Thermal behaviors of poly(N-(1,3-dioxolan-2-ylmethyl)-N-methylacrylamide [DIOMMA]) and its cross-linked analogue in water or in alcohols have been studied by means of the cloud points (CP) in solutions, temperature dependences of the swelling of gels, and proton NMR spectra. We have deduced relationships between the line widths of proton NMR spectra and the intermolecular polymer-polymer, polymer-solvent, and solvent-solvent interactions. We have then integrated these qualitative relationships to formulate one consistent model. This model qualitatively describes the relative strength and the modes of three intermolecular interactions in water, methanol, or ethanol. Among the macroscopic properties, the CP in polymer solutions and temperature dependences of the swelling of the polymer gels have been elucidated on the basis of the above model. Transient NMR spectral changes observed in water and ethanol around the CP seemed to be caused by reduced motional averaging. This effect is probably associated with polymer aggregation processes, and it can be understood in terms of the state of intermolecular interactions described in the above model.