Surfactant-free Emulsion Polymerization Ntawm Vinylidene Fluoride Mediated Los ntawm RAFT / MADIX Reactive Poly (ethylene Glycol) Polymer Chains

Thov hu rau oscar.xiao@wecistanche.com yog xav paub ntxiv

Taw qhia

Poly (vinylidene fluoride) yog ib qho semicrystalline fluoropolymer nrog cov thermal thiab mechanical zog ua ke nrog cov tshuaj zoo heev, UV thiab abrasion tsis kam, thiab electrochemical thiab oxidation stability. Nws yog li pom cov appli-cations hauv ntau qhov chaw, xws li sab nraum zoov txheej, lithium-ion roj teeb, photovoltaics, porous membranes, cables, thiab cov xov hlau, tsuas yog rau npe rau ob peb lub hlis xwb. 1-3 PVDF yog industrially tsim los ntawm aqueous dawb radical emulsion thiab suspension polymerization. Txawm li cas los xij, VDF emulsion polymerization yog cov ntaub ntawv tsis zoo nyob rau hauv cov ntaub ntawv qhib hais txog kinetics thiab cov txheej txheem.{4-'Qhov no tej zaum yog los ntawm qhov tseeb tias nws yuav tsum tau muab cov kev siv cov tshuab hluav taws xob siab ua haujlwm nrog cov roj VDF, cov siab reactivity ntawm propagating radicals, thiab ua rau complex lub cev chemistry ntawm no dawb radical polymerization thaum ua nyob rau hauv dej. Tsis tas li ntawd, VDF emulsion polymerization yuav tsum muaj surfactant kom ruaj khov PVDF hais. Txawm li cas los xij, tsis tshua muaj molar mass surfactants tuaj yeem muaj qhov tsis zoo rau cov khoom kawg ntawm cov khoom vim lawv tuaj yeem txav tau nrog lub sijhawm.8 Ib txoj hauv kev zoo nkauj heev ntawm kev zam kev siv cov molecules no yog siv cov reactive hydrophilic macro-molecules, uas tuaj yeem koom nrog. "Poly (ethylene glycol) (PEG)-raws li molecules feem ntau yog siv los ua stabilizers hauv kev lag luam latex. Tseeb, steric stabilization muab los ntawm PEG chains tuaj yeem ua kom cov khoom ruaj khov tiv thaiv khov-thaw, shear, lossis hauv muaj polyelectrolyte.cistancheLub neej txuas ntxiv 10 Nyob rau hauv qhov kev hwm, PEG-raws li macro-molecules koom nrog cov pab pawg reactive xws li macromonomers, 11-13 macroinitiators, 14-16 thiab macromolecular chain transfer agents (macroCTA)10,17-20 tau tshaj tawm. rau polymerization nyob rau hauv dispersed media.

Thov nias ntawm no kom paub ntxiv

Txhawm rau daws cov teeb meem cuam tshuam nrog kev siv fluorinated thiab molar surfactants tsawg, ntau yam poly (ethylene glycol) (PEG) raws li molecules tau siv thiab piav qhia hauv cov ntaub ntawv patent ntsig txog VDF emulsion polymerization, tab sis feem ntau yog rau cov synthesis ntawm poly (vinylidene). fluoride-co-hexafluoropropylene). Kuj ceeb tias, unreactive hydrosoluble PEG-OH chains ib leeg kuj tseem tuaj yeem ua tus precursors ntawm stabilizers thaum lub sij hawm emulsion polymerization txheej txheem los ntawm kev muab cov latexes ruaj khov. Txawm li cas los xij, cov ntaub ntawv patent uas tau hais los saum toj no tsis tau muab cov ntsiab lus ntawm kev lag luam PEG-OH tuaj yeem ua rau muaj kev ruaj ntseg. Txawm li cas los xij, VDF dawb radical polymerization yog paub tias yuav ua rau cov kev hloov pauv hloov mus rau cov monomer, rau cov polymer (ntawm inter-(ntev saw branching) los yog intramolecular (luv saw branching) hloov cov tshuaj tiv thaiv) thiab cov saw hloov cov tshuaj xws li ethyl. acetate.45726 Tseeb tiag, labile hydrogen atoms nqa los ntawm cov tsiaj no tuaj yeem pom los ntawm cov reactive PVDF heev propagating macroradicals ua rau cov radicals tshiab, uas yuav tsum pib tshiab PVDF polymer chains. Nyob rau hauv cov ntsiab lus ntawd, cov saw hlau hloov pauv tshwm sim raws li PEG-OH chains thaum lub sij hawm emulsion (co)polymerization ntawm VDF tuaj yeem tsim luv PVDF grafts raws PEG chains thiab ua rau hauv qhov chaw tsim ntawm amphiphilic stabilizer.

Cistanche tuaj yeem tiv thaiv kev laus

Cov kev nce qib ua tiav hauv polymer synthesis los ntawm reversible-deactivation radical polymerization (RDRP) cov tswv yim nyob rau hauv 20 xyoo dhau los tau thawb mus rau pem hauv ntej kev siv cov nyob hydro-philic polymers rau synthesis ntawm polymer hais nyob rau hauv emul-sion. Qhov tseeb, cov lus txhais tau zoo thiab muaj zog macromolecules tuaj yeem txuas ntxiv nrog hydrophobic monomer ncaj qha rau hauv dej uas ua rau muaj qhov tsim ntawm amphiphilic block copolymers uas ib txhij sib sau ua ke rau hauv polymer nanoparticles. Cov txheej txheem, coined polymerization-induced self-assembly (PISA), tuaj yeem siv rau cov txheej txheem polymerization sib txawv, 'tab sis feem ntau tau kawm ib qho undoubtedly tseem reversible ntxiv-fragmentation saw hloov (RAFT) / macromolecular tsim los ntawm kev sib hloov ntawm xanthates (MADIX) .3132PISA kuj muaj feem xyuam rau hauv dispersion polymerization (qhov twg cov tub ntxhais txoj kev monomer yog soluble nyob rau hauv lub continuous theem), ob qho tib si nyob rau hauv aqueous thiab organic media.31, 33-35 Li no, dej-soluble chains tau los ntawm RAFT polymerization ntawm hydrophilic monomers los yog los ntawm kev hloov tshuaj lom neeg ntawm preformed polymers tuaj yeem ua raws li tus neeg sawv cev hloov chaw (thiab hu ua macroCTA) tsim cov stabilizers thaum lub sij hawm emulsion polymerization los ntawm kev tsim amphiphilic block copolymer nyob rau hauv qhov chaw. PEG-raws li macroCTA yog li tau tshaj tawm rau PISA synthesis ntawm ntau yam hais, 36-51 tab sis rau qhov zoo tshaj plaws ntawm peb cov kev paub, yeej tsis rau PVDF latexes.

