Synthesis And Thermoresponsive Property Of Well-Defined Poly(N-isopropylacrylamide) With Aryl End-Group

Poly(N-isopropylacrylamide) (PNIPAm) in aqueous solution is well known to exhibit a thermoreversible phase transition at 32℃ This transition temperature is called a lower critical solution temperature (LCST). Below the LCST, this polymer is water-soluble and hydrophilic, existing in an extended chain form. PNIPAm undergoes a reversible phase transition to an insoluble and hydrophobic aggregate above the LCST.In this thesis, it mainly discussed the synthesis of well-defined and end-functionalized PNIPAm with hydrophobic aryl groups by ATRP. N-isopropylacrylamide(NIPAm) was polymerized using 2-chloropropionates with a series of hydrophobic groups as initiators and CuCl/Me6TREN as a catalyst system in DMF/water mixed solvent at 20℃. Kinetic experiments showed that the polymerization process was controllable. Good controlled polymer molecular weights and olwer molecular weight distributions were obtained. Thermoresponsive property of well-definded PNIPAm with end aryl groups was discussed Measurement indicated that the terminal group significantly affected the behavior of the polymer in aqueous solution due to the formation of the PNIPAm-aggregates. LCST of PNIPAm with end groups decreased.