Anovelbiphenylside-chaineddiaminewithalkyloxyspacerandalkyloxytail,4'-butoxy-4-(3,5-diaminobenzoyloxy)hexyloxybiphenyl(C6BBC4),wassynthesizedandcharacterizedbyFTIRand1HNMR.Aseriesofpolyimide(PI)filmswithdifferentsidechaincontentswassynthesizedfrombiphenyltetracarboxylicdianhydride(BPDA),4,4'-oxydianiline(ODA)andC6BBC4,andtheirthermalproperties,opticaltransparencyandliquidcrystalalignmentproperty,andsoon,wereinvestigatedbythermogravimetricanalysis(TGA),differentialscanningcalorimetry(DSC),crystalrotationmethod,polarizingmicroscopyandUV-Visspectra.Withthecontentofsidechaineddiamineincreasingfrom0to100%,theηinhofpoly(amideacid)(PAA)decreasedrapidlyfrom3.0to0.51,theglasstransitiontemperature(Tg)ofpolyimides(PIs)decreasedfrom274℃to203℃andtheVis-lighttransmittanceofalignmentfilmssubstantiallyincreased.Asforthealignmentproperties,thepretiltangleofPIalignmentfilmswithoutrubbingcouldreach90°whenthecontentofC6BBC4was60%ormore.Atthesametime,thealignmentstabilitycouldmeettheindustrialrequirements.Itwasconsideredthatthealkoxyspacer,thebiphenylunitandthealkoxytailmayallplayimportantrolesinachievingalargepretiltangleevenupto90°,andtheintroductionofonlythealkoxyspaceroralkoxytailcanalsoimprovethepretiltangle,butnotbymuch.
