JOURNAL OF SCIENCE OF HNUE Natural Sci., 2014, Vol. 59, No. 4, pp. 84-89 This paper is available online at http://stdb.hnue.edu.vn
TONG HOP VA TINH CHAT OXI HOA - KHXJ CUA MANG POLYPYRROLE DUOC PHA TAP B 6 I ANION HEXAFLOROTITANAT TiF^"
Le Minh DiJc\ Nguyen Thi Hu6ng^ DUdng Thi Huyen Hai^
Phan Thi Bi'ch Ngoc'^, Ha Manh Hung^ va Vu Qu6c Trung^
^Khoa Hda hpc, Trudng Dai hpc Bdch khoa Dd Ndng, '^Khoa Hda hoc.
Trudng Dai hoc Supham Dd Nang, ^Khoa Hda hpc, Trudng Dai hoc Supluim Hd Ndi, '^Trudng Cao ddng Duoc Phii Thp,
''Khoa Dai hpc Dai cuang. Trudng Dai hoc Md - Dia chat Tom tat. Gan day mang phu polypyrrole dUpc quan tam nghien cUu do co nhieu dac tinh quy bau nhU do dSn cao, ben va dl tong hdp. Co nhilu chSt pha tap duoc sU dung de nang cao chSl lUpng ciia mang polypyrrole, bao gom ca anion hexafluorodlanat TiF,^". Trong qua trinh oxi hoa - khU, dien ird va dien dung cua mang polyme se thay doi do qua trinh kel hdp/giai phdng anion va cauon doi vdi mang polyme. Bai bao nay nghien cdu qua trinh oxi hoa - khU ciia mang polypyrrole trong dung dich C4H9)4NBr 0,1 M va NaCl 0,1 iVl bang phUdng phap quet the tuan hoan va tong trd dien hoa. Ket qua cho thay rang anion TiFj^"" dUOc giai phong khdi mang polyme dan trong qua trinh khU. Dien dung va dien trd cua mang polypyrrole thay doi chut it trong qua trinh khU. Tinh chat oxi hoa khU ciia mang polyme khdng bi anh hudng nhieu bdi cation trong dung djch.
TU khda: Polypyrrole, long trd dien hda, qua trinh oxi hoa - khU, quet thS tuan hoan.
1. Mot dau
Polyme dan la loai vat lieu mdi, co tilm nang ting dung trong nhilu linh vUc nhU chdng an mon kim loai, cam bien hoa hpc, vat lieu dien cue cho nguon dien hda hpc...
Nhieu bai bao, cdng trinh khoa hpc, phat minh sang che mdi lien quan d i n polyme da dUdc cdng bd. Dac biet, nghien cUu vl polyme dan cimg phat trien manh me hdn sau khi ba nha khoa hpc Shirakawa, A. MacDiarmid va A. Hecger phat hicn hien tUPng tang do dan dien ciia polyaxetilen (giai Nobel vl Hoa hoc, 2000) [1].
Ngay nhan bai' 10/1/2014. Ngay nhan dang: 21/5/2014.
Tac gia lien lac: Vu Quoc Trung, dia chi e-mail: [email protected]
Tdng hap vd tinh chdt oxi hda - khd cua mang polypyrrole duac pha tap bdi anion...
Polyme dSn co the d cac trang thai d i n dien, ban dan va each dien phu thuoc trang thai ton tai cua polyme - oxi hda hay khu[ hda. Tinh oxi hoa - khii cua polyme ludn dupc quan tam do co anh hu6ng Idn den kha nang Ung dung cua nd. Qua trinh oxi hoa/khijf cua polyme dan luon kem (heo sU di chuyen vao/ra cua cac anion pha tap trong nd [2-5]. Bang cac phUdng phap khac nhau nhU phUdng phap can vi lUdng thach anh dien hda, cac nha khoa hpc da phat hien thay sii giam khdi lupng cQa mang PPy khi anion di chuyfin ra khoi mang [6]. Nhieu anion khac nhau da dUdc nghien cUu, pha tap vao PPy nhUng cac anion dang phUc vdi Ti nhU Ti^~ chUa dUdc d l cap din [7].
Cac kit qua nghien ciiu pha tap anion Ti^" vao mang polypyrrole dupc trinh bay trong bili bao nay vdi hi vpng t^o dUdc Idp phu PPy thong minh trong tU bao ve kim loai.
