Ntau tus neeg txaus siab rau cov lus nug ntawm cov qauv polymers muaj dab tsi. Cov lus teb rau nws yuav muab rau hauv kab lus no. Polymer khoom (tom qab no - P) feem ntau muab faib ua ob peb chav nyob ntawm qhov ntsuas ntawm cov cuab yeej tau txhais, nrog rau nws lub cev. Qhov zoo tshaj plaws ntawm cov tshuaj no yog tus kheej ntawm lawv cov monomers (M). Cov txheej txheem thib ob, hu ua microstructure, qhov tseem ceeb qhia txog kev npaj ntawm cov Ms hauv P ntawm qhov ntsuas ntawm ib Z. Cov yam ntxwv ntawm cov qauv no ua lub luag haujlwm tseem ceeb hauv kev txiav txim siab lub cev ntawm cov khoom no, uas qhia tias P coj li cas. cov khoom siv macroscopic. Cov khoom siv tshuaj lom neeg ntawm nanoscale piav qhia yuav ua li cas chains cuam tshuam los ntawm ntau lub zog ntawm lub cev. Ntawm qhov ntsuas macro, lawv qhia tias P sib cuam tshuam li cas nrog lwm cov tshuaj thiab cov kuab tshuaj.
Identity
Tus kheej ntawm qhov rov qab txuas uas ua rau P yog thawj zaug thiabtus cwj pwm tseem ceeb tshaj plaws. Cov nomenclature ntawm cov tshuaj no feem ntau yog ua raws li hom ntawm monomer residues uas ua rau cov P. Polymers uas muaj tsuas yog ib hom rov qab unit yog hu ua homo-P. Tib lub sijhawm, Ps muaj ob lossis ntau hom kev rov ua dua tshiab yog hu ua copolymer. Terpolymers muaj peb hom kev rov ua dua tshiab.
Polystyrene, piv txwv li, tsuas yog muaj cov styrene M residues thiab yog li muab cais ua Homo-P. Ethylene vinyl acetate, ntawm qhov tod tes, muaj ntau dua ib hom kev rov ua dua tshiab thiab yog li copolymer. Qee cov Ps lom neeg muaj ntau yam sib txawv tab sis muaj feem cuam tshuam nrog monomeric residues; Piv txwv li, polynucleotides xws li DNA yog tsim los ntawm plaub hom nucleotide subunits.
A polymer molecule uas muaj ionizable subunits yog hu ua polyelectrolyte los yog ionomer.
Microstructure
Lub microstructure ntawm ib lub polymer (qee zaum hu ua configuration) muaj feem xyuam rau lub cev ntawm M residues raws cov saw tseem ceeb. Cov no yog cov ntsiab lus ntawm cov qauv P uas yuav tsum tau tawg ntawm covalent daim ntawv cog lus kom hloov. Cov qauv muaj kev cuam tshuam rau lwm yam khoom ntawm P. Piv txwv li, ob qho piv txwv ntawm cov roj hmab ntuj tuaj yeem pom qhov sib txawv ntawm qhov ntev txawm tias lawv cov molecules muaj tib lub monomers.
qauv thiab cov khoom ntawm polymers
nqe lus no tseem ceeb heev los qhia meej. Ib qho tseem ceeb microstructural feature ntawm cov qauv polymer yog nws cov architecture thiab cov duab, uas muaj feem xyuam rau yuav ua li casceg cov ntsiab lus ua rau muaj kev sib txawv ntawm ib qho yooj yim linear saw. Cov ceg molecule ntawm cov khoom no muaj ib lub ntsiab saw nrog ib los yog ntau sab chains los yog hloov ceg. Hom ceg Ps suav nrog hnub qub Ps, zuag Ps, txhuam Ps, dendronized Ps, ntaiv Ps, thiab dendrimers. Kuj tseem muaj ob-dimensional polymers uas muaj cov topologically tiaj tus rov qab units. Ntau hom kev siv tshuab tuaj yeem siv los ua ke P-khoom siv nrog ntau hom khoom siv, xws li nyob hauv polymerization.
Lwm yam zoo
Cov khoom sib xyaw thiab cov qauv ntawm cov polymers hauv kev tshawb fawb txog kev tshawb fawb muaj feem cuam tshuam txog yuav ua li cas cov ceg ntoo ua rau kev sib txawv ntawm cov kab P-chain nruj me ntsis. Cov ceg ntoo tuaj yeem tshwm sim, lossis cov kev cuam tshuam yuav raug tsim los rau cov phiaj xwm tshwj xeeb. Qhov no yog ib qho tseem ceeb microstructural feature. Cov qauv ntawm cov polymer cuam tshuam rau ntau yam ntawm nws lub cev, nrog rau kev daws thiab yaj viscosity, solubility nyob rau hauv ntau yam compositions, iav hloov kub, thiab qhov luaj li cas ntawm tus neeg P-coils nyob rau hauv kev daws. Qhov no yog qhov tseem ceeb rau kev kawm txog cov khoom muaj thiab cov qauv ntawm cov polymers.
