Efficient and Rapid Synthesis of Polyureas and Polythioureas

通过微波辐射合成聚脲 的 文章

EfficientandRapidSynthesisofPolyureasand

PolythioureasfromtheReactionofUreaandThioureawithDiaminesunderMicrowaveIrradiation

AHMADBANIHASHEMI,1HASSANHAZARKHANI,2AMIRABDOLMALEKI1

1

DepartmentofChemistry,CollegeofSciences,ShirazUniversity,Shiraz,Iran,71454

DepartmentofChemistry,InstituteforAdvancedStudiesinBasicSciences,P.O.Box45195-159,GavaZang,Zanjan,Iran

2

Received4June2003;accepted9January2004

Polyureasandpolythioureaswerereadilysynthesizedbythereactionof

aromaticandaliphaticamineswithureaandthioureas,respectively,ingoodtoexcel-lentyieldsundermicrowaveirradiation.Theeffectsofthemicrowaveirradiationtimeandpower,thenatureofthesolvent,andthesolidcontentofthemonomersontheinherentviscosityofthepolymerswereinvestigated.©2004WileyPeriodicals,Inc.JPolym

ABSTRACT:

SciPartA:PolymChem42:2106–2111,2004

Keywords:polycondensation;viscosity;linear

INTRODUCTION

Polyureasarepolyamidesofcarbonicacidthathavehighermeltingpointsandaretougherthanpolyamides.1Theyareusedinmanyindustrialapplications;forexample,theyhavebeenusedinthepreparationofelastomers,2 bers,3inks,anddyes,intheencapsulationofpharmaceuticals,andinthemodi cationofinterfacialgraftingtechniquessuitableforelastomers.3Thesynthe-sisofpolyureasandpolythioureashasbeenex-tensivelyinvestigated.Polyureasaregenerallypreparedfromthereactionofdiaminewithcar-bondioxide(CO2),4phosgene,5anddiisocyanate.6Triphosgene,7carbonateesters,1andbiscarbamylchloride8havealsobeenusedinthesynthesisofpolyureas.However,thesynthesisofpolythio-ureashasattractedlessattention,andtheyare

Correspondenceto:A.Banihashemi(E-mail:banihashemi@chem.susc.ac.ir)

JournalofPolymerScience:PartA:PolymerChemistry,Vol.42,2106–2111(2004)©2004WileyPeriodicals,Inc.

usuallypreparedfromthepolycondensationofdiamineswithcarbondisul des(CS2).9

Eachofthesemethodshasitsownmeritsandsomedrawbacks.Forexample,thepolycondensa-tionofdiamineswithCO2andCS2onlyproceedsinthepresenceofpyridineandaphosphorouscompoundsuchasdiphenylphosphateorinasealedtubeunderdrasticconditions(hightem-peratureandpressure).Inthecaseofaliphaticdiamines,thereactionsprogressinlowyields.Becausethephosgeneanddiisocyanatesarehighlytoxicandcarcinogenic,theirhandlingisdif cult,andsomeprecautionsarerequired.Moreover,CS2hasabadodor.

Aliteraturesurveyhasshownthatmicrowaveirradiationhasbroughtanewperspectivetosyn-theticorganicchemistry,notonlyintermsofhighyieldsandselectivitybutalsointermsofeasyreactionconditions.10,11Theapplicationofmicro-waveenergyincommercialdomesticovenstoor-ganicsynthesisbeganinthemid1980s.Asanalternativetoconventionalheatingtechniques,theenergyandmoleculardipolemomentsofthestartingmaterialsareused.Thisinsitumodeof

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