TAP CHI HOA HOC
DOL I0.I5625/0866-7I44.20I5-00173
53(4) 520-525 T H A N G 8 N A M 2 0 1 5
NGHIEN CLTU BI^N T I N H B ^ MAT 6 N G CACBON NANO
B A N G P H A N U'NG ESTE HOA FISCHER Chu Anh Van', Le Hong Hai^ Ho Thi O a n h \ Do Quang Khang^''Truong Dgi hgc Suphgm Hd Ngi 2
^ Vien Nghiin cdu Polyme Dresden CHLB Due
^Viin Hoa hgc, Viin Hdn ldm Khoa hgc vd Cong ngh$ Vi$t Nam Din Tda sogn 22^-2015; Chip nhgn dang 26-8-2015
Abstract
In this work, carbonnanotubes (CNT) was firstly purified to remove residual metal catalyst in the preparation process. Afterward, H2O2/NH3 mixture was used as the oxidizing agent for CNT treatment in order to form functional groups COOH and NH2 on CNT surface. Polyethyleneglycol and bis(3-friethoxysilylpropyl) tetrasulfide (TESPT) were then grafted onto tbe oxidized surface of CNT under appropriate conditions of Fischer esterification reaction. The structure of CNT and modified CNT were characterized by infrared specfroscopy, Raman, transmission elecfron microscopy (TEM) and weight thermal analysis (TGA). The results have proven that organic functional groups (-COOH and -NH2) were successfully attached onto the surface of CNT and the content ofthe organic functional group is about 27.85 %. By the CNT modified with PEG and TESPT tiie content of-CO-PEG and -CO-TESPT are about 24.66 % and 3.28 %, respectively.
Keywords. Carbonnanotube, surface modification, TESPT.
I. MO DAU
Do nhiing dgc diem ve cau tnic bf mgt dng cacbon nano (CNT), nen vifc phan tan cung nhu tuong tac vdi nen polyme ndi cbung va cao su noi rifng rat hgn che. Dac bift la do dnh hudng cua hifu ling kich thudc va hifu iing be mat xay ra vdi cdc vgt lifu nano nfn CNT rit de xay ra hien tugng kit ty. Sy ket ty nay dugc hd frg thfm bdi lien kit Van der Walls khiln cho CNT cang khd khdn phan tan frfn nen hiiu co, Idra suy yeu tfnh chat co hgc ciia vat lifu polyme/CNT nanocompozit. CQng chfnh hifn tugng nay lam cho khd nang bam dinh cua CNT vdi nfn polyme khdng dugc tdt, vd dudi nhiing tac dgng nhdt djnh se df ddng keo CNT ra khdi bl mat polyrae nen [I]. Chinh vi vdy, dl giiip cho qua trinh phan tdn CNT vao nfn polyme cung nhu tuong tac ciia chiing vdi vdt lifu nen dugc tdt, ngudi ta thudng phdi bifn tinh be mat bang cdch gan nhimg nhdm cd kha nang tuang \\Qp hodc lien kit tdt vdi vat lifu nln polyme tuong iing. Trong cdng frinh nay, diu tien bl mdt CNT dugc oxi hda dk gin nhom COOH va NH2, tiep theo dd ghep polyetylenglycol (PEG) hoge bis(3-trietoxysilylpropyl) teti^sulphit (TESPT) theo phdn img este hda Fischer. Kit qua chiic hda bl mat
CNT dugc xac djnh bdng cac phuang phap pho hong ngoai (IR), phd Raman, kinh hien vi difn tir truyen qua (TEM) va phuang phap phan tich nhift trgng lugng (TGA).
2. VAT LI$U VA PHU'ONG P H A P NGHIEN ClTU 2.1. Vgt lifu nghien ciiru
Ong cacbon nanotube (CHI) cua hdng Nanocyl S.A. (Bi); cac hda chat va dung moi gom: thionyl cloma (SOCI2), dimetylforaamid (DMF), tetrahydro fiiran (THF), H2O2, NH3, polyetylen glycol (PEG) (cd khdi lugng phdn tii khoang 6000 g/mol), bis(3- frietoxysilylpropyt) tefrasulphit (TESPT) diu cua Trung Quoc.
