1.Sebopeho le molao-motheo oa ho lokisetsa cellulose ether
Setšoantšo sa 1 se bontša sebopeho se tloaelehileng sa cellulose ethers. Yuniti e 'ngoe le e' ngoe ea bD-anhydroglucose (yuniti e pheta-phetoang ea selulose) e nka sebaka sa sehlopha se le seng maemong a C (2), C (3) le C (6), ke hore, ho ka ba le lihlopha tse tharo tsa ether. Ka lebaka la li- intra-chain le inter-chain hydrogen bond tsacellulose macromolecules, ho thata ho qhibiliha ka metsing le hoo e batlang e le lihlahisoa tsohle tsa tlhaho. Ho kenngoa ha lihlopha tsa ether ka etherification ho senya li-intramolecular le intermolecular hydrogen bonds, ho ntlafatsa hydrophilicity ea eona, 'me ho ntlafatsa haholo ho qhibiliha ha eona mecheng ea metsi.
Maemo a tloaelehileng a etherified ke lihlopha tsa alkoxy tse boima ba molek'hule (1 ho isa ho 4 liathomo tsa khabone) kapa lihlopha tsa hydroxyalkyl, tse ka nkeloang sebaka ke lihlopha tse ling tse sebetsang joalo ka lihlopha tsa carboxyl, hydroxyl kapa amino. Li-substitute li ka ba tsa mofuta o le mong, tse peli kapa ho feta tse fapaneng. Haufi le ketane ea cellulose macromolecular, lihlopha tsa hydroxyl tse maemong a C(2), C(3) le C(6) tsa yuniti e' ngoe le e 'ngoe ea tsoekere li nkeloa sebaka ka likarolo tse fapaneng. Ha re bua hantle, cellulose ether ka kakaretso ha e na sebopeho sa lik'hemik'hale se hlakileng, ntle le lihlahisoa tse nkeloang sebaka ke mofuta o le mong oa sehlopha (lihlopha tse tharo tsa hydroxyl li nkeloa sebaka). Lihlahisoa tsena li ka sebelisoa feela bakeng sa tlhahlobo ea laboratori le lipatlisiso, 'me ha li na boleng ba khoebo.
(a) Sebopeho se akaretsang sa liyuniti tse peli tsa anhydroglucose tsa ketane ea molek'hule ea cellulose ether, R1~R6=H, kapa ntho e 'ngoe ea lintho tse phelang;
(b) Sekhechana sa ketane ea molek'hule ea carboxymethylhydroxyethyl cellulose, tekanyo ea ho kenya sebaka sa carboxymethyl ke 0.5, tekanyo ea ho fetola hydroxyethyl ke 2.0, 'me tekanyo ea ho fetola molar ke 3.0. Sebopeho sena se emela boemo bo tloaelehileng ba ho fapanyetsana ha lihlopha tsa etherified, empa tse nkeloang sebaka ha e le hantle ke tse sa reroang.
Bakeng sa sebaka se seng le se seng, kakaretso ea palo ea etherification e hlahisoa ke tekanyo ea phallo ea boleng ba DS. Mefuta e fapaneng ea DS ke 0~3, e lekanang le palo e tloaelehileng ea lihlopha tsa hydroxyl tse nkeloang sebaka ke lihlopha tsa etherification yuniti e 'ngoe le e 'ngoe ea anhydroglucose.
Bakeng sa li-ethers tsa hydroxyalkyl cellulose, karabelo e ncha e tla qala etherification ho tsoa ho lihlopha tse ncha tsa hydroxyl tse sa lefelloeng, 'me tekanyo ea ho fetola e ka lekanyetsoa ka boleng ba MS, ke hore, tekanyo ea molar ea substitution. E emela palo e tloaelehileng ea li-moles tsa etherifying agent reactant e kentsoeng yuniting e 'ngoe le e 'ngoe ea anhydroglucose. Reactant e tloaelehileng ke ethylene oxide mme sehlahisoa se na le sebaka sa hydroxyethyl. Setšoantšong sa 1, boleng ba MS ba sehlahisoa ke 3.0.
Ka khopolo, ha ho na moeli o ka holimo oa boleng ba MS. Haeba boleng ba DS ba tekanyo ea ho kenya sebaka sehlopheng se seng le se seng sa lesale la tsoekere bo tsejoa, bolelele ba ketane e tloaelehileng ea ketane ea lehlakore la etherBaetsi ba bang hangata ba sebelisa karoloana ea boima (wt%) ea lihlopha tse fapaneng tsa etherification (joalo ka -OCH3 kapa -OC2H4OH) ho emela boemo ba substitution le degree sebakeng sa DS le MS boleng. Karolo e boima ea sehlopha ka seng le boleng ba eona ba DS kapa MS e ka fetoloa ka lipalo tse bonolo.
