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1、Macromolecules2008,41,9345-93519345DynamicSelf-AssemblyInducedRapidDissolutionofCelluloseatLowTemperatures†,††††‡JieCai,LinaZhang,*ShilinLiu,YatingLiu,XiaojuanXu,XumingChen,‡§§§§BenjaminChu,XinglinGuo,JianXu,HeCheng,CharlesC.Han,and
2、ShigenoriKugaDepartmento
3、fChemistry,WuhanUniVersity,Wuhan430072,China;DepartmentofChemistry,StonyBrookUniVersity,StonyBrook,NewYork11794-3400;StateKeyLaboratoryofPolymerPhysicsandChemistry,InstituteofChemistry,ChineseAcademyofSciences,Beijing100080,China;andGraduateSchoolofAgricult
4、uralandLifeSciences,TheUniVersityofTokyo,Tokyo,JapanReceiVedMay18,2008;ReVisedManuscriptReceiVedSeptember18,2008ABSTRACT:Cellulosecanbedissolvedinprecooled(-12°C)7wt%NaOH-12wt%ureaaqueoussolutionwithin2min.Thisinterestingprocess,toourknowledge,representsthe
5、mostrapiddissolutionofnativecellulose.Theresultsfrom13CNMR,15NNMR,1HNMR,FT-IR,small-angleneutronscattering(SANS),transmissionelectronmicroscopy(TEM),andwide-angleX-raydiffraction(WAXD)suggestedthatNaOHhydratescouldbemoreeasilyattractedtocellulosechainsthrou
6、ghtheformationofnewhydrogen-bondednetworksatlowtemperatures,whiletheureahydratescouldnotbeassociateddirectlywithcellulose.However,theureahydratescouldpossiblybeself-assembledatthesurfaceoftheNaOHhydrogen-bondedcellulosetoformaninclusioncomplex(IC),leadingto
7、thedissolutionofcellulose.Scatteringexperiments,includingdynamicandstaticlightscattering,indicatedthatmostcellulosemolecules,withlimitedamountsofaggregation,couldexistasextendedrigidchainsindilutesolution.Further,thecellulosesolutionwasrelativelyunstableand
8、couldbeverysensitivetotemperature,polymerconcentration,andstoragetime,leadingtoadditionalaggregations.TEMimagesandWAXDprovidedexperimentalevidenceontheformationofawormlikecelluloseICbeingsurroundedwithurea.Therefore,weproposethatthecellulosedissolutionat-12
9、°Ccouldariseasaresultofafastdynamicself-assemblyprocessamongsolventsmallmolecules(NaOH,urea,andwater)andthecellulosemacromolecules.IntroductionItiswell-knownthatdissolutionofnormalpolymersincludesNumer
