Imvelaphi yoPhando
Njengomthombo wendalo, ubuninzi kunye nokuhlaziywa kwakhona, i-cellulose ihlangabezana nemingeni emikhulu kwizicelo eziphathekayo ngenxa yokunganyibiliki kwayo kunye neepropati ezilinganiselweyo zokunyibilika.I-crystallinity ephezulu kunye ne-high-density hydrogen bonds kwisakhiwo se-cellulose yenza ukuba ihlaziywe kodwa inganyibiliki ngexesha lenkqubo yokuphatha, kwaye i-insoluble emanzini kunye ne-solvents ezininzi zezinto eziphilayo.Izinto eziphuma kuzo ziveliswa yi-esterification kunye ne-etherification yamaqela e-hydroxyl kwiiyunithi ze-anhydroglucose kwikhonkco le-polymer, kwaye ziya kubonisa iimpawu ezithile ezahlukeneyo xa kuthelekiswa neselulosi yendalo.Ukusabela kwe-etherification ye-cellulose kunokuvelisa i-ethers ezininzi ze-cellulose e-soluble yamanzi, njenge-methyl cellulose (MC), i-hydroxyethyl cellulose (HEC) kunye ne-hydroxypropyl cellulose (HPC), ezisetyenziswa ngokubanzi ekutyeni, kwizinto zokuthambisa, kumayeza kunye namayeza.I-CE enyibilikayo emanzini inokwenza iipholima ezibotshwe nge-hydrogen kunye ne-polycarboxylic acid kunye ne-polyphenols.
I-Layer-by-layer assembly (LBL) yindlela esebenzayo yokulungiselela iifilimu ezincinci ezidibeneyo ze-polymer.Oku kulandelayo kuchaza ngokuyintloko indibano ye-LBL yee-CEs ezintathu ezahlukeneyo ze-HEC, i-MC kunye ne-HPC kunye ne-PAA, ithelekisa ukuziphatha kwabo kwendibano, kwaye ihlalutya impembelelo yababambeli kwindibano ye-LBL.Phanda umphumo we-pH kubukhulu befilimu, kunye nokwahlukana okwahlukileyo kwe-pH ekubunjweni kwefilimu kunye nokutshatyalaliswa, kunye nokuphuhlisa iimpawu zokufunxa amanzi ze-CE / PAA.
Izixhobo zoMfuniselo:
I-Polyacrylic acid (PAA, Mw = 450,000).I-viscosity ye-2wt.% isisombululo samanzi se-hydroxyethylcellulose (HEC) yi-300 mPa·s, kwaye iqondo lokutshintshwa yi-2.5.I-Methylcellulose (MC, i-2wt.% isisombululo se-aqueous kunye ne-viscosity ye-400 mPa·s kunye neqondo lokutshintshwa kwe-1.8).I-Hydroxypropyl cellulose (i-HPC, i-2wt.% isisombululo samanzi esine-viscosity ye-400 mPa · kunye neqondo lokutshintshwa kwe-2.5).
Ukulungiselela ifilimu:
Ilungiselelwe yindibano yekristale elulwelo kwi-silicon kwi-25°C.Indlela yonyango ye-matrix yesilayidi ngolu hlobo lulandelayo: gcoba kwisisombululo esine-acidic (H2SO4 / H2O2, 7/3Vol / VOL) kwi-30min, uze uhlambulule ngamanzi adibeneyo amaxesha amaninzi de i-pH ingathathi hlangothi, kwaye ekugqibeleni yome nge-nitrogen ecocekileyo.Indibano ye-LBL yenziwa kusetyenziswa oomatshini abazenzekelayo.I-substrate ifakwe ngenye indlela kwisisombululo se-CE (0.2 mg / mL) kunye nesisombululo se-PAA (0.2 mg / mL), isisombululo ngasinye sifakwe kwi-4 min.Iisofu ezintathu zokuhlanjululwa kwe-1 min nganye emanzini adibeneyo zenziwe phakathi kwesisombululo ngasinye ukuze kususwe i-polymer edibeneyo.Amaxabiso e-pH esisombululo sendibano kunye nesisombululo sokuhlanjululwa zombini zihlengahlengiswe kwi-pH 2.0.Iifilimu ezilungiselelwe njengoko zichazwe njenge (CE / PAA) n, apho i-n ibonisa umjikelo wendibano.(HEC/PAA)40, (MC/PAA)30 kunye (HPC/PAA)30 zilungiselelwe ikakhulu.
Ubume befilimu:
Imbonakalo yembonakalo ekufutshane neqhelekileyo yarekhodwa kwaye yahlalutywa nge-NanoCalc-XR Ocean Optics, kwaye ubukhulu beefilimu ezifakwe kwi-silicon bulinganiswa.Nge-silicon substrate engenanto njengengasemva, imbonakalo ye-FT-IR yefilimu ebhityileyo kwi-silicon substrate yaqokelelwa kwi-Nicolet 8700 ye-infrared spectrometer.
