Bayanan Bincike
A matsayinsa na halitta, mai yawa da sabuntawa, cellulose yana fuskantar babban kalubale a aikace-aikace masu amfani saboda rashin narkewa da ƙayyadaddun kaddarorin narkewa. Babban crystallinity da high-yawa hydrogen bond a cikin cellulose tsarin sa shi ƙasƙanta amma ba narke a lokacin mallaka tsari, da kuma insoluble a cikin ruwa da kuma mafi Organic kaushi. Abubuwan da aka samo su ana samar da su ta hanyar esterification da etherification na ƙungiyoyin hydroxyl akan raka'a anhydroglucose a cikin sarkar polymer, kuma za su nuna wasu kaddarorin daban-daban idan aka kwatanta da cellulose na halitta. A etherification dauki na cellulose iya haifar da da yawa ruwa-soluble cellulose ethers, irin su methyl cellulose (MC), hydroxyethyl cellulose (HEC) da hydroxypropyl cellulose (HPC), wanda aka yadu amfani a abinci, kayan shafawa, a Pharmaceuticals da kuma magani. CE mai narkewar ruwa na iya samar da polymers masu haɗakar hydrogen tare da polycarboxylic acid da polyphenols.
Ƙungiyar Layer-by-Layer (LBL) hanya ce mai tasiri don shirya fina-finai na polymer composite na bakin ciki. Abubuwan da ke biyowa galibi suna bayyana taron LBL na CEs daban-daban guda uku na HEC, MC da HPC tare da PAA, suna kwatanta halayen taron su, kuma suna nazarin tasirin masu maye gurbinsu akan taron LBL. Bincika tasirin pH akan kauri na fim, da bambance-bambance daban-daban na pH akan samuwar fim da rushewar, da haɓaka abubuwan sha ruwa na CE/PAA.
Kayayyakin Gwaji:
Polyacrylic acid (PAA, Mw = 450,000). Dankowar 2wt.% bayani mai ruwa na hydroxyethylcellulose (HEC) shine 300mPa·s, kuma matakin maye gurbin shine 2.5. Methylcellulose (MC, 2wt.% bayani mai ruwa tare da danko na 400 mPa·s da digiri na maye gurbin 1.8). Hydroxypropyl cellulose (HPC, 2wt.% bayani mai ruwa tare da danko na 400 mPa·s da digiri na maye gurbin 2.5).
Shirye-shiryen fim:
An shirya shi ta hanyar taro na kristal na ruwa akan silicon a 25 ° C. Hanyar magani na matrix slide shine kamar haka: jiƙa a cikin maganin acidic (H2SO4/H2O2, 7/3Vol/VOL) na tsawon minti 30, sannan a wanke tare da ruwa mai tsabta sau da yawa har sai pH ya zama tsaka tsaki, kuma a karshe ya bushe tare da nitrogen mai tsabta. Ana yin taron LBL ta amfani da injina ta atomatik. An jiƙa madaidaicin madaidaicin a cikin maganin CE (0.2 mg/mL) da maganin PAA (0.2 mg/mL), kowane bayani an jiƙa don 4 min. Soaks kurkura guda uku na 1 min kowanne a cikin ruwa mai tsafta an yi tsakanin kowane jiƙan bayani don cire polymer da aka haɗe. Ma'auni na pH na maganin taro da maganin rinsing an daidaita su zuwa pH 2.0. Fina-finan da aka shirya kamar yadda (CE/PAA) n, inda n ke nuna zagayowar taron. (HEC/PAA)40, (MC/PAA)30 da (HPC/PAA) 30 an shirya su.
Siffar Fim:
NanoCalc-XR Ocean Optics an yi rikodin abubuwan gani na kusa-na al'ada kuma an gwada su tare da auna kaurin fina-finan da aka ajiye akan silicon. Tare da madaidaicin siliki mara tushe azaman bango, bakan FT-IR na fim ɗin bakin ciki akan silinda aka tattara akan sikirin infrared na Nicolet 8700.
