Mbiri Yakufufuza
Monga gwero lachilengedwe, lochuluka komanso longowonjezedwanso, cellulose amakumana ndi zovuta zazikulu pazogwiritsa ntchito chifukwa chosasungunuka komanso kusungunuka kwake kochepa.The mkulu crystallinity ndi mkulu-kachulukidwe hydrogen zomangira mu mapadi kamangidwe kamene kamapangitsa kuti kunyozeka koma osasungunuka panthawi yomwe ali nayo, komanso osasungunuka m'madzi ndi zosungunulira zambiri za organic.Zotulutsa zawo zimapangidwa ndi esterification ndi etherification yamagulu a hydroxyl pamagulu a anhydroglucose mu unyolo wa polima, ndipo adzawonetsa zinthu zosiyanasiyana poyerekeza ndi cellulose yachilengedwe.The etherification anachita pa cellulose akhoza kupanga ambiri madzi sungunuka mapadi ethers, monga methyl cellulose (MC), hydroxyethyl mapadi (HEC) ndi hydroxypropyl mapadi (HPC), amene ankagwiritsa ntchito mu chakudya, zodzoladzola, mu mankhwala ndi mankhwala.Madzi osungunuka a CE amatha kupanga ma polima opangidwa ndi haidrojeni okhala ndi ma polycarboxylic acid ndi ma polyphenols.
Layer-by-layer assembly (LBL) ndi njira yothandiza pokonzekera mafilimu opangidwa ndi polima.Zotsatirazi zikufotokozera makamaka kusonkhana kwa LBL kwa ma CE atatu osiyanasiyana a HEC, MC ndi HPC ndi PAA, kufananiza khalidwe lawo la msonkhano, ndikuwunika mphamvu za olowa m'malo pa msonkhano wa LBL.Fufuzani momwe pH imakhudzira makulidwe a filimu, ndi kusiyana kosiyana kwa pH pakupanga ndi kusungunuka kwa filimuyo, ndikupanga mayamwidwe amadzi a CE/PAA.
Zida Zoyesera:
Polyacrylic acid (PAA, Mw = 450,000).Kukhuthala kwa 2wt.% yamadzimadzi amadzimadzi a hydroxyethylcellulose (HEC) ndi 300 mPa · s, ndipo mlingo wolowa m'malo ndi 2.5.Methylcellulose (MC, 2wt.% yamadzimadzi yamadzimadzi yokhala ndi viscosity ya 400 mPa · s ndi digiri ya 1.8).Hydroxypropyl cellulose (HPC, 2wt.% yankho lamadzi lamadzimadzi lokhala ndi viscosity ya 400 mPa · s ndi digiri ya 2.5).
Kukonzekera filimu:
Zokonzedwa ndi gulu lamadzimadzi la crystal layer pa silicon pa 25 ° C.Njira yochiza ya masanjidwewo ndi motere: zilowerere mu acidic yankho (H2SO4/H2O2, 7/3Vol/VOL) kwa 30min, ndiye muzimutsuka ndi madzi deionized kangapo mpaka pH salowerera ndale, ndipo potsiriza youma ndi koyera asafe.Kusonkhana kwa LBL kumachitika pogwiritsa ntchito makina odzipangira okha.Gawo laling'ono lidalowetsedwa mosinthana mu njira ya CE (0.2 mg / mL) ndi yankho la PAA (0.2 mg / mL), yankho lililonse linanyowa kwa 4 min.Kutsuka katatu konyowa kwa mphindi imodzi iliyonse m'madzi opangidwa ndi deionized kunachitika pakati pa njira iliyonse yonyowa kuti muchotse polima.Makhalidwe a pH a yankho la msonkhano ndi yankho lochapira zonse zidasinthidwa kukhala pH 2.0.Makanema okonzekera amatchulidwa kuti (CE/PAA) n, pomwe n amatanthauza kuzungulira kwa msonkhano.(HEC/PAA)40, (MC/PAA)30 ndi (HPC/PAA)30 anakonzedwa makamaka.
Mawonekedwe a Mafilimu:
Zowonera zapafupipafupi zowoneka bwino zidajambulidwa ndikuwunikidwa ndi NanoCalc-XR Ocean Optics, ndipo makulidwe amafilimu oyikidwa pa silicon adayesedwa.Ndi gawo lapansi lopanda kanthu la silicon ngati chakumbuyo, mawonekedwe a FT-IR a filimu yopyapyala pagawo la silicon adasonkhanitsidwa pa Nicolet 8700 infrared spectrometer.