Unxibelelwano lwebhondi yeHydrogen phakathi kwe-PAA kunye nee-CEs:
INdibano ye-HEC, i-MC kunye ne-HPC kunye ne-PAA kwiifilimu ze-LBL.I-spectra ye-infrared ye-HEC/PAA, MC/PAA kunye ne-HPC/PAA iboniswe kumfanekiso.Iimpawu ze-IR ezinamandla ze-PAA kunye ne-CES zinokubonwa ngokucacileyo kwi-spectra ye-IR ye-HEC/PAA, MC/PAA kunye ne-HPC/PAA.I-FT-IR spectroscopy inokuhlalutya ukudityaniswa kwebhondi ye-hydrogen phakathi kwe-PAA kunye ne-CES ngokubeka iliso ekutshintsheni kophawu lokufunxa bands.Ukudityaniswa kwe-hydrogen phakathi kwe-CES kunye ne-PAA kwenzeka ikakhulu phakathi kwe-oksijini ye-hydroxyl ye-CES kunye neqela le-COOH le-PAA.Emva kokuba ibhondi ye-hydrogen yenziwe, i-peak yokwelula ebomvu itshintshela kwi-low frequency direction.
Incopho ye-1710 cm-1 yabonwa kwi-PAA ecocekileyo powder.Xa i-polyacrylamide ihlanganiswe kwiifilimu ngee-CEs ezahlukeneyo, iincopho ze-HEC / PAA, MC / PAA kunye neefilimu ze-MPC / PAA zazifumaneka kwi-1718 cm-1, 1720 cm-1 kunye ne-1724 cm-1, ngokulandelanayo.Xa kuthelekiswa ne-PAA powder ecocekileyo, ubude obude be-HPC / PAA, MC / PAA kunye neefilimu ze-HEC / PAA zitshintshwe yi-14, i-10 kunye ne-8 cm-1, ngokulandelanayo.Ibhondi ye-hydrogen phakathi kwe-ether ioksijini kunye ne-COOH iphazamisa i-hydrogen bond phakathi kwamaqela e-COOH.Okukhona iibhondi ze-hydrogen zenziwe phakathi kwe-PAA kunye ne-CE, kokukhona ukutshintshwa okuphezulu kwe-CE/PAA kwi-IR spectra.I-HPC ineqondo eliphezulu le-hydrogen bond complexation, i-PAA kunye ne-MC ziphakathi, kwaye i-HEC yeyona iphantsi.
Ukukhula kokuziphatha kweefilimu ezihlanganisiweyo ze-PAA kunye nee-CEs:
Ukuziphatha kwefilimu ye-PAA kunye ne-CEs ngexesha lendibano ye-LBL yaphandwa kusetyenziswa i-QCM kunye ne-interferometry ye-spectral.I-QCM iyasebenza ekubekeni iliso ekukhuleni kwefilimu kwi-situ ngexesha lemijikelo embalwa yokuqala yendibano.I-interferometers ye-Spectral ifanelekile kwiifilimu ezikhule ngaphezu kwemijikelo ye-10.
Ifilimu ye-HEC / PAA ibonise ukukhula komgca kuyo yonke inkqubo yendibano ye-LBL, ngelixa iifilimu ze-MC / PAA kunye ne-HPC / PAA zibonise ukukhula okubonakalayo kwiinqanaba zokuqala zendibano kwaye emva koko ziguqulwa zibe ukukhula komgca.Kummandla wokukhula ohambelanayo, iqondo eliphezulu lokuntsonkotha, kokukhona ukukhula kobunzima kumjikelo ngamnye wendibano.
Impembelelo yesisombululo pH ekukhuleni kwefilimu:
Ixabiso le-pH lesisombululo lichaphazela ukukhula kwefilimu edibeneyo ye-polymer edibeneyo ye-hydrogen.Njenge-polyelectrolyte ebuthakathaka, i-PAA iya kuba yi-ionized kwaye ihlawuliswe kakubi njengoko i-pH yesisombululo inyuka, ngaloo ndlela inqanda umbutho we-hydrogen bond.Xa idigri ye-ionization ye-PAA ifikelele kwinqanaba elithile, i-PAA ayikwazanga ukuhlanganisana kwifilimu kunye nabamkeli be-hydrogen bond kwi-LBL.