Siv cov nyiaj tsawg heev ntawm cov macroCTA hauv ib qho emulsion polymerization zoo li yog ib qho kev lag luam zoo rau kev nkag mus rau surfactant-free latexes. Nyob rau hauv tas li ntawd, tus nqi pib ntawm macroCTA yog xws li tias txaus amphiphilic block copolymer yog tsim nyob rau hauv situ los xyuas kom meej stabilization ntawm cov hais uas ua ib txhij los ntawm emulsion polymerization. Txoj hauv kev no yog qhov txaus nyiam heev rau kev sib koom ua ke ntawm cov khoom lag luam muaj feem xyuam rau cov khoom siv polymer latexes, piv txwv li hauv cov xim thev naus laus zis, qhov twg feem ntawm cov hom hydrophilic nyob rau hauv txheej txheej kawg yuav tsum nyob qis. Siv cov tswv yim no, peb tau npaj cov ntsiab lus siab siab (ca. 40 wt feem pua) polymer latexes suav nrog tsawg dua 2 wt feem pua ​​​​ntawm cov hom hydrophilic nrog poly (vinylidene chloride) 5253 thiab polyacrylics. particle nto ntawm qhov kawg ntawm emulsion polymerization, cov latexes tau coj mus rau cov yeeb yaj kiab polymer nrog kev txhim kho dej thaiv cov khoom. Lub tswv yim tseem ua tiav rau kev sib txuas ntawm poly (vinyl acetate-co-ethylene).

Nyob rau hauv daim ntawv tam sim no, emulsion polymerization ntawm VDF yog thawj zaug nyob rau hauv lub xub ntiag ntawm hydrophilic RAFT / MADIX macroCTA. Txhawm rau kom nkag siab meej txog lub luag haujlwm ntawm cov saw hlau thiothiocarbonylated kawg hauv cov txheej txheem,

PEG-OH chains thiab lawv cov analogs nruab nrog dithiocarbamate (xanthate) moiety (PEG-X) tau raug soj ntsuam los ntawm kev sib piv ntawm kev sib xyaw ntawm surfactant-free synthesis ntawm PVDF latexes. Ob peb qhov tsis sib txawv xws li PEG molar mass thiab macroCTA qauv (mono piv rau bifunctional xanthate) (Scheme 1).

Cov khoom siv sim

Poly（ethylene glycol）methyl ether（PEG-OH, Mn ≈2000 and 750 g moll, Aldrich), a,o-dihydroxy poly(ethylene glycol)（HO-PEG-OH,Mn ≈2050 g mol-1,Aldrich）,poly（ethylene glycol）methyl ether thiol（PEG-SH,Mn ≈2000 g mol-1,Aldrich),1,4-dioxane (Alfa Aesar,99.8%), triethylamine (Aldrich,99.5%),2-bromopropionyl bromide (Aldrich,97%), sodium hydrogen carbonate (NaHCO3, Aldrich,99.7%), ammonium chloride (NHACl, Aldrich, 99.5%), dichloromethane (Aldrich, 99.8%), magnesium sulfate (Aldrich, >99.9 feem pua), O-ethyl xanthic acid (Aldrich, 96 feem pua), poov tshuaj per-sulfate (KPS, Aldrich, 99 feem pua), sodium acetate (Aldrich, 99 feem pua) tau siv raws li tau txais. Vinylidene fluoride (VDF) tau ua siab zoo los ntawm Arkema (Pierre Benite, Fabkis) thiab siv raws li tau txais. Dej tau deionized nrog PureLab system (Purelab Classic UV, Elga LabWater). Tetrahydrofuran (THF, HPLC, stabilized / BHT, Sigma Aldrich) tau siv rau SEC analyses.

Cov txheej txheem

Synthesis ntawm poly (ethylene glycol)-xanthate (PG-X) macroCTA. PEG-X tau tsim los raws li cov txheej txheem uas twb muaj lawm nrog kev hloov kho me me.67 Poly(ethylene glycol)methyl ether (Mn=2000 g mol-1)(20 g; {{13} }. 2-Bromopropionyl bromide (4.97 g; 0.023 mol) tau ntxiv dropwise rau qhov sib tov muab tso rau hauv da dej dej khov. Cov tom kawg raug tshem tawm tom qab ua tiav cov reagent ntxiv thiab cov tshuaj tiv thaiv sib xyaw yog nplawm rau 16 teev.ceg nzTom qab kev lim dej ntawm cov ntsev seem, cov theem ntawm cov organic tau ntxuav nrog cov dej saturated aqueous ntawm NHaCl (1 × 15 mL), NaHCO3 (1 × 15 mL) thiab dej (1 × 15 mL). Lub sijhawm ntxuav cov organic tau qhuav nrog magnesium sulfate thiab cov kuab tshuaj evaporated hauv lub tshuab nqus tsev. Cov khoom tau txais (15.41 g; 0.0066 mol) tau yaj hauv dichloromethane (55 mL). Tom qab ntawd, O-ethyl xanthic acid (3.17 g; 0.0198 mol) tau ntxiv los ntawm me me hauv qab nplawm.Tom qab ntawd cov tshuaj tiv thaiv sib xyaw yog nplawm ib hmos. KBr ntsev raug tshem tawm los ntawm kev pom. Cov sib tov yog ntxuav nrog ib tug saturated aqueous tov ntawm NHaCl (2 × 15 mL) thiab NaHCO3 (2 × 15 mL) ces dej (1 × 15 mL). Lub sijhawm ntxuav cov organic tau qhuav nrog magnesium sulfate thiab cov kuab tshuaj evaporated hauv lub tshuab nqus tsev. Thaum kawg, cov polymer yog precipitated nyob rau hauv txias roj av ether thiab qhuav nyob rau hauv lub nqus tsev vacuum. Lub 'H NMR spec-trum ntawm cov khoom kawg yog pom nyob rau hauv Fig. S1,t thaum Fig. S2t qhia cov chromatogram tau los ntawm SEC tsom xam hauv THF (Mn,sEc=2300g mol-1;D =1.03/PS cov qauv).

H NMR (400 MHz, CDCl3, δ)∶ 4.6(q,2H, O-CH2-CH3); 4.4 (q,1H,CH-S); 4.3(t,2H,CH{{15}) }CH2-CH2-O);3.75-3.5(s,180H, (CH-CH-O)n); 3.35(s,3H,CH-O) ;1.6(d,3H,CHCH:1.4(t, 3H, CH2-CH3).

Cov txheej txheem tib yam tau ua raws li lwm yam kev lag luam PEG-OH (Mn=750 g mol-'), ua rau PEG-X nrog Mn, sec =1300 g mol-2 thiab D{{6 }}.10. Lub 'H NMR spectrum ntawm cov khoom kawg yog pom nyob rau hauv Fig. S3, t thaum Fig. S4t qhia cov chromatogram tau los ntawm SEC tsom xam hauv THF siv cov qauv PS.