2.2. Bien tinh be mat CNT bdng phan ung este hda Fischer
CNT dugc logi bd kim logi con du trcng qua tiinh tdng hgp ldng dgng hoi hda hgc (CVD) bdng each ngam vdi HCI va khuay frong 2 gid d 50 "C dudi dilu kifn tiiudng, nia nhilu lan bing nude cdt cho tdi khi pH = 7, lara khd trong 12 gid, san phim
TCHH, 53(4), 2015
k^ hifu p-CNT. Hda tan 0,3 g p-CNT trong 25 ml hdn hgp NH4OH va H2O2 (ti If 1:1). Khuiy hdn hgp frong 5 gid 6 80 °C dudi ap suit tiiudng [2]. Hdn hgp san phim dugc lgc bdng mdng lgc PTFE (kich thudc mao quan 0,2 pm), nia bdng nude cat vl mdi tmdng frung tfnh va lam sgch bdng axeton nhieu lan.
San phdm bifn tfnh ki hifu CNT-Oxy hda dugc say 80 "C frong 48 gid.
- Ghep nhom -COCl lin CNT
Cdn 0,5 gam CNT-Oxy hda cho vao binh cdu 100ml cd sdn 20 ml SOCI2 vd 10 ml DMF, tiln hdnh khuiy frgn dudi ap suit thudng frong 24 gid d 70 °C, sau khi kft thuc phan iing dugc hdn hgp man ndu den CNT-COCI, rira sgch bdng THF va lam khd d nhift dg phdng.
- Tong hgp CNT-CO-TESPT
5 ml TESPT dugc thiiy phan trong 20 ml cdn 96", 10 ml nude cat va 5 ml NaOH 10 % d 50 °C frong 2 gid, tifn hdnh cit quay logi bd dung mdi, sau ct6 chdt rdn mdu vang TESPT-OH dugc ldm khd d 50 °C frong 4 gid [3]. Cdn 0,lg CNT-COCI va lg TESPT-OH rdi cho vdo binh ciu 100 ml cd sdn 30 ml C2H3OH khan, tien hanh khuiy frgn frong 5 gid d 60 °C, hdn hgp san phim dugc run^ sieu dm 60 phiit d 60 °C, tic dg 6000 vdng/phut nhdm nang cao hifu suit, sau dd lgc qua mang lgc PTFE, nia sgch nhilu lan bing nude ndng dl loai bd silan cdn du, lam khd va riia tiep bdng axeton. Sdn phdm thu dugc dem siy chan khong d 60 °C trong 5 gid [4].
- Tdng hgp CNT-CO-PEG
Can 1 gam PEG, dun ndng chdy d 90 °C, cho vao binh ciu chiia sdn 0,1 gam CNT-COCI, khuiy frfn 10 phiit rdi thera tilp 40 rai hdn hgp benzen/THF (ti If the tich 3:1), tien hanh phan iing d 80 °C trong 40 gid. Ket thie phaii img, hdn hgp sdn pham dugc rung sieu dm 30 phiit d 60 "C, toe dg 3000 vong/phut, sau dd lgc qua mang lgc PTFE, hdn hgp rin mau den dugc nia sgch bdng axeton va ete
Do Quang Khdng vd cgng su diu hda 3 lin, lam khd d 90 °C frong 12 gid [4].
2 J . Cac phuong phdp phSn tich, danh gid Kit qua chiic hda bl mgt CNT dugc xac djnh bang cdc phuang phap phdn tfch nhu pho hong ngogi (IR) dudi dgng ep vien vdi KBr tren may FTS-6000 (ciia hdng Biorad, My), phd Raman vdi may HR LabRAM 800 (ciia hdng Horiba, Jobm Yvon), kinh hien vi difn hi truyin qua (TEM) fren may Jeol 1010 (cua hang Jeol, Nhgt Bdn), phuang phap phan tfch nhift frgng lugng fren may Setaram (Phdp), toe dg ndng nhift Id lO^C/phiit frong mdi frudng khdng khi frong khoang nhift dg nghifn ciiu hi 25 din 800 "C.
