Tsvagiridzo Yekare
Sechisikwa, chakawanda uye chinodzokororwa, cellulose inosangana nematambudziko makuru mukushandiswa kwayo nekuda kwehunhu hwayo husina kunyunguduka uye hushoma hwekunyunguduka. Kusimba kwakanyanya kwe crystallinity uye high-density hydrogen bonds mu cellulose structure zvinoita kuti iparare asi isanyunguduke panguva yekubatwa, uye isanyunguduke mumvura uye mune zvakawanda zvinonyunguduka zve organic. Zvinobva kwavari zvinogadzirwa ne esterification uye etherification ye hydroxyl groups pa anhydroglucose units mu polymer chain, uye zvicharatidza humwe hunhu hwakasiyana zvichienzaniswa ne natural cellulose. Etherification reaction ye cellulose inogona kugadzira akawanda water-soluble cellulose ethers, akadai se methyl cellulose (MC), hydroxyethyl cellulose (HEC) uye hydroxypropyl cellulose (HPC), ayo anoshandiswa zvakanyanya mukudya, zvizoro, mumishonga nemumishonga. Water-soluble CE inogona kugadzira hydrogen-bonded polymers ne polycarboxylic acids uye polyphenols.
Kuungana kweLayer-by-layer (LBL) inzira inoshanda yekugadzira mafirimu matete epolymer composite. Izvi zvinonyanya kutsanangura kuungana kweLBL kwemaCE matatu akasiyana eHEC, MC neHPC nePAA, kuenzanisa maitiro avo ekuungana, uye kuongorora simba rezvinhu zvinotsiva pakubatana kweLBL. Ongorora mhedzisiro yepH pakukora kwefirimu, uye mutsauko wakasiyana wepH pakuumbwa kwefirimu nekunyungudika, uye gadzira hunhu hwekunwa kwemvura hweCE/PAA.
Zvinhu Zvekuyedza:
Polyacrylic acid (PAA, Mw = 450,000). Kuwanda kwe2wt.% yehydroxyethylcellulose (HEC) i300 mPa·s, uye mwero wekutsiva i2.5. Methylcellulose (MC, mhinduro ye2wt.% yemvura ine viscosity ye400 mPa·s uye mwero wekutsiva we1.8). Hydroxypropyl cellulose (HPC, mhinduro ye2wt.% yemvura ine viscosity ye400 mPa·s uye mwero wekutsiva we2.5).
Kugadzirira firimu:
Yakagadzirwa ne liquid crystal layer assembly pasilicon pa25°C. Nzira yekurapa nayo slide matrix ndeiyi inotevera: kunyikwa mu acidic solution (H2SO4/H2O2, 7/3Vol/VOL) kwemaminitsi makumi matatu, wozosuka nemvura yakabviswa ion kakawanda kusvika pH yava neutral, wozopedzisira waoma ne pure nitrogen. LBL assembly inoitwa uchishandisa automatic machinery. Substrate yakanyikwa neimwe CE solution (0.2 mg/mL) uye PAA solution (0.2 mg/mL), mhinduro yega yega yakanyikwa kwemaminitsi mana. Kunyorova katatu kweminiti imwe neimwe mumvura yakabviswa ion kwakaitwa pakati pekunyorova kwega kwega kwe solution kubvisa polymer yakasungirirwa zvisina kusimba. pH values ye assembly solution uye rinsing solution zvese zvakagadziriswa ku pH 2.0. Mafirimu akagadzirwa anoratidzwa se (CE/PAA)n, apo n inomiririra assembly cycle. (HEC/PAA)40, (MC/PAA)30 uye (HPC/PAA)30 akagadzirwa zvakanyanya.
Kutsanangurwa kweMafirimu:
Maspectra ekupenya ari pedyo neakajairika akanyorwa uye akaongororwa neNanoCalc-XR Ocean Optics, uye ukobvu hwemafirimu akaiswa pasilicon hwakayerwa. Nesimbi isina chinhu yesilicon semusana, FT-IR spectrum yefirimu rakatetepa pasilicon substrate yakaunganidzwa paNicolet 8700 infrared spectrometer.