1H NMR (400 MHz, (CD3)2CO, δ)∶ 4.6 ​​(q,2H, O-CH2-CH3); 4.4 (q,1H,CH-S); 4.3(t,2H,CH{ {17}}CH2-O);3.8-3.5(s,70H, (CH-CH-O)m)3.3(s,3H,CH-O);1.55(d ,3H,CH-CH-CH3); 1.4 (t,3H,CH2-CH3).

Synthesis ntawm di-functional poly (ethylene glycol)-xanthate (X-PEG-X) macroCTA tus neeg sawv cev

a,o-Dihydroxy poly(ethylene glycol)(Mn=2050 g mol-1)(20 g;0.01 mol) tau yaj nyob rau hauv dichloromethane (8{27}} mL) nyob rau hauv ib puag ncig hauv qab hwj thiab triethylamine (5.46 g; 0.054 mol) tau ntxiv. Cov sib tov tau ntxiv dropwise hauv 2-bromopro-pionyl bromide (9.94 g; 0.046 mol) tso rau hauv da dej dej khov. Lub hwj tau muab tshem tawm los ntawm cov dej khov nab kuab tom qab sib tov sib xyaw thiab cov tshuaj tiv thaiv sib xyaw ua ke rau 16 teev. Tom qab kev lim dej ntawm cov ntsev seem, cov theem ntawm cov organic yog ntxuav nrog cov dej saturated aqueous ntawm NHaCl (1 × 15 mL), NaHCO3 (1 × 15 mL) thiab dej (1 × 15 mL).The ntxuav organic theem yog ces qhuav nrog magnesium. sulfate thiab cov kuab tshuaj evaporated hauv lub tshuab nqus tsev. Cov khoom tau txais (16.20 g; 0.0079 mol) tau yaj hauv dichloromethane (55 mL). Tom qab ntawd, O-ethyl xanthic acid (7.60 g; 0.0474 mol) tau ntxiv los ntawm me me hauv qab nplawm. Cov tshuaj tiv thaiv sib tov yog nplawm ib hmos. KBr ntsev raug tshem tawm los ntawm kev pom. Cov sib tov yog ntxuav nrog ib tug saturated aqueous tov ntawm NH4Cl (2 × 15 mL) thiab NaHCO3 (2 × 15 mL) ces dej (1 × 15 mL). Lub sijhawm ntxuav cov organic tau qhuav nrog magnesium sulfate thiab cov kuab tshuaj evaporated hauv lub tshuab nqus tsev. Tom qab ntawd lub polymer yog preci-pitated nyob rau hauv txias petroleum ether. Thaum kawg, cov khoom tau qhuav hauv lub tshuab nqus tsev. Lub 'H NMR spectrum ntawm cov khoom kawg yog pom nyob rau hauv Fig. S5,t thaum Fig. S6t qhia cov chromatogram tau los ntawm SEC tsom xam hauv THF (Mn,sec=3420 g mol-';D=1 .10/PS cov qauv).

1H NMR (400 MHz, CDCl3, §): 4.6(q,2H, O-CH2-CH3); 4.4 (q,1H,CH-S);4.3(t,2H,CH{{16}) }CH2-CH2-O);3.75-3.5(s,220H, (CH2-CH2-O)n);1.6( d,3H,CHCH3); 1.4(t,3H,CHZ-CH3).

Emulsion polymerization ntawm vinylidene fluoride

VDF emulsion polymerizations tag nrho tau ua tiav hauv 50 mL stainless hlau autoclave nruab nrog nitrogen inlet, tus pas ntsuas kub, tus neeg kho tshuab stirrer thiab lub siab sensor. Nyob rau hauv cov txheej txheem polymerization raug, KPS, PEG-OH (los yog PEG-X lossis X-PEG-X), sodium acetate siv los ua tsis muaj dej thiab dej deionized (25 mL) tau qhia hauv lub reactor. Qhov nruab nrab yog deox-ygenated nyob rau hauv nitrogen rau 30 min. VDF roj tau muab tso rau hauv lub reactor kom txog rau thaum lub hom phiaj siab (30 bar).Tam sim ntawd tom qab, qhov chaw txhaj tshuaj raug kaw thiab nruab nrab rhuab ntawm qhov kub thiab txias ntawm 80 degree. Thaum kawg ntawm qhov kev sim, lub reactor tau txias nrog dej khov. Thaum qhov kub hauv lub reactor poob qis dua 25 degree, qhov seem ntawm lub siab tau ua tib zoo tso tawm, thiab cov latex tau txais los ntawm kev sib xyaw ua ke, thiab ntsuas qhov loj me. Ib feem ntawm cov tau latex tau qhuav rau cov ntsiab lus khib nyiab (SC) ntsuas, uas tom qab rho tawm ntawm hom nonpolymeric muab cov ntsiab lus polymer (PC, feem pua). Tom qab ntawd cov polymer qhuav tau siv rau polymer characterization los ntawm DSC.

Rau kev ntsuas ntsuas, VDF emulsion polymerization tau ua nyob rau hauv 4 L high-pressure stainless hlau autoclave nruab nrog ib tug nitrogen inlet, tus pas ntsuas kub, ib tug neeg kho tshuab stirrer thiab lub siab sensor. Qhov ntsuas kub ntawm lub tshuab hluav taws xob tau ntsuas los ntawm lub thermocouple J Atex, tiv thaiv los ntawm lub raj hlau thiab muab tso rau hauv lub reactor. Roj (Ultra 350, Lauda) circulating nyob rau hauv lub tsho yog siv los tswj lub reactor kub (tsis muaj roj circulated nyob rau hauv lub cover thiab hauv qab). Lub inlet thiab qhov hluav taws xob kub ntawm cov roj circulating nyob rau hauv lub reactor tsho yog ntsuas nrog ib tug platinum kuj Pt100. Lub reactor siab tau soj ntsuam nrog lub siab sensor Atex (hom PA-23EB, Keller). Hauv cov txheej txheem polymerization raug, KPS, PEG-OH (los yog PEG-X), buffer (sodium acetate) thiab dej deionized (2 L) tau nkag rau hauv lub reactor. Qhov nruab nrab yog deoxygenated nyob rau hauv nitrogen rau 30 min. VDF roj tau muab tso rau hauv lub reactor kom txog thaum lub hom phiaj siab (30 bar). Tam sim ntawd tom qab, qhov chaw txhaj tshuaj raug kaw thiab qhov nruab nrab rhuab ntawm qhov ntsuas kub ntawm 80 degree.cistanche noov lojThaum qhov kub hauv lub reactor poob qis dua 25 degree, qhov seem siab tau ua tib zoo tso tawm, thiab cov latex tau muab khaws cia, thiab ntsuas qhov loj me me.Ib feem ntawm cov tau latex tau qhuav rau SC ntsuas, uas tom qab rho tawm ntawm cov tsis- polymeric hom muab rau PC. Tom qab ntawd cov polymer qhuav tau siv rau polymer characterization los ntawm DSC.

