^a Department of Chemistry, School of Sciences, Wuhan University of Technology, Wuhan, Hubei 430070, China
^b State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of
Technology, Wuhan, Hubei 430070, China

The electrostatic self-assembly of polymer on proton exchange membrane was studied by calorimetric technique. The titration of poly diallyldimethylammonium chloride (PDDA) into Nafion membrane was designed and performed to determine the thermodynamic parameters. The enthalpy change and binding constant K in the process of self-assembly were obtained from data analysis with the help of Origin. According to the calculated thermodynamic parameters, the electrostatic self-assembly of PDDA on the proton exchange membrane is an “enthalpy-driven” reaction. The released heat indicates decrease of energy, which is helpful for the occurrence of the self-assembly process, and the degree of disorder is reduced, which went against the adsorption process. As to every ion bond, the value of of DDA is beyond PDDA because a small molecule can bind itself to the membrane without steric hindrance.