Ubunzima befilimu behla ngokunyuka kwesisombululo pH, kwaye ubukhulu befilimu behla ngokukhawuleza kwi-pH2.5 HPC/PAA kunye ne-pH3.0-3.5 HPC/PAA.Inqaku elibalulekileyo le-HPC / PAA li malunga ne-pH 3.5, ngelixa i-HEC / PAA imalunga ne-3.0.Oku kuthetha ukuba xa i-pH yesisombululo sendibano iphezulu kune-3.5, ifilimu ye-HPC / PAA ayikwazi ukubunjwa, kwaye xa i-pH yesisombululo iphezulu kune-3.0, ifilimu ye-HEC / PAA ayinakusekwa.Ngenxa yeqondo eliphezulu le-hydrogen bond complexation ye-HPC / PAA membrane, ixabiso elibalulekileyo le-pH le-HPC / PAA membrane liphezulu kune-HEC / PAA membrane.Kwisisombululo esingenatyuwa, ixabiso le-pH elibalulekileyo le-complex eyenziwe yi-HEC / PAA, MC / PAA kunye ne-HPC / PAA yayimalunga ne-2.9, 3.2 kunye ne-3.7, ngokulandelanayo.I-pH ebalulekileyo ye-HPC / PAA iphezulu kune-HEC / PAA, ehambelanayo ne-LBL membrane.
Ukusebenza kokufunxa kwamanzi kwe-CE/PAA inwebu:
I-CES ityebile kumaqela e-hydroxyl ukuze ibe nokufunxa kakuhle kwamanzi kunye nokugcinwa kwamanzi.Ukuthatha i-HEC / PAA i-membrane njengomzekelo, umthamo we-adsorption we-hydrogen-bonded CE / PAA membrane emanzini kwindawo yafundwa.Ebonakaliswe yi-interferometry ye-spectral, ubukhulu befilimu buyanda njengoko ifilimu ithatha amanzi.Ibekwe kwindawo enomswakama olungelelanisiweyo kwi-25 ° C kwiiyure ze-24 ukuphumeza ukulingana kokufunxa kwamanzi.Iifilimu zomiswe kwi-oven vacuum (40 ° C) kwi-24 h ukususa ngokupheleleyo ukufuma.
Njengoko umswakama usanda, ifilimu iyaqina.Kwindawo yomswakama ophantsi we-30% -50%, ukukhula kobunzima kuyacotha.Xa ukufuma kudlula i-50%, ubukhulu bukhula ngokukhawuleza.Xa kuthelekiswa ne-hydrogen-bonded PVPON / PAA membrane, i-HEC / PAA membrane inokuthatha amanzi amaninzi kwindalo.Ngaphantsi kwemeko yomswakama ohambelana ne-70% (25 ° C), uluhlu olubanzi lwefilimu ye-PVPON / PAA malunga ne-4%, ngelixa ifilimu ye-HEC / PAA iphezulu malunga ne-18%.Iziphumo zibonise ukuba nangona inani elithile lamaqela e-OH kwinkqubo ye-HEC / PAA inxaxheba ekubunjweni kweebhondi ze-hydrogen, kusekho inani elikhulu lamaqela e-OH asebenzisana namanzi kwindawo engqongileyo.Ke ngoko, inkqubo ye-HEC/PAA ineempawu ezilungileyo zokufunxa amanzi.
ukuququmbela
(1) Inkqubo ye-HPC / PAA eneqondo eliphezulu le-hydrogen bonding ye-CE kunye ne-PAA inokukhula ngokukhawuleza phakathi kwabo, i-MC / PAA iphakathi, kwaye i-HEC / PAA iyona ephantsi.
(2) Ifilimu ye-HEC / PAA ibonise imodi yokukhula ehambelanayo kulo lonke inkqubo yokulungiselela, ngelixa ezinye iifilimu ezimbini ze-MC / PAA kunye ne-HPC / PAA zibonisa ukukhula okubonakalayo kwimijikelezo embalwa yokuqala, kwaye emva koko iguqulelwe kwindlela yokukhula yomgca.
(3) Ukukhula kwefilimu ye-CE / PAA kuxhomekeke kakhulu kwisisombululo pH.Xa isisombululo se-pH siphezulu kuneyona ndawo ibalulekileyo, i-PAA kunye ne-CE ayinakuhlanganisana kwifilimu.I-membrane ye-CE / PAA edibeneyo yayinyibilika kwizisombululo eziphezulu ze-pH.
(4) Ekubeni ifilimu ye-CE / PAA isisityebi kwi-OH kunye ne-COOH, unyango lobushushu lenza ukuba lidibanise.I-membrane ye-CE / PAA edibeneyo inozinzo oluhle kwaye ayinyibiliki kwizisombululo eziphezulu ze-pH.
(5) Ifilimu ye-CE/PAA inomthamo olungileyo we-adsorption yamanzi kwindawo engqongileyo.
Ixesha lokuposa: Feb-18-2023