2. Noi d u n g nghien cihi 2.1. Thtfc nghiem
* Ilda chdt
Monome pyrrole (bao quan d 4 °C, chung cSt trUdc khi sii dung), axit H2TiF(i, NaCl, (C4H())4NBr dUdc cung cap bdi Sigma-Aldrich. Binh dien hda la loai binh 3 dien cUc - dien cUc doi la lUdi Pt, dien cue so sanh la dien cUc calomen.
* Dung cu
Thiet bi Potentiostat loai EG&G 263A (Hoa Ky) dUdc ghep ndi vdi binh do de khong che dong, the dien cUc theo dieu kien thi nghiem. Dien the dien cUc deu dUdc so sanh vdi dien cUc calomen.
Tong trd dien hda dupc do tren may IM6 cua hang ZAHNER-elektrik (CHLB DUc).
VCing tan so khao sat trong khoang 100 kHz - 0,1 Hz. DUa tren cac so lieu tong trd va gdc lech pha thu dUdc, cac gia tri dien trd mang, dien dung cua mang dUdc tinh loan sau khi I3p ghep, tdi Uu hda theo md hinh vat li nhU sau;
Hinh 1. Mach dien tUdng dUdng deldp ghep, toi Uu hda sd lieu do tong trd R^: dien trd dung dich do. RRM- dien trd mdng polyme;
CpM-- dien dung Idp mdng polyme; Ra-' dien trd chuyen dien lich qua Idp dien tich kep;
C,ti: dien dung tu dim do U'fp dien tich kep tao nen
Le Minh DiJc, Nguyen Thi Hudng, DiMng Thi Huyen Hai, Phan Thi Bich Ngpc. Ha Manh Hung va Vii Quoc Trung
2.2. Ket qua va thao luan 2.2.1. TS'ng hop polypyrrole (PPy)
Mang PPy pha tap bdi anion Ti^" (PPy(Ti^")) dUdc tdng hap bang phUdng phap dien hda tren nen dien cUc Pt d mat do ddng dien Idiong doi 1,0 m A/cm^, trong dung djch H2TiF8 0,1 M, nong dp monome pyrrole 0,1 M. Dien ciic Pt dang t t o , dien tfch 1,0 cm^
dildc tay sach be mat bang, Dubng cong bieu diSn moi quan he ddng dien-thdi gian cua qua trinh tao mang dien hda dude the hien d Hinh 2,
Hinh 2. Budng cong the-thdi gian cua qud trinh polyme hda dien hoa pyrrole trong dung dich H^TiFis 0,1 M, monome pyrrole 0,1M, mat do dong 1,0 mAJcnt^
Dien the polyme hda cua monome pyrrole nhanh chdng dat gia tri on dinh d +0,7V so vdi dien cUc so sanh calomen. Mang PPyCTig") thu diidc Icha on dinh, bam chac Iren nen, Ichong cd d§u hieu bong trdc. Mang PPy thu dupc cd ciiu true kha dong nhlit, trong dd ciu true hoa sup Id cd the nhan thay d mot vai vi tri (Hinh 3).
Hinh 3. Anh SEM cua mdng PPy(Ti\-) Iren nin Pt
Tong hpp vd tinh chdt oxi hda - khd cua mdng polypyrrole dupc pha tap bdi anion...
2.2.2. Quyet t h i vong t u i n hoan
Hinh 4. Dudng cong quet the vong cua mdng PPy(Til~) trong dung dich (C^Htfj^NBr 0,1 M, tdc dp quet 20,0 mV/s
Chd sd canh dudng cong Id sd vong quet
Tinh oxi hda khif cua mang PPy(TiQ~) dupc khao sat bang quel thi vong tuSn hoan.
Mang dUdc long hpp tren dien cue Pt, vdi chi dp dien phan nhU da trinh bay d tren. Dudng cong quel thi vong tuSn hoan trong dung dich 0,1 M (C4Hc))4NBr the hien tren Hinh 4.
Cd the nhan thay cac dinh pic khii va oxi hda kha rd rang tren dUdng cong the vong tu5n hoan (Hinh 4). Vong quel khii dau tien the hien sU di chuyen ra khdi mang cua anion Tig". Sau vong thii nhdt, mang nhanh chdng on dinh the hien qua cac dudng quet thi gan nhu chdng khi't len nhau. Anion trong dung dich la Br" se tham gia vao qua trinh di chuyen vao ra mang, trao ddi anion vdi mang PPy cung vdi qua trinh oxi hda khu:. Nhu vay, tinh oxi hda khii cua mang dUdc the hien ro net. Mang kha ben sau nhieu vong quel the tuSn hoan [2, 3].