Branching
Branches tuaj yeem tsim thaum qhov kawg ntawm cov khoom siv polymer txuas nrog (a) rov qab rau nws tus kheej lossis (b) mus rau lwm P-strand, ob qho tib si, los ntawm kev tshem tawm hydrogen, tuaj yeem tsim thaj chaw loj hlob rau nruab nrab. chain.
Branching effect - chemical crosslinking -tsim ntawm covalent bonds ntawm chains. Crosslinking nyiam nce Tg thiab nce lub zog thiab toughness. Ntawm lwm cov kev siv, cov txheej txheem no yog siv los ntxiv dag zog rau cov roj hmab hauv cov txheej txheem hu ua vulcanization, uas tso siab rau cov sulfur crosslinking. Cov log tsheb, piv txwv li, muaj lub zog siab thiab sib txuas sib txuas kom txo tau cov pa tawm thiab ua kom lawv cov kav ntev. Cov roj hmab, ntawm qhov tod tes, tsis yog kev sib txuas, uas tso cai rau cov roj hmab tev tawm thiab tiv thaiv kev puas tsuaj rau daim ntawv. Lub polymerization ntawm ntshiab sulfur ntawm qhov kub thiab txias kuj piav qhia vim li cas nws thiaj li khov rau ntawm qhov kub siab dua hauv lub xeev molten.
Grid
Ib tug hla-txuas polymer molecule yog hu ua P-network. Qhov siab txaus crosslink-rau-strand piv (C) tuaj yeem ua rau tsim kom muaj lub npe hu ua infinite network lossis gel, uas txhua ceg txuas nrog tsawg kawg ib leeg.
Nrog rau kev txhim kho txuas ntxiv ntawm kev ua neej nyob polymerization, kev sib txuas ntawm cov tshuaj no nrog cov qauv tshwj xeeb tau yooj yim dua. Architectures xws li hnub qub, zuag, txhuam, dendronized, dendrimers thiab nplhaib polymers yog ua tau. Cov chemical compounds nrog complex architecture tuaj yeem ua ke los ntawm kev siv tshwj xeeb xaiv cov khoom sib txuas, los yog ua ntej los ntawm kev sib txuas cov kab sib txuas uas ua rau muaj kev cuam tshuam ntxiv rau kev sib txuas. Knotted Ps muaj ntau yam intramolecular cyclizationtxuas hauv ib P-chain (PC).
Branching
Feem ntau, qhov siab dua ntawm cov ceg ntoo, qhov sib npaug ntawm cov saw hlau polymer ntau dua. Lawv kuj cuam tshuam cov saw entanglement, muaj peev xwm swb dhau ib leeg, uas ua rau muaj feem cuam tshuam rau lub cev ntau. Cov hlua ntev ntev tuaj yeem txhim kho lub zog ntawm polymer, toughness, thiab iav hloov pauv kub (Tg) vim qhov nce ntawm cov ntawv cog lus hauv cov khoom sib xyaw. Ntawm qhov tod tes, tus nqi random thiab luv luv ntawm Z tuaj yeem txo lub zog ntawm cov khoom vim yog kev ua txhaum ntawm lub peev xwm ntawm cov saw hlau sib cuam tshuam nrog ib leeg lossis crystallize, uas yog vim yog cov qauv ntawm cov khoom siv polymer.
Ib qho piv txwv ntawm cov txiaj ntsig ntawm cov ceg ntawm lub cev muaj zog tuaj yeem pom hauv polyethylene. High density polyethylene (HDPE) muaj ib tug tsawg degree ntawm branching, yog kuj nruj thiab siv nyob rau hauv lub tsim ntawm, piv txwv li, mos mos vests. Ntawm qhov tod tes, low density polyethylene (LDPE) muaj qhov tseem ceeb ntawm cov hlua ntev thiab luv luv, yog qhov hloov tau yooj yim, thiab siv rau hauv cov ntawv thov xws li cov yeeb yaj kiab yas. Cov qauv tshuaj ntawm cov polymers nyiam cov kev siv no xwb.
Dendrimers
Dendrimers yog ib qho tshwj xeeb ntawm cov ceg ntoo polymer, qhov twg txhua chav monomeric kuj yog ceg taw tes. Qhov no zoo li txo qis cov saw hlau sib xyaw ua ke thiab crystallization. Ib qho kev sib raug zoo, lub dendritic polymer, tsis zoo kawg nkaus branched tab sis muaj cov khoom zoo sib xws rau dendrimersvim lawv kawm ntawv siab heev.
