Lub synthesis ntawm polycarbonate (PC) yog txheej txheem ntawm kev tsim cov saw hlau los ntawm polymerization cov tshuaj tiv thaiv ntawm monomers. Lub hauv paus ntawm cov txheej txheem no yog nyob rau hauv kev sib txuas zoo ntawm bisphenol A (BPA) nrog cov carbonate los tsim cov polymer nrog cov qauv tshwj xeeb thiab cov khoom. Tam sim no, cov txheej txheem kev lag luam uas paub tab yog muab faib ua ob pawg: txoj kev phosgene thiab txoj kev transesterification. Ob txheej txheem no muaj lawv tus kheej yam ntxwv ntawm kev xaiv raw khoom, cov tshuaj tiv thaiv mechanisms, thiab kev cuam tshuam ib puag ncig.
Txoj kev phosgene yog txoj kev ntxov tshaj plaws kom ua tiav kev tsim khoom lag luam. Nws lub hauv paus ntsiab lus yog siv cov tshuaj tiv thaiv interfacial condensation ntawm BPA thiab phosgene nyob rau hauv alkaline tej yam kev mob. Hauv cov tshuaj tiv thaiv, phenolic hydroxyl pawg ntawm BPA daim ntawv phenolates nyob rau hauv qhov kev txiav txim ntawm alkali, uas tom qab ntawd undergo nucleophilic hloov nrog phosgene yaj nyob rau hauv cov organic theem, maj mam tsim carbonate bonds thiab precipitating lub polymer. Qhov zoo ntawm cov txheej txheem no yog cov tshuaj tiv thaiv ceev ceev, nqaim molecular hnyav faib ntawm cov khoom, thiab ruaj khov kho qhov muag thiab cov khoom siv kho qhov muag, ua rau nws tsim nyog rau kev tsim khoom siab -purity PC resin. Txawm li cas los xij, phosgene yog cov pa roj uas muaj kuab lom heev, yuav tsum muaj cov qauv kev nyab xeeb ntawm kev ua haujlwm siab, thiab nws tsim ntau cov hydrogen chloride thiab sodium chloride raws li cov khoom lag luam, uas ua rau lub nra hnyav hnyav thiab ua rau muaj teeb meem rau ib puag ncig thiab kev noj qab haus huv.
Txhawm rau kov yeej qhov kev pheej hmoo ntawm ib puag ncig thiab kev nyab xeeb ntawm cov txheej txheem phosgene, transesterification (tseem hu ua yaj polycondensation) tau siv dav. Txoj kev no siv bisphenol A thiab diphenyl carbonate (DPC) ua raw khoom. Nyob rau hauv ib qho chaw inert thiab nrog ib tug catalyst, ib tug transesterification cov tshuaj tiv thaiv tsim phenol thiab oligomers. Tom qab ntawd cov phenol raug tshem tawm hauv qhov kub thiab txias thiab lub tshuab nqus tsev siab, ua raws li polycondensation kom tau txais qhov hnyav molecular PC. Transesterification tshem tawm qhov xav tau ntawm phosgene, siv cov ntaub ntawv me me, thiab cov khoom siv phenol tuaj yeem rov ua dua tshiab, ua rau tag nrho cov txheej txheem ntau dua nyob rau hauv txoj kab nrog ntsuab tshuaj engineering hauv paus ntsiab lus. Txawm li cas los xij, txoj kev no yuav tsum muaj kev tswj xyuas meej ntawm cov tshuaj tiv thaiv; Piv txwv li, qhov kub thiab txias, lub tshuab nqus tsev, thiab hom catalyst ncaj qha cuam tshuam rau kev loj hlob ntawm molecular hnyav thiab cov xim ntawm cov khoom, yuav tsum muaj kev tswj xyuas kom zoo los xyuas kom meej qhov ua tau zoo.
Nyob rau hauv xyoo tas los no, txhawm rau txhim kho kev ruaj khov thiab kev lag luam kev lag luam, tsis yog -phosgene melt transesterification thev naus laus zis tau maj mam koom nrog bio-raws li los yog rov ua dua carbonate qhov chaw, tshawb xyuas qis - carbon emission txoj kev. Tsis tas li ntawd, copolymerization hloov kho synthesis tau siv los kho qhov toughness, kub ua hauj, los yog ua fluidity ntawm PC los ntawm kev qhia me me ntawm peb monomers los yog saw segment regulators thaum lub sij hawm polymerization kom ua tau raws li kev ua tau zoo.
Zuag qhia tag nrho, cov txheej txheem synthesis ntawm PC tau hloov zuj zus los ntawm txoj kev muaj tshuaj lom thiab pheej hmoo ua rau muaj kev nyab xeeb dua, huv dua, thiab tswj tau ntau dua. Cov txheej txheem xaiv yuav tsum tau ua tib zoo xav txog cov khoom zoo, kev tiv thaiv ib puag ncig, thiab kev ua haujlwm ntawm kev lag luam. Nyob rau hauv lub neej yav tom ntej, ntsuab thiab functional synthesis yuav tseem yog cov lus qhia tseem ceeb rau kev txhim kho thev naus laus zis.