Polymerization hauv organic chemistry yog dab tsi?

Polymerization yog tus txheej txheem ntawm kev txais ib qho loj molecule los ntawm ib hom pib thawj. Lub polymer resulting yog ib tug macromolecule uas muaj ib tug xov tooj ntawm cov khoom txaus ntsuas txaus.

Lub ntsiab hom polymerization

Teb cov lus nug txog tias lub polymerization nyob hauv chemistry, peb nco ntsoov tias qhov tshwm sim tshwm sim nyob rau hauv muaj cov catalyst (tus txheej txheem accelerator).

Homopolymer - ib qhov chaw sib xyaw ua ke, uas tau txais thaum lub sijhawm ua ke ntawm tib lub tshuab pib.

Heteropolymer yog ib cov tshuaj tiv thaiv cov khoom sib txawv.

Cov qauv ntawm polymer

Muab hais tias lub polymerization - yog ib tug complex tshuaj txheej txheem, lub molecular ceeb thawj ntawm lub polymer ua tej zaum yuav muaj ib tug txawv tus nqi. Nyob rau hauv cov tshuab ua kua molecular muaj "xaus pawg" uas txawv ntawm rov thooj. Xws li pawg no muaj nyob hauv tus qauv ntawm cov polymer hauv ib qho nyiaj tsawg, yog li lawv tus cwj pwm tsis raug thas nriav thaum tshawb fawb cov tshuaj thiab lub cev cov khoom ntawm cov khoom polymer uas tau txais.

Cationic Polymerization

Dabtsi yog cov kabmob polymerization? Qhov no txoj kev yuav siv sij hawm qhov chaw nyob rau hauv tus ntawm ib tug Lewis acid (sib tov ntawm txhuas chloride, boron fluoride, acid) los ntawm ib tug mechanism uas yog zoo li tus txheej txheem ntawm electrophilic tas li ntawd mus rau lub ob (ob chav) bonds.

Thaum thawj theem, cov proton txuas nrog cov alkene, uas ua rau tsim kom muaj carbocation.

Tsis tas li ntawd, vim muaj kev sib txuas hauv tshuab, lwm tus alkene molecule nkag mus rau hauv kev sib txuam, nws thiaj li tsim kom muaj cov khoom siv nrog lub zais muag ntev.

Ntau ntau rov qab ntawm qhov txheej txheem yuav siv qhov chaw, raws li qhov tshwm sim ntawm cov khoom siv uas yog tsim muaj, uas muaj lub siab ua rau muaj siab ploj zuj zus.

Muaj qhov siab yuav tawg ntawm qhov chaw cation, uas tuaj yeem ntxeem tau kev sib cais los ntawm proton molecule.

Piv txwv

Cia peb xav txog cov lus nug txog dab tsi polymerization hauv chemistry. Piv txwv ntawm txoj kev zoo li no yog muab los ntawm polymerization ntawm isobutylene. Cov txheej txheem tau txais los ntawm txoj cai cationic, vim hais tias muaj cov khoom noj khoom haus ntawm cov neeg siv khoom.

Qhov tsim ntawm cov saw hlau ntawm polyisobutylene tshwm sim nyob rau hauv xws li ib txoj kev uas cov ntaub ntawv ruaj khov tshaj plaws ntawm nws kawg. Vim li ntawd, nws muaj kev sib koom tes ntawm "lub taub hau los Tail".

Thaum lub sij hawm siv tshuaj lom neeg, suab tsis muaj dej, tsim muaj lub polymer uas muaj cov saw ntev.

Yuav ua li cas yog polymerization ntawm tus neeg sawv cev hauv chav kawm ntawv ntawm unsaturated hydrocarbons? Yog hais tias xaiv catalyst , concentrated sulfuric acid, muaj cai tom qab tsim ntawm lub polymerization sib tov ntawm ob dimers. Tom qab ob lub lwg dej ntawm isobutylene txuas nrog, cov saw lov tawm. Nyob rau hauv rooj plaub no, lub nruab nrab (carbocation) muab nws proton rau cov dej ua ntej nws nkag mus rau hauv kev sib txuas nrog lwm molecule ntawm unsaturated alkene.

Anionic polymerization

Anionic polymerization yog dab tsi? Cov txheej txheem no xav tias lub polymerization ntawm alkene ntawm ib qho ntawm qhov xaus ntawm cov nyiaj ntau. Polymerization yog ua tau thaum ib qho alkene molecule tawm tsam los ntawm tej yam nucleophilic reagents.

Piv txwv, tus amide anion sib cuam tshuam nrog acrylonitrate hauv qhov nyiaj ua ob leeg, ua rau muaj carbanion uas tsis muaj tus nqi qis ntawm cov cyanide thiab carbon atom. Yog hais tias txoj hauv kev hloov mus ua kom ruaj khov, nws qhov ntxiv mus rau alkene molecule tom ntej yog pom.

Txoj kev txiav ntawm ib cov saw pheej loj zuj zus tuaj yeem ua rau cov tshuaj tiv thaiv ua rau kev tshem tawm ntawm tus nqi tsis zoo tom qab ntawm cov saw hlau.

Dawb radical polymerization

Tus txheej txheem ntawm ethylene polymerization tuaj yeem pib ua ntej ntawm peroxides (thaum muaj siab thiab siab). Lub caij nyoog ntawm lub saw yog facilitated los ntawm tus txheej txheem ntawm recombination los yog disproportionation ntawm radicals.

Nyob rau hauv cov roj carbon dioxide ntawm polyethylene muaj ntau ntau yam qauv ntawm ethylene. Nws yog cov qauv no uas qhia txog qhov tseem ceeb ntawm cov khoom zoo siab ntawm cov qib high-molecular compound, contributes rau nws daim ntawv thov nyob rau hauv qhov khoom ntawm ib lub hnab ntim rau ib qho kev lag luam. Tsis tas li ntawd, polyethylene yuav tsum tsim khoom los ntawm molding thiab casting.

Nyob rau hauv cov ntaub ntawv ntawm ib tug dawb radical hom polymerization nyob rau hauv ib tug nonsymmetric alkene, loj hlob kawg yuav sawv cev raws li ib tug ruaj radical, thiab txoj kev yog sawv cev los ntawm lub "lub taub hau rau Tail" hom.

Isobutylene thiab propylene tsis polymerize rau dawb-radical mechanism. Tag nrho cov polymers uas tau txais hauv cov kev lag luam tshuaj nrhiav tau lawv daim ntawv thov rau ntau lub ceg ntoo, chaw muag tshuaj, thiab tshuaj. Feem ntau cov polymers uas tau los ntawm cov roj carbon monoxide ntawm cov ethylene series yog cov polyethylene xwb, thiab cov homologue-propylene.