Kuyanjana kwa hydrogen pakati pa PAA ndi CEs:
Msonkhano wa HEC, MC ndi HPC wokhala ndi PAA kukhala makanema a LBL.Mawonekedwe a infrared a HEC/PAA, MC/PAA ndi HPC/PAA akuwonetsedwa pachithunzichi.Zizindikiro zamphamvu za IR za PAA ndi CES zitha kuwoneka bwino mu mawonekedwe a IR a HEC/PAA, MC/PAA ndi HPC/PAA.FT-IR spectroscopy imatha kusanthula kuchuluka kwa ma hydrogen bond pakati pa PAA ndi CES poyang'anira kusintha kwa mayamwidwe am'magulu.Kulumikizana kwa haidrojeni pakati pa CES ndi PAA makamaka kumachitika pakati pa okosijeni wa hydroxyl wa CES ndi gulu la COOH la PAA.Pambuyo popanga hydrogen chomangira, nsonga yowongoka yofiira imasinthira kumayendedwe otsika pafupipafupi.
Pamwamba pa 1710 cm-1 adawonedwa pa ufa woyera wa PAA.Pamene polyacrylamide idasonkhanitsidwa m'mafilimu okhala ndi ma CE osiyanasiyana, nsonga za mafilimu a HEC/PAA, MC/PAA ndi MPC/PAA zinali pa 1718 cm-1, 1720 cm-1 ndi 1724 cm-1, motsatana.Poyerekeza ndi ufa woyera wa PAA, kutalika kwapamwamba kwa mafilimu a HPC / PAA, MC / PAA ndi HEC / PAA adasinthidwa ndi 14, 10 ndi 8 cm-1, motsatira.Mgwirizano wa haidrojeni pakati pa okosijeni wa ether ndi COOH umasokoneza mgwirizano wa haidrojeni pakati pa magulu a COOH.Kuchulukirachulukira kwa ma hydrogen pakati pa PAA ndi CE, kumapangitsanso kusintha kwakukulu kwa CE/PAA mu mawonekedwe a IR.HPC ili ndi digiri yapamwamba kwambiri ya hydrogen bond complexation, PAA ndi MC ali pakati, ndipo HEC ndiyotsika kwambiri.
Kukula kwamakanema ophatikizika a PAA ndi ma CE:
Makhalidwe opangira filimu a PAA ndi CEs pamsonkhano wa LBL adafufuzidwa pogwiritsa ntchito QCM ndi spectral interferometry.QCM ndiyothandiza pakuwunika kukula kwa kanema mu situ pamisonkhano ingapo yoyamba.Spectral interferometers ndi oyenera mafilimu omwe amakula mozungulira 10.
Kanema wa HEC/PAA adawonetsa kukula kofananira pamisonkhano yonse ya LBL, pomwe makanema a MC/PAA ndi HPC/PAA adawonetsa kukula kokulirapo m'magawo oyambilira a msonkhano ndikusinthidwa kukhala kukula kwa mzere.M'dera la kukula kwa mzere, kuchuluka kwa kuchuluka kwa zovuta, kumapangitsanso kukula kwa makulidwe pa nthawi ya msonkhano.
Zotsatira za yankho pH pakukula kwa filimu:
Phindu la pH la yankho limakhudza kukula kwa filimu ya hydrogen yomangidwa polima.Monga polyelectrolyte yofooka, PAA idzakhala ionized ndikuyimbidwa molakwika pamene pH ya yankho ikuwonjezeka, motero imalepheretsa mgwirizano wa hydrogen bond.Pamene digiri ya ionization ya PAA inafika pamlingo wina, PAA sinathe kusonkhana mufilimu yokhala ndi ma hydrogen bond acceptors mu LBL.
