.1985.tb03020.x.
Three methods--radiotracer, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)--have been employed to evaluate moisture interactions in aqueous-based hydroxypropyl methylcellulose films containing polyethylene glycol 400, polyethylene glycol 1000 or polyvinyl alcohol. The radiotracer employed was tritiated water. Using a proposed classification, the water present in the films was placed in three categories: tightly bound, moderately bound and free. The tightly bound water in hydroxypropyl methylcellulose and hydroxypropyl methylcellulose/polyvinyl alcohol films was related to the crystallinity of the films whilst tightly bound water was practically non-existent in the plasticized systems thus indicating the absence of crystallinity. Free (or freezable) water could not be detected in the films using DSC. The moisture content data obtained by TGA were considered to represent moderately bound water. The moderately bound water content of the film systems was in the rank order of the hydrophilicity of the polymer additives: polyethylene glycol 400 greater than polyethylene glycol 1000 greater than polyvinyl alcohol. This order was reversed for the calculated free water content.
已采用三种方法——放射性示踪法、差示扫描量热法（DSC）和热重分析法（TGA）——来评估含有聚乙二醇400、聚乙二醇1000或聚乙烯醇的水基羟丙基甲基纤维素薄膜中的水分相互作用。所使用的放射性示踪剂是氚化水。根据一种提议的分类方法，薄膜中存在的水被分为三类：紧密结合水、中度结合水和自由水。羟丙基甲基纤维素和羟丙基甲基纤维素/聚乙烯醇薄膜中的紧密结合水与薄膜的结晶度有关，而在增塑体系中几乎不存在紧密结合水，因此表明不存在结晶度。使用DSC无法在薄膜中检测到自由（或可冷冻）水。通过TGA获得的水分含量数据被认为代表中度结合水。薄膜体系的中度结合水含量按聚合物添加剂亲水性的顺序排列为：聚乙二醇400大于聚乙二醇1000大于聚乙烯醇。对于计算出的自由水含量，此顺序则相反。
