ABSTRACT
Polymerscontainingheterocyclicunitscanbepreparedbyutilizingtwoapproaches.Accordingtothefirstapproach,theformationofheterocyclicringitself isthepolymer-formingreaction.Polymerssuchaspolyimidesandpolyoxadiazolesaresynthesizedinthismanner.Inthisapproachthereexiststhepossibility offormingdefectivestructuresalongthepolymerbackboneand,therefore,the desiredthermalstabilityofpolymersisnotreached.Thisdifficultycanbe avoidediftheheterocyclicringispre-formedinthemonomeritself.Thissynthesisapproachinvolvesaromaticnucleophiliedisplacementreactionofpre-formed heterocyclichalidesorbisphenolswithanucleophilesuchasabisphenolateoran activatedarylhalide,respectively.Thus,theheterocyclicringcanbepartofeither theactivatedhalideoractivatedbisphenol,butmostlyheterocyclic-ring-basedactivatedhalidesarepreferredbecausetheringactsasanactivatinggroupforthe nucleophilicsubstitutionreaction.Wehavealsousedthelatteraprroachforour polymerizationreactions.Tocarryoutthepolymerizationreactions,novelheterocyclic-ring-baseddifluoromonomersweresynthesized.Theheterocyclicringacts asanactivatinggroupforthenucleophilicsubstitutionreaction.Commertially availablebisphenols,suchashydroguinone,4,4'-biphenol,BisphcnolA,BisphenolAFand9,9'-dihydroxyfluorene,wereusedforpolymerizationreactions.The polymerizationreactionsbetweenactivatedaromaticheterocyclicdihalidesand bisphenolswerecatTiedoutinpolaraproticmedia,mostlyN-methylpyrrolidone (NMP),usingpotassiumcarbonateasthebaseatelevatedtemperaturesundernitrogenatmosphere(Scheme1).
