Preparation And Functionalization Of Iodine-containing Poly(Aryl Ether)s

In recent years, poly(aryl ether)s have attracted large attention due to their uniquecombination of toughness, stiffness, thermooxidative stability, electrical performance,flame retardancy and retention of physical properties at high temperatures. So thesematerials have been successfully applied in areas such as aviation, spaceflight, nuclearenergy, communication, telecom, petroleum, machine manufacturing and traffic.However, through the rapid development of science and technology, higherrequirements are provided by people today. Especially, new function such as optical,electrical, magnetic are badly needed in order to improve their proformances. The bestway to introduce these unique properties is by introducing functional groups in topolymers.Since the halogen have strong nucleophilicity, the introduction of them will help toimprove the functionalization of poly(arly ether)s. Comparing to other halogen, iodinepossess the strongest nucleophilicity, so the thesis mainly focused on thefunctionalization of iodine-containing poly(aryl ether)s.Firstly, we successfully synthesis iodine-containing poly(aryl ether sulfone)(IPES)and try to use Ullmann reaction to introduce perfluoroalkyl sulfonic acid pendentgroup into the polymer. However, the trial fail because gelation happened when thetemperature is higher than100oCSecondly, we did research on the crosslinking reaction of IPES. We preparedpolymer membranes and put them under circumstance with high temperature.Through experiment we found out that when the membrane began to crosslink when itwas heated under280oC for2hours. We also found out that the degree ofcrosslinking increased together with temperature and reaction time. For example, the gel content of the membrane in a reaction temperature of280oC for8hours reachedup to. When the temperature reached300oC and the membrane was heated for2hours, the gel content was about69%.Finally,4’-iodobiphenyl-2,5-diol (IPHQ) was synthesized through a two-stepreaction. Polymers consisting of iodo groups in the side-chain were obtained by thearomatic nucleophilic substitution reaction. The above polymers were grafted by theUllmann coupling reaction with potassium1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonate. Poly(arylene ether ketone)scontaining pendant perfluoroalkyl sulfonic acid (PEEK-PFS) were synthesized andinvestigated for fuel cell applications. The membranes with ion exchange capacity(IEC) of0.95-1.37mmol/g were prepared by solution casting. The flat and smoothmembrane materials showed high oxidative stability against hot Fenton’s reagent. Theproton conductivity of PEEK-PFS with IEC of1.37mmol/g was0.065S/cm at80oCwhich was higher than some other post-sulfonated PEEKs with the same IEC.