3. KET QUA VA T H A O LUAN
3.1. Oxi hda be m^t CNT
3 1.1. Pho hdng ngogi vdphS Raman ciia vgt li^u Kit qua phan tich phd h6ng ngogi ciia mdu CNT (hinh la) cho thiy cd sy xuit hifn pic 1659 cm' d§c trung cho dao dgng biln dgng ciia 60c va pic 2974 cm'' cd cudn^ dg mgnh dgc trung cho dao dgng hda frj ciia lien kft Vc<:, dieu nay hoan toan phii hgp vdi ciu true dgng graphit ciia CNT. Trfn pho IR ciia CNT-COOH (hinh lb) xudt hifn pic cd cudng dg mgnh d 3316 cm"' dgc trung cho dao dgng nhdm OH (tham gia Hen kit hydro nfi phdn tur -CO-O-H...NH2-) va hai pic khac d 1192 cm"' va 1684 cm"' ddc trung cho dao dgng cua lien kit C-O vd C^O cua nhdm cacboxyl (cdc pic nay khdng thiy xudt hifn frfn phd IR ciia CNT). Trfn phi IR cua CNT-Oxy hda ciing thu dugc tfn hifu cua pic hdp thy cd cudng df mgnh d 3668 cm'' d|c tnmg cho dao dgng hda frj ddi xiing ciia lifn kit N-H va pic 1492 cm"' dgc trung cho dao dOng hda frj ciia lien kit C-N. Tir nhung du kifn tren day cd the khdng djnh bl m§t (UNT bj oxi hda va dugc dfnh nhdm 2 nhdm chirc COOH vd NH2.
JWy^V^U
3000 2500 2000 -1SM 1000 N M xm sow
Hinh 1: Pho IR.cua va CNT (a) vd CNT-Oxy hda (b)
TCHH, 53(4), 2015
D 4 lam ro them nhan dpib tF»i, phd tan xg Raman tai budc sdng 632,81 nm ciia cac vat lifu tren tilp tyc dugc chyp (hinh 2). Nhgn thiy rdng, tren phd dd cua CNT cd hai vimg phd dac trung cho trang thai hon logn (dinh D) d 1323 cm"' va vung trgt ty (dmh G) d 1587 cm". Dinh G smh ra tu mgng graphit cua C^NT ddc trung cho tinh trgt ty ciia ciu trtc gdm cdc nguyen tii cacbon sap xep dgng vdng 6 cgnh. Trong khi dd dmh D lgi dac tnmg cho cac khuylt tdt frong cau true cua CNT, su xudt hifn cua
Nghien Cliu bien tinh be dng...
dmh D la do dao dgng ciia cac nguyen tu - d traiig thai sp^. Sau phan iing oxi hda, dinh D ^a G cua CNT-COOH djch chuyen tuong iing voi 1325 va 1595 cm'. Muc d$ tiat tu cua ciu true graphit cd tbe dugc xac djnh thong qua ty so gi&a hai dinh D, G tue gja tri M b - Gia trj nay tang tfr 1,70 ( ^ i vdi CNT) ien 1,79 (doi vdi CNT-Oxy hda). Dieu ndy dugc giai thfch la do qua frinh oxy hda dd lam phi vd cau triic mgng graphit, chuyen tir C lai hda sp sang Csp^ bxmg nhdm COOH.