Qib ntawm cov txheej txheem nyuaj uas tshwm sim thaum lub sijhawm polymerization yuav nyob ntawm qhov ua haujlwm ntawm cov monomers siv. Piv txwv li, nyob rau hauv cov dawb radical polymerization ntawm styrene, qhov sib ntxiv ntawm divinylbenzene, uas muaj ib tug functionality ntawm 2, yuav ua rau lub tsim ntawm branched P.
Engineering polymers
Engineered polymers suav nrog cov khoom siv ntuj xws li roj hmab, hluavtaws, yas thiab elastomers. Lawv yog cov khoom siv raw zoo heev vim tias lawv cov qauv tuaj yeem hloov pauv thiab hloov kho los tsim cov ntaub ntawv:
- nrog ntau yam ntawm cov khoom siv kho tshuab;
- nyob rau hauv ntau yam xim;
- nrog cov khoom sib txawv pob tshab.
qauv molecular ntawm polymers
A polymer yog tsim los ntawm ntau cov molecules yooj yim uas rov ua cov txheej txheem hu ua monomers (M). Ib qho molecule ntawm cov khoom no tuaj yeem muaj ntau pua mus rau lab ntawm M thiab muaj cov kab, ceg lossis cov qauv sib txuas. Covalent daim ntawv cog lus tuav cov atoms ua ke thiab cov ntawv cog lus thib ob ces tuav cov pab pawg ntawm cov saw hlau ua ke los tsim cov khoom siv. Copolymer yog hom tshuaj no, muaj ob lossis ntau hom sib txawv ntawm M.
A polymer yog cov khoom siv organic, thiab lub hauv paus ntawm txhua yam khoom siv yog cov saw hlau ntawm carbon atoms. Ib tug carbon atom muaj plaub electrons nyob rau hauv nws lub plhaub sab nrauv. Txhua yam ntawm cov valence electrons tuaj yeem tsim covalentib daim ntawv cog lus nrog lwm cov pa roj carbon atom lossis nrog txawv teb chaws atom. Tus yuam sij rau kev nkag siab txog cov qauv ntawm cov polymer yog tias ob lub atoms tuaj yeem muaj txog li peb daim ntawv cog lus sib koom thiab tseem muaj kev sib raug zoo nrog lwm cov atoms. Cov ntsiab lus feem ntau pom muaj nyob rau hauv cov tshuaj no thiab lawv cov lej valence yog: H, F, Cl, Bf thiab kuv nrog 1 valence electron; O thiab S nrog 2 valence electrons; n nrog 3 valence electrons thiab C thiab Si nrog 4 valence electrons.
Piv txwv ntawm polyethylene
Lub peev xwm ntawm cov molecules los tsim cov saw ntev yog qhov tseem ceeb rau kev ua cov polymer. Xav txog cov khoom siv polyethylene, uas yog tsim los ntawm ethane gas, C2H6. Ethane roj muaj ob lub pa roj carbon atom nyob rau hauv cov saw, thiab txhua tus muaj ob valence electrons nrog rau lwm yam. Yog tias ob lub ethane molecules raug sib koom ua ke, ib qho ntawm cov pa roj carbon monoxide nyob rau hauv txhua lub molecule yuav tawg, thiab ob lub molecules tuaj yeem koom nrog cov pa roj carbon-carbon. Tom qab ob meters txuas nrog, ob lub valence electrons dawb nyob ntawm txhua qhov kawg ntawm cov saw txuas rau lwm cov meters lossis P-strands. Cov txheej txheem muaj peev xwm txuas ntxiv mus txuas ntxiv cov meters thiab cov polymers ua ke kom txog thaum nws raug tso tseg los ntawm kev sib ntxiv ntawm lwm cov tshuaj (terminator) uas ua rau muaj cov ntawv cog lus ntawm txhua qhov kawg ntawm cov molecule. Qhov no yog hu ua linear polymer thiab yog lub tsev thaiv rau cov thermoplastic compounds.
Cov saw hlau polymer feem ntau pom nyob rau hauv ob qhov loj me, tab sis nws yuav tsum tau muab sau tseg tias lawv muaj peb-dimensional polymer qauv. Txhua qhov txuas yog ntawm kaum ntawm 109 ° rauTom ntej no, thiab yog li cov pa roj carbon monoxide khiav los ntawm qhov chaw zoo li ib txoj hlua sib tw ntawm TinkerToys. Thaum siv hluav taws xob, cov chains no ncab, thiab elongation P tuaj yeem ua tau ntau txhiab zaus ntau dua li cov qauv crystalline. Cov no yog cov yam ntxwv ntawm cov polymers.
