Kev sib txuas ntawmAdipic dihydrazide (ADH)thiabDiacetone Acrylamide (DAAM)cuam tshuam txog kev tsim ntawmcovalent bondsnruab nrab ntawm ob lub molecule no, uas ua rau muaj kev loj hlob ntawm ib qhopeb-seem network, feem ntau nyob rau hauv cov ntsiab lus ntawm polymer chemistry. Lub tshuab no muaj feem cuam tshuam rau ntau yam kev siv, tshwj xeeb tshaj yog hauv kev tsim cov polyurethane coatings, adhesives, thiab lwm yam khoom siv nrog cov khoom siv kho tshuab zoo dua.
Yuav kom nkag siab txog txoj kev sib txuas ntawm cov tshuaj, nws yog ib qho tseem ceeb uas yuav tsum xub tshuaj xyuas cov qauv tshuaj thiab cov pab pawg reactive uas muaj nyob hauv ADH thiab DAAM, ua raws li qhov xwm txheej ntawm cov txheej txheem sib txuas ntawm nws tus kheej.
1. Cov Qauv Tshuaj thiab Kev Ua Haujlwm ntawm ADH thiab DAAM
Adipic dihydrazide (ADH):Aryl diisocyanates yog cov organic compounds uas muaj ob pawg isocyanate (-NCO) txuas rau lub nplhaib aromatic. Cov isocyanates no yogua xua heevthiab ua haujlwm ua cov khoom siv nruab nrab tseem ceeb hauv kev tsim cov khoom siv polyurethane. Cov pawg isocyanate yog electrophilic thiab yooj yim cuam tshuam nrog cov pawg nucleophilic xws li hydroxyls, amines, thiab lwm yam pawg ua haujlwm reactive, ua rau lawv yog cov neeg sib tw tseem ceeb rau kev sib txuas lus.
Diacetone Acrylamide (DAAM):DAAM feem ntau yog ib qho acrylate monomer uas tau hloov kho uas muaj ib qhopawg hydroxyl (-OH) thiab pawg acrylicHauv qee cov versions, nws kuj suav nrog DMPA, uas yog ib pawg hydrophilic uas tuaj yeem pab txhawb kev sib kis hauv cov dej-raws li cov kab ke. Lub ntsiab lus tseem ceeb ntawm DAAM rau kev sib txuas yog pawg hydroxyl (-OH), uas yog nucleophilic thiab tuaj yeem cuam tshuam nrog pawg electrophilic isocyanate.
2. Kev Sib Txuas Lus
Cov txheej txheem crosslinking ntawm ADH thiab DAAM yog ib homkev ua kom sib xyaw ua ke, qhov twg ob lub molecule sib koom ua ke los ua ib lub qauv loj dua, nyuaj dua nrog kev tso tawm ntawm ib lub molecule me me, feem ntau yog carbon dioxide (CO₂) lossis dej. Lub tshuab tshwj xeeb tuaj yeem piav qhia ib kauj ruam zuj zus:
a. Kev sib xyaw ntawm Isocyanate thiab Hydroxyl Group
Kauj ruam thawj zaug thiab tseem ceeb tshaj plaws hauv cov txheej txheem crosslinking yog qhov kev cuam tshuam ntawmpawg isocyanate ntawm ADH thiab pawg hydroxyl ntawm DAAM. Isocyanates muaj kev cuam tshuam ntau heev vim yog qhov xwm txheej polarized ntawm N = C = O daim ntawv cog lus. Thaum ADH thiab DAAM sib xyaw, pawg hydroxyl ntawm DAAM ua haujlwm ua nucleophile thiab tawm tsam cov pa roj carbon electrophilic ntawm pawg isocyanate. Qhov no ua rau muaj kev tsim ntawm ib qhoKev sib txuas urethane (–NH–C(O)–O–)thiab kev tso tawm cov pa roj carbon dioxide (CO₂) ua ib yam khoom seem. Cov kauj ruam no ua tau zoo tsim kom muaj kev sib txuas ntawm ob lub molecule.
b. Kev Tsim Cov Kev Sib Txuas Urethane
Thaum muaj kev sib xyaw ua ke, pawg isocyanate los ntawm ADH sib xyaw nrog pawg hydroxyl ntawm DAAM, tsim ib qhokev sib txuas urethane (lossis carbamate)Cov kauj ruam no rov ua dua thaum ntau lub DAAM molecule, txhua tus muaj ib pawg hydroxyl, ua rau cov pawg isocyanate ntawm ADH muaj. Qhov tshwm sim yog kev tsim cov network ntawm cov urethane bonds sib txuas, tsim cov crosslinked polymer network.