Ranan (cm )
Hinh 2: Pho Raman cua CNT va CNT-Oxy hda
3.1.2. Dgc tinh phdn tdn trgng nu&c vd cdu trdc hinh thdi cua vgt Iigu
- Dgc tinh phdn tdn trong nuac cua vgt li^u Sy khac bift ciia CNT va CNT-Oig' hda cdn dugc danh gid mgt each trye quan thong qua dgc tmh phdn tan ciia chung frong nude (hlnh 3). Nhgn thiy rang, sy phan tan cua CNT va CNT-0}Q' hda trong nuoc sau khi nmg sieu dm I gid khac hdn nhau. Difu dd cd thf giai thich, do sy xuit hifn cac nhdm cbiic COOH va NH2 tren bl mat CNT cd khd
Hmh 3: Su phan tan cua CNT (a) va CNT-Oxy hda (b) trong nude sau khi rung sieu am 1 gid nang tao lien ket hydro lien phdn tu vdi H2O, nen CNT cd kha nang phan tan diu trong nude (3b).
Trong khi do, CNT chua biln tmh hoan toan khong tan frong nude (3a). Ket qua nay ciing tuong ty ket qua cua tac gja da cdng bo ciia tac gia Zhiyuan Zhao va cgng sy [5].
- Cdu trdc hinh thdi cOa vgt li^u
c i u fruc hinh thai ciia CNT va CNT-Oxy hda dugc xac djnh bdng phuong phap hien vi dien tiir truyin qua (TEM). Tren hmh 4 la anh chyp TEM cua cac mdu vgt lifu.
Hmh 4: Anh TEM cua CNT (a) va CNT-Oxy hoa (b)
TCHH, 53(4), 2015
Tfr hinh 4 cho thiy, so vdi CNT, ciu tnic bl m$t CNT-Oxy hda da thay ddi khd nhilu. Cdu true ciia CNT tnrdc oxi hda kha co cym, xuit hifn thdnh biii chdng chit len nhau (hinh 4a). Sau khi oxi hda, ciu triic kha ding diu ft thiy hifn tugng tfch ty thdnh cac bd (hinh 4b). Dgc biet qud frinh oxi hda da gdn nhdm chirc COOH va NH2 lam gia tang dang ke dudng kinh dng tdng len den 16,0 din 17,7 nra (tmdc khi oxi hoa chi cd 10,7 din 12,4 nm).
Do Quang Khdng vd cgng su 3.1.3. Tinh chdt nhiit ciia vdt liiu vd hdm Itegng cdc nhom gdn Iin bi mat CNT
D I danh gid tinh chit nhift cung nhu lugng cdc nhdm chuc h&u ca dugc gdn frfn be mgt CNT, phuang phap phan tich nhift frgng lugng (TGA) dd dugc Sli dyng. Kit qua phan tich thu dugc, dugc till hifn frong bdng 1.
Bdng 1: Kit qud phan tich TGA cua CNT trudc vd sau khi oxi hda Mlu v?t li?u
CNT CNT - Oxy hoa
Nhi^t do bat dau phan huy (°C)
500 460
Nhi^t do phan huy manh nhat 1 ("C)
577 535
Nhi?t do phan huy manh nhat 2 (°C)
-
615
Tdn hao khoi luting din 750 °C (%)
53,67 81,52 Ttr bang 1 nhdn thiy rdng, frong khodng nhift dg
phdng tdi 500 "C (doi vdi mdu CNT) tdi 460 "C (doi vdi mdu CNT-Oxy hda, qua trinh tdn hao khoi lugng do vifc boc hoi nude vd phan hiiy ciia cdc thanh phin carbon vd djnh hinh cdn ldn frong cac mdu la khong dang kl. Den 500 °C, CNT bit ddu phdn huy vd phdn hiiy mgnh nhit d 577 °C. Qud frinh phdn hiiy keo ddi din khodng 750 "C thi khoi lugng mau hau nhu khdng ddl, liic nay khoi lugng mdu rait di 53,67 % do CNT bj phan hiiy. Trong khi dd, d mdu CNT-Oxy hoa, din 460 °C dd bit ddu phdn huy vd phdn buy manh nhat d 535 °C. Trong khodng nhift dg nay cd thf la xdy ra qua trinh phan huy ciia cac nhdm hihi co
kit h(;^ vdi vifc bat diu phan hi^ ciia CNT, qua nhift dg do, toe dg phan buy giam m^t chiit va din khodng 615 °C lgi tilp tyc mit khii lugng manh (cd thi do qud trinh phdn buy ciia CNT) vd cho din 750 "C khdi lugng raau khdng ddi vd liic nay da bj mat di 81,52
%. Cung tu nhiing kit qua frfn cho thdy ring, ham lugng nhdra COOH vd NH2 dugc gdn Ifn bl raat CNT chiera khodng 27,85 % khoi lugng vat lifu.
