Synthesis, Characterization And Solution Properties Of Thermoresponsive Hyperbranched Polyamidoamine

In this dissertation, a new type of hyperbranched polyamidoamine(HYPAMAM) with different molecular weight was synthesized. It is similar in chemical nature to dendritic polyamidoamine(PAMAM) which has been commercialized. Moreover, the synthesis of HYPAMAM is more simple and convenient than PAMAM. Then we make the end groups of HYPAMAM modified with isobutyl anhydride (IBAm) by amidation reaction. So the HYPAMAM-IBAm was obtained, which has the unique reversible thermoresponsive nature.The HYPAMAM-IBAms with different molecular weight were characterized by the 1HNMR spectrometer and FTIR spectrometer. With the diversification of the concentration of polymers solution or pH value, we analyzed the variation of the Lower Critical Solution Temperature(LCST) of HYPAMAM-IBAm aqueous solution by UV-Vis spectrometer. We also changed the condition of the polymer solution by adding various inorganic salts to summarize the regular pattern of the LCST. The results showed that when the pH value and the concentration of salt are fixed, the LCST will cut down with the exaltation of the molecular weight or concentration of HYPAMAM-IBAm. In addition, the LCST is also very sensitive to pH value, which will decrease rapidly with the increase of the alkaline. But when the pH increases to a certain value, LCST will not response to the pH again.In addition, various inorganic salts also have significant impact on the LCST of polymer solution. The cation has little effect to the LCST of polymers, but the influence of anions on the polymer is very notable. The LCST of polymer solution will reduce with the increase of radius of the halogen ion, while the concentration of anions extremely lowly. However, the phenomenon will be contrary when the concentration of halogen ions is high-up. The LCST will increase with the increase of radius of negative ions (apart from halogen ions) which having the same valence. We also find that the greater valence, the smaller the corresponding LCST of solution with the same concentration of negative ions. And the diversification of LCST has not arithmetic connection. All of these variations of LCST are caused by the difference of particle radius, which is called salting-in or salting-out effect.