Kudyidzana kwehydrogen bond pakati pePAA neCEs:
Kuungana kweHEC, MC neHPC nePAA muLBL films. Ma infrared spectra eHEC/PAA, MC/PAA neHPC/PAA anoratidzwa mumufananidzo. Zviratidzo zveIR zvakasimba zvePAA neCES zvinogona kuonekwa zvakajeka muIR spectra yeHEC/PAA, MC/PAA neHPC/PAA. FT-IR spectroscopy inogona kuongorora hydrogen bond complexation pakati pePAA neCES nekutarisa kuchinja kwema characteristic absorption bands. Kubatana kwehydrogen pakati peCES nePAA kunonyanya kuitika pakati pehydroxyl oxygen yeCES neCOOH group yePAA. Mushure mekunge hydrogen bond yaumbwa, stretching peak red inoshanduka kuenda kune low frequency direction.
Pakaonekwa hupfu hwePAA hwakachena hwe1710 cm-1. Polyacrylamide payakaunganidzwa kuita mafirimu ane maCE akasiyana, misoro yemafirimu eHEC/PAA, MC/PAA uye MPC/PAA yaive pa1718 cm-1, 1720 cm-1 uye 1724 cm-1, zvichiteerana. Zvichienzaniswa nehupfu hwePAA hwakachena, hurefu hwepamusoro hwemafirimu eHPC/PAA, MC/PAA uye HEC/PAA hwakachinjwa ne14, 10 uye 8 cm−1, zvichiteerana. Chisungo chehydrogen pakati pe ether oxygen neCOOH chinomisa chisungo chehydrogen pakati pemapoka eCOOH. Kana zvisungo zvehydrogen zvakawanda zvichiumbwa pakati pePAA neCE, ndipo panowedzera kuchinja kweCE/PAA muIR spectra. HPC ine mwero wepamusoro wehydrogen bond complexation, PAA neMC zviri pakati, uye HEC ndiyo yakaderera.
Kukura kwemaitiro emafirimu akabatanidzwa ePAA neCEs:
Maitiro ekugadzira mafirimu ePAA neCEs panguva yeLBL akaitwa ongororo uchishandisa QCM uye spectral interferometry. QCM inoshanda pakutarisa kukura kwefirimu panzvimbo panguva yekutanga yekuunganidza. Spectral interferometers dzakakodzera mafirimu akakura anopfuura gumi.
Firimu reHEC/PAA rakaratidza kukura kwakarongeka panguva yese yeLBL assembly, nepo mafirimu eMC/PAA neHPC/PAA akaratidza kukura kwakarongeka mumatanho ekutanga ekuunganidza uye akazoshanduka kuita kukura kwakarongeka. Munzvimbo yekukura kwakarongeka, kukura kwakasimba kwehuwandu hwezvinhu, ndiko kukura kwakasimba kwehuwandu hwezvinhu pachikamu chekuunganidza.
Mhedzisiro ye pH yemushonga pakukura kwefirimu:
Kuwanda kwepH yemushonga kunokanganisa kukura kwehydrogen bonded polymer composite film. Se polyelectrolyte isina simba, PAA ichaiswa ion uye ichaiswa negative charge sezvo pH yemushonga ichiwedzera, nokudaro ichidzivisa hydrogen bond association. Kana ionization yePAA yasvika padanho rakati, PAA yaisagona kuungana kuita firimu ine hydrogen bond acceptors muLBL.