3.2. Bien tinh be mat CNT vdi TESPT va PEG So dd chfrc hda bl m&t CNT dugc md td tren hinh 5.
/(CH2)3Si(OC2H,)3 C.H.OH NaOH I0%/50X,
"(CH2)3Si(OC2H5)3
Hinh 5: Sa dd biln tinh bl m§t CNT bdng phdn ung este hda Fischer 3.2.1. Xdc dfnh cdu triic cua vgt li?u
c i u true cua vgt tifu tong hgp dugc, dugc xdc djnh bdng phuang phdp quang pho hong ngogi. Trfn hinh 6 la phd IR ciia CNT-CO-TESPT va CNT-CO- PEG.
Nhgn thay rdng, fren pho IR ciia CNT-CO- TESPT (hmh 6a) xuit hifn pic 876 cm"' vd 1030 cm"' dgc trung cho dao dgng hda trj vd bien dgng cua lifn kft Si-O. Ngoai ra vin xuat hifn cac pic ddc hung cua nhdm C=0 este tiiom d 1715-1750 cm"', pic 1406 cm"' dac trung cho lien kit N-H frong nhdm
TCHH, 53(4), 2015 Nghien cmt biin tinh be '• • ong...
NH2, pic 3410 cm'' d§c tnmg nhom OH a cuoi mach cuong d? m^nh la tin hieu cua nhom C=0 sste. rho (CNT-COO)3Si(CH2)3S4(CHj)3Si(OH)3. Tren ph6 d6 IR cua CNT-CO-PEG cung xuit hien pic 1038 cm cua CNT-CO-PEQ Qnnh 6b) co pic 3254 c m ' dac dmrc gan cho nhom C-O trong PEG, hai pK 2835 trung cho dao dong cila nhom OH a cuoi m?ch cm'' va 3019 cm"' dac tnm^ cho dao dpng doi xung CNT-COO-{CH2-CH2).-OH, pic 3524 cm' va 1558 va phan dSi xihig cua lien ket C-H trong PEG.
cm'' biSu thi tm hieu cua nhom N-H, pic 1715 cm'
J JlKwACtfiM
Hinh 6: Ph6 IR cua CNT-CO-TESPT (a) va CNT-CO-PEG (b) 3.2.2. Ham luong nh6m CO-PEG va nhom
CO-TESPT ghep len CNT
ghep len be mat CNT cung duoc xac dinh bang phuang phap phan tich nhiet trpng lugng (TGA). Ket qua phan tich thu dugc, dugc the hi8n tren bang 2.
