What is the fine-grained topic of the following text: The FT-IR shows that the peak of functional groups –COOH and -CONH2 of AAc and AAm, ,respectively ; then the DSC shows that the Tg is 6℃；the swelling is about one hundred ratio；then SEM micrographs to observation structure of hydrogels. Only return the topic.
Analysis of Hydrogel Characteristics and Composition