2.2.3. Pho tong trd dicn hoa
Pho long trd cua mang PPy(Ti5") dUpc the hien tren Hinh 5a, 5b, trong dd Hinh 5a la tong trd dien hda ciia mang PPy(Tig") thu dUdc trong hai dung djch (C4H.,)4NBr (cation Idn), ITmh 5b - trong NaCl (cation nhd, linh dpng). T h i khU cua mang tU +0,1 V den -1,0 V so vdi dien cue calomen.
Trong ca hai trUdng hdp, anion pha tap trong mang Ppy co the dUdc di chuyen ra khdi mang. Mang PPy bi khu" cd the nhan thay qua sU tang dien trd ciia mang RPM, dong thdi giam dien dung cua mang CPM (viing tan s6 cao). SU di chuyen ciia anion Ti^" ra khoi mang lam giam tinh chdt dien dung ciia mang. Cd the nhan thay quy luat khd cOa mang PPy dudng nhu it bi anh hudng bdi kich thudc ciia cation trong dung dich. Anion Ti,V dupc Uu lien irao doi trong qua trinh khd. Bang qua trinh ghep ndi s6 lieu do vao md hinh vat li tUdng dUdng the hien d Hinh 1 (qua trinh fitting sau khi do), cac so lieu ciia RPM, CPM dupc bieu diln d Hinh 6.
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Le Minh DUc, Nguyin Thi Hudng, DUdng Thi Huyin Hai, Phan Thi Bfch Ngpc, Ha Manh Hiing va Vu Qudc Trung
Hinh 5. Dudng cong khd mdng PPy(Tifr) trong dung dich (C^H^UNBr 0,1 M (a); NaCl 0,1 M (b) Duimg net ddt the hien gdc lech pha, diidng lien Id tcmg trd
Hinh 6. Su thay doi dien trd mdng RPM vd dien dung mdng CPM trong dung dich (C4Hq)^NBr 0,1M (a); trong dung dich NaCl 0,1 M (b)
Gia tri RPM, CPM trong ca hai trUdng hpp deu thay doi theo dien the va kha tUdng dong. Dieu nay chd'ng to, sU khii ciia mang, su di chuyen vao ra cua cac anion trong mang PPy it phu thuoc vao cation trong dung dich. Dien dung CPM chi sai khac it trong hai dung dich 110 nF va 60 nF. So sanh vdi anion molybdate, Ti^" Unh dpng hdn, it phu thuoc vao loai cation trong dung dich do [2, 5].
3. Ket luan
Mang polypyrrole da dupc long hpp thanh cong bang phUdng phap dien hda trong dung dich H2TiF(,. Mang the hien tinh oxi hda khii rd ret trong ca hai loai dung dich cation Idn va cation nho. Dien trd va dien dung ciia mang biin thien phii hpp quy luat thudng gap. Su di chuyen vao ra mang ciia cac anion pha tap trong mang co the nhan thay qua sU thay doi gia tri ciia dien dung va dien trd mang PPy.
IJii cdm an. Nghien cUu nay dUpc tai trd bdi Quy phat trien Khoa hpc va Cong nghe Qudc gia (NAFOSTED) trong de tai ma s6 104,02-2013.69.
Tdng hpp vd linh chdt oxi hda - khd cua mdng polypyrrole diipc pha tap hdi anion...
TAI LIEU THAM KHAO
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ABSTRACT
Synthesis and redox properties of polypyrrole film duped with hexafluorotitanat TiF^,"
A film made from polypyrrole (PPy) has received a geal deal of attention in the recent years due to its high conductivity, stability and case of synthesization.
Many dopants have been used to improve the properties of PPy film, including hexafluorotitanate Ti^" anion. During redox process the resistance and capacitance of the film will be changed due lo the incorporation/releasing of anions and cations to/from the film. In this paper, a redox process of the PPy film was .studied in a cation solution containing 0.1 M (C^H-^jNEr and 0.1 M NaCI using cyclic voltammctry and Electrochemical Inpedancc Spectroscopy. The results showed that anion Tij^ could be released from the polymer film during the reduction. The capacitance and resistance of the PPy film changed a little during reduction. The redox properly of the film was not greatly cfliscled by cations in the solution.
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