Cov Lus Nug Piv Txwv thiab Kev Sib Tham Txog Kev Txhais thiab Cov Qauv ntawm Polymers
Cov polymers yog cov tshuaj macromolecular uas muaj cov chav rov ua dua hu ua monomers. Hauv chemistry, polymers ua lub luag haujlwm tseem ceeb hauv ntau yam kev siv, los ntawm kev lag luam yas thiab textile mus rau biomedicine. Tsab xov xwm no yuav tham txog kev txhais ntawm polymers thiab lawv cov qauv, nrog rau muab ntau qhov piv txwv teeb meem thiab kev daws teeb meem los ua kom peb nkag siab tob txog lub tswv yim no.
Kev Nkag Siab Txog Cov Polymers
Lo lus polymer los ntawm cov lus "poly," txhais tau tias ntau, thiab "mer," txhais tau tias ib feem lossis ib feem. Yog li, qhov tseeb, polymer yog ib lub molecule loj uas muaj ntau lub units me me hu ua monomers. Cov monomers no sib xyaw ua ke los ntawm kev sib xyaw ua ke los tsim cov qauv saw ntev.
Piv txwv ntawm Cov Polymers Ntuj thiab Cov Khoom Siv Ua Los Ntawm Tshuaj:
1. Cov Khoom Siv Polymer Ntuj:
- Cellulose: Muaj cov glucose monomers hauv cov phab ntsa cell ntawm cov nroj tsuag.
- Cov protein: Muaj cov amino acids ua monomers.
– Roj hmab ntuj: Ua los ntawm isoprene polymer.
2. Cov Khoom Siv Polymer Ua Los Ntawm:
– Polyethylene (PE): Siv rau hauv kev tsim cov hnab yas.
– Polypropylene (PP): Siv rau hauv ntau yam thawv yas thiab cov khoom siv hauv tsev.
– Polyvinyl chloride (PVC): Cov khoom siv rau cov kav dej thiab cov khoom siv kho mob.
Cov Qauv Polymer
Raws li cov qauv, cov polymers muaj peev xwm muab faib ua ntau hom raws li lawv cov duab thiab kev teeb tsa saw. Cov hauv qab no yog cov hom qauv polymer:
1. Cov Qauv Tawm:
– Cov polymers uas muaj cov qauv kab ncaj muaj cov saw ntev, ncaj ntawm cov monomers sib txuas. Piv txwv li suav nrog polyethylene thiab polystyrene.
2. Cov Qauv Ceg:
– Cov polymers uas muaj ceg muaj ib txoj saw hlau loj nrog cov ceg luv luv tawm ntawm txoj saw hlau loj. Ib qho piv txwv yog polypropylene uas muaj ceg.
3. Cov Qauv Network (Txuas):
– Cov polymers no muaj cov saw hlau uas sib txuas ua ke los ua ib lub network peb-seem. Piv txwv li suav nrog epoxy resin thiab bakelite.
4. Cov qauv Copolymer thaiv:
– Muaj ob lossis ntau hom monomers uas tau teeb tsa ua ib qho kev txiav txim thiab tsim cov blocks tshwj xeeb raws li cov saw polymer. Ib qho piv txwv yog SBS (styrene-butadiene-styrene).
Cov Lus Nug Piv Txwv thiab Kev Sib Tham
Yuav kom nkag siab zoo dua txog lub ntsiab lus thiab cov qauv ntawm cov polymers, ntawm no yog qee cov lus nug piv txwv thiab lawv cov kev sib tham.
Lo lus nug thib 1:
Lo lus nug: Hais peb qhov sib txawv tseem ceeb ntawm cov thermoplastic thiab thermoset polymers!
Kev Sib Tham:
- Thermoplastics:
- Yuav yaj thaum sov thiab tawv thaum txias, cov txheej txheem no tuaj yeem rov ua dua ntau zaus.
- Cov qauv molecular yog linear lossis me ntsis branched.
– Piv txwv li: Polyethylene (PE), Polypropylene (PP).
- Thermoset:
- Raug kev hloov pauv tshuaj lom neeg uas tsis tuaj yeem rov qab tau thaum raug cua sov, thawj qhov cua sov ua rau lawv tawv, tab sis tom qab ntawd lawv tsis tuaj yeem yaj dua.
- Muaj ib lub qauv network peb sab uas tsis hloov pauv tau.
