简介:Poly(aryleneetherdiketone)swerepreparedbythearomaticnucleophilicdisplacementreactionof4,4’-difluorobenzilwithdifferentbisphenolsinthepresenceofan-hydrouspotassiumcarbonateindiphenylsulfoneatelevatedtemperature.Thepolymersobtainedhadinherentviscosityof0.51~0.63dL/g,andexhibitedglasstransitiontemper-aturerangingfrom136~217℃mainlydependingonthebisphenolsusedinthepolymersynthesis.Thermogravimetryofthesepolymersshowedexcellentthermalstability,indi-catingthat10%weightlossesofthepolymerswereobservedintherangeabove428℃and438℃inairandnitrogen,respectively.ThemechanicalpropertiesofthesepolymerswerealsodescribedandthepermeabilityoffivepolymersforH2,O2andN2wasdeterminedat30℃.
简介:Baker'syeastmediatedreductionofopticallyactivediketoneisdescribed.Thetwoketogroupsareefficientlydifferentiatedandtheeevalueoftherecoveredmaterialisconsiderablyraised.Itaffordshighlyopticallyactivekeyintermediatesefficientlyforthesynthesisofnaturalpolyhydroxylatedagarofuranproducts.
简介:Anewtypeofβ-diketonebasedsidechainliquidcrystallinepolysiloxanes(DKLCP)withdifferentlengthofflexiblespacersandendgroupshavebeensynthesizedbyhydrosilationreaction.Thisisliquidcrystalpolymers(LCP)usingcoordinatingβ-diketoneligandasmesogens.ThephasebehaviourofDKLCPpolymerswasstudiedbydifferentialscanningcalorimetryandpolarizingmicroscopy.X-raydiffractioninvestigationsdemonstratedthatthepolysiloxaneswithsufficientlylongflexiblespacersweresmecticliquidcrystalpolymers,whilethosewithmuchshorterspacerswerenematicones.
简介:Anewtypeofpalladiumchelateofβ-diketone-basedsidechainliquidcrystalpolysiloxane(Pd-DKLCP)hasbeensynthesizedbychelationreactionofpalladiumdichloridewithpolymericligand,β-diketonepolysiloxane(DKLCP),usingTHFassolventatR.T..ThePd-chelationresultsingreatlyincreasingthephasetransitiontemperatureTKandtheenthalpychange△HKfromcrystaltoliquidcrystalstateandmakingthetemperaturerangeofLCstate△T(△T=TCl-TK)widened.AllthesechelatesPd-DKLCP’sdonotshowTCluntildecompositionat205℃.ItisnoteworthythatthePd-chelationcanexertmorepositiveeffectonthemesomorphicbehaviourofthepolymerligandthanthecounterpartCu-DKLCPdoes.Itisprobableduetothebiggersizeofdisc-likemesogenformedfromβ-diketoneandPd+2ionwith4dorbital.