Muaj pes tsawg hom txheej txheem mis muaj rau polycarboxylic superplasticizer niam cawv?

Thawj Txoj Kev: Post-Polymerization Functionalization

Txoj kev no feem ntau siv cov polymers uas twb muaj lawm rau kev hloov kho. Feem ntau, polycarboxylic acids uas paub txog qhov hnyav molecular yog esterified nrog polyethers ntawm kub kub nyob rau hauv lub xub ntiag ntawm ib tug catalyst, tsim graft copolymer. Txoj kev no tsuas yog txwv los ntawm hom thiab cov lus qhia tshwj xeeb ntawm cov khoom siv polycarboxylic acid, ua rau kev hloov kho kom muaj nuj nqis thiab qhov hnyav molecular nyuaj. Tsis tas li ntawd, thaum lub sij hawm kev npaj, polycarboxylic acids thiab polyethers pom tsis zoo compatibility, thiab esterification yog ib qho nyuaj rau ua. Raws li esterification zuj zus, dej tsis tu ncua khiav, ua rau muaj peev xwm sib cais.

Txheej txheem synthesis: Alkanoxy amine H₂N (BO)–R yog siv los ua reactant rau graft mus rau polycarboxylic acid (BO sawv cev rau ib pawg oxyalkyl, n yog tus lej, thiab R yog pawg C₁–C₄ alkyl). Lub solubility ntawm polycarboxylic acid nyob rau hauv alkanoxy amine tso cai rau ib tug ntau tiav immidation txheej txheem. Thaum lub sij hawm cov tshuaj tiv thaiv, cov amine reactant feem ntau yog ntxiv rau ntawm 10-20% molar piv piv rau -COOH. Cov tshuaj tiv thaiv sib tov yog thawj zaug rhuab mus rau saum 150 degree thiab tuav rau 1.5-3 teev. Tom qab ntawd nws yog txias rau 100-130 degree, thiab lub catalyst yog ntxiv rau ntxiv 1.5-3 teev los tsim cov khoom xav tau.

Txoj Kev Thib Ob: Hauv-Situ Polymerization thiab Grafting

Txoj kev no kov yeej qhov tsis zoo ntawm txoj kev ua haujlwm tom qab-polymerization los ntawm kev siv polyethers ua cov tshuaj tiv thaiv nruab nrab rau carboxylic-hom unsaturated monomers. Qhov no integrates polymerization thiab esterification, tiv thaiv cov teeb meem compatibility ntawm polycarboxylic acids thiab polyethers.

Txheej txheem npaj: Ib qho sib xyaw ntawm acrylic monomer, saw hloov tus neeg sawv cev, thiab tus neeg pib pib maj mam ntxiv rau cov tshuaj aqueous uas muaj methoxy polyethylene glycol nrog ib qho hnyav molecular ntawm 2000. Tom qab reacting ntawm 60 degree rau 45 feeb, qhov kub yog nce mus rau 120 degree. Raws li kev tiv thaiv nitrogen, dej tsis tu ncua (kwv yees li 50 feeb). Tom qab ntawd ntxiv ib qho catalyst, thiab qhov kub thiab txias tau nce mus rau 165 degree rau 1- teev cov tshuaj tiv thaiv kom ua tiav ntxiv grafting. Txawm hais tias txoj kev no tso cai rau kev tswj hwm qhov hnyav ntawm cov khoom siv polymer, cov saw tseem ceeb feem ntau txwv rau cov monomers uas muaj -COOH pawg, ua rau grafting nyuaj. Tsis tas li ntawd, cov tshuaj tiv thaiv grafting no yog qhov rov qab sib npaug ntawm cov tshuaj tiv thaiv, thiab vim tias cov dej tseem ceeb twb muaj nyob rau hauv lub cev ua ntej cov tshuaj tiv thaiv, qhov grafting degree feem ntau qis thiab nyuaj rau kev tswj. Txoj kev no yog qhov yooj yim thiab muaj tus nqi tsim khoom tsawg, txawm tias tsim qauv molecular tuaj yeem nyuaj.

Txoj Kev Thib Peb: Direct Copolymerization ntawm Polymerizable Monomers

Txoj kev sib txuas no feem ntau xav tau kev npaj ntawm macromonomer nrog cov haujlwm polymerizable, xws li methoxy polyethylene glycol methacrylate. Ib qho piv txwv tshwj xeeb ntawm monomers yog tom qab sib xyaw thiab raug rau kev daws teeb meem polymerization kom tau txais cov khoom kawg. Tus yuam sij rau txoj kev no yog nyob rau hauv kev sib txuas ntawm cov nquag macromonomer, uas cuam tshuam nrog kev sib cais thiab kev ua kom huv, ua rau cov nqi ntau dua.

Nyob rau hauv Nyiv, ib qho kev sib xyaw ua ke nrog kev khaws cia zoo tau tsim los ntawm kev sib txuas ncaj qha ntawm cov saw luv methoxy polyethylene glycol methacrylate, cov saw ntev methoxy polyethylene glycol methacrylate, thiab methacrylic acid.Piv txwv synthesis: Nyob rau hauv lub khob tshuaj tiv thaiv lub nkoj uas muaj tus pas ntsuas kub, stirrer, xa me nyuam rov funnel, N₂ inlet tube, thiab reflux condenser, 500 qhov chaw ntawm dej (los ntawm huab hwm coj) yog ntxiv thiab nplawm nrog nitrogen rau deoxygenate. Nyob rau hauv N₂ kev tiv thaiv, qhov sib tov yog rhuab mus rau 80 degree, thiab ib tug sib tov ntawm 250 qhov chaw luv luv-chain methoxy polyethylene glycol methacrylate (nrog 4 moles ntawm ethylene oxide ntxiv), 50 qhov chaw ntev-chain methoxy polyethylene glycol methacrylate (nrog 23 moles ntawm ethylene. oxide ntxiv), 200 qhov chaw methacrylic acid, 150 cov dej, thiab 13.5 qhov chaw saw hloov neeg sawv cev 3-mercaptopropionic acid yog ntxiv rau 4 teev nrog rau 40 qhov chaw ntawm 10% ammonium persulfate tov. Tom qab tag nrho ntxiv, ib qho ntxiv 10 feem ntawm 10% ammonium persulfate tov yog dripped nyob rau hauv ntau tshaj 1 teev, thiab cov sib tov yog tuav rau 1 teev, uas ua rau ib tug polymer tov nrog ib tug luj-qhov nruab nrab molecular luj ntawm 15,{{22} } raws li cov khoom kawg.