Cim xeeb

Nuclear magnetic resonance (NMR).NMR yog siv los txiav txim-mine lub macroCTA purity. Cov tshuaj tau yaj nyob rau hauv CDCla los yog (CD3)2CO ntawm ib tug concentration nyob ib ncig ntawm 30 mg g-1.Cov spectra raug kaw nyob rau hauv chav tsev kub nrog ib tug high-resolu-tion spectrometer (Bruker Avance III 400) siv ib tug sojntsuam BBFO 5 mm. Kev hloov tshuaj lom neeg raug ntsuas raws li qhov siab tshaj ntawm CHCl3.

Gravimetric tsom xam. Gravimetric tsom xam tau siv los txiav txim-mine cov ntsiab lus khib nyiab (SC) thaum lub sij hawm emulsion polymerization.

Loj cais chromatography (SEC). SEC hauv THF tau siv los txiav txim siab molar pawg ntawm PEG macroCTAs. Lub polymer concentration nyob nruab nrab ntawm 1 thiab 5 mg L-¹ thiab tom qab dissolution cov qauv raug lim los ntawm 0.45 μm pore membranes. Cov kev soj ntsuam tau ua nyob rau ntawm 40 degree nrog tus nqi ntws ntawm 1 mL min-l.Qhov kev sib cais tau ua nrog peb kab los ntawm Malvern Instruments [T6000 General Mixed Org (300 × 8mm)]. Lub kaw lus (Viscotek TDA305) tau nruab nrog lub ntsuas ntsuas qhov ntsuas (RI) ntsuas ({12}} nm) thiab lub ntsuas UV. Cov chromatograms tau txais tau kho nrog software OmniSEC 4.6. Qhov kev sim tus lej nruab nrab (Mn) thiab qhov hnyav nruab nrab (Mw) molar masses nrog rau qhov sib txawv (D=Mw/Mn) tau muab los ntawm RI teeb liab uas siv lub calibration nkhaus raws li cov qauv polystyrene (PS) los ntawm Polymer Laboratories.

Dynamic light scattering (DLS).Z-nruab nrab txoj kab uas hla (D2) ntawm cov latex hais thiab qhov dav ntawm qhov loj tis (qhia los ntawm polydispersity Performance index, PdI) tau ntsuas ntawm 25 degree nrog ib tug scattering kaum sab xis ntawm 173 degree siv Zetasizer. Nano Series (Nano ZS) los ntawm Malvern Instrument. Ua ntej ntsuas ntsuas, cov qauv tau diluted nrog dej deionized. Tus naj npawb ntawm cov khoom ib liter ntawm latex, Np (L-') raug xam raws li qhov sib npaug hauv qab no:

qhov twg Np yog tus naj npawb ntawm cov khoom (L-1), PC cov ntsiab lus polymer (g L-1), Dz qhov nruab nrab particle loj (cm) thiab dp cov polymer ntom (g cm ~ 3). Ntawm no, dp tau teeb tsa ntawm 1.78g cm ~ 3.

Cryo-transmission electron microscopy (Cryo-TEM). PVDF particles tau soj ntsuam los ntawm cryo-TEM txhawm rau khaws cov particle morphology. Ib qho poob ntawm cov latex tau muab tso rau ntawm Quantifoil R2 / 1 daim phiaj tooj liab nrog 100 holey carbon txhawb zaj duab xis thiab quench-krozen hauv kua ethane. Cov qauv tau hloov pauv hauv lub tshuab ntsuas (Philips CM120, Center Technologique des Microstructures (CTu) - Platform ntawm University Claude Bernard Lyon 1, Villeurbanne, Fabkis) thiab pom ntawm qhov nrawm ntawm 120 kV.

Kev ntsuas qhov nro. Kev ntsuas tau tsim ib qho ntawm KRUSS K20 tensiometer thermostated ntawm 20 degree siv platinum phaj (Wilhelmy txoj kev) latex tempera-ture yog teem rau ntawm 20 degree thiab ces muab tso rau hauv lub cell. Lub xovtooj ntawm tes tau tsa kom txog thaum kev sib cuag ntawm lub latex nto thiab lub phaj.cistanche hmoovPEG-OH / PEG-X cov kev daws teeb meem tau npaj nrog ntau qhov sib txawv ntawm PEG-OH / PEG-X hauv cov dej deionized (25 mL) rau cov calibration curves. Tus nqi nro saum npoo (hauv N m ~ 1) yog qhov nruab nrab ntawm peb qhov ntsuas txhua 3 vib nas this.

Sib txawv scanning calorimetry (DSC). Kev ntsuas tau ua tiav ntawm Mettler Toledo DSC-1. Cov qauv qhuav tau xa mus rau ob qhov cua sov ua tiav (-20 txog 210 degree ntawm 10 degree min-1) thiab txias (210 txog -20 degree ntawm -10 degree min{{8 }}) cycles nyob rau hauv tus qauv 40 μL txhuas crucible nrog ib qho khoob siv crucible.cistanche salsa extractThermal keeb kwm ntawm cov qauv raug tshem tawm los ntawm thawj qhov cua sov ntawm 210 degree. Cov ntaub ntawv txheeb xyuas, piv txwv li, crystallization kub Te, melting kub Tm thiab qib ntawm crystallinity Xe (hauv feem pua) tau muab rho tawm los ntawm qhov cua sov thib ob. Lub degree ntawm crystallinity yog xam nrog cov kab zauv hauv qab no qhov twg △Hf, ~ yog 105 J g ~ 1.

Xe(%){{0}}(△Hf, ntsuas/△Hf,o0) × 100

Cov txiaj ntsig thiab kev sib tham

Raws li tau hais nyob rau hauv Kev Taw Qhia, piv txwv ntawm kev siv PEG-OH chains raws li stabilizer precursors nyob rau hauv emulsion (co)polymerization ntawm VDF tsuas yog tau piav nyob rau hauv patent lit-erature yam tsis muaj ib qho qhia txog ntawm stabilization hom ntawm cov khoom. Hauv qab no, peb xub tshawb xyuas cov polymerization ntawm VDF hauv qab 30 bar siab hauv 25 mL dej thaum tsis muaj molecular surfactant thiab siv cov poov tshuaj persulfate (KPS, 50 mg) ua tus pib ntawm 80 degree. Ob peb qhov kev sim ua ntej ua ntej muaj ntau qhov ntau ntawm PEG-OH (Mn=2000 g mol-1) nrog ib txwm KPS / PEG-OH qhov hnyav piv qis dua 1, piv txwv li. PEG-OH ntau dua 50 mg. Cov kev sim thawj zaug no tau tsim los ntawm qhov pom ntawm kev siv qhov tsawg kawg nkaus ntawm PEG-OH (thiab ntxiv rau ntawm PEG-X) thaum tseem tuaj yeem ua tus yam ntxwv hloov kho struc-tural ntawm PEG qaum qaum thaum lub sij hawm emulsion polymerization. Txawm li cas los xij, tsis muaj qhov kev sim no coj mus rau polymerization. Tseeb tiag, nrog 50 mg ntawm KPS nyob rau hauv daim ntawv qhia, qhov hnyav piv KPS / PEG-OH yuav tsum tau hloov mus rau 2.5 los tsim ib tug ruaj khov PVDF latex thiab ntsuas kev txaus siab hloov ntawm VDF (Table1-L01,11.2 wt feem pua ​​​​cov khib nyiab tom qab 4 hnub).