Haɗin haɗin hydrogen tsakanin PAA da CEs:
Majalisar HEC, MC da HPC tare da PAA cikin fina-finan LBL. Ana nuna sifofin infrared na HEC/PAA, MC/PAA da HPC/PAA a cikin adadi. Ana iya ganin siginar IR mai ƙarfi na PAA da CES a fili a cikin yanayin IR na HEC/PAA, MC/PAA da HPC/PAA. FT-IR spectroscopy na iya yin nazarin hadaddun haɗin hydrogen tsakanin PAA da CES ta hanyar sa ido kan motsi na maƙallan sha. Haɗin hydrogen tsakanin CES da PAA galibi yana faruwa ne tsakanin oxygen hydroxyl na CES da ƙungiyar COOH na PAA. Bayan an sami haɗin haɗin hydrogen, jan kololuwar miƙewa yana juyawa zuwa ƙananan mitar alkibla.
An lura da kololuwar 1710 cm-1 don tsabtataccen foda na PAA. Lokacin da aka haɗa polyacrylamide a cikin fina-finai tare da CE daban-daban, kololuwar HEC/PAA, MC/PAA da MPC/PAA fina-finai sun kasance a 1718 cm-1, 1720 cm-1 da 1724 cm-1, bi da bi. Idan aka kwatanta da foda mai tsabta na PAA, tsayin tsayi na HPC / PAA, MC / PAA da HEC / PAA fina-finai sun canza ta 14, 10 da 8 cm-1, bi da bi. Haɗin hydrogen tsakanin ether oxygen da COOH yana katse haɗin hydrogen tsakanin ƙungiyoyin COOH. Ƙarin haɗin gwiwar hydrogen da aka samu tsakanin PAA da CE, mafi girma kololuwar motsi na CE/PAA a cikin sifofin IR. HPC yana da mafi girman matakin haɗin haɗin hydrogen, PAA da MC suna tsakiyar, kuma HEC shine mafi ƙasƙanci.
Halayen haɓakar fina-finai masu haɗaka na PAA da CEs:
Halin ƙirƙirar fim na PAA da CE a yayin taron LBL an bincika ta amfani da QCM da interferometry na spectral. QCM yana da tasiri don sa ido kan ci gaban fim a wurin yayin zagayowar taro na farko. Spectral interferometers sun dace da fina-finan da suka girma sama da hawan keke 10.
Fim din HEC / PAA ya nuna ci gaban layi a cikin tsarin taro na LBL, yayin da fina-finai na MC / PAA da HPC / PAA suka nuna girma mai girma a farkon matakan taro sannan kuma ya canza zuwa ci gaban layi. A cikin yanki na ci gaba na linzamin kwamfuta, mafi girman matsayi na hadaddun, mafi girma girma girma a kowane zagaye na taro.
Tasirin bayani pH akan ci gaban fim:
Ƙimar pH na maganin yana rinjayar ci gaban fim ɗin polymer bonded hydrogen. A matsayin polyelectrolyte mai rauni, PAA za a yi ionized kuma za a caje mara kyau yayin da pH na maganin ke ƙaruwa, ta haka ya hana ƙungiyar haɗin gwiwar hydrogen. Lokacin da matakin ionization na PAA ya kai wani matakin, PAA ba za ta iya haɗawa cikin fim tare da masu karɓar haɗin hydrogen a cikin LBL ba.
