Scratch resistantsilicaaerogelfilmswitha 77%porosityand 1 . 1 2refractiveindexatambientpressureisreportedusingtheexchangeofsolventandmodificationof—CH3 group.Thesilicafilmswerepreparedinasol gelprocessbyadip coatingmethod ,andthenwerepostannealedinairandamixedgasatmosphere.Thefilmswerecharacterizedwithtransmissionelectronmicroscope,scanningelectronmicroscope,FourierTransforminfraredspectroscope,anellipsometer,andtheabrasiontest,respectively.Withthepostannealing,thefrequencyshiftofFTIRabsorptionω4(TO3 )peakofthefilmstoalowerwavenumberresultsfromadecreaseintheaverageSi—O—Sibridgingangle.Anincreaseinthefullwidthathalf maximum (FWHM)oftheω4peakisascribedtoawidedistributionofthebridginganglebecauseoftheformationofstrainedSi—O—Sibondscausedbythepostannealing.Theabrasionandadhesiontestsindicatethatthemixedgastreatmentnoticeablystrengthensthesilicanetwork .TheincreaseinstrengthisattributedtomoreSi—O—Sibondcross linkagesbetweensilicaparticlesformedbythemixedgastreatment.