– Piv txwv li: Epoxy resin, bakelite.
Lo lus nug thib 2:
Lus Nug: Yuav ua li cas txiav txim siab qhov nruab nrab ntawm qhov hnyav molecular (Mn) thiab qhov hnyav nruab nrab ntawm qhov hnyav molecular (Mw) ntawm cov polymer?
Kev Sib Tham:
- Tus lej nruab nrab ntawm qhov hnyav molecular (Mn):
– Mn = Σ(Ni Mi) / ΣNi
- Qhov twg Ni yog tus naj npawb ntawm cov molecule nrog molecular hnyav Mi.
- Qhov hnyav nruab nrab ntawm qhov hnyav molecular (Mw):
– Mw = Σ(Ni Mi^2) / Σ(Ni Mi)
- Mw muab qhov hnyav dua rau cov molecule uas muaj qhov hnyav molecular siab dua thiab feem ntau loj dua Mn.
Lo lus nug thib 3:
Lo lus nug: Txheeb xyuas hom polymer los ntawm cov lus hauv qab no: "Cov polymer no muaj cov qauv yooj yim uas muaj cov chav rov ua dua ntawm ethylene thiab muaj cov khoom yooj ywm dua."
Kev Sib Tham:
- Raws li cov lus hais tias cov polymer muaj cov chav rov ua dua ntawm ethylene thiab muaj cov khoom yooj ywm, cov polymer no yuav yog Polyethylene (PE).
Lo lus nug thib 4:
Lus Nug: Piav qhia txog cov txheej txheem ntawm kev ntxiv polymerization thiab condensation polymerization los ntawm kev muab piv txwv rau txhua yam.
Kev Sib Tham:
- Kev ntxiv polymerization:
- Cov txheej txheem uas cov monomers nrog ob daim ntawv cog lus (piv txwv li, alkenes) sib xyaw ua ke yam tsis muaj kev tsim cov khoom seem.
- Piv txwv: Polyethylene los ntawm ethylene.
– n(C2H4) → [-CH2-CH2-]n
- Kev sib xyaw ua ke polymerization:
- Ib qho txheej txheem uas ob lossis ntau dua monomers nrog ob pawg sib txawv ua haujlwm sib txawv, tsim cov polymer thiab tsim cov khoom seem xws li dej lossis methanol.
– Piv txwv li: Nylon-6,6 los ntawm hexamethylenediamine thiab adipic acid.
H2N-(CH2)6-NH2 + HOOC-(CH2)4-COOH → [-NH-(CH2)6-NH-CO-(CH2)4-CO-]n + 2nH2O
Lo lus nug thib 5:
Lus Nug: Lub ntsiab lus ntawm regiospecificity hauv polymerization yog dab tsi thiab nws cuam tshuam li cas rau cov qauv ntawm cov polymer?
Kev Sib Tham:
- Kev tshwj xeeb ntawm thaj chaw:
- Regiospecificity hais txog qhov tsis tu ncua uas cov monomers koom nrog hauv cov saw hlau, txiav txim siab qhov kev teeb tsa ntawm cov tshuaj sib txuas.
- Cov polymers muaj peev xwm muaj cov qauv isotactic (txhua tus substituents nyob rau ib sab ntawm cov saw), syndiotactic (substituents hloov pauv hauv qhov chaw), lossis atactic (substituents raug faib tawm random).
– Piv txwv li: Polypropylene tuaj yeem tsim ua isotactic PP, syndiotactic PP, lossis atactic PP uas cuam tshuam rau nws cov khoom siv lub cev, xws li crystallinity thiab melting point.
Xaus
Cov polymers muaj ntau yam qauv thiab cov khoom sib txawv, nyob ntawm hom monomer thiab lawv tau teeb tsa li cas hauv cov saw polymer. Kev nkag siab txog cov qauv thiab cov qauv ntawm cov polymers, nrog rau lawv tau synthesized li cas, yog qhov tseem ceeb rau lawv cov ntawv thov hauv kev lag luam thiab thev naus laus zis. Cov kev tawm dag zog thiab kev sib tham tau muab kuj pab txhawb cov ntsiab lus tseem ceeb hauv polymer chemistry. Nrog kev nkag siab zoo, peb tuaj yeem siv cov polymers hauv ntau yam kev siv tshiab yav tom ntej.
