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 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