Fim ɗin fim ɗin ya ragu tare da haɓaka pH na bayani, kuma nauyin fim ɗin ya ragu ba zato ba tsammani a pH2.5 HPC / PAA da pH3.0-3.5 HPC / PAA. Mahimmin mahimmanci na HPC/PAA shine game da pH 3.5, yayin da na HEC/PAA ya kasance kusan 3.0. Wannan yana nufin cewa lokacin da pH na maganin taro ya fi 3.5, ba za a iya samar da fim din HPC / PAA ba, kuma lokacin da pH na maganin ya fi 3.0, ba za a iya samar da fim din HEC / PAA ba. Saboda mafi girman matakin haɗin haɗin hydrogen na HPC/PAA membrane, ƙimar pH mai mahimmanci na HPC/PAA membrane ya fi na HEC/PAA membrane. A cikin maganin ba tare da gishiri ba, ƙimar pH mai mahimmanci na ɗakunan da HEC/PAA, MC/PAA da HPC/PAA suka kafa sun kasance kusan 2.9, 3.2 da 3.7, bi da bi. Mahimmin pH na HPC/PAA ya fi na HEC/PAA, wanda ya yi daidai da na LBL membrane.
Ayyukan sha ruwa na CE/PAA membrane:
CES yana da wadata a cikin ƙungiyoyin hydroxyl don ya sami kyakkyawan shayar da ruwa da riƙe ruwa. Ɗaukar membrane HEC/PAA a matsayin misali, an yi nazarin ƙarfin adsorption na membrane CE/PAA da aka haɗa hydrogen zuwa ruwa a cikin muhalli. Halin da ke tattare da interferometry, kauri na fim yana ƙaruwa yayin da fim ɗin ke sha ruwa. An sanya shi a cikin wani yanayi mai daidaitacce zafi a 25 ° C na sa'o'i 24 don cimma daidaiton sha ruwa. An bushe fina-finai a cikin tanda (40 ° C) na tsawon sa'o'i 24 don cire danshi gaba daya.
Yayin da zafi ya karu, fim din yana girma. A cikin ƙananan yanayin zafi na 30% -50%, girman girma yana da ɗan jinkirin. Lokacin da zafi ya wuce 50%, kauri yana girma da sauri. Idan aka kwatanta da membrane PVPON/PAA mai haɗin hydrogen, membrane HEC/PAA zai iya sha ruwa mai yawa daga muhalli. A ƙarƙashin yanayin yanayin zafi na 70% (25 ° C), girman girman fim ɗin PVPON/PAA yana da kusan 4%, yayin da na HEC/PAA fim ɗin ya kai kusan 18%. Sakamakon ya nuna cewa ko da yake wasu adadin ƙungiyoyin OH a cikin tsarin HEC/PAA sun shiga cikin samar da haɗin gwiwar hydrogen, har yanzu akwai adadi mai yawa na ƙungiyoyin OH da ke hulɗa da ruwa a cikin muhalli. Saboda haka, tsarin HEC/PAA yana da kyawawan abubuwan sha na ruwa.
a karshe
(1) Tsarin HPC/PAA tare da mafi girman matakin haɗin gwiwar hydrogen na CE da PAA yana da girma mafi sauri a tsakanin su, MC/PAA yana tsakiyar, kuma HEC / PAA shine mafi ƙasƙanci.
(2) Fim din HEC / PAA ya nuna yanayin ci gaba na layi a cikin tsarin shirye-shiryen, yayin da sauran fina-finai biyu na MC / PAA da HPC / PAA sun nuna girma mai girma a cikin 'yan ƙananan hawan keke na farko, sa'an nan kuma ya canza zuwa yanayin girma na layi.
(3) Ci gaban fim ɗin CE / PAA yana da dogaro mai ƙarfi akan maganin pH. Lokacin da pH bayani ya fi girma fiye da mahimmancinsa, PAA da CE ba za su iya haɗuwa cikin fim ba. Membran CE/PAA da aka haɗu ya kasance mai narkewa a cikin manyan hanyoyin pH.
(4) Tun da fim din CE / PAA yana da wadata a OH da COOH, maganin zafi ya sa ya haɗu. Membran CE/PAA mai haɗin giciye yana da kwanciyar hankali mai kyau kuma ba shi da narkewa a cikin manyan hanyoyin pH.
(5) Fim ɗin CE / PAA yana da ƙarfin talla mai kyau don ruwa a cikin yanayi.
Lokacin aikawa: Fabrairu-18-2023