Bongata ba li-cellulose ethers ke li-polymer tse qhibilihang ka metsing, 'me tse ling li boetse li qhibiliha ka mokhoa o itseng ka har'a metsoako ea tlhaho. Cellulose ether e na le litšoaneleho tsa ts'ebetso e phahameng, theko e tlase, ts'ebetso e bonolo, chefo e tlase le mefuta e mengata e fapaneng, 'me masimo a tlhokahalo le kopo a ntse a atoloha. Joaloka moemeli ea thusang, cellulose ether e na le bokhoni bo boholo ba ts'ebeliso likarolong tse fapaneng tsa indasteri. e ka fumanoa ka MS/DS.
Li-cellulose ethers li arotsoe ho ea ka sebopeho sa lik'hemik'hale tsa li-substituents ho anionic, cationic le nonionic ethers. Li-ether tsa Nonionic li ka aroloa ka lihlahisoa tse qhibilihang ka metsing le tse qhibilihang ka oli.
Lihlahisoa tse entsoeng liindasteri li thathamisitsoe karolong e ka holimo ea Lethathamo la 1. Karolo e ka tlaase ea Lethathamo la 1 e thathamisa lihlopha tse ling tse tsejoang tsa etherification, tse e-s'o fetohe lihlahisoa tsa bohlokoa tsa khoebo.
Taelo ea khutsufatso ea li-substituents tse tsoakiloeng tsa ether e ka bitsoa ho latela tatellano ea alfabeta kapa boemo ba DS (MS), mohlala, bakeng sa 2-hydroxyethyl methylcellulose, khutsufatso ke HEMC, hape e ka ngoloa joalo ka MHEC ho totobatsa sebaka sa methyl.
Lihlopha tsa hydroxyl ka selulose ha li fumanehe habonolo ke li-etherification agents, 'me mokhoa oa etherification o atisa ho etsoa tlas'a maemo a alkaline, ka kakaretso ho sebelisoa motsoako o itseng oa NaOH aqueous solution. Selulose e qala ho bopeha hore e be selulose ea alkali e ruruhileng e nang le mokelikeli oa metsi oa NaOH, ebe e kenella karabelo ea etherification ka etherification agent. Nakong ea tlhahiso le ho lokisa li-ether tse tsoakiloeng, mefuta e fapaneng ea li-etherification e lokela ho sebelisoa ka nako e le 'ngoe, kapa etherification e lokela ho etsoa mohato ka mohato ka ho fepa ka nakoana (ha ho hlokahala). Ho na le mefuta e mene ea karabelo ho etherification ea selulose, e akaretsoang ka mokhoa oa karabelo (cellulosic e nkeloa sebaka ke Cell-OH) ka tsela e latelang:
Equation (1) e hlalosa karabelo ea Williamson etherification. RX ke inorganic acid ester, 'me X ke halogen Br, Cl kapa sulfuric acid ester. Chloride R-Cl hangata e sebelisoa indastering, mohlala, methyl chloride, ethyl chloride kapa chloroacetic acid. Palo ea stoichiometric ea motheo e jeoa karabelong e joalo. Lihlahisoa tsa indasteri ea cellulose ether methyl cellulose, ethyl cellulose le carboxymethyl cellulose ke lihlahisoa tsa Williamson etherification reaction.
Rection formula (2) ke karabelo ea tlatsetso ea base-catalyzed epoxides (joalo ka R=H, CH3, kapa C2H5) le lihlopha tsa hydroxyl limolek'huleng tsa cellulose ntle le ho ja setsi. Boitšoaro bona bo ka 'na ba tsoela pele ha lihlopha tse ncha tsa hydroxyl li hlahisoa nakong ea karabelo, e lebisang ho thehoeng ha liketane tsa mahlakoreng a oligoalkylethylene oxide: Boitšoaro bo tšoanang le 1-aziridine (aziridine) bo tla theha aminoethyl ether: Cell-O-CH2-CH2-NH2 . Lihlahisoa tse kang hydroxyethyl cellulose, hydroxypropyl cellulose le hydroxybutyl cellulose kaofela ke lihlahisoa tsa base-catalyzed epoxidation.
Rection formula (3) ke karabelo lipakeng tsa Cell-OH le metsoako ea organic e nang le li-bond tse peli tse sebetsang ka har'a alkaline medium, Y ke sehlopha se hulang elektronike, joalo ka CN, CONH2, kapa SO3-Na+. Kajeno mofuta ona oa karabelo ha o sebelisoe hangata indastering.
Rection formula (4), etherification e nang le diazoalkane ha e so ntlafatsoe indastering hajoale.