Kuchuluka kwa filimuyi kunachepa ndi kuwonjezeka kwa yankho pH, ndipo makulidwe a filimuwo anatsika mwadzidzidzi pa pH2.5 HPC/PAA ndi pH3.0-3.5 HPC/PAA.Mfundo yovuta ya HPC / PAA ili pafupi pH 3.5, pamene HEC / PAA ili pafupi 3.0.Izi zikutanthauza kuti pamene pH ya yankho la msonkhano ili pamwamba kuposa 3.5, filimu ya HPC / PAA singapangidwe, ndipo pamene pH ya yankho ili pamwamba kuposa 3.0, filimu ya HEC / PAA singapangidwe.Chifukwa cha kuchuluka kwa hydrogen bond complexation ya HPC/PAA membrane, pH mtengo wa HPC/PAA membrane ndi wapamwamba kuposa wa HEC/PAA nembanemba.Mu njira yopanda mchere, zovuta za pH za ma complexes opangidwa ndi HEC / PAA, MC / PAA ndi HPC / PAA zinali pafupifupi 2.9, 3.2 ndi 3.7, motsatira.PH yovuta ya HPC/PAA ndi yapamwamba kuposa ya HEC/PAA, yomwe ikugwirizana ndi ya LBL nembanemba.
Mayamwidwe amadzi a CE/PAA membrane:
CES ndi yolemera m'magulu a hydroxyl kotero kuti imakhala ndi madzi abwino komanso kusunga madzi.Kutengera HEC/PAA nembanemba monga chitsanzo, mphamvu yotsatsira ya hydrogen-bonded CE/PAA nembanemba kumadzi m'chilengedwe idaphunziridwa.Wodziwika ndi spectral interferometry, makulidwe a filimu amawonjezeka pamene filimuyo imatenga madzi.Anayikidwa m'malo okhala ndi chinyezi chosinthika pa 25 ° C kwa maola 24 kuti akwaniritse mayamwidwe amadzi.Mafilimuwo adawumitsidwa mu uvuni wa vacuum (40 ° C) kwa maola 24 kuti achotseretu chinyezi.
Pamene chinyezi chikuwonjezeka, filimuyo imakhuthala.M'malo otsika chinyezi a 30% -50%, kukula kwa makulidwe kumakhala pang'onopang'ono.Chinyezi chikaposa 50%, makulidwewo amakula mwachangu.Poyerekeza ndi nembanemba ya PVPON/PAA yokhala ndi hydrogen, nembanemba ya HEC/PAA imatha kuyamwa madzi ambiri kuchokera ku chilengedwe.Pansi pa chinyezi cha 70% (25 ° C), kukhuthala kwa filimu ya PVPON/PAA ndi pafupifupi 4%, pomwe filimu ya HEC/PAA ndi yokwera pafupifupi 18%.Zotsatira zinasonyeza kuti ngakhale kuti magulu ena a OH mu dongosolo la HEC / PAA adagwira nawo ntchito popanga ma hydrogen bond, panalibe magulu ambiri a OH omwe amagwirizana ndi madzi m'chilengedwe.Chifukwa chake, dongosolo la HEC/PAA lili ndi zinthu zabwino zoyamwa madzi.
Pomaliza
(1) Dongosolo la HPC / PAA lomwe lili ndi digiri yapamwamba kwambiri ya haidrojeni yolumikizana ndi CE ndi PAA ikukula mwachangu pakati pawo, MC/PAA ili pakati, ndipo HEC/PAA ndiyotsika kwambiri.
(2) Kanema wa HEC / PAA adawonetsa kukula kwa mzere nthawi yonse yokonzekera, pomwe mafilimu ena awiri a MC / PAA ndi HPC / PAA adawonetsa kukula kwakukulu m'mizere yoyambirira, kenako adasinthidwa kukhala njira yokulirapo.
(3) Kukula kwa filimu ya CE / PAA kumadalira kwambiri yankho la pH.Pamene yankho la pH liri lalitali kuposa mfundo yake yovuta, PAA ndi CE sangathe kusonkhana mufilimu.Nembanemba ya CE / PAA yosonkhanitsidwa idasungunuka mumayankho apamwamba a pH.
(4) Popeza filimu ya CE / PAA ndi yolemera mu OH ndi COOH, kutentha kwa kutentha kumapangitsa kuti ikhale yolumikizana.Nembanemba yolumikizidwa ndi CE/PAA imakhala yokhazikika bwino ndipo siyisungunuka muzothetsera za pH zambiri.
(5) Kanema wa CE / PAA ali ndi mphamvu yabwino yotsatsa madzi m'chilengedwe.
Nthawi yotumiza: Feb-18-2023