Ham lupng nhom CO-PEG va nhom CO-TESPT
Bang 2: KSt qua phan tfch TGA cua CNT-CO-PEG va CNT- CO-TESPT Mau vat lieu
CNT CNT-CO-PEG CNT- CO-TESPT
Nhiet do bM diu phan huy (°C)
500 400 400
Nhiet do phan hiiy manh nhat 1 ("C)
577 443 441
Nhiet do phan buy manh nhat 2 (°C)
-
607 687
Ton hao kh6i lupng den 750 °C (%)
53,67 78,52 56,96 Sy phan bdy nhift cua CNT-CO-PEG bit diu
khoang 400 °C vd dgt cyc dgi tgi 443 °C keo dai cho din 607 "C, sau dd tde dg gidm ddn cho tdi khi dgt
" din 750 °C kbdng cdn tdn hao khdi lugng, luc nay miic dg ton hao khdi lugng khoang 78,52 %, cd thi tinh todn so bg ham lugng nhdm chiic CO-PEG dugc gin len bl mat CNT tuong iing khodng 24,85
%. Tir kit qua phdn tich nhift frgng lugng cua miu C : N T - C 0 - T E S P T cho tiiiy, vgt lifu nay bdt dau bi phan hiiy d khoang 395 "C vd xay ra mgnh tgi 441
°C keo dai cho den 687 "C. Nhift dg bat diu phdn buy thip ciing nhu cyc dai phdn buy ddu tien thip Id cua cac nhdm hfru co gdn tren bl mat CNT cung nhu nhung thanh phin ciu tnic kem chat che ciia CNT bit dau phdn hiiy. Sy phdn hiiy tuong iing cua nhdm amin va tach logi nguyen tir luu huynh theo phan ling:
(CNT-COO)3Si(CH2)3S4(CH2)3Si(OH)j '°^ >
(CNT-COO)3Si(CH2)3SH [6]
Tiep theo do la qua trinh phan buy cua CNT cung nhung thanh phan ben nhift cua nd. Qua frinh keo dai cho din khodng 750 °C thi khdi lugng khdng thay ddi nita, tai nhift dg nay ton hao khdi lugng cua toan radu la 56,96 %, nhu vay cd the tfnh toan so bg hara lugng nhdm CO-TESPT ghep len bl mat CNT khodng 3,29 %.
4. KET LUAN
- Vdi phdn irng oxi hda bdng H2O2/NH3 trong 5 gid d 80 "C da gdn dugc khoang 27,85 % cdc nhdra COOH yd NH2 ten be raat CNT.
- Bdng phan irng este hda Fischer da ghep dugc TESPT hoge PEG len be mat CNT da oxi hda vdi ham lugng tuong ung khodng 24,85 % va 3,29 %.
- CNT dugc gin cdc nhdm hOxi co fren cd thi df dang phan tan frong nln mgt so polyme ndi chung va cao su ndi rieng d l che tao ra cac loai cao su-
TCHH, 53(4), 2015 CNT nanocompozit.
Ldi cam on. Nghien ciru ndy dirge tdi trg b&i Qi^
Phdt triin khoa hgc vd cong nghi Qudc gia (Nafosted) di tdi md s6104.02-2014.90.
TAI LIEU THAM K H A O
1. Cuba S. Ahmeda, Adawiya J. Haiderb, M. R.
Mohammad. Comparison of Functionalization of multi walled carbon nanotubes treated by oil olrve and nitric acid and their characterization, Energy Procedia, 36,1111-1118(2013).
2. Yun Peng and Hewen Liu. Effects of Oxidation by Hydrogen Per oxy de on the Structures of Multiwalled Carbon Nanotubes, Ind. Eng. Chem. Res., 45(19), 643-648 (2006).
Do Quang Khdng vd cgng su F. Avilds, J. V. Cauich-Rodrfguez, J. A. Rodriguez- Gonzalez, A. May-Pat. Oxidation and silanizalion of MWCNTs for MWCNT/vinylester composites.
Express Polymer Letters, 5(9), 766-776 (2011), Salam, M. Abdel. Chemical Modification and Characterization of Multi-Walled Carbon Nanotubes Using Octadecylamine and Polyethylene Glycol, Joumal of Environmental Science & Engineering 5(5), 557 (2011).
Zhiyuan Zhao, Zbanhong Yang, Youwang Hue, Jianping Li, Xinming Fan. Multiple functionalization of multi-walled carbon nanotubes with carboxyl and amino groups. Applied Surface Science, 276, 476-481(2013).
Tommy Seppa The effect of different nanofillers on properties and mixing of ethylene propylene diene rubber. Master of Science Thesis (2010).
Lien hi: DS Quang Khang Vifn Hda hgc
Vifn Han Idm Khoa hgc va Cdng nghf Vift Nam So 18, Hoang Quoc Vift, Ciu Giiy HaNgi
E-mail: [email protected]; Difn tiiogi; 0437569010/ 09I3345I82.
