The response-ability to the external and internal environmental condition qualifies the smart polymer material to be successfully applied in artificial muscle, drug delivery and water treatment. A three-dimensional polymer network based on the phenyl monomer, 2-phenoxy ethyl acrylate (PEA), was polymerized under ultraviolet (UV) radiation using the Darocur 1173 as an initiator of the polymerization reaction, and the 1,6-hexane-diol diacrylate (HDDA) as a chemical cross-linker. The analysis of the thermophysical properties of this elaborated polymeric material represents the main goal of the present work. The infrared spectroscopy (FTIR) and the dynamic scaling calorimetry (DSC) were used to examine, respectively, the vibration of the carbon double bond (C=C) and the glass transition temperature Tg. It is found that parameters, the rate of reticulation and monomer composition have a remarkable effect on the variation of Tg. The swelling behavior of the cross-linked poly(PEA/HDDA) was investigated; the effects of solvent nature, the degree of cross-linking, temperature and chemical structure have a significant influence on material swelling properties. The theoretical investigation based, especially on the Voigt model, Flory–Rehner theory and solubility approximation, permits to give much information about several parameters such as the swelling time constant, swelling equilibrium constant, solubility prediction, entropy and enthalpy. It ended interestingly that the Voigt model shows a good agreement with swelling experimental results.