Polyimide feem ntau yog npaj los ntawm polycondensation cov tshuaj tiv thaiv ntawm dianhydrides thiab diamines. Cov txheej txheem synthesis, nyob ntawm txoj kev tshuaj tiv thaiv thiab kev ua cov txheej txheem, feem ntau poob rau hauv ob pawg: ob- kauj ruam thiab ib qho - kauj ruam txoj kev.
Ob -Txoj Kev Kauj Ruam (Polyamic Acid Method)
Ob txoj kev -kauj ruam tam sim no yog txoj kev npaj siv dav tshaj plaws. Ua ntej, nyob rau hauv lub polar solvent, ib qho aromatic dianhydride reacts nrog ib tug diamine los tsim ib tug soluble polyamic acid (PAA) precursor. Tom qab ntawd, los ntawm kev kho cua sov los yog tshuaj lom neeg lub cev qhuav dej, cov polyamic acid tau dhau los ua cov tshuaj tiv thaiv cyclization (iminolation), hloov mus rau hauv cov khoom siv polyimide insoluble thiab infusible. Txoj kev no muaj qhov zoo xws li cov tshuaj tiv thaiv me me thiab yooj yim ntawm kev ua cov yeeb yaj kiab thiab txheej txheej, ua rau nws txoj hauv kev tseem ceeb rau kev tsim cov khoom siv polyimide films thiab txheej txheej.
Ib -Txoj Kev Kauj Ruam (Direct Polycondensation Method)
Ib txoj hauv kev - kauj ruam muaj feem cuam tshuam ncaj qha cov tshuaj tiv thaiv polycondensation ntawm dianhydrides thiab diamines nyob rau hauv siab -boiling- cov kuab tshuaj los yog cov tshuaj tiv thaiv tshwj xeeb, ib txhij ua tiav cov cyclization los tsim polyimide. Txoj kev no muaj cov txheej txheem yooj yim heev, tab sis nws yuav tsum muaj kev ua haujlwm siab hauv kev tswj cov tshuaj tiv thaiv kab mob thiab feem ntau yog siv rau kev npaj tshwj xeeb ntawm polyimides.
Copolymerization thiab Cov Txheej Txheem Txheej Txheem
Hauv kev siv cov tswv yim, txhawm rau txhim kho kev ua tau zoo, hloov pauv, lossis cov khoom siv hluav taws xob ntawm polyimides, cov qauv sib txawv ntawm cov monomers feem ntau tau qhia los ntawm cov tshuaj tiv thaiv copolymerization los kho cov rigidity, yooj, thiab polarity ntawm cov saw hlau molecular. Tsis tas li ntawd, kev hloov kho tuaj yeem nqa tawm thaum lub sijhawm lossis tom qab polymerization los ntawm txoj kev xws li sau thiab sib xyaw kom tau txais cov khoom siv polyimide ua haujlwm nrog cov khoom tshwj xeeb.