- Mefuta ea li-cellulose ethers
Cellulose ether e ka ba monoether kapa ether e tsoakiloeng, 'me thepa ea eona e fapane. Ho na le lihlopha tsa hydrophilic tse nkeloang sebaka ka tlase ho macromolecule ea cellulose, joalo ka lihlopha tsa hydroxyethyl, tse ka fang sehlahisoa ka tekanyo e itseng ea ho qhibiliha ha metsi, ha lihlopha tsa hydrophobic, tse kang methyl, ethyl, joalo-joalo, ho nka sebaka se itekanetseng feela tekanyo e phahameng e ka khona. fa sehlahisoa ho qhibiliha ho itseng ha metsi, 'me sehlahisoa se nkeloang sebaka se tlase se ruruha feela metsing kapa se ka qhibiliha ka tharollo ea alkali e hlapollang. Ka lipatlisiso tse tebileng mabapi le thepa ea li-cellulose ethers, li-ether tse ncha tsa cellulose le masimo a tsona a ts'ebeliso li tla tsoela pele ho ntlafatsoa le ho hlahisoa, 'me matla a maholohali a ho khanna ke 'maraka o pharaletseng le o hloekisitsoeng ka ho tsoelang pele.
Molao o akaretsang oa tšusumetso ea lihlopha ka har'a li-ether tse tsoakiloeng ka thepa ea ho qhibiliha ke:
1) Eketsa litaba tsa lihlopha tsa hydrophobic sehlahisoa ho eketsa hydrophobicity ea ether le ho theola ntlha ea gel;
2) Eketsa litaba tsa lihlopha tsa hydrophilic (tse kang lihlopha tsa hydroxyethyl) ho eketsa ntlha ea eona ea gel;
3) Sehlopha sa hydroxypropyl se khethehile, 'me hydroxypropylation e nepahetseng e ka fokotsa mocheso oa gel oa sehlahisoa,' me mocheso oa gel oa sehlahisoa sa hydroxypropylated se mahareng se tla tsoha hape, empa boemo bo phahameng ba ho nkela sebaka bo tla fokotsa ntlha ea eona ea gel; Lebaka ke ka lebaka la sebopeho se khethehileng sa ketane ea k'habone ea sehlopha sa hydroxypropyl, hydroxypropylation ea boemo bo tlase, bofokoli bo fokolang ba haedrojene le lipakeng tsa limolek'hule tsa cellulose macromolecule, le lihlopha tsa hydrophilic hydroxyl ka liketane tsa makala. Metsi a rena. Ka lehlakoreng le leng, haeba ho nkeloa sebaka ho phahame, ho tla ba le polymerization ka lehlakoreng la sehlopha, karolo e lekanyelitsoeng ea sehlopha sa hydroxyl e tla fokotseha, hydrophobicity e tla eketseha, 'me ho qhibiliha ho tla fokotseha ho e-na le hoo.
Tlhahiso le lipatlisiso tsacellulose ethere na le nalane e telele. Ka 1905, Suida o ile a tlaleha ka lekhetlo la pele ka etherification ea selulose, e neng e le methylated ka dimethyl sulfate. Li-alkyl ethers tsa Nonionic li ne li e-na le tokelo ea molao ke Lilienfeld (1912), Dreyfus (1914) le Leuchs (1920) bakeng sa li-cellulose ethers tse qhibilihang ka metsing kapa ka oli, ka ho latellana. Buchler le Gomberg ba ile ba hlahisa benzyl cellulose ka 1921, carboxymethyl cellulose e ile ea hlahisoa ka lekhetlo la pele ke Jansen ka 1918, 'me Hubert a hlahisa cellulose ea hydroxyethyl ka 1920. Mathoasong a 1920, carboxymethylcellulose e ne e rekisoa Jeremane. Ho tloha 1937 ho isa 1938, tlhahiso ea indasteri ea MC le HEC e ile ea phethahala United States. Sweden e ile ea qala tlhahiso ea EHEC e qhibilihang ka metsing ka 1945. Ka mor'a 1945, tlhahiso ea cellulose ether e ile ea eketseha ka potlako Europe Bophirimela, United States le Japane. Qetellong ea 1957, China CMC e ile ea qala ho kenngoa tlhahisong ea Shanghai Celluloid Factory. Ka 2004, tlhahiso ea naha ea heso e tla be e le lithane tse 30,000 tsa ionic ether le lithane tse 10,000 tsa ether e seng ea ionic. Ka 2007, e tla fihla ho lithane tse 100,000 tsa ionic ether le lithane tse 40,000 tsa Nonionic ether. Likhamphani tse kopaneng tsa theknoloji lapeng le kantle ho naha le tsona li lula li hlaha, 'me matla a tlhahiso ea selulose ea ether ea China le boemo ba tekheniki li ntse li ntlafala kamehla.
Lilemong tsa morao tjena, li-cellulose monoethers tse ngata le li-ether tse tsoakiloeng tse nang le litekanyetso tse fapaneng tsa DS, li-viscosities, bohloeki le thepa ea rheological li 'nile tsa ntlafatsoa khafetsa. Hajoale, sepheo sa nts'etsopele lefapheng la li-cellulose ethers ke ho amohela theknoloji e tsoetseng pele ea tlhahiso, theknoloji e ncha ea ho itokisa, lisebelisoa tse ncha, lihlahisoa tse ncha, lihlahisoa tsa boleng bo holimo le lihlahisoa tse hlophisitsoeng li lokela ho batlisisoa ka botekgeniki.
Nako ea poso: Apr-28-2024