Qhov txiaj ntsig no tau piav qhia los ntawm qhov peculiar reactivity ntawm propagating radicals hauv VDF polymerization. Tseeb tiag, raws li cov txiv neej-tioned nyob rau hauv cov lus qhia thiab piav nyob rau hauv cov ntaub ntawv, irre-versible hloov kev tshwm sim yog tshwj xeeb tshaj yog pronounced nyob rau hauv lub xub ntiag ntawm hydrogenated hom. Tag nrho cov hydrogens atoms ntawm PEG-OH yog nyob ib sab ntawm cov pa atoms thiab yog li labile. Tej zaum lawv yog lub luag haujlwm rau qhov inhibition pom. Cov kev sim ua tsis tiav thawj zaug no muab cov ntaub ntawv ntxiv-mation. Qhov kev txwv tsis pub pom yog qhov tseeb raws li kev hloov pauv ntawm cov saw hlau degradative, piv txwv li tsis muaj kev rov ua haujlwm zoo tom qab ntawm VDF polymerization (Scheme 2A-a). Txo tus nqi ntawm PEG piv rau KPS yuav tso cai, ib zaug txaus reactive hloov chaw ntawm PEG chains (hydrogen atoms uas nyob ib sab ntawm cov pa oxygen) tau neutralized los ntawm kev tsim cov qauv amphiphilic tom qab coupling (Scheme 2A-b), los tsim cov radicals txaus rau zoo pib lub polymer-ization. Tseeb tiag, L01 tau muab cov latex ruaj khov nrog qhov loj me ntawm 234 nm. Qhov ruaj khov ntawm cov latex tau txais tsis tuaj yeem piav qhia tsuas yog los ntawm cov nqi uas tau muab los ntawm tus pib KPS. Cov txiaj ntsig tom kawg yog qhov tseeb tiag, raws li tau lees paub los ntawm kev tsim cov PVDF latex ruaj khov nyob rau hauv ib qho ntawm KPS nyob rau hauv tib yam mob (Table 1,L02,7.8 wt feem pua ​​​​ntawm cov khib nyiab tom qab 1 h). Txawm li cas los xij, qhov loj me me tau txais nyob rau hauv cov ntaub ntawv ntawd (378 nm) piv rau cov latex tsim nyob rau hauv lub xub ntiag ntawm PEG-OH (L01,234 nm) qhia tau hais tias muaj txiaj ntsig zoo ntawm cov macromolecule ntawm cov particle stability. Raws li tau hais los saum toj no, hauv L01, tus nqi ntawm PEG siv (20 mg, rau qhov kawg ntawm qhov hnyav ntawm 0.7 wt feem pua ​​​​ntawm PVDF, Table 1) ua rau kev sib cais thiab cov cwj pwm-terization ntawm stabilizer tsim yuav luag tsis yooj yim sua. Muab rau hauv tus account qhov pom inhibition thaum KPS / PEG-OH qhov hnyav piv qis dhau, cov qauv no yuav tsis yog qhov tshwm sim ntawm kev rov ua dua ntawm polymerization ntawm VDF ntawm PEG tom qab hloov pauv cov tshuaj tiv thaiv, txawm hais tias qhov no tsis tuaj yeem txiav txim siab tag nrho.

Tseeb tiag, rov pib dua ntawm VDF polymerization los ntawm -CH2-CH(OMe) tau tshaj tawm hauv cov ntaub ntawv. Hauv kev ua haujlwm no, kev ua tiav zoo ntawm block copolymers raws li poly (methyl vinyl ether) (PMVE) thiab PVDF ntu tau ua tiav los ntawm kev sib xyaw ntawm cationic RAFT thiab RAFT polymerizations. PMVE chains nqa dithiocarbamate saw kawg (PMVE-DTC) tau siv los tswj RAFT polymerization ntawm VDF. Qhov no txawm li cas los xij tshwm sim hauv dimethylcarbonate, qhov hnyav zoo rau VDF, thaum VDF tsuas yog me ntsis soluble hauv dej. Tsis tas li ntawd, VDF affinity rau ib hydrophilic polymer xws li PEO yaj nyob rau hauv dej yog tsawg piv rau affinity ntawm VDF rau PMVE hauv DMC. Tsis tas li ntawd, oligomers ntawm PVDF tsim nyob rau hauv dej nyob rau hauv ib tug emulsion txheej txheem ("K, OSO3-PVDF) yuav nqa ib tug anionic nqi (los ntawm lub KPS pib) thiab lawv affinity nrog hydrosoluble hom yuav muaj zog txaus nyiam ob qho tib si hloov cov tshuaj tiv thaiv tab sis Nyob rau hauv tas li ntawd, lub bimolecular termination ntawm ib tug loj hlob hydrosoluble 'K, "OSO3-PVDF" oligoradical thiab lub radical generated los ntawm kev hloov ntawm lwm cov hydro-soluble 'K, "OSO-PVDF. " oligoradical thiab PEG (Scheme 2A-b) yuav nyiam nyiam. Cov nqi tsis zoo nqa los ntawm OSO3-PVDF oligomers lossis los ntawm cov qauv grafted, yuav pab txhawb rau kev ruaj khov ntawm cov khoom.

