Transmission electron microscopy (TEM) pictures show that the intramolecularly crosslinked macromlecules (ICMs) have two kinds of networks: the “chemical network” and the “mechanical network”. The “chemical network” depends on the reactants and the feed ratio; the “mechanical network” is formed by the globules that are formed in the earlier stage of polymerization. The TEM pictures show that the morphologies of ICMs differ greatly from each other; the molecular size reaches hundreds of nanometers. It was found that the size of ICM with a high degree of cross-linking almost remains constant after the sample was dissolved, based on which we calculated the number-averaged molecular weight (Mn) of sample 1568EA-0.25, Mn ) 2.91  108.