Cov tshuaj tiv thaiv dav dav rau kev tsim cov urethane bond yog:
Cov tshuaj tiv thaiv no yog exothermic heev thiab tuaj yeem txuas ntxiv mus ntev li ntev tau tias muaj cov hydroxyl thiab isocyanate pawg.
c. Kev Sib Txuas Ntxiv thiab Kev Ua Polymerization
Thaum cov tshuaj tiv thaiv mus ntxiv, ntau pawg isocyanate los ntawm ADH tuaj yeem cuam tshuam nrog lwm pawg hydroxyl los ntawm cov molecule DAAM ntxiv, ua rau muaj kev sib xyaw ntxiv thiab kev loj hlob ntawm lub network crosslinked. Tus naj npawb ntawm cov crosslinks hauv lub network polymer kawg nyob ntawm qhov piv ntawm ADH rau DAAM thiab cov xwm txheej ntawm cov tshuaj tiv thaiv.
d. Kev Tsim Ib Lub Network Peb-Seem
Thaum ntau thiab ntau dua DAAM molecules cuam tshuam nrog ADH, cov qauv ntawm cov khoom hloov pauv los ntawm cov polymer linear lossis branched mus rau ib qhopeb-seem network. Lub network crosslinked no ruaj khov heev thiab tiv taus kev puas tsuaj, uas yog ib qho laj thawj vim li cas cov ntaub ntawv zoo li polyurethanes muaj txiaj ntsig zoo hauv kev pleev xim, nplaum, thiab lwm yam kev siv. Qhov muaj cov qauv acrylate DMPA-hloov kho hauv DAAM kuj tso cai rau kev yaj dej lossis kev sib kis, ua rau cov khoom siv kawg muaj peev xwm ua tau ntau yam rau cov dej-raws li cov qauv.
3. Tej Yam Uas Cuam Tshuam Rau Txoj Kev Sib Txuas Lus
Muaj ntau yam uas cuam tshuam rau qhov dav thiab kev ua haujlwm ntawm cov txheej txheem crosslinking ntawm ADH thiab DAAM:
a. Stoichiometry ntawm ADH thiab DAAM
Qhov piv ntawm cov pawg isocyanate (ADH) rau cov pawg hydroxyl (DAAM) yogqhov tseem ceeb rau kev tswj hwm qib ntawm kev sib txuasYog tias qhov piv ntawm cov khoom no siab dhau rau ADH (piv txwv li, muaj ntau cov isocyanates thiab tsis muaj hydroxyls txaus), qee cov isocyanate pawg yuav tsis muaj zog, uas yuav ua rau muaj kev sib txuas tsis tiav thiab txo cov khoom siv. Ntawm qhov tod tes, ntau dhau DAAM yuav ua rau muaj kev sib txuas ntau dhau, uas yuav ua rau cov khoom siv tawg yooj yim dhau.
b. Kub thiab Sijhawm
Qhov kub thiab lub sijhawm uas tso cai rau kev ua tshuaj kuj yog cov yam tseem ceeb. Kev ua tshuaj ntawm isocyanates thiab hydroxyl pawg feem ntau tshwm sim ntawmkub siab (piv txwv li, 50 ° C txog 100 ° C), vim qhov no ua rau cov urethane tsim sai dua. Lub sijhawm teb ntev dua kuj tso cai rau kev sib txuas ua tiav ntau dua thiab cov khoom siv zoo dua.
c. Cov tshuaj catalysts thiab cov khoom ntxiv
Qee cov catalysts tuaj yeem siv los uaua kom cov tshuaj tiv thaiv isocyanate-hydroxyl sai duaPiv txwv li, cov tshuaj catalysts uas ua los ntawm hlau xws li tin (Sn) lossis amine-based catalysts tuaj yeem ntxiv rau kom yooj yim rau kev sib xyaw, txhim kho kev ua haujlwm zoo thiab kev ceev ntawm kev sib txuas. Cov tshuaj ntxiv xws li stabilizers lossis plasticizers kuj tseem yuav suav nrog los hloov kho cov khoom kawg.
4. Kev Siv Cov Polymers ADH-DAAM Crosslinked
Cov polymers crosslinked uas tsim los ntawm ADH thiab DAAM yog siv rau ntau yam kev siv, xws li:
- Cov Txheej Txheem Polyurethane:Cov ntaub ntawv no feem ntau siv rau hauv cov txheej txheem tsheb, cov txheej txheem kev lag luam, thiab cov khoom tiv thaiv, vim tias cov tes hauj lwm sib txuas ua rau muaj kev ruaj khov, tiv taus tshuaj lom neeg, thiab cov khoom siv kho tshuab.
- Cov nplaum thiab cov khoom foob:Lub zog siab thiab cov khoom sib txuas ntawm cov kab ke no ua rau lawv zoo tagnrho rau kev sib txuas cov ntaub ntawv hauv kev tsim kho, tsheb, thiab khoom siv hluav taws xob.
- Cov Khoom Siv Kho Mob:Cov polymers sib txuas feem ntau siv rau hauv cov khoom siv biomedical thiab cov tshuab xa tshuaj, qhov twg kev tso tawm tswj hwm thiab biocompatibility yog qhov tseem ceeb.
Lub mechanism ntawm kev sib txuas ntawm cov khoom sib txuasADHthiabDAAMcuam tshuam nrog cov tshuaj tiv thaiv ntawm isocyanate pawg nrog hydroxyl pawg los tsim cov urethane txuas, ua rau muaj kev sib txuas ua ke,peb-seem polymer networkCov tshuaj tiv thaiv no raug cuam tshuam los ntawm cov yam xws li stoichiometry, kub, thiab catalysts, thiab nws yog siv dav hauv kev tsim cov ntaub ntawv nrog cov khoom siv kho tshuab, thermal, thiab tshuaj lom neeg xav tau. Qhov ua tau ntau yam thiab lub zog ntawm cov crosslinked network ua rau cov ntaub ntawv no muaj txiaj ntsig zoo rau ntau yam kev siv.
Lub sijhawm tshaj tawm: Lub Rau Hli-12-2025