Raws li tau hais los saum toj no, muaj cov PVDF ntxiv uas tshwm sim los ntawm kev rov pib dua tom qab hloov pauv (yog li tsis nqa cov pab pawg sulfate) tsis tuaj yeem txiav txim siab tag nrho (Tshooj 2B, liab PVDF grafts). Thaum kawg, kev hloov pauv ntawm hydrogen ntawm tertiary carbon atom tsim los ntawm cov kev xav tau yav dhau los (coupling lossis reinitiation) kuj tseem muaj peev xwm txawm hais tias xav txog cov teebmeem steric, tsim ntawm ob grafts ntawm tib cov pa roj carbon monoxide tej zaum yuav tsis txaus siab (Tshaj 2B, ntsuab PVDF grafts. ). Scheme 2B sawv cev rau cov qauv uas txhua qhov kev muaj peev xwm saum toj no suav nrog. Txhawm rau kom pom tseeb, cov qauv no tsuas yog tso nyiaj rau ib txwm lub taub hau-rau-tail ntxiv ntawm propagating radicals (-CH2CF2-CHZCF-) mus rau VDF thiab tsis yog rau qhov paub zoo thiab nyuaj micro-structure ntawm PVDF. ua los ntawm cov dawb radical polymerization, uas ntxiv nrog rau lub taub hau-rau-lub taub hau (-CHZCF-CFCH-) thiab tail-to-tail (-CF2CH2-CH2CF2-) ntxiv.1,60

Muaj zog ntawm cov thawj kev nkag siab ntawm lub peev xwm stabilization mechanisms thiab ntawm lub luag hauj lwm ntawm PEG-OH raws li ib tug precursor ntawm stabilizer nyob rau hauv VDF emulsion polymerization, peb mam li soj ntsuam kev siv ntawm PEG-X (Mn=2300 g mol{{3}). } thiab D=1.03) ua stabilizer ua ntej. Kev xaiv ntawm kev teeb tsa ntawm xanthate moiety ntawm qhov kawg ntawm PEG chains tau hais los ntawm kev tswj xyuas zoo thaum RAFT polymerization ntawm VDF tau ua nyob rau hauv cov kuab tshuaj organic61-68 thiab los ntawm kev ua tiav block copolymer syntheses qhia nyob rau hauv cov organic hnyav. los ntawm cov saw txuas ntxiv siv cov polymers ua haujlwm nrog xanthate saw xaus, 69-72 suav nrog kev sim ua VDF PISA hauv dimethyl carbonate los ntawm poly (vinyl acetate) macroCTA.70 Cov txiaj ntsig no yog qhov qhia tau tias muaj cov saw txuas ntxiv ntawm PEG-X. nrog VDF tuaj yeem tshwm sim hauv peb lub tshuab txawm tias nws tsis suav nrog qhov tshwm sim ntawm grafting cov tshuaj tiv thaiv tshwj xeeb los ntawm cov txheej txheem emulsion polymerization thiab txheeb xyuas saum toj no. Kev lag luam PEG-OH siv saum toj no tau hloov kho los ua kom paub txog kev ua haujlwm xanthate. Lub xanthate yog tsim los txhawb kev hloov pauv hloov pauv ntawm qhov kawg ntawm cov saw hlau thiab txo qis cov saw hlau hloov pauv hloov pauv raws li PEG saw raws li pom thaum RDRP ntawm VDF tau ua.61,63,73-75 Ib qho ruaj khov PVDF latex yog tiag tiag tau txais. nyob rau hauv lub xub ntiag ntawm PEG-X(Table 1-L03). Tom qab 4 teev ntawm polymerization, cov ntsiab lus ntawm cov khoom khib nyiab (10.4 feem pua) zoo ib yam li cov tau txais nrog PEG-OH (11.2 feem pua, L01) qhia tias qhov muaj cov xanthate saw xaus tsis cuam tshuam loj heev.

cov yield ntawm polymer ua. Nws yog ib qho tsim nyog hais tias qhov kev sib piv kinetic txoj kev tshawb fawb tau nthuav tawm hauv daim duab S71 qhia tau hais tias qhov snapshot muab tom qab 4 teev ntawm polymerization tsis zais qhov txawv txav ntawm tus cwj pwm ntawm PEG-OH thiab PEG-X. Qhov tseeb, qhov zoo sib xws kinetic profiles tau pom, nrog qhov sib txawv tab sis ruaj khov polymerization tus nqi hauv ob qho tib si.

Dhau li ntawd, isometric hais nrog qhov loj ntawm 72 nm tau muab piv rau 234 nm nrog PEG-OH. Cov txiaj ntsig no qhia tau hais tias muaj zog thiab muaj txiaj ntsig zoo ntawm kev nyiam cov saw hlau hloov pauv los ntawm pawg xanthate ntawm particle stabilization. Qhov no mus nrog ntau dua ntawm cov khoom tsim thaum siv PEG-X (yuav luag 30 npaug siab dua, saib L01 thiab L03 hauv Table 1). Qhov no tau lees paub ntxiv los ntawm cov duab cryo-TEM ntawm cov khoom siv PVDF latexes (Daim duab 1). Qhov sib txawv ntawm qhov ntau thiab tsawg pom nrog DLS tau lees paub los ntawm cryo-TEM. Tsis tas li ntawd, thaj chaw ci ntsa iab sib raug rau qhov tsawg dua electron-dense yog pom los ntawm cryo-TEM hauv PVDF cov khoom sib txuas nrog PEG-OH (Fig.1A). Qhov tshwm sim no twb tau tshaj tawm rau cov khoom sib txuas nrog PEG-raws li macroCTA, 1976 PEG-based stabilizers778 lossis cov pib, 7 degree lossis txawm tias KPS ib leeg. Cov khoom no tej zaum yuav raug tsim los ntawm cov hnab ntim dej thaum lub sij hawm emulsion polymerization, uas tshwm sim los ntawm faus PEG-raws li hom nyob rau hauv cov hais thiab ua rau lub brighter cheeb tsam pom thaum lub sij hawm cryo-TEM tsom xam. Qhov no corroborates qhov tseeb tias cov qauv qhia hauv Scheme 2B yog tej zaum tsis yog qhov zoo tshaj plaws los ua tus stabilizer thiab stabilize dej / PVDF interfaces. Qhov loj me me thiab qhov tsis muaj cov khoom siv hluav taws xob tsawg tsawg hauv cov khoom thaum siv PEG-X (Fig.1C) paub meej tias lub peev xwm zoo tshaj ntawm PEG-X los ua tus (pre-cursor ntawm) stabilizer hauv qhov no. Kev tsim ntawm PVDF ntu los ntawm cov saw kawg ntawm PEG-X, PVDF ntu tej zaum ntev dua li sab PVDF grafts vim yog kev hloov pauv rov qab los ntawm xanthate saw kawg, yuav tom qab ntawd tsav lub thauj tog rau nkoj ntawm tag nrho cov qauv raws li tau piav qhia hauv Scheme 2C. , nyob rau saum npoo ntawm cov hais optimizing lub stabilization.

Cov txiaj ntsig zoo ntawm kev thim rov qab ntawm kev hloov pauv cov tshuaj tiv thaiv los ntawm xanthate moiety tuaj yeem txhawb nqa los ntawm kev sim L04 uas PEG chains nqa thiol saw kawg (PEG-SH-Mn=2000} g mol-1) tau siv los hloov PEG-X. Nyob rau hauv cov ntaub ntawv no, ib tug qis yield (khoom cov ntsiab lus 8.1 feem pua) tau tom qab 3.25 h thaum lub particle loj twb loj (95 nm, Fig.1B) dua ib tug tau nrog PEG-X.PEG-SH tau yav tas los siv nyob rau hauv emulsion polymerization ntawm styrene rau gene-rate block copolymer surfactant thaum lub sij hawm txheej txheem.14 Tsis tas li ntawd, thiols paub tias induce irreversible chain transfer reactions hauv VDF polymerization. Raws li qhov tshwm sim, cov khoom me me tau txais nrog PEG-SH paub meej tias qhov tsim ntawm luv PVDF ntu los ntawm PEG los ntawm kev hloov pauv tsis hloov pauv thiab yog li nyob rau hauv qhov tsim ntawm stabilizers. Nws ntxiv qhia qhov zoo tshaj ntawm cov kev hloov pauv hloov pauv cov tshuaj tiv thaiv los ntawm xanthate rau stabilization ntawm PVDF latex.