Ukobvu hwefirimu hwakadzikira nekuwedzera kwe pH ye solution, uye ukobvu hwefirimu hwakadzikira kamwe kamwe pa pH2.5 HPC/PAA uye pH3.0-3.5 HPC/PAA. Chinhu chakakosha cheHPC/PAA chiri pH 3.5, nepo cheHEC/PAA chiri 3.0. Izvi zvinoreva kuti kana pH ye assembly solution yakakwira kupfuura 3.5, firimu reHPC/PAA harigone kuumbwa, uye kana pH ye solution yakakwira kupfuura 3.0, firimu reHEC/PAA harigone kuumbwa. Nekuda kwehuwandu hwakakwira hwe hydrogen bond complexation yeHPC/PAA membrane, kukosha kwepH kweHPC/PAA membrane kwakakwira kupfuura kweHEC/PAA membrane. Mu salt-free solution, kukosha kwepH kwe complexes dzakaumbwa neHEC/PAA, MC/PAA neHPC/PAA dzaive 2.9, 3.2 uye 3.7, zvichiteerana. pH yakakosha yeHPC/PAA yakakwira kupfuura yeHEC/PAA, izvo zvinoenderana neiyo yeLBL membrane.
Kushanda kwemushonga weCE/PAA membrane pakunyudzwa kwemvura:
CES yakapfuma mumapoka ehydroxyl zvekuti inopinza mvura zvakanaka uye inochengetedza mvura. Tichitora membrane yeHEC/PAA semuenzaniso, kugona kwekubatanidza membrane yeCE/PAA yakasungirirwa nehydrogen mumvura munzvimbo yakapoteredza kwakadzidzwa. Ichiratidzwa ne spectral interferometry, ukobvu hwefirimu hunowedzera sezvo firimu richipinza mvura. Yakaiswa munzvimbo ine hunyoro hunogadziriswa pa25°C kwemaawa makumi maviri nemana kuti mvura ikwane zvakaenzana. Mafirimu acho akaomeswa muovheni ye vacuum (40°C) kwemaawa makumi maviri nemana kuti abvise hunyoro zvachose.
Sezvo hunyoro huchiwedzera, firimu rinokora. Panzvimbo ine hunyoro hushoma hwe30%-50%, kukura kwehukobvu kunononoka. Kana hunyoro huchipfuura 50%, ukobvu hunokura nekukurumidza. Kana hunyoro huchipfuura 50%, membrane yeHEC/PAA inokweva mvura yakawanda kubva munharaunda. Kana hunyoro huchisvika 70% (25°C), firimu rePVPON/PAA rinokora ne4%, nepo firimu reHEC/PAA richikwira ne18%. Zvakabuda zvakaratidza kuti kunyangwe mamwe mapoka eOH muHEC/PAA system akatora chikamu mukuumbwa kwehydrogen bonds, pakanga pachine huwandu hwakawanda hwemapoka eOH akabatana nemvura munzvimbo. Nokudaro, HEC/PAA system ine hunhu hwakanaka hwekunwa mvura.
mukupedzisa
(1) Sisitimu yeHPC/PAA ine hydrogen bonding degree yepamusoro yeCE nePAA ndiyo inokura nekukurumidza pakati padzo, MC/PAA iri pakati, uye HEC/PAA ndiyo yakaderera.
(2) Firimu reHEC/PAA rakaratidza nzira yekukura yakatsetseka panguva yese yekugadzirira, nepo mamwe mafirimu maviri eMC/PAA neHPC/PAA akaratidza kukura kwakakura mumatanho ekutanga, ndokuzoshandurwa kuita nzira yekukura yakatsetseka.
(3) Kukura kwefirimu reCE/PAA kunoenderana zvakanyanya ne pH yemhinduro. Kana pH yemhinduro yakakwira kupfuura iyo yakakosha, PAA neCE hazvigone kuungana kuita firimu. Kamudzira keCE/PAA kakasanganiswa kakanyungudika mumhinduro dze pH yakakwira.
(4) Sezvo firimu reCE/PAA rakapfuma muOH neCOOH, kurapwa nekupisa kunoita kuti rive rakasanganiswa. Kamudzira keCE/PAA kakabatana kane kugadzikana kwakanaka uye hakanyungudike mumhinduro dze pH yakakwira.
(5) Firimu reCE/PAA rine mukana wakanaka wekunyudza mvura munzvimbo yakapoteredza.
Nguva yekutumira: Kukadzi-18-2023