Cov txiaj ntsig saum toj no tau pom tias qhov muaj ntawm xanthate saw kawg ua rau cov saw hlau thim rov qab thaum kawg ntawm PEG chains dhau qhov kev hloov pauv cov saw hlau tsis zoo raws li PEG qaum qaum. X nyob rau hauv lub formulation tsis txo qis ntau dhau ntawm cov khoom khib nyiab kawg rau tib lub sijhawm polymerization. Qhov no kuj tseem tuaj yeem txo qhov kev txheeb xyuas ntawm cov tshuaj hloov pauv uas tshwm sim ntawm PEG thaum lub sijhawm txheej txheem emulsion. Txawm li cas los xij, thaum nce tus nqi ntawm PEG-X hauv daim ntawv qhia (KPS / PEG-X qhov hnyav piv ntawm 1.25 hauv L05, Table 1), cov ntsiab lus ntawm cov khib nyiab poob qis heev rau 2.4 feem pua ​​​​txawm tias tom qab lub sijhawm polymerization ntev (8 teev). Qhov tshwm sim no ncaj qha txuas mus rau qhov nce hauv cov ntsiab lus ntawm hydrogenated hom. Qhov tseeb, txo qis ntawm PEG-X cov ntsiab lus kom ncav cuag KPS / PEG-X piv ntawm 5 (L06) tso cai tsim 100 nm PVDF hais, nrog cov ntsiab lus ntawm 14.4 feem pua ​​​​hauv 4 teev.

Raws li tau hais los saum no, thawj tus nqi ntawm PEG-X tsis tuaj yeem tso cai rau cov qauv tsim qauv ntawm PEG chains tom qab polymerization. Qhov tseeb, qhov kawg ntawm qhov hnyav ntawm PEG (nrog rau qhov tsim PVDF) hauv cov latexes no feem ntau qis dua 1 wt feem pua ​​(tshwj tsis yog cov SC latex L05, Table 1). Txawm li cas los xij, lub tswv yim tseem nthuav heev vim nws txo qis tus nqi ntawm stabilizer precursor thiab thaum kawg cov feem ntawm hydrophilic hom nyob rau hauv kawg latexes. Cov ntaub ntawv tsis ncaj nraim ntawm cov qauv ntawm cov stabilizer tuaj yeem sib sau ua ke los ntawm kev ntxiv physicochemical characterizations ntawm qhov kawg latex. Kev soj ntsuam nro saum npoo yog li ua tiav ntawm L01 (PVDF latex los ntawm PEG-OH) thiab L03 (PVDF latex los ntawm PEG-X) txhawm rau kom muaj nuj nqis nyob rau hauv ob qho tib si, cov nyiaj pub dawb PEG chains, piv txwv li, tsis koom nrog particle stabilization. Calibration curves yog thawj tsim los ntawm kev ntsuas qhov nro ntawm aqueous cov kev daws teeb meem ntawm ntau qhov ntau ntawm PEG-OH thiab PEG-X (Fig. S81). Raws li kev ntsuas nkhaus, 82.5 wt feem pua ​​​​ntawm thawj tus nqi ntawm PEG-OH tam sim no yog cov saw dawb nyob rau hauv qhov kawg latex L01, qhov tsuas yog 1.0 wt feem pua ​​​​ntawm thawj tus nqi ntawm PEG-X tam sim no yog cov khoom siv dawb polymer hauv cov latex. l03 ua. Cov txiaj ntsig zoo sib xws no tau ua tiav nrog qhov zoo tshaj ntawm PEG-X piv rau PEG-OH kom ruaj khov PVDF latex tau los ntawm emulsion polymerization. Raws li kev sib piv, siv tib qhov kev ntsuas qhov nro, 23 wt feem pua ​​​​ntawm thawj PEG-SH tam sim no yog cov saw dawb, cov txiaj ntsig zoo ib yam nrog kev ua haujlwm qis ntawm kev ruaj khov hauv qhov no, raws li tau hais los saum toj no. Txawm li cas los xij, tag nrho cov ntaub ntawv no yuav tsum tau txiav txim siab nrog kev saib xyuas raws li qhov ntsuas qhov nro tuaj yeem tsis yog qhov kev xav ntawm kev koom tes ntawm PEG dawb chains hauv cov dej theem. Qhov tseeb, cov theem aqueous kuj tseem muaj grafted fluorinated PEG hom (saib Scheme 2), qhov kev koom tes ntawm cov uas yuav tsis raug cuam tshuam los ntawm calibration curves tau los ntawm thawj hom PEG (ie, PEG-OH, PEG-X, lossis PEG. -SH).

VDF emulsion polymerizations ua nrog PEG-X tau pom tias muaj cov xanthate saw kawg ntawm PEG yog qhov tseem ceeb, tab sis kuj tseem hais tias cov ntsiab lus ntawm cov khib nyiab tuaj yeem ncav cuag rau lub sijhawm polymerization ntawm cov polymerization tau txuas nrog ntau hom hydrogenated ( Hauv lwm lo lus, tus nqi ntawm PEG-X pib qhia). Txhawm rau hais txog qhov txiaj ntsig zoo ntawm xanthate reactive moiety rau kev tsim PVDF latex, kev sim tau tsim nrog qis molar pawg PEG-X (Mn=1300} g mol-) lossis los ntawm kev qhia xanthate moieties ntawm ob txoj hlua xaus (X -PEG-X, Mn=3420g mol-')(Scheme 1). Kev sim L07 hauv Table 1 yog li ua nrog PEG-X ntawm 1300 g mol-' thiab tib qhov KPS / PEG-X qhov hnyav piv li hauv L03. Tus naj npawb ntawm xanthates moieties yog li ob npaug piv rau L03 nrog ntau qhov chaw muaj peev xwm raws PEG chains rau kev hloov cov tshuaj tiv thaiv uas tseem tshuav tib yam (Scheme 3, case 1). Qhov loj me me uas tau txais yog me dua hauv L07 (62 nm) piv rau L03 (72 nm) thaum cov ntsiab lus ntawm cov khib nyiab tseem tsis hloov pauv (10.4 feem pua), ua rau tsim cov khoom ntau dua (47.5 × 1016 vs. 30.3 × 1046). Raws li kev cia siab, qhov txiaj ntsig no qhia tau hais tias muaj txiaj ntsig zoo ntawm kev txhawb nqa-kev hloov pauv hloov pauv cov tshuaj tiv thaiv ntawm xanthate cov saw hlau xaus ntawm cov saw hloov mus raws PEG qaum. Nyob rau hauv tib yam

cov hlab ntsha, txo qis tus nqi pib ntawm PEG-X rau ib qho zoo sib xws ntawm xanthate saw xaus nrog rau L03 (L08, KPS/PEG-X=6.7, Scheme 3, case 2) zoo txo ​​qhov tshwm sim-rence ntawm irreversible saw hloov cov tshuaj tiv thaiv ua rau 99 nm PVDF latex nrog cov ntsiab lus siab dua (15.9 feem pua), hauv kev pom zoo zoo ntawm cov txiaj ntsig tau txais hauv kev sim L06.

Qhov cuam tshuam zoo ntawm pawg xanthate reactive ntawm particle stabilization kuj tau pom nyob rau hauv qhov kev sim dhau los ua nrog X-PEG-X, ua kom KPS / X-PEG-X piv rau 2.5 (L09). Qhov no txhais tau hais tias tus naj npawb ntawm xanthate moieties koom nrog hauv qhov polymerization yog ob npaug ntawm tus lej koom nrog L03, rau tib tus naj npawb ntawm cov saw hlau hloov pauv tsis tau raws li PEG qaum qaum (Tshooj 3, rooj plaub 3). Qhov no kuj txhais tau hais tias yog tias ob qho tib si xanthate moieties tau txais txiaj ntsig zoo, PEG chains yuav tsim cov voj voog ntawm qhov chaw. Qhov loj me me zoo ib yam rau ob lub latexes (72 nm). Txawm li cas los xij, SC qis dua nyob rau hauv cov ntaub ntawv ntawm L09 (8.5 feem pua) piv rau L03 (10.5 feem pua) .Larger particle loj yog li xav tau rau L09 rau cov khoom sib xws. Qhov tshwm sim tsis yog tawm tsam qhov tsim ntawm qhov xav tau ob sab PVDF thaiv ntawm ob lub PEG saw xaus. Txawm li cas los xij, kev thauj mus los ntawm qhov tshwm sim amphiphilic qauv mus rau qhov tsim PVDF cov khoom tuaj yeem cuam tshuam qhov kev xa tawm ntawm qhov hydrophilic (PEG nraub qaum nrog sab PVDF grafts) ntawm qhov sib thooj stabilizer ntawm qhov chaw. Qhov qis dua ntawm cov khoom tau txais rau L09 (24.1 × 1046) com-pared rau L03 (30.3 × 1046) tej zaum yuav muaj kev cuam tshuam me ntsis stabiliz-ation efficiency.

Cov khoom siv hluav taws xob ntawm PVDF polymers tau siv cov khoom sib txawv saum toj no-hais PEG-raws li stabilizer tau tshawb xyuas siv DSC (Table S1). Lub ana-lyses tau pom tias semi-crystalline polymers tau tsim, nrog Tm, Te thiab Xe qhov tseem ceeb nyob rau hauv ntau yam ntawm cov feem ntau pom rau PVDF polymers tsim los ntawm emulsion polymerization.2,82

Nws thiaj li, kev sim L01 thiab L03 hauv Table 1, ua nrog PEG-OH thiab PEG-X raws, tau ntsuas hauv 4 L reactor hauv kev sim L10 thiab L11, raws li (Table 1).Cov ntsiab lus tau txais tom qab 4 h15 (7.6. wt feem pua ​​​​thiab 6.8 wt feem pua ​​​​) zoo ib yam li cov L01 thiab L03 (11.2 wt feem pua ​​​​thiab 10.4 wt feem pua) txawm tias qis dua me ntsis. Qhov no tej zaum suav rau qhov sib txawv heev nplawm thiab ntim ntau tshaj qhov sib piv hauv ob txheej txheej. Txawm li cas los xij, nws qhia tau hais tias cov thev naus laus zis no muaj zog thiab nws txoj kev hloov mus rau qhov loj dua tuaj yeem ua tau.83

Cov lus xaus

Txoj haujlwm no piav qhia txog kev sib txuas ntawm tus kheej-stabilized PVDF par-ticles los ntawm kev sib txuas qhov zoo ntawm emulsion polymeriz-ation nrog cov tswj radical polymerization siv cov txheej txheem RAFT. Ua ntej, ib qho kev lag luam uas muaj methoxy poly (ethylene glycol) nqa ib txoj haujlwm hydroxyl (PG-OH, Mn =2000} g mol-1) tau siv rau kev ruaj khov ntawm PVDF hais. Cov khoom ruaj khov PVDF tau txais nrog txoj kab uas hla ntawm 234 nm. Lub stabilization yog muab los ntawm irreversible hloov tshwm sim tshwm sim raws PEG-OH chains ua rau tsim ib tug grafted copolymer stabilizer nyob rau hauv situ. Tib yam PEG-OH ces saw-kawg functionalized los qhia ib pab pawg xanthate (PEG-X).Cov kev sim ua nyob rau hauv lub xub ntiag ntawm PEG-X qhia tau hais tias muaj txiaj ntsig zoo ntawm reactive xanthate saw-kawg hauv VDF emulsion polymer- txheej txheem ization. Tseeb, tsis muaj kev cuam tshuam loj rau cov ntsiab lus ntawm cov khoom khib nyiab (ca.10 wt feem pua ​​​​tau tom qab 4 h rau PEG-OH- lossis PEG-X-mediated emulsion polymerization), qhov loj me me tau txo qis (72 nm) nyob rau hauv lub xub ntiag ntawm PEG- X. Kev sim ntxiv tau ua nyob rau hauv lub xub ntiag ntawm PEG-X nrog qis molar pawg (Mn=1300 g mol-1) lossis nqa ob xanthate saw kawg (X-PEG-X, Mn=3420 g mol-') tau lees paub cov txiaj ntsig yav dhau los thiab qhov txiaj ntsig zoo ntawm kev teeb tsa ntawm xanthate saw kawg ntawm PEG chains.Rau txhua qhov xwm txheej, feem ntawm PEG hom hauv qhov kawg PVDF tseem qis (feem ntau tsawg dua lossis sib npaug rau 1. wt feem pua). Lub zog ntawm cov thev naus laus zis no tau lees paub los ntawm qhov ntsuas-up emulsion polymerizations ntawm VDF hauv 4 L reactor uas ua rau muaj qhov tsis muaj surfactant-dawb stabilized PVDF latex tau txais nyob rau hauv tib lub xub ntiag ntawm PEG-X li precursor ntawm stabilizer thiab nrog tib yam ntxwv. raws li ib tug tau nyob rau hauv me me ntim.

Kab lus no yog muab rho tawm los ntawm Polym